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MetaFun - Pragma ADE

1. 1 0x10 Figure 9 2 An example of a graphic with labels along the axes Drawing functions function 2 5log x x 1 10 1 xyscaled 10cm 2cm withpen pencircle scaled 5mm withcolor transparent 1 5 blue The first argument to the function macro specifies the drawing method The last three arguments are the start value end value and step The second and third argument specify the function to be drawn In this case the pairs x x and 5log x x are calculated textextoffset ExHeight drawoptions withpen pencircle scaled 50pt draw hlingrid 10 10 1 10cm 10cm draw vlingrid 0 20 1 10cm 20cm shifted 0 10cm drawoptions draw function 2 x sind x 0 360 10 xyscaled 1cm 36 10cm withpen pencircle scaled 5mm withcolor transparent 1 5 blue draw function 2 x sin x pi 0 epsed 2 1 xyscaled 10cm 2 5cm withpen pencircle scaled 5mm withcolor transparent 1 5 yellow draw function 2 x cosd x 0 360 10 xyscaled 1cm 36 10cm withpen pencircle scaled 5mm withcolor transparent 1 5 red draw function 2 x cos x pi 0 epsed 2 1 xyscaled 10cm 2 5cm withpen pencircle scaled 5mm withcolor transparent 1 5 green In this example we draw sinus and cosine functions using degrees and radians In the case of radians t
2. framed offset none TeX tt offset none framed offset overlay TeX tt offset overlay framed offset Opt TeX tt offset Opt framed offset 1pt TeX tt offset 1pt framed offset 2pt TeX tt offset 2pt framed offset 4pt TeX tt offset 4pt framed offset 3pt TeX tt offset 3pt framed frameoffset 3pt TeX tt frameoffset 3pt framed backgroundoffset 3pt TeX tt backgroundoffset 3pt stopcombination x x offset none offset overlay offset Opt offset 1pt offset 2pt offset 4pt offset 3pt frameoffset 3pt backgroundoffset 3pt Figure 4 1 The three offsets As the first row in figure 4 1 demonstrates instead of a value one can pass a keyword The overlay keyword implies that there is no offset at all and that the lines cover the content With none the frame is drawn tight around the content When the offset is set to Opt or more the text is automat ically set to at least the height of a line You can turn this feature of by saying strut off More details can be found in the CONTEXT manual In figure 4 2 we have set offset to 3pt frameoffset to 6pt and backgroundoffset to 9pt Both the frame and background offset are sort of imaginary since they don t contribute to the size of the box ruledhbox framed Enhancing the layoul Overlays offset 3pt fram
3. startMPpage 4 Your mp code goes here You can use the textext 4 macro as discussed later to deal with typeset text stopMPpage When you process that file with the context command you will get a PDF file that you can include in any application that can embed a PDF image In this case your exposure to CONTEXT is minimal 3 5 Graphic buffers In addition to the macros defined in the previous section you can use CONTEXT s buffers to handle graphics This can be handy when making documentation so it makes sense to spend a few words on them A buffer is a container for content that is to be re used later on The main reason for their existence is that they were needed for typesetting manuals and articles on TX By putting the code snippets in buffers we don t have to key in the code twice since we can either show the code of buffers verbatim or process the code as part of the text flow This means that the risk of mismatch between the code shown and the typeset text is minimized startbuffer You are reading the METAFUN manual stopbuffer This buffer can be typeset verbatim using typebuffer and processed using getbuffer as we will do now An other advantage of using buffers is that they help you keeping the document source clean In many places in this manual we put table or figure definitions in a buffer and pass the buffer to another command like Mplacefigure A very big table
4. AAW linejoin mitered linejoin mitered linejoin mitered linecap butt linecap rounded linecap squared linejoin rounded linejoin rounded linejoin rounded linecap butt linecap rounded linecap squared linejoin beveled linejoin beveled linejoin beveled linecap butt linecap rounded linecap squared Figure 1 1 The nine ways to end and join lines By setting the variable miterlimit you can influence the mitering of joints The next example demonstrates that the value of this variable acts as a trigger interim linejoin mitered for i 1 step 1 until 5 interim miterlimit i pt draw 0 0 5 1 1 0 shifted 1 5i 0 scaled 50pt withpen pencircle scaled 10pt withcolor 625red endfor The variables 1 linecap and miterlimit are so called internal variables When we prefix their assignments by interim the setting will be local within groups like beginfig endfig Joining lines 1 13 Colors So far we have seen some colors in graphics It must be said that mETRPOST color model is not that advanced although playing with colors in the metarost way can be fun In later chapters we will discuss some extensions that provide shading Colors are defined as vectors with three components a red green and blue one Like pens colors have their with command withcolor 4 5 6 You can define color variables like color da
5. Enhancing the layout Graphics and macros This works as expected RotatedText 165 Some Rotated Text 1X O S It is now a small step towards an encapsulating macro we assume that you are familiar with TEx macro definitions def RotatedText 1 2 setupMPvariables RotatedText 1 7 setMPtext RotatedText 2 useMPgraphic RotatedText setupMPvariables RotatedText rotation 90 startuseMPgraphic RotatedText draw MPbetex RotatedText rotated MPvar rotation stopuseMPgraphic Again we default to a 90 degrees rotation and pass both the settings and text in an indirect way This method permits you to build complicated graphics and still keep macros readable RotatedText rotation 240 Some Rotated Text S f You may wonder why we don t use the variable mechanism to pass the text The main reason is that the text mechanism offers a few more features one of which is that it passes the text straight on without the danger of unwanted expansion of embedded macros Using setMPtext also permits you to separate and code and reuse it multiple times imagine using the same graphic in a section head command There are three ways to access a text defined with setMPtext Imagine that we have the following definitions setMPtext 1 Now is this TeX or not setMPtext 2 See what happens here setMPtext 3 Text stream
6. vardef randomscaledpath expr p begingroup save r numeric r r round 1 uniformdeviate 4 p xscaled s r yscaled s r endgroup enddef In this particular case we could have omitted the grouping since vardef macros are always grouped automatically Therefore we could have defined the macro as vardef randomscaledpath expr p s save r numeric r r round 1 uniformdeviate 4 p xscaled s r yscaled s r enddef The command save r declares that the variable r is local to the macro Thus any changes to the new numeric variable r are local and will not interfere with a variable r defined outside the macro This is important to understand as variables outside the macro are global and accessible to the code within the body of the macro Macro definitions may be nested but since most METRPOST code is relatively simple it is seldom needed Nesting is discouraged as it makes your code less readable Besides def and vardef also provides the classifiers primarydef secondarydef and tertiarydef You can use these classifiers to define macros like those provided by metarost itself primarydef x mod y enddef secondarydef p intersectionpoint q enddef tertiarydef p softjoin enddef A primary macro acts like the binary operators or scaled and shifted Secondary macros are like and logical or and take less precedence The tertiary operat
7. Linear equations Because we want to call this macro more than once we first have to save the locally used values Instead of declaring local variables one can hide their use from the outside world In most cases variables behave globally If we don t save them subsequent calls will lead to errors due to con flicting equations We can omit the grouping commands because we wrap the graphic in a figure and figures are grouped already We will use the predefined z variable or actually a macro that returns a variable This variable has two components an x and y coordinate So we don t save z but the related variables x and y Next we draw four squares and instead of hard coding their corner points we use METRPOST s equation solver Watch the use of which means that we just state dependencies In languages like PERL the equal sign is used in assignments but in MeTAPOST it is used to express relations In a first version we will just name a lot of simple relations as we can read them from a sketch drawn on paper So we end up with quite some z related expressions For those interested in the mathematics behind this code we add a short explanation Absolutely key to the construction is the fact that you traverse the original quadrilateral in a clockwise ori entation What is really going on here is vector geometry You calculate the vector from 211 to 212 the first side of the original quadrilateral with
8. Debugging Libraries Of course you may want to take a look at the MeTAPOsT manual for its built in more verbose tracing options One command that may prove to be useful is show that you can apply to any variable This command reports the current value if known to the terminal and log file The previous picture shows what is typeset when we also say showmakeup This command visu alizes TEX s boxes skips kerns and penalties As you can see there are some boxes involved which is due to the conversion of METAPOST output to PDF Nstartlinecorrection blank the graphic stoplinecorrection The small bar is a kern and the small rectangles are penalties More details on this debugger can be found in the CONTEXT manuals and the documentation of the modules involved Libraries Libraries 12 Defining styles Since the integration of METAPOST into CONTEXT a complete new range of layout fetaures became available In this document we have introduced several ways to include graphics in your document definition In this chapter we go one step further and make dynamic graphics part of a document style 12 1 Adaptive buttons So far we have seen a lot of graphic ingredients that you can use to make your documents more attractive In this chapter we will define a simple document style This style was written for the PDFTEX presentat
9. p fullcircle scaled 2 length loc ori shifted ori freesquare xyscaled urcorner s llcorner s l point xpart p intersectiontimes ori loc of draw q shifted loc withpen pencircle scaled 5pt draw 1 shifted loc withcolor 625yellow draw loc withcolor 625red S enddef The macro xyscaled is part of METAFUN and scales in two directions at once The METRPOST primi tive intersectiontimes returns a pair of time values of the point where two paths intersect The first part of the pair concerns the first path We are now a small step from the exact placement If we change the last line of the macro into s shifted 1 we get the displacement we want Although the final look and feel is also determined by the text itself the average result is quite acceptable Because we also want to pass pictures and add a bit of offset too the final implementation is slightly more complicated The picture is handled with an additional condition and the offset with the METAFUN macro enlarged newinternal freelabeloffset freelabeloffset 3pt vardef thefreelabel expr str loc ori save S p q l picture s path p q pair 1 interim labeloffset freelabeloffset S 7 if string str thelabel str loc else str shifted center str shifted loc fi setbounds s to boundingbox s enlarged freelabeloffset E Free labels
10. etex the code in textext command is expanded but as long as CONTEXT is used this is seldom a problem because most commands are somewhat protected If we define a graphic with text to be typeset by there is a good chance that this text is not frozen but passes as argument A solution for passing arbitrary content to such a graphic is the following def RotatedText 1 2 startuseMPgraphic RotatedText draw btex 2 etex rotated 1 stopuseMPgraphic useMPgraphic RotatedText This macro takes two arguments the identifies an argument RotatedText 15 Some Rotated Text The text is rotated over 15 degrees about the origin in a counterclockwise direction In CONTEXT we seldom pass settings like the angle of rotation in this manner You can use setupMPvariables to set up graphic specific variables Such a variable can be accessed with MPvar setupMPvariables RotatedText rotation 90 startuseMPgraphic RotatedText draw btex Some Text etex rotated MPvarf rotation stopuseMPgraphic An example RotatedText 15 Some Rotated Text Som Rota teq Text In a similar fashion we can isolate the text This permits us to use the same graphics with different settings setupMPvariables RotatedText rotation 270 setMPtext RotatedText Some Text startuseMPgraphic RotatedText draw MPbetex RotatedText rotated MPvar rotation stopuseMPgraphic
11. enddef stopuseMPgraphic The calculation of the button itself comes down to combining segments of the main shape and auxiliary lines The rightpath macro returns the right half of the path provided This half is shown as a non dashed line Topics are identified with Topic which is an instance of chapter headings The number is made invisible Since it still is a numbered section header CONTEXT will write the header to the table of contents definehead Topic chapter setuphead Topic number no We will use a bold font in the table of contents We also force a complete list setuplist Topic criterium all style bold before after The TitlePage macro looks horrible because we want to keep the interface simple a list of small sentences separated by def TitlePage 1 startstandardmakeup switchtobodyfont big def vfill bfb let par bfd setupinterlinespace gray vskip 5cm 1 vskip 5cm NN is really needed stopstandardmakeup A presentation that uses this style may look like the one below You can choose among three alternatives useenvironment pre organic setupoutput pdftex setupMPvariables page alternative 1 starttext TitlePage A Few Nice Quotes A Simple Style Demo Hans Hagen August 2000 Topic Douglas R Hofstadter input douglas page Topic Donald E Knuth input knuth page Adaptive buttons
12. fullcircle scaled 2 length loc ori shifted ori freesquare xyscaled urcorner s llcorner s l point xpart p intersectiontimes ori loc of setbounds s to boundingbox s enlarged freelabeloffset s shifted 1 enddef Watch how we temporarily enlarge the bounding box of the typeset label text We will now test this macro on a slightly rotated circle using labels typeset by The reverse is there purely for cosmetic reasons to suit the label texts funny macros defining we We can and on goon pickup pencircle scaled imm path p p reverse fullcircle rotated 25 scaled 3cm draw p withcolor 625yellow pair cp center p freedotlabel btex strut We can etex point O of p cp freedotlabel btex strut go on etex point 1 of p cp freedotlabel btex strut and on etex point 2 of p cp freedotlabel btex strut in etex point 3 of p cp freedotlabel btex strut defining etex point 4 of p cp freedotlabel btex strut funny etex point 5 of p cp freedotlabel btex strut macros etex point 6 of p cp freedotlabel btex strut Can t we etex point 7 of p cp Unfortunately we can run into problems due to rounding errors Therefore we use a less readable but more safe expression for calculating the intersection points Instead of using point loc as endpoint we use loc shifted over a very small distance into the direction loc from ori
13. Topic Edward Tufte input tufte page Topic Hermann Zapf input zapf page stoptext We will not implement the two other alternative shapes squeezed and randomized A Few Nice Quotes A Few Nice Quotes page 1 page 2 page 3 page 4 page 5 We combine all alternatives into one page graphic The alternative is chosen by setting the alternative variable as we demonstrated in the example startuseMPgraphic page includeMPgraphic rightsuperbutton StartPage numeric alternative seed superness squeezeness randomness path transform t This is one of those cases where a transform variable is useful We need to store the random seed value because we want the larger path that is used in the calculations to have the same shape alternative MPvarfalternative seed uniformdeviate 100 if alternative gt 10 85 realfolio 1 lastpage 25 superness squeezeness 12pt realfolio 1 lastpage 10pt else superness 90 squeezeness 12pt fi randomness squeezeness Adaptive buttons Detining styles alternative alternative mod 10 If you read closely you will notice that when we add 10 to the alternative we get a page dependant graphic So in fact we have five alternatives We use CONTEXT macros to fetch the real page number and the number of the last page In further calculations we use the lower
14. Consider the next definition pickup pencircle scaled O fill unitsquare xscaled 400pt yscaled 5cm withcolor 625red fill unitsquare xscaled 400bp yscaled 5cm withcolor 625yellow drawoptions withcolor white label rt 400 pt origin shifted 0 25cm label rt 400 bp origin shifted 0 25cm When processed the difference between a pt and bp shows rather well Watch how we use rt to move the label to the right you can compare this with TEX s macro rlap You might want to experiment with 1ft top bot ulft urt 11ft and 1rt The difference between both bars is exactly 1 5pt as calculated by TEX Where is anchored in tradition and therefore more or less uses the pt as the default unit Post much like POSTSCRIPT has its roots in the computer sciences There to simplify calculations an inch is divided in 72 big points and 72pt is sacrificed When you consider that POSTSCRIPT is a high end graphic programming language you may won der why this sacrifice was made Although the difference between 1bp and 1pt is miniscule this difference is the source of much unknown confusion When users talk about a 10pt font a desktop publisher hears 10bp In a similar vein when we define a papersize having a width of 600pt and a height of 450pt which is papersize 56 in CONTEXT a POSTSCRIPT or PDF viewer will report slightly smaller values as page dimensions This is because those p
15. Figure 3 1 The logo is defined in the file my logos mp as figure 21 and processed by means of the mprun method Optionally you can specify aname and an instance This has the advantage that the graphics don t interfere with the regular inline graphics Here the instance used is extrafun and the name where the run is stored is mydemo startMPrun mydemo input mfun mrun demo mp stopMPrun placefigure An external file can have multiple graphics Here we show a few images that we used to use on the PRAGMA CONTEXT website fNstartcombination 2 2 Integrated graphics externalfigure mprun extrafun externalfigure mprun extrafun externalfigure mprun extrafun externalfigure mprun extrafun stopcombination mydemo 1 height 6cm downloads mydemo 2 height 6cm links mydemo 3 height 6cm mirrors mydemo 4 height 6cm team Keep in mind that the whole file will be processed using the built in library in order to get one graphic Normally this is no big deal downloads mirrors team Figure 3 2 An external file can have multiple graphics Here we show few images that we used to use on the PRAGMA ADE CONTEXT website 3 4 Using METAFUN but not CONTEXT If you don t want to use CONTEXT but still want to use METAFUN a rather convenient method is the following Create a file that Using METAFUN but not CONTEXT
16. The second line does just as it says it draws a rectangle of certain dimensions in a certain color In the third line we draw a colored dot at the origin of the coordinate system in which we are drawing Finally we set up a smaller pen and draw the bounding box of the current picture using the variable currentpicture Normally all drawn shapes end up in this picture variable 2 2 Bounding boxes If you take a close look at the last picture in the previous section you will notice that the bounding box is larger than the picture This is one of the nasty side effects of mETRPOST s bbox macro This macro draws a box but with a certain offset The next example shows how we can manipulate this offset Remember that in order to process the next examples you should embed the code in beginfig and endfig macros Also in stand alone graphics don t forget to say Ninput mp tool first pickup pencircle scaled 5cm draw unitsquare xscaled 8cm yscaled withcolor 625white path bb bboxmargin Opt bb bbox currentpicture draw bb withpen pencircle scaled withcolor 625red draw origin withpen pencircle scaled 5pt withcolor 625yellow In the third line we define a path variable We assign the current bounding box to this variable but first we set the offset to zero The last line demonstrates how to draw such a path Instead of setting the pen as we did in the first line we pass the dimensions directly Where dra
17. atom numeric expression expression numeric primary primary numeric tertiary tertiary numeric variable variable internal variable pair expression expression pair primary primary path expression expression path subexpression subexpression pen expression expression picture expression expression picture variable variable rgbcolor expression expression string expression expression suffix parameter parameter transform primary primary program statement list end statement list empty statement list statement statement empty equation assignment declaration macro definition compound pseudo procedure command compound begingroup statement list endgroup beginfig numeric expression statement list endfig equation expression right hand side Syntax diagrams assignment variable right hand side internal variable right hand side right and side expression equation assignment declaration type declaration list declaration list generic variable declarationlist generic variable generic variable Symbolic token generic suffix generic suffix empty generic suffix tag generic
18. has no graphic capabilities built in a graphic is referred to as an external figure A METAPOST graphic often has a number as suffix so embedding such a graphic is done by externalfigure graphic 123 width 4cm Getting started Embedd An alternative method is to separate the definition from the inclusion An example of a definition is useexternalfigure pentastar star 803 height 4cm useexternalfigure octostar star 804 pentastar Here the second definition inherits the characteristics from the first one These graphics can be summoned like placefigure A five point star drawn by METAPOST externalfigure pentastar Here the stars are defined as stand alone graphics in a file called star mp Such a file can look like def star expr size n pos for a 0 step 360 n until round 360 1 1 n draw origin size 2 0 rotatedaround origin a shifted pos endfor enddef beginfig 803 pickup pencircle scaled 2mm star 2cm 5 origin endfig beginfig 804 pickup pencircle scaled 1mm star 1cm 8 origin pickup pencircle scaled 2mm star 2cm 7 3cm 0 endfig end This star macro will produce graphics like X X K KK But now that we have instant MeTaPost available in LUATEX there is no need for external images and we can collect them in libraries as we will see later on 3 3 Integrated graphics An inte
19. subexpression expression tertiary binop tertiary path subexpression direction specifier path subexpression path join cycle path knot tertiary path join direction specifier basic path join direction specifier direction specifier empty curl numeric expression pair expression numeric expression numeric expression basic path join tension tension controls tension tension numeric primary tension atleast numeric primary tension numeric primary and numeric primary controls controls pair primary controls pair primaryiandhpair primary argument symbolic token Syntax diagrams number or fraction number number number not followed by numberi scalar multiplication op number or fractioni not followed by add op number transformer rotated numeric primary Scaled numeric primary Shifted pair primary slanted numeric primary transformed transform primary xscaled numeric primary yscaled numeric primary zscaled pair primary xyscaled numeric or pair primary reflectedabout pairexpression pair expressioni rotatedaround pairexpression numeric expression xsized numeric primary ysized numeric primary xysized num
20. Arguments eWelcome MetaPost_ 114 min u enddef The special sequence is used to pick up a so called delimited argument vardef TryMe expr x 4 we can now use which is just text enddef This feature is used in the definition of z as used in z1 or z234 vardef 20 x y enddef Other applications can be found in the label drawing macros where the anchor point is assigned to the obscure variable Pens When drawing three attributes can be applied to it a dashpattern a pen and or a color You may consider an arrowhead an attribute but actually it is just an additional drawing appended to the path The predefined pencircle attribute looks like withpen pencircle where pencircle is a special kind of path stored in a pen variable Like any path you can trans form it You can scale it equally in all directions withpen pencircle scaled imm You can also provide unequal scales creating an elliptically shaped and rotated pen withpen pencircle xscaled 2mm yscaled 4mm rotated 30 In the following graphic the circle in the center is drawn without any option which means that the default pen is used being a pencircle with a radius of half a base point The other three circles are drawn with different pen specifications Welcome fo MetaPost Fens If you forget about the colors the meTaPosT code
21. a b 212 211 This gives a vector that points from 211 to 212 Now how about an image that shows that the vector b a is a 90 degree rotation in the counterclockwise direction Thus the points 213 and 214 are easily calculated with vector addition z13 z14 zi2 b a zii b a This pattern continues as you move around the original quadrilateral in a clockwise manner The code that calculates the pairs a through h can be written in a more compact way a b e f 212 211 c d z32 z31 g h 222 221 242 241 The centers of each square can also be calculated by metarost The next lines define that those points are positioned halfway the extremes 21 23 0 5 211 213 z2 0 5 231 233 z4 0 5 221 223 0 5 241 243 Once we have defined the relations we can let MeTAPOST solve the equations This is triggered when a variable is needed for instance when we draw the squares and their diagonals We connect the centers of the squares using a dashed line style Just to be complete we add a symbol that marks the right angle First we determine the common point of the two lines that lays at whatever point finds suitable The definition of mark rt angle is copied from the vETRPOST manual and shows how compact a definition can be see page 13 for an introduction to zscaled Thanks to David Arnold for this bonus explanation Linear equations
22. test shade origin origin shifted 25cm 0 50cm 1cm 6066 Shading test shade origin shifted 25cm 0 origin Ocm icm test shade origin shifted 25cm 0 origin 25cm 1cm test shade origin shifted 25cm 0 origin 50cm 1cm In a similar fashion we can define a linear shade This time we only pass two points and two colors def test shade expr a b pickup pencircle scaled imm color ca ca 1 color cb cb MPcolor b color cc cc MPcolorf c sh define_linear_shade a b ca cb fill fullsquare scaled 2cm withshade sh draw a withcolor cc draw b withcolor cc enddef Although one can control shading to a large extend in practice only a few cases really make sense test shade origin origin shifted 1cm 0 test shade origin shifted 1cm 0 origin shifted 1cm 0 test shade origin shifted 1cm 1cm origin shifted 1cm 1cm 8 2 Transparency In the screen version we use a light gray background color As a result some of the transparency methods demonstrated here give unexpected results The A4 version of this document demonstrates the real effects Although transparent colors have been around for some time already it was only around 2000 that they made it as a high level feature into document format languages like PDF Supporting Transparency such a feature at a higher abstraction level is not
23. withcolor 625 red draw 0 0 0 1 1 1 scaled 2cm withcolor 625 yellow The scaled operates on the previous expression which in the first case is the point 1 1 and in the second case the whole path pickup pencircle scaled 2pt draw 0 0 0 1 1 1 cycle scaled withcolor 625 red draw 0 0 0 1 1 1 cycle scaled 2cm withcolor 625 yellow Here the last element in the first case is not the cycle and the next alternative does not help us much in discovering what is going on Well at least something is going on because the result seems to have some dimensions pickup pencircle scaled 2pt draw 1 1 cycle scaled 1cm withcolor 625 draw 1 1 cycle scaled 1 withcolor 625 yellow The next lines demonstrate that we re dealing with the dark sides of mETRPOST and from that we may conclude that in case of doubt it s best to add parenthesis when such fuzzy situations threaten to occur pickup pencircle scaled 2pt draw 0 1 1 1 cycle scaled withcolor 625 red draw 0 1 1 1 cycle scaled 1cm withcolor 625 yellow Pitfalls There are more cases where the result may surprise you Take the following code drawarrow 0 0 10 0 withpen pencircle scaled 2pt withcolor red randomized 4 9 currentpicture currentpicture scaled 8 The arrow is made up out of two pieces and each piece gets a different s
24. zi 0 height 2 22 width 2 height 4 y1 z3 width 2theight 4 y4 z4 width 0 25 x4theight 2 y1 26 x4 2y1 z7 1 5 25 26 path p p 21 22 23 24 path q 23 24 25 27 numeric d 1 ly ux uy d line 2 1 3d d 3 ly d ux rt x5 d 3 uy top path r r 1x ly ux ly ux uy 1x uy cycle lx lx delta ly ly delta ux uxtdelta uy uytdelta path s s 1x ly ux ly ux uy 1ux uy cycle draw p withcolor nsblue draw withcolor nsblue addto currentpicture also currentpicture rotatedaround 5 z2 z3 180 shifted height 4 height 2 picture savedpicture savedpicture currentpicture clip currentpicture to r setbounds currentpicture to savedpicture currentpicture currentpicture nullpicture fill s withcolor nsyellow addto currentpicture also savedpicture For practical use it makes sense to package this definition in a macro to which we pass the dimen sions A few applications Simple Logos 13 8 Music sheets The next example demonstrates quite some features Imagine that we want to make us a couple of sheets so that we can write a musical masterpiece Let s also forget that can draw lines which means that somehow we need to use METAPOST Drawing a bar is not that complicated as the follo
25. In meTaPosT you can ask for all four points of the bounding box of a path or picture as well as the center llcorner p lower left corner lrcorner p lower right corner urcorner p upper right corner ulcorner p upper left corner center p the center point You can construct the bounding box of path p out of the four points mentioned llcorner p lrcorner p urcorner p ulcorner p cycle You can set the bounding box of a picture which can be handy if you want to build a picture in steps and show the intermediate results using the same dimensions as the final picture or when you want to show only a small piece fill fullcircle scaled 2cm withcolor 625yellow setbounds currentpicture to unitsquare scaled icm draw unitsquare scaled 1cm withcolor 625red Here we set the bounding box with the command setbounds which takes a path Clipping The graphic extends beyond the bounding box but the bounding box determines the placement and therefore the spacing around the graphic We can get rid of the artwork outside the bounding box by clipping it fill fullcircle scaled 2cm withcolor 625yellow clip currentpicture to unitsquare scaled The resulting picture is just as large but shows less of the picture 1 18 Some extensions We will now encounter a couple of transformations that can make your life easy when you use METRPOST for making graphics like th
26. Now we get Drawing functions Of course we could extend this LUA function with all kind of options and we might even do that when we need it Drawing functions Drawing functions 10 Typesetting in METRPOST It is said that a picture tells more than a thousand words So you might expect that text in graphics becomes superfluous Out of experience we can tell you that this is not the case In this chapter we explore the ways to add text to METAPOST graphics and let you choose whether or not to have it typeset by 10 1 The process You can let METRPOST process text that is typeset by TEX Such text is first embedded in the vETRPOST file in the following way btex Some text to be typeset by etex This returns a picture but only after has made sure that has converted it into some thing useful This process of conversion is slightly system dependent and even a bit obscure Traditional calls a program that filters the btex etex commands next it calls TEX by passing the output routine in order to make sure that each piece of text ends up on its own page and afterwards it again calls a program that converts the DVI pages into METRPOST pictures In CONTEXT MKII when using WEB2C you can generate the graphics at run time This takes more time than processing the graphics afterwards but has the advantage that knows immediately what gra
27. 43 Next we draw two circles of equal radius one centered at point A the other at point B startbuf fer d def draw_circles path circleA circleB numeric radius distance distance xpart pointB xpart pointA radius 2 3 distance circleA fullcircle scaled 2 radius circleB circleA shifted pointB draw circleA draw circleB enddef stopbuffer As you can see we move down the stand_out macro so that only the additions are colored red startbuffer 2 start_everything draw_basics stand_out draw_circles stop_everything stopbuffer We now use processMPbuffer a b c d 2 to include the latest step The next step in the construction of the perpendicular bisector requires that we find and label the points of intersection of the two circles centered at points A and B The intersection points are calculated as follows Watch the reverse operation which makes sure that we get the second intersection point startbuffer def draw_intersection pair pointC pointD These spacing commands try to get the spacing around the content visually compatible and take the height and depth of the preceding and following text into account applications Growing graphics pointC circleA intersectionpoint circleB pointD reverse circleA intersectionpoint reverse circleB draw dot pointC la
28. btex colored r 375 g 375 Meta is a female lion etex xysized btex colored r 625 Meta is a female lion etex xysized path b b boundingbox p draw p for i 28w 90h 85w 90h w 05h picture r r q path s s fullsquare xscaled 05w yscaled 4h shifted i clip to s draw r 4 draws endfor setbounds currentpicture to b stopMPcode Figure 10 2 shows the previous sentence in a slightly different look You may consider coloring the dots to be an exercise in clipping An environment can be reset with resetMPenvironment or by passing reset as key to startMPenvironment startMPenvironment reset usetypescript postscript texnansi mkii setupbodyfont postscript stopMPenvironment So to summarize if you re using CONTEXT MKIV you might as well forgot what you just read 10 3 Labels In METPPOST you can use the label macro to position text at certain points label x origin ypesetting in Meraebsme Labels Figure 10 2 An example of clipping The font and scale are determined by two variables defaultfont and defaultscale the former expecting the name of a font in the form of a string the latter expecting a numeric to be used in the scaling of the font Should you choose not to set these yourself they default to cmr10 and 1 0 respectively However you can change the defaults as follows
29. Since METRPOST is unaware of kerning we have to use to keep track of the positions We will split the text into tokens often characters and store the result in an array of pictures pic We will also store the accumulated width in an array len The number of characters is stored in n In a few paragraphs we will see why the other arrays are needed While defining the graphic we need Tex to do some calculations Therefore we will use startMPdrawing to stepwise construct the definition The basic pattern we will follow is resetMPdrawing startMPdrawing metapost code stopMPdrawing tex code startMPdrawing metapost code stopMPdrawing MPdrawingdonetrue getMPdrawing In the process we will use a few variables We will store the individual characters of the text in the variable pic its width in wid and the length of the string so far in len Later we will use the pos array to store the position where a character ends up The variable n holds the number of tokens resetMPdrawing startMPdrawing picture pic numeric wid len pos n wid 0 len 0 pos 0 n 0 stopMPdrawing We also started fresh by resetting the drawing From now on each start command will add some more to this graphic The next macro is responsible for collecting the data Each element is passed on to using the btex construct So METRPOST itself will call TEX def whatever 1 appendtoks 1 to MPtoks setbox MPbox
30. def draw_circles enddef def draw_intersection enddef def draw_bisector enddef def draw_midpoint enddef def stand_out enddef We can safe some code by letting the _everything take care of the beginfig and endfig macros Growing graphics Figure 13 6 Bisecting line segment with compass and straightedge Just click here to walk through the construction This stack is only visible in a PDF viewer that supports widgets def start everything expr n beginfig n enddef def stop everything endfig enddef The five graphics now become start everything 1 stand out draw basics Stop everything start everything 2 draw basics stand out draw circles Stop everything start everything 3 draw basics draw circles stand out draw intersection Stop everything start everything 4 draw basics draw circles draw intersection stand out draw bisector Stop everything start everything 5 draw basics draw circles draw intersection draw bisector Stand out draw midpoint Stop everything The definitions of the symbols now refer to an external figure definesymbol step 1 externalfigure step 1 definesymbol step 2 externalfigure step 2 definesymbol step 3 externalfigure step 3 definesymbol step 4 externalfigure step 4 definesymbol st
31. defaultfont tir defaultscale 1 2 These settings select Adobe Times at about 12pt You can also set these variables to CONTEXT related values For CONTEXT graphics they are set to defaultfont truefontname Regular defaultscale the bodyfontsize 10 This means that they will adapt themselves to the current body font in this document file tex gyrepagella regular and the current size of the bodyfont here 10 0pt 10 10 4 text In the next example we will use a special mechanism for building graphics step by step The advantage of this method is that we can do intermediate calculations in Tpx Our objective is to write a macro that draws text along a circular path While doing so we want to achieve the following e the text should be properly kerned i e the spacing between characters should be optimal e the position on the circle should vary and e the radius of the circle should vary This implementation is not the most straightforward one but by doing it step by step at least we see what is involved Later we will see a better method If you run these examples yourself you must make sure that the environment of your document matches the one used by We let the bodyfont match the font used in this document and define RotFont to be the regular typeface the one you are reading right now but bold definefont RotFont RegularBold
32. no endgroup enddef Once you start writing your own METAPOST macros you will appreciate this always global behav iour As with other differences between the two languages they make sense if you look at what the programs are supposed to do 2 13 Internals and Interims Related to grouping is the internal numeric datatype When numeric variables are defined as interim you can quickly overload them inside a group newinternal mynumber mynumber 1 begingroup interim mynumber 0 endgroup You can only interim a variable if it is already defined using newinternal Among the metarost macros is one called drawdot This macro is kind of redundant because at least at first sight you can use draw to achieve the same result There is however a very subtle difference a dot is slightly larger than a drawn point We guess that it s about the device pixel so you may not even notice it It may even be due to differences in accuracy of the methods to render them pickup pencircle scaled 50pt drawdot origin shifted 120pt 0 draw origin shifted 60pt 0 drawdot origin draw origin withcolor white setbounds currentpicture to boundingbox currentpicture enlarged ipt A few nore details Internals and Interims 3 Embedded graphics In addition to the beginf ig endfig method there are other ways to define and include a METAPOST graph
33. p btex COPYRIGHT etex rotated 90 setbounds p to boundingbox p enlarged ipt draw p withcolor 8white xyscale_currentpicture the leftmarginwidth the textheight stopuniqueMPgraphic setuptexttexts margin uniqueMPgraphic copyright The graphic goes into the outer margin The second argument can be used to put something in the inner margin 6 3 Multiple overlays You can stack overlays Consider the next case where we assume that you have enabled interaction support using setupinteraction state start setupbackgrounds page background color nextpage backgroundcolor darkyellow Here the page gets a colored background and a hyperlink to the next page previously defined by defineoverlay nextpage overlaybutton nextpage An overlaybutton is just a button with all attributes color frame etc set to nothing having the dimensions of the overlay The argument is one of the permitted destinations like nextpage firstpage SearchDocument and alike For efficiency reasons the background areas like text text are calculated only when their definition has changed When a background changes per page we have to recalculate it on each page In the next example the macro overlaybutton generates a different button on each page But since we don t explicitly set the background at each page there is no way the background drawing mechanism can know that this button has changed Therefore we must force
34. sin 3x 0 2pi pi 40 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 blue The next alternative uses a larger step and as a result in drawing mode 2 gives worse results Without the epsed it would have looked even worse in the end points draw function 2 x sin x 0 epsed 2pi pi 10 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 red draw function 2 x sin 2x 0 epsed 2pi pi 10 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 green draw function 2 x sin 3x 0 epsed 2pi pi 10 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 blue Drawing functions There are enough applications out there to draw nice functions like gnuplot for which Mojca Miklavec made a backend that works well with CONTEXT Nevertheless it can be illustrative to explore the possibilities of the CONTEXT LUATEX METRPOST combination using functions First of all you can use LUA to make paths and this is used in some of the debugging and tracing options that come with CONTEXT For instance if you process a document with context timing yourdoc tex then you can afterwards process a file that is generated while processing this document context extras timing yourdoc This will give you a document with graphics that show where LUATEX spent its time on Of course these graphics are generated with METAPOST The
35. where the six numeric quantities ta tytrestrystyxt yy determine T Transformations In literature concerning POSTSCRIPT and PDF you will find many references to such transformation matrices A matrix of sx 0 0 5 0 0 is scaling by sx in the horizontal direction and s in the vertical direction while 1 0 t 1 0 ty is a shift over t t Of course combinations are also possible Although these descriptions seem in conflict with each other in the nature and order of the trans form components in the vectors the concepts are the same You normally populate transformation matrices using scaled shifted rotated transform t path p t identity shifted a b rotated c scaled d fullcircle transformed t The previous lines of code are equivalent to path p p fullcircle shifted a b rotated c scaled You always need a starting point in this case the identity matrix identity 0 0 1 0 0 1 By the way in POSTSCRIPT the zero vector is 1 0 0 1 0 0 So unless you want to extract the components using xpart xypart xxpart ypart yxpart and or yypart you may as well forget about the internal representation You can invert a transformation using the inverse macro which is defined as follows using an equation vardef inverse primary T transform T T transformed T identity T enddef Using transform matrices makes sense when similar transformations need to be appli
36. 1 currentpicture xscaled 3 50 TAA lt toa currentpicture nutsiol currentpicture MetaFun currentpicture INES ENU currentpicture xscaled 1 currentpicture yscaled 5 currentpicture yscaled 1 Transformations currentpicture currentpicture slanted 5 MetaFun currentpicture currentpicture slanted 5 currentpicture zscaled 75 25 currentpicture currentpicture currentpicture reflectedabout llcorner currentpicture urcorner currentpicture A path has a certain direction When the turningnumber of a path is larger than zero it runs in clockwise direction The metarost primitive reverse changes the direction while the macro counterclockwise can be used to get a path running in a well defined direction drawoptions withpen pencircle scaled 2pt withcolor 625red path p fullcircle scaled icm drawarrow shifted 2cm 0 drawarrow counterclockwise p shifted 4cm 0 drawarrow counterclockwise reverse p shifted 6cm 0 drawarrow reverse counterclockwise p shifted 8cm 0 OOOO00 2 8 Only this far When you take a close look at the definitions of the Computer Modern Roman fonts defined in the metaront book you will notice a high level of abstraction Instead of hard coded points you will find points defined in terms of being the same as t
37. 625yellow 2 Curve construction Chapter 3 of the book explains the mathematics behind the construction of curves Both METRFONT and MeTAPOST implement B zier curves The fact that these curves are named after Pierre B zier obscures the fact that the math behind them originates with Sergei Bernshtein The points on the curve are determined by the following formula z t 1 21 3 1 ttz 3 1 t z3 24 Curve construction Here the parameter f runs from 0 1 As you can see we are dealing with four points In practice this means that when we construct a curve from multiple points we act on two points and the two control points in between So the segment that goes from 21 to z4 is calculated using these two points and the points that METAFONT MeTAPOST calls post control point and pre control point 21 22 27 ZB Z5 The previous curve is constructed from the three points 21 z4 and 27 The curve is drawn in META POST by 21 24 27 and is made up out of two segments The first segment is determined by the following points point 21 of the curve the postcontrol point 22 of 21 the precontrol point z3 of z4 point z4 of the curve p ox or On the next pages we will see how the whole curve is constructed from these quadruples of points The process comes down to connecting the mid points of the straight lines to the points mentioned We do
38. 978 94 90688 02 8 website www boekplan nl Info internet www pragma ade com support ntg contextGntg nl context www contextgarden net Introduction This document is about and The former is a graphic programming language the latter a typographic programming language However in this document we will not focus on real programming but more on how we can interface between those two languages We will do so by using CONTEXT a macro package written in in which support for mETRPOST is integrated in the core The macros are integrated in CONTEXT and the vETRPOST macros are bundled in METAFUN When Donald Knuth wrote his typographical programming language he was in need for fonts especially mathematical fonts So as a side track he started writing METAFONT a graphical lan guage When you read between the lines in the wEraFONrT book and the source code the name John Hobby is mentioned alongside complicated formulas It will be no surprise then that since he was tightly involved in the development of MeTAFONT after a few years his mEraPosr showed up While its ancestor METRFONT was originally targeted at designing fonts MeTAPOST is more oriented to drawing graphics as used in scientific publications Since METRFONT produced bitmap output some of its operators make use of this fact on the other hand produces POSTSCRIPT code which means that it has some features not p
39. They draw axis and tickmarks drawticks unitsquare xscaled 4cm yscaled 3cm shifted 1cm 1cm The system drawn is based on the bounding box specification of the path passed to the macro You can also draw one axis using drawxticks or drawyticks Here we show the previous command Libraries By default the ticks are placed at 5cm distance but you can change this by setting tickstep to different value tickstep 1cm ticklength 2mm drawticks fullsquare xscaled 4cm yscaled 3cm tickstep tickstep 2 ticklength ticklength 2 drawticks fullsquare xscaled 4cm yscaled 3cm The ticklength variable specifies the length of a tick Here we manipulated both the variables to get a more advanced system If visualizing a path would mean that we would have to key in al those draw commands you could hardly call it a comfortable tool Therefore we can say drawwholepath fullsquare scaled 3cm rotated 30 randomized 5mm The drawwholepath command shows everything except the axis If even this is too much labour you may say visualizepaths This redefines the draw and 111 command in such a way that they also show all the information visualizepaths draw fullsquare scaled 3cm rotated 30 randomized 2mm You may compare this feature to the showmakeup command available in CONTEXT that redefines the Tpx primitives that deal with boxes glues penalties and alike
40. angle 45 linewidth overlaylinewidth linecolor overlaylinecolor The last step in this process is to define the different alternatives as overlays def metahashoverlay 1 uniqueMPgraphic meta hash angle 1 def ineoverlay meta hash right metahashoverlay 45 def ineoverlay meta hash left metahashoverlay 45 def ineoverlay meta hash horizontal metahashoverlay 180 defineoverlay meta hash vertical metahashoverlay 90 As we can see in the definition of the table we can pass settings to the command Actually we can pass such settings to each command that supports backgrounds or more precisely framed Table 7 3 is for instance defined as bTABLE frame off meta hash linewidth 4pt align middle offset 2ex bTR bTD background meta hash left meta hash right 181 Shape libraries Shape NbTD background i meta hash horizontal meta hash vertical linecolor darkyellow par amp par right eTD linecolor darkred horizontal par amp par vertical eTD meta hash left meta hash eTR eTABLE The long names are somewhat cumbersome but in that way we can prevent name clashes Also since the Metarost interface is english the variables are also english VAT Symbol collections Table 7 3 A double hashed table In CONTEXT a symbol can be defined without much coding The advantage of
41. color watercolor watercolor 0 9 0 95 1 0 remapcolor skycolor 8skycolor remapcolor watercolor 8watercolor recolor currentpicture resetcolormap Changing colors Including another metarost graphic refilling redrawing and recoloring are all relatively simple features that use no real tricks Opposite to the next feature which is implemented using the METAPOST special driver that comes with CONTEXT METRPOST is not really meant for manipulating graphics but the previous examples demonstrated that we have some control over individual colors In the next series of examples we will treat the picture as a whole First we invert the colors using inverted loadfigure gracht mp number 1 scaled 5 addto currentpicture also inverted currentpicture shifted bbwidth currentpicture 5cm 0 This is a special case of uncolored In the next example we explicitly specify the color loadfigure gracht mp number 1 scaled 5 addto currentpicture also currentpicture uncolored green shifted bbwidth currentpicture 5cm 0 You can also multiply each color using softened In the next sample the colors have 80 of their value E Changing colors 1 loadfigure gracht mp number 1 scaled 5 addto currentpicture also currentpicture softened 8 shifted bbwidth currentpicture 5cm 0 You
42. dashed evenly fi endfor draw 1 0 1 1 0 1 zscaled unitvector z 1 z 0 10pt shifted z 0 endgroup enddef Ithink that we could argue quite some time about the readability of this code If you start from a sketch and the series of equations does a good job there is hardly any need for such improvements to the code On the other hand there are situations where the simplified reduced case can be extended more easily for instance to handle 10 points instead of 4 It all depends on how you want to spend your free hours 1 17 Clipping For applications that do something with a drawing for instance embedding a graphic in a text flow it is important to know the dimensions of the graphic The maximum dimensions of a graphic are specified by its bounding box Clipping Welcome to MetaPost A bounding box is defined by its lower left and upper right corners If you open the POSTSCRIPT file produced by metarost you may find lines like A BoundingBox 46 46 46 46 or when supported AAHiResBoundingBox 45 35432 45 35432 45 35432 45 35432 The first two numbers define the lower left corner and the last two numbers the upper right corner From these values you can calculate the width and height of the graphic A graphic may extend beyond its bounding box It depends on the application that uses the graphic whether that part of the graphic is shown
43. p 0 1 1 0 1 0 cycle scaled 65pt stopuseMPgraphic This shape is not that beautiful but it has a few characteristics that will help us to identify border cases startuseMPgraphic text draw drawarrow p withpen pencircle scaled withcolor red stopuseMPgraphic Now we use CONTEXT s includeMPgraphic command to build our graphic from the previously defined components startuseMPgraphic text includeMPgraphic text path includeMPgraphic text draw stopuseMPgraphic When called with useMPgraphic text we get For the moment we start the path at x 0 y gt 0 but later using more complicated macros we will see that we can use arbitrary paths We are going to split the path in two and will use the points that make up the bounding box as calcutated by metarosrt The next graphic shows one of these points the lower left corner available as point llcorner p Typesetting in vetar bsta Talking to Tex startuseMPgraphic text draw draw p withpen pencircle scaled 3pt withcolor red draw boundingbox p withpen pencircle scaled ipt draw llcorner p withpen pencircle scaled 5pt stopuseMPgraphic The five points that MeTAPosT can report for each path or picture are llcorner lower left corner lrcorner lower right corner urcorner upper right corner ulcorner upper left corner center intersection of the diagonals If we want to typeset tex
44. providing me these fabulous tools Of course I also need to thank H n Th Th nh for giving the community as well as providing me the hooks I considered neccessary for implementing some of the features presented here I also want to thank David Arnold and Ton Otten for their fast proofreading for providing me useful input and for testing the examples Without David s patience and help this document would be far from perfect English and less complete Without Ton s help many small typos would have gone unnoticed This is the second version of this document The content has been adapted to CONTEXT MKIV that uses and the built in metarost library Of course most still applies to MeTAPOsT in general g introduction and therefore to CONTEXT as well Maybe some of the solutions presented here be done easier in future versions of MKIV but it does not hurt to see the more general variants Hans Hagen Hasselt NL October 8 2010 Content Conventions 5 1 Welcome to MetaPost 7 11 Paths 422254 ene xs 7 1 2 Transformations 11 1 3 Constructing paths 14 LA Angeles Pererin eie 23 1 5 Drawing pictures 24 1 6 Variables 28 17 Conditions 30 1 8 LOOPS ce RR ERR ReRES 31 1 9 Macros ich bess
45. s not that hard to prove that the angle is indeed 90 degrees As soon as you can see a clear pattern in some code it s time to consider using loops In the previous code we used semi indexes like 12 in z12 In this case 12 does reflect something related to square 1 and 2 but in reality the 12 is just twelve This does not harm our expressions Linear equations Weleomesto MetaPost_ 0 0 0 4 0 0 0 2 0 0 0 0 Figure 1 3 The solution Linear equations A different approach is to use a two dimensional array In doing so we can access the variables more easily using loops If we omit the labels and angle macro the previously defined macro can be reduced considerably def draw problem expr n p r s number and 4 positions begingroup save x y z 1 1 p gt 2 11 q z 3 1 z 4 1 s for 1 1 upto 4 z i 1 x il i1 ylil 1 z if i 1 4 else i 1 fi 2 z i 2 x i 2 y i 2 z i 3 x i 2 y i 2 y i 1 y i 2 x i 2 x i 1 z i 4 x i 1 y i 2 y i 1 y i 1 x i 2 x i 1 5 z i 0 5 z i 1 z i 3 endfor z 0 whatever z 1 z 3 whatever z 2 z 4 pickup pencircle scaled 5pt for i 1 upto 4 draw z i 1 z i 2 z i 3 z i 4 cycle draw z i 1 z i 3 draw z ill2 z ill4 if 1 lt 3 draw z i z i 2
46. specified as a vector There are four predefined vectors up down left right These are defined as follows pair up down left right up down 0 1 right left 1 0 We can use these predefined pairs as specifications and in calculations dotlabel top up up icm dotlabel bot down down dotlabel lft left left 1cm dotlabel rt right right icm drawoptions withpen pencircle scaled 25mm withcolor 625 red drawarrow origin up icm drawarrow origin down drawarrow origin left 1cm drawarrow origin right 1cm up left right down This graphic can also be defined in a more efficient but probably more cryptic way The next definition demonstrates a few nice tricks Instead of looping over the four directions we loop over their names Inside the loop we convert these names or strings into a pair by scanning the string using scantokens The freedotlabel macro is part of METAFUN and takes three arguments a label string or alternatively a picture a point location and the center of gravity The label is positioned in the direction opposite to this center of gravity pair destination for whereto up down left right destination scantokens whereto 1cm freedotlabel whereto destination origin drawarrow origin destination withpen pencircle scaled 25mm withcolor 625 red endfor So in this code fragme
47. symbols and paragraph being the graphic The line correction is needed to get the spacing around the rule graphic right We pass a blank skip identifier that is mapped to a convenient medium skip Why is this called an English line startnarrower EnglishRule Is it because they cannot draw a straight one This could be true after a few strong beers but then how do Germans draw a line EnglishRule stopnarrower As expected the rule adapts itself to the current width of the text The height of the rule in the middle matches the height of a character with no ascenders and descenders Why is this called an English line Is it because they cannot draw a straight one This could be true after a few strong beers but then how do Germans draw a line 7 2 Random graphics Given enough time and paper we can probably give you some ff LAT LAT LHT PT IHE Wr T LUE HT RT HT LHT LHE AHT AHT JT MT Mr Ut Vot Mtt LAT HT MT ME LHT HT Lhit JH MAT HT WE MT LA AT LHA LHT LH HHT MT IT MT VAT LHT Mtf WITH VT Ju HET JHT LHT HIT T Vet MIT IIT Ht MT Jr MT JHT HT T TAT MATE HE LHE T ME WI LT HT T LAT VT HT Mf LT
48. we need to repeat this move in order to draw the red path really inside the other one pair q q top top 5 11 p lrcorner p Operations like top and its relatives bot 1ft and rt can be applied sequentally We already showed that q was defined as a series of rotations draw q q rotated 90 q rotated 180 q rotated 270 cycle withcolor 625red As an intermezzo we will show an alternative definition of q Because each point is rotated 90 degrees more we can define a macro that expands into the point and rotates afterwards Because each consecutive point on the path is rotated an additional 90 degrees we use the METAPOST macro hide to isolate the assignment The hide command executes the hidden command and afterwards continues as if it were never there You must not confuse this with grouping since the hidden commands are visible to its surroundings def qq q hide q q rotated 90 enddef draw qq qq qq qq cycle withcolor 625red The macro top uses the characteristics of the current pen to determine the displacement However for the more complicated pen shapes we need a different trick to get an inside path Let s start by defining an elliptical path pickup pencircle xscaled 3mm yscaled 5mm rotated 30 path p p fullcircle xscaled 6cm yscaled 3cm draw p withcolor 625white Only this far A few more details We draw this pat
49. xpart lrcorner q xpart llcorner q vsize ypart urcorner q ypart lrcorner stopuseMPgraphic We adapt the text split code to use the reduced path instead of the original startuseMPgraphic text split t ulcorner q urcorner q intersectionpoint b 11 q lrcorner q intersectionpoint l cutbefore t 1 1 cutafter b r q cutbefore b r r cutafter t stopuseMPgraphic In order to test what we have reached so far we draw the original path the left and right part of the reduced path and both the top and bottom point startuseMPgraphic text draw drawarrow p withpen pencircle scaled withcolor red draw t withpen pencircle scaled 2pt draw b withpen pencircle scaled 2pt drawarrow 1 withpen pencircle scaled ipt withcolor green drawarrow withpen pencircle scaled ipt withcolor blue stopuseMPgraphic Again we use includeMPgraphic to combine the components into a graphic startuseMPgraphic text includeMPgraphic text path includeMPgraphic text vars includeMPgraphic text move includeMPgraphic text split includeMPgraphic text draw stopuseMPgraphic Then we use useMPgraphic text to call up the picture Talking to Typesetting in The offset is not optimal Note the funny gap at the top We could try to fix this but there is a better way to optimize both paths We lower the t
50. 0 2 5cm 0 5cm 0 10 3cm 0 withpen pencircle scaled 2pt withcolor 625red and numeric u u 1mm pickup pencircle scaled u 2 drawoptions withcolor 625red draw 0 0 50 0 250 0 5 0 10 300 0 drawoptions dashed evenly withcolor 5white draw 0 0 spring 5u 0 35u 0 25 35 5u 0 10 40u 0 13 2 Free labels The metarost label macro enables you to position text at certain points This macro is kind of special because it also enables you to influence the positioning For that purpose it uses a special kind of syntax which we will not discuss here in detail pickup pencircle scaled imm path p fullcircle scaled 3cm draw p withcolor 625yellow dotlabel rt right point O of p dotlabel urt upper right point 1 of p dotlabel top point 2 of p dotlabel ulft upper left point 3 of p dotlabel lft left point 4 of p dotlabel llft lower left point 5 of p dotlabel bot bottom point 6 of p dotlabel lrt lower right point 7 of p The label command just typesets a text while dotlabel also draws a dot at the position of the label The thelabel command returns a picture top upper left upper right left right lower left lower right bottom Aew applications Free labels There is a numeric constant labeloffset that can be set to influence the dista
51. 0 enddef We can now apply this macro as follows path p fullcircle scaled 3cm pickup pencircle scaled 2mm draw p withcolor 625white drawarrow leftarrow p 4 2cm withcolor 625red drawarrow centerarrow p point 5 of p 2cm withcolor 625yellow draw point 4 along p withcolor 625yellow draw point 5 of p withcolor 625red Welcome to MetaPost Cutting and pasting Watch how we can pass a point point 5 of well as a fraction 4 The following graphic demonstrates a few more alternatives The arrows are drawn using the previously defined macros Watch the positive and negative off sets in call to pointarrow drawarrow leftarrow p point 1 of p 2cm withcolor red drawarrow centerarrow p point 2 of p 2cm withcolor blue drawarrow rightarrow p point 3 of p 2cm withcolor green drawarrow pointarrow p 60 4cm 5cm withcolor yellow drawarrow pointarrow p 75 3cm 5cm withcolor cyan E drawarrow centerarrow p 90 3cm withcolor magenta 1 20 Current picture When you draw paths texts and or pictures they are added to the so called current picture You can manipulate this current picture as is demonstrated in this manual Let s show a few current picture related tricks draw fullcircle scaled withpen pencircle scaled imm withcolor 625red We can manipulate the picture as a whole draw fullcircle scaled withpe
52. 1 1 metapost primitive tension numeric 0 03 75 0 tonadon 2 5 1 25 01 0 metapost primitive tension num and num 0 0 75 0 tension 2 5 and 1 5 1 25 1 1 metapost primitive Paths tension atleast numeric 0 0 75 0 tension atleast 1 1 25 1 1 metapost primitive cycle 0 0 1 0 1 1 cycle metapost primitive curl numeric 0 0 curl 1 75 0 1 25 1 1 metapost primitive dir numeric 0 0 dir 30 1 1 metapost primitive left 0 0 1eft 1 1 metapost macro Paths right 0 0 right 1 1 metapost macro I u 0 0 up 1 1 metapost macro DN down 0 0 down 1 1 metapost macro ath amp path 0 0 75 25 amp 75 25 1 1 metapost primitive unitvector origin unitvector 1 1 I C L mumy metapost variable metapost primitive dir origin dir 45 Paths angle origin dir angle 1 1 metapost primitive fullcircle fullcircle metapost variable unitcircle unitcircle metafun variable fullsquare fullsquare metafun variable unitsquare unitsquare metapost variable fulldiamond fulldiamond metafun variable Paths unitdiamond unitdiamond metafun var
53. 127 Overlays 2 m ems 127 Overlay variables 129 Stacking overlays 129 Foregrounds 130 Typesetting graphics 131 Graphics and macros 133 Positional graphics 143 The concept 143 Anchors and layers 145 More layers 147 Complex text in graphics 152 Page backgrounds 155 The basic layout 155 Setting up backgrounds 160 Multiple overlays 162 Crossing borders 163 Bleeding 22 170 Shapes symbols and buttons 175 Interfacing to 175 Random graphics 176 Graphic variables 179 Shape libraries 180 Symbol collections 182 Special effects 185 Shading 185 Transparency 189 Clipping return ees 194 Including graphics 198 Changing colors 201 Outline fonts 205 CO 9 Functions 211 9 1 Overview 211 9 2 213 9 3 Drawing functions 216 10 Typesetting in METRPOST 225 10 1 Theprocess 225 102 Environments 225 10 3 Labels 226 10 4 TpXtext 227 105 Talking to TEX 238 1
54. 4 x 3 w 3 x 5 x 4 w 4 3u w 4 1u h 4 iu h 5 width height 11 1u 5u y 2 1 5u y 3 2 5u y 4 y 3 5u y 5 y 4 3u w 5 2u 1u h 1 5u h 2 5u h 3 5u h 4 5u Because we are going to repeat ourselves we draw the areas using a macro Depending on its importance we color it red or yellow def do_it expr xx yy cc draw unitsquare xyscaled w xx h yyl shifted x xxl ylyyl withcolor if cc enddef 625red else fill unitsquare xyscaled width height do it 1 1 false do it 2 1 false do it 1 2 false do it 2 2 true do it 1 3 false do it 2 3 true The basic layout do it do it do it do it do it do it 5 1 false 3 1 false 5 2 false 3 2 true 5 3 false 3 3 true 625yellow fi withcolor 85white do it 4 1 false do it 4 2 true do it 4 3 true we 0 Page The basic layout do it 1 4 false do it 5 4 false do it 2 4 true do it 3 4 true do it 4 4 true do it 1 5 false do it 5 5 false do it 2 5 false do it 3 5 false do it 4 5 false This picture in itself is not yet explanatory so we add som
55. Guw 0 ww hh w hh ww 0 cycle This path fails because of the way POSTSCRIPT implements its fill operator More details on how POSTSCRIPT defines fills can be found in the reference manuals Some of the operations we have seen are hard coded into metarost and are called primitives Others are defined as macros that is a sequence of METAPOST commands Since they are used Drawing pictures 1 6 often you may expect draw and fill to be primitives but they are not They are macros defined in terms of primitives Given a path pat you can consider a draw to be defined in terms of addto currentpicture doublepath pat The 2111 command on the other hand is defined as addto currentpicture contour pat Both macros are actually a bit more complicated but this is mainly due to the fact that they also have to deal with attributes like the pen and color they draw with You can use doublepath and contour directly but we will use draw and 2111 whenever possible Given a picture pic the following code is valid addto currentpicture also pic You can add pictures to existing picture variables where currentpicture is the picture that is flushed to the output file Watch the subtle difference between adding a doublepath contour or picture Here is another nice example of what happens when you fill a path that is partially reversed fill fullsquare rotated 45 scaled 2cm withcolor 625 red fil
56. I remember having seen before in books on psychology physiology and or ergonomics One of the articles was by Edward H Adelson of MIT and we will use a few of his example graphics in our exploration to what extend can be of help in those disciplines Since such graphics normally occur in typeset documents we will define them in the document source Figure 13 2 White s illusion Unless you belong to the happy few whose visual capabilities are not distorted by neural opti mizations in figure 13 2 the gray rectangles at the left look lighter than those on the right Alas you can fool yourself but Metarost does not cheat This graphic referred to as White s illusion is defined as follows startbuffer interim linecap butt numeric u u 1 pickup pencircle scaled 5u for i 1u step u until 5u draw 0 i 5u i endfor for i 2u step u until 4u A few applicali ns o Fool yourself draw u i 2u i withcolor 5white draw 3u i 4u i shifted 0 5u withcolor 5white endfor stopbuffer Watch how we include the code directly We have packaged this graphic in a buffer which we include as a floating figure placefigure here fig tricked 1 White s illusion processMPbuffer When passed to this code is encapsulated in its beginfig and endfig macros and thereby grouped But any change to a variable t
57. If you want to process these examples yourself you should add those commands yourself or if you use CONTEXT you don t need them at all pickup pencircle scaled 5cm draw unitsquare xscaled 8cm yscaled 1cm withcolor 625white draw origin withcolor 625yellow pickup pencircle scaled draw bbox currentpicture withcolor 625red In this example we see a mixture of so called primitives as well as macros A primitive is something hard coded a built in command while a macro is a collection of such primitives packaged in a way that they can be recalled easily Where scaled is a primitive and draw a macro unitsquare is a path variable an abbreviation for unitsquare 0 0 1 0 1 1 0 1 cycle The double dash is also a macro used to connect two points with a straight line segment However cycle is a primitive which connects the last point of the unitsquare to the first on unit square s path Path variables must first be declared as in path unitsquare A large collection of such macros is available when you launch metarost Consult the METAPOST manual for details In the first line of our example we set the drawing pen to 5cm You can also specify such a dimension in other units like points pt When no unit is provided will use a big point bp the POSTSCRIPT approximation of a point few more details Making graphics
58. MPcolor a MPcolor b endfor At first sight in the next situation we would expect something similar because we simply copy the same circle 5 times However due to the way we have implemented shading in CONTEXT we do indeed copy the circles but the shade definition is frozen and the same one is used for all 5 circles This means that the center of the shading stays at the first circle circular shade fullcircle scaled 1cm 0 MMPcolor a MMPcolorib picture s S currentpicture currentpicture nullpicture for i 0 step 2cm until 8cm addto currentpicture also s shifted i 0 endfor Unlike METRPOST does not keep its specials attached to the current path and flushes them before the graphic data Since we use these specials to register shading information it is rather hard to tightly connect a specific shade with a certain fill especially if an already performed fill is not accessible which is the case when we copy a picture This may seem a disadvantage but fortunately it also has its positive side In the next example we don t copy but reuse an already defined shade By storing the reference to this shade and referring to it by using withshade we can use a shade that operates on multiple shapes Sh define circular shade origin origin 0 8cm MPcolor a MPcolor b for i 0 step 2cm until 8cm fill fullcircle scaled 1cm shifted 1 0 withshade sh endfor The low level macro
59. The array variables are accessed by using constants horizontal vertical LeftEdge Top LeftEdgeSeparator TopSeparator LeftMargin Header LeftMarginSeparator HeaderSeparator Text Text RightMarginSeparator FooterSeparator RightMargin Footer RightEdgeSeparator BottomSeparator RightEdge Bottom In addition to these there are Margin InnerMargin and OuterMargin which adapt themselves to the current odd or even page The same is true for Edge InnerEdge and OuterEdge although these will seldom be used since interactive documents are always single sided We started this chapter with spending a lot of code to simulate the page areas It will be clear now that in practice this is much easier using the mechanism described here Crossing borders R Tufte Bike fotos vd bene emu ris and ele opc org e ew dip into flip through browse glance into leaf through PPE ip into flip through browse glance into leaf through skim refine efine Synopsize winnow the wheat from the cha and separate the sheep from is vede are dati E eee al us Le sco te ctione Sgro of anew system must not only be the implemented eles so write the first user manual oneris would have rt TeX ignem HE had uld never have b eem them or perceived why they were important em is too strongly in
60. The left picture demonstrates what happens when you have a printer that is capable of printing from edge to edge If you have such a printer you re lucky The middle picture demonstrates what happens if you have a properly set up printing program and or printer the page is scaled down so that the content fits into the non printable area of the printer One reason why printers don t print from edge to edge is that the engine is not that happy when toner or ink ends up next to the page The third picture shows what happens when a printer simply ignores content that runs over the non printable area In many cases it s best to make sure that the content leaves a margin of 5mm from the edges Books and magazines seldom use the popular desk top paper sizes Here the designer determined the paper size and layout more or less independent from the size of the sheet on which the result is printed Instead of one page per sheet arrangements of 2 upto 32 or more pages per sheet are made The process of arranging pages in such a way that these sheets can be folded and combined into books is called page imposition CONTEXT supports a wide range of page imposition schemes More information on this can be found in the CONTEXT manuals The fact that the sheet on which a page is printed is larger than the page itself opens the possibil ity to use the full page for content In that case especially when you use background graphics you need to make sure that indeed the
61. The next table has some hashed backgrounds More information about how to define tables can be found in the CONTEXT documentation and Up To Date documents Table7 2 A hashed table buttons Shape libraries This table is defined as bTABLE frame off meta hash linecolor darkyellow offset 3ex bTR bTD background meta hash right right eTD bTD background meta hash left left eTD bTD background meta hash horizontal horizontal eTD bTD background meta hash vertical vertical eTR eTABLE The graphics themselves are defined in a MeTAPOsT module In this particular example the macro some hash is defined in the file mp back mp This macro takes six arguments some hash width height linewidth linecolor angle gap Because we don t want to define a specific overlay for each color and linewidth we will use vari ables in the definition of the unique graphic NstartuniqueMPgraphicimeta hash h linewidth linecolor angle gap if unknown context back input mp back fi some hash overlaywidth overlayheight MPvar linewidth MPvar linecolor 1 MPvar gap stopuniqueMPgraphic These variables are preset using setupMPvariables setupMPvariables meta hash gap 25 bodyfontsize
62. This example demonstrates that when we enlarge a graphic the bounding box also gets larger Because this can interfere with the placement of such a graphic we need to make sure that the bleeding is there but not seen path p p fullsquare xyscaled 4cm 1icm path q p leftenlarged 2mm topenlarged 2mm fill p withcolor transparent 1 5 625yellow fill q withcolor transparent 1 5 625yellow setbounds currentpicture to p draw boundingbox currentpicture withcolor 625red Bleeding There are two more operators innerenlarged and outerenlarged These expand to either leftenlarged or rightenlarged depending on the page being left or right hand Bleeding Bleeding 7 Shapes symbols and buttons One can use METRPOST to define symbols and enhance buttons Here we introduce some of the gadgets that come with CONTEXT as well as explain how to integrate such gadgets yourself 7 1 Interfacing to TEX In the early days of wErePosr support in CONTEXT Tobias Burnus asked me if it was possible to define English rules What exactly does an english rule look like Here is one As you can see such a rule has to adapt itself to the current text width normally hsize in TEX or on request localhsize in CONTEXT We need to set the height to a reasonable size related to the font size and we also need to take care of proper spacing Of cour
63. YourLayer We can now move some framed text to this layer using set layer with the directive position set to yes here setlayer YourLayer position yes inframed Here here Here You can influence the placement by explicitly providing an offset hoffset and or voffset a position x and or y or a location directive location Normally you will use the offsets for the layer as a whole and the positions for individual contributions The next example demonstrates the use of a location directive here setlayer YourLayer position yes location c inframed Here he Here Many layers can be in use at the same time In the next example we put something in the page layer By default we turn on position tracking which visualizes the bounding box of the content and shows the reference point definelayer BackLayer position yes setupbackgrounds page background BackLayer Next we define an overlay that we can put behind for instance framed texts We use METAPOST to draw Shape defineoverlay Shape BackLayer uniqueMPgraphic Shape startuniqueMPgraphic Shape path p p fullcircle xyscaled OverlayWidth OverlayHeight Positionalgraphies More layers This goes to the background fill p withcolor MPcolor lightgray draw p withpen pencircle scaled 1pt withcolor MMPcolor darkred stopuniqueMPgraphic We can now put
64. a bit of playing with drawing paths between the two points you decide to make a macro We want to feed the angle between the paths but also the connecting path So we have to pass a path but unfortunately we don t have direct access to the points By splitting the argument definition we can pass an expression first and a wildcard argument next startuseMPgraphic gamble def Gamble expr rot text track path a a fullcircle scaled 3cm path b b fullcircle scaled 2cm rotated rot pair aa aa point 0 of a pair bb bb point O of b path ab ab track draw a withpen pencircle scaled imm withcolor 625red draw b withpen pencircle scaled imm withcolor 625yellow draw aa withpen pencircle scaled 2mm draw bb withpen pencircle scaled 2mm drawarrow ab withpen pencircle scaled imm withcolor 625white setbounds currentpicture to boundingbox a enlarged 2mm draw boundingbox currentpicture withpen pencircle scaled 25mm enddef stopuseMPgraphic Because at this distance nobody will bother us with the thickness of the pen and colors we code them the hard way We create our own universe by setting a fixed boundingbox We leave the Earth in the most popular way straight upwards and after a few cycles we leave it parallel to the surface The path drawn reminds much of the trajectories shown in popular magazines 16 In case you wonder why metarost talks about the time on a path you now have a c
65. a bit when paths have multiple intersection points Again we could follow a more secure mathematical method but the next one took only a few minutes of trial and error To save some memory we redefine the colors graphic When we call this macro as colorcircle 4cm red green blue we get vardef colorcircle expr size red green blue save r g b rr gg bb cc mm yy save radius path r g b rr bb gg cc mm yy numeric radius radius 5cm pickup pencircle scaled radius 25 r g b fullcircle scaled radius shifted O radius 4 r rotatedaround origin 15 g g rotatedaround origin 135 b b rotatedaround origin 255 r r rotatedaround center r 90 g rotatedaround center g 90 gg buildcycle buildcycle reverse r b g cc buildcycle buildcycle b reverse g r rr gg rotatedaround origin 120 bb gg rotatedaround origin 240 Color circles ar c Waa 288 yy cc rotatedaround origin 120 cc rotatedaround origin 240 B fill fullcircle scaled radius withcolor white fill rr withcolor red fill cc withcolor white red 5 fill gg withcolor green fill mm withcolor white green fill bb withcolor blue fill yy withcolor white blue for i rr gg bb cc mm yy draw i withcolor 5white endfor currentpicture currentpicture xsized size enddef Since we don t want
66. a macro Analyzing pictures A few These circles were drawn using colorcircle 4cm 4 6 8 4 8 6 6 4 8 addto currentpicture also inverted currentpicture shifted 5cm 0 When we draw a path or stroke a path as it is called officially we actually perform an addition addto currentpicture doublepath somepath The fill command is actually addto currentpicture contour somepath We will need both doublepath and contour operations in the definition of inverted When metrpost has digested a path into a picture it keeps track of some characteristics We can ask for them using part operators The following operators can be applied to a transform vector one of METRPOST S data types but also to a picture Say that we have drawn a circle draw fullcircle xscaled 3cm yscaled 2cm dashed dashpattern on 3mm off 3mm withpen pencircle scaled imm withcolor 625red picture p p currentpicture This circle looks like We can now ask for some of the characteristics of currentpicture like its color We could write the values to the log file but it is more convenient to put them on paper label rt redpart amp decimal redpart 4cm 5cm label rt greenpart amp decimal greenpart p 4cm Ocm label rt bluepart amp decimal bluepart 4cm 5cm Analyzing pictures Here the amp glues strings together wh
67. and text areas startuseMPgraphic page StartPage pickup pencircle scaled 2pt fill Page fill Field OuterMargin Text fill Field Text Text draw Field OuterMargin Text draw Field Text Text StopPage stopuseMPgraphic This background is assigned to the page layer by saying withcolor withcolor withcolor withcolor withcolor def ineoverlay page useMPgraphic page setupbackgrounds page background page As you can see in figure 6 3 the text is typeset rather tightly between the left and right margins cc ae first large scale user the designer should also write the first l and esthetic Sra important ms ane by The OEE ot Me ont even Figure 6 3 A background with split areas This can easily be solved by enlarging the areas a bit The next example demonstrates this on the text area which is shown in figure 6 4 Crossing borders in I felt min important scs nb by Concept ofa Me 625white 850white 850white 625red 625red startuseMPgraphic page StartPage pickup pencircle scaled 2pt fill Page fill Field Text Text enlarged 5cm withcolor 850white draw Field Text Text enlarged 5cm withcolor 625red StopPage stopuseMPgraphic The enlarged macro can be used like shifted and accepts either a numeric or a pair How do we define a background as in figure 6 2 Because Field provides us the position
68. are also composed of 8 points Because in most cases the label is to be positioned in the direction of the center of a curve and the point at hand it makes sense to take circles as the starting points for positioning the labels To help us in positioning we define a special square path freesquare This path is constructed out of 8 points that match the positions that are used to align labels path freesquare freesquare 1 0 1 1 0 1 C41 1 1 0 1 1 0 1 1 1 cycle scaled 5 We now show this free path together with a circle using the following definitions drawpath fullcircle scaled 3cm drawpoints fullcircle scaled 3cm drawpointlabels fullcircle scaled 3cm currentpicture currentpicture shifted 5cm 0 drawpath freesquare scaled 3cm drawpoints freesquare scaled 3cm drawpointlabels freesquare scaled 3cm We use two drawing macros that are part of the suite of visual debugging macros 7 6 5 2 e e e 3 e 1 e e 8 0 e 4 4 e 0 e e e e 5 e 7 1 2 3 6 As you can see point 1 is the corner point that suits best for alignment when a label is put at point 1 of the circle We will now rewrite thefreelabel in such a way that the appropriate point of the associated freesquare is found vardef thefreelabel expr str loc ori save S q l picture s path p q pair 1 s thelabel str loc Free labels _ A applications
69. b draw p withcolor black setbounds currentpicture to a stopuseMPgraphic There is not so much basic instruction as of now as there was in the old days showing the differences between good and bad typo graphic design Because we use a random graphic we cannot guarantee beforehand that the left and right edges of the small shape touch the horizontal lines in a nice way The next alternative displaces the small shape plus text so that its center lays on the line On the average this looks better startuseMPgraphic FunnyFrame picture p numeric o path a b pair p textext rt MPstring FunnyFrame a unitsquare xyscaled OverlayWidth OverlayHeight o BodyFontSize _ Enhancing the layout _ Graphics and macros p shifted 2o 0verlayHeight ypart center p drawoptions withpen pencircle scaled ipt withcolor 625red b a randomized 0 2 fill b withcolor 85white draw b c center p c 7 b intersectionpoint c shifted 0 0 c shifted 0 0 p shifted c center p b boundingbox p randomized 0 8 fill b withcolor 85white draw b draw p withcolor black setbounds currentpicture to a stopuseMPgraphic There is not so much basic instruction as of now as there was in the old days showing the differences between good and bad typo graphic design Yet another definition uses super ellip
70. be split off As a result we can hardly predict how a document will come out Therefore when we want graphics to adapt themselves to this text we have to deal with this asynchronous feature of in a rather advanced way Before we present one way of dealing with this complexity we will elaborate on the nature of such graphics When Tx entered the world of typesetting desktop printers were not that common let alone color desktop printers But times have changed and nowadays we want color and graphics and if possible we want them integrated in the text To accomplish this several options are open 1 Usea backend that acts on the typeset text This is the traditional way using specials to embed directives in the DVI output file 2 Use the power of a second language and pass snippets of code to the backend which takes care of proper handling of those snippets of text Impressive results are booked by passing POSTSCRIPT to the DVI file 3 Extend in such a way that itself takes care of these issues This is the way and its decendants work The first method is rather limited although for business graphics the results are acceptable The second method is very powerful but hardly portable since it depends on the DVI to POSTSCRIPT postprocessor But what about the third method There has been some reluctance to divert from traditional and DVI but with the development of the third option h
71. box is constructed We will also pay attention to the usage of units and the side effects of scaling and shifting since they can contradict our expectations in unexpected ways Furthermore we will explore a few obscure areas 24 Making graphics In this manual we will use Metarost in a rather straightforward way and we will try to avoid complicated math as much as possible We will do a bit of drawing clipping and moving around Occasionally we will see some more complicated manipulations When defined as stand alone graphic a metarost file looks like this Let s draw a circle beginfig 7 draw fullcircle scaled 3cm withpen pencircle scaled icm endfig end The main structuring components in such a file are the beginfig and endfig macros Like in a big story the file has many sub sentences where each sub sentence ends with a semi colon Although the end command at the end of the file concludes the story putting a period there is a finishing touch Actually after the end command you can put whatever text you wish your comments your grocery list whatever Comments in MeTAPOST prefixed by a percent sign as in Let s draw a circle are ignored by the interpreter but useful reminders for the programmer If the file is saved as yourfile mp then the file is processed by metarost by issuing the following command mpost yourfile after which you will have a graphic called yourfile 7 which contains a series of POSTSCRI
72. boxes you can lie about the dimensions of a graphic This is a very useful feature In the rare case that you want to know the truth and nothing but the truth you can tweak the truecorners numeric variable We will demonstrate this with a few examples fill fullcircle scaled 1cm withcolor 625yellow fill fullcircle scaled 1cm withcolor 625yellow setbounds currentpicture to boundingbox currentpicture enlarged 2mm fill fullcircle scaled 1cm withcolor 625yellow setbounds currentpicture to boundingbox currentpicture enlarged 2mm interim truecorners 1 fill fullcircle scaled 1cm withcolor 625yellow interim truecorners 1 setbounds currentpicture to boundingbox currentpicture enlarged 2mm Bounding boxes As you can see here as soon as we set truecorners to 1 the bounding box settings are ignored There are two related macros bbwidth and bbheight that you can apply to a path fill unitcircle xscaled 4cm yscaled 2cm withpen pencircle scaled imm withcolor 625red draw origin bbwidth currentpicture 0 withpen pencircle scaled imm withcolor 625yellow draw origin O bbheight currentpicture withpen pencircle scaled imm withcolor 625white Units Like METAPOST supports multiple units of length In these units are hard coded and han dled by the parser where the in
73. broad increases the raggedness We defined three different graphics a b and c because we want some to be unique which saves some processing Of course we don t reuse the random graphics In the definition of processword we have to use noindent because otherwise will put each graphic on a line of its own Watch the space at the end of the macro 4 6 Graphics and macros Because 5 typographic engine and metarost s graphic engine are separated interfacing be tween them is not as natural as you may expect In CONTEXT we have tried to integrate them as much as possible but using the interface is not always as convenient as it should be What method you follow depends on the problem at hand The official way to embed code into graphics is to use btex etex As soon as CONTEXT writes the graphic data to the intermediate metarost file it looks for these commands When it has encountered an etex CONTEXT will make sure that the text that is to be typeset by TEx is not expanded This is what you may expect because when you would embed those commands a stand alone graphic they would also not be expanded if only because MeTAPosT does not know With expansion we mean that commands are replaced by their meaning which can be quite extensive Users of CONTEXT MKIV can skip the next paragraph When metArost sees a btex command it will consult a so called mpx file This file holds the me
74. buffers to ensure that the code used to produce the accompanying graphic is identical to the typeset code in the document Here is an example startbuffer dummy draw fullcircle xscaled 3cm yscaled 2cm rotatedaround origin 30 withcolor 625red stopbuffer Instead of using getbuffer we used the following command startlinecorrection blank processMPbuffer dummy stoplinecorrection The line correction commands take care of proper spacing around the graphic If you want to process more buffers at once you can pass their names as a comma separated list Alternatively we could have said startuseMPgraphic dummy draw fullcircle xscaled 3cm yscaled 2cm rotatedaround origin 30 withcolor 625red stopuseMPgraphic When including this graphic we again take care of spacing startlinecorrection blank useMPgraphic dummy stoplinecorrection The first version of this manual was produced with PDFIgx and calls out to werePosr Because the number of graphics is large we processed that version using the automp directive using TEXEXEC And even then runtime was so unconveniently long that updating this manual became less and less fun The current version is produced with LUATEX and CONTEXT MKIV which brings down the runtime including runtime calls to independent CONTEXT runs for the outline examples to some 45 seconds on a 2 2 Gig Dell M90 Given that at the time of writing this over 1700 graphics are gener
75. c voffset 5cm width 50pt height 50pt startMPcode externalfigure somecow pdf xscaled 100bp yscaled 100bp rotated 25 stopMPcode Positional g aphics layers The previous example also demonstrated the use of METRPOST for rotating the picture The MPfigure macro encapsulates the code in a shortcut You can achieve special effects by using the layers behind floating bodies and alike but always keep in mind that the readability of the text should not be violated too much startbuffer setlayer BackLayer Figure 5 2 position yes voffset 1 5cm width 3cm height 2cm MPfigure somecow pdf scaled 5 slanted 5 stopbuffer placefigure right ruledhbox getbuffer In these examples we added a ruledhbox around the pseudo graphics so that you can see what the size is of those graphics We have already seen a lot of parameters that can be used to control the content of a layer There are a few more General housekeeping takes place with state start enable the layer stop disable the layer position no use absolute positions yes use relative positions overlay idem but ignore the size direction normal put new data on top reverse put new data below old data Sometimes all data needs to be offset in a similar way You can use both offset parameters for that hoffset an addition
76. chapter to be an appetizer for the following chapters If you want to get started quickly you can safely skip this chapter now T Paths Paths are the building blocks of 5 graphics In its simplest form a path is a single point 1cm 1 5cm e Such a point is identified by two numbers which represent the horizontal and vertical position often referred to as x and or x y Because there are two numbers involved in METAPOST this point is called a pair Its related datatype is therefore pair The following statements assigns the point we showed previously to a pair variable pair somepoint somepoint 1cm 1 5cm A pair can be used to identify a point in the two dimensional coordinate space but it can also be used to denote a vector being a direction or displacement For instance 0 1 means go up Looking through math glasses you may consider them vectors and if you know how to deal with them may be your friend since it knows how to manipulate them You can connect points and the result is called a path A path is a straight or bent line and is not necessarily a smooth curve An example of a simple rectangular path is In the next examples we use the debugging features discussed in chapter 11 to visualize the points paths and bounding boxes Paths This path is constructed out of four points
77. circle setMPpositiongraphic G 2 mypos circle setMPpositiongraphic G 3 mypos circle setMPpositiongraphic G 4 mypos circle stoppositionoverlay startpositionoverlay foregraphics setMPpositiongraphic G 1 mypos line to G 2 setMPpositiongraphic G 2 mypos line to G 3 setMPpositiongraphic G 3 mypos line to G 4 stoppositionoverlay First we have defined an overlay can be attached to some overlay layer like in our rds hese are drawn as soon as the page overlay is typeset SYC text while the lines do The Because they located in the background they don t cover previous paragraph was typeset by saying First we have defined an hpos G 1 overlay This overlay can be attached to some overlay layer like in our case the hpos G 2 page We define four small hpos 06 3 circles These are drawn as soon as the page overlay is typeset Because they are located in the background they don t cover the hpos G 4 text while the lines do The previous paragraph was typeset by saying As said the circles are on the background layer but the lines are not They are positioned on top of the text This is a direct result of the definition of the page background Anchors and layers Positional graphics _ defineoverlay foregraphics positionoverlay foregraphics defineoverlay backgraphics positionoverlay backgraphics setup
78. color expression withrgbcolor rgbcolor expression withcmykcolor cmykcolor expression withoutcolor withprescript string expression withostscript string expression withpen pen expression dashed picture expression withshade numeric expression drawing command draw picture expression option list fill type path expression option list fill type fill unfill refill draw undraw redraw filldraw drawfill unfilldraw drawarrow drawdblarrow cutdraw newinternal command newinternal internal type symbolic token list newinternal symbolic token list message command errhelp string expression errmessage string expression filenametemplate string expression message string expression mode command batchmode nonstopmode scrollmode errorstopmode special command fontmapfile fontmapline special tracing command tracingall loggingall tracingnone Syntax diagrams 2 if test if boolean expression balanced tokens alternatives fi alternatives empty else balanced tokens elseif boolean expression balanced tokens alternatives loop loop header loop text endfor loop header for symbolic token progression for symbolic token for list for symbolic token within picture expression forsuffixe
79. currentpicture scaled 4 enddef stopbuffer The graphic itself is defined as follows Watch how we use the default buffer to keep the definitions readable startbuffer startcombination 5 1 processMPbuffer a b c h d e f g 1 step 1 processMPbuffer a b c h d e f g 2 step 2 processMPbuffer a b c h d e f g 3 step 3 processMPbuffer a b c h d e f g 4 step 4 processMPbuffer a b c h d e f g 5 step 5 stopcombination stopbuffer placefigure here fig 1 till 5 The five graphics each with the same bounding box getbuffer As the original purpose of these graphics was not to show them side by side but to present them as field stack in a document to be viewed at the computer screen For this purpose we have to define the graphics as symbols definesymbol step 1 processMPbuffer a b c d e f g 1 definesymbol step 2 processMPbuffer a b c d e f g 2 Growing graphics T Bew applications 5 1 step 2 step 3 step 4 step 5 Figure 13 5 The five graphics each with the same bounding box definesymbol step 3 processMPbuffer a b c d e f g 3 definesymbol step 4 processMPbuffer a b c d e f g 4 definesymbol step 5 processMPbuffer a b c d e f g 5 A field stack is a sequence of overlayed graphics We will arrange these to cycle manually with clicks of the mouse through the sequen
80. cycle metafun macro laddered path laddered 0 0 1 4 8 2 8 1 2 6 2 1 6 metafun macro Paths path paralleled distance 0 0 5 1 paralleled 25 metafun macro shortened path 0 0 6 1 shortened 1 metafun macro unspiked path unspiked 0 0 1 0 1 1 2 1 1 1 0 12 metafun macro simplified path simplified 0 0 1 0 2 0 2 1 0 1 cycle metafun macro ath blownup numeric pair fullcircle scaled 1 5 blownup 1 metafun macro Paths ath stretched numeric pair fullcircle scaled 1 5 stretched 1 1 0 8 metafun macro roundedsquare num num num roundedsquare 2 1 2 metafun macro tensecircle num num num tensecircle 2 1 2 metafun macro air crossed size origin crossed 1 metafun macro Paths path crossed size fullcircle scaled 2 crossed 5 metafun macro C 2 Transformations ath scaled numeric fullcircle scaled 50 metapost primitive fullcircle xscaled 25 metapost primitive fullcircle yscaled 25 metapost primitive Transformations ath zscaled pair fullcircle zscaled 2 25 metapost primitive ath xyscaled numeric pair fullcircle xyscaled 5 7 metapost primitive fullcircle xyscaled 2 25 metapost primitive ath shifted pair fullcircle shifted 2 25 met
81. depth we have to determine which part touches first startuseMPgraphic text calc vardef found_point expr lin pat sig pair a b a pat intersection_point lin shifted 0 strutheight if intersection_found a a shifted 0 strutheight else pat intersection point lin fi b pat intersection_point lin shifted 0 strutdepth if intersection_found if sig if xpart b gt xpart a a b shifted 0 strutdepth fi else if xpart b lt xpart a fi fi a enddef stopuseMPgraphic b shifted O strutdepth fi Instead of using METRPOST s intersectionpoint macro we use one that comes with CONTEXT That way we don t get an error message when no point is found and can use a boolean flag to take further action Since we use a vardef all calculations are hidden and the a at the end is returned so that we can use this macro in an assignment The sig variable is used to distinguish between the beginning and end of a line the left and right subpath startuseMPgraphic text step path line pair 111 rrr for i topskip step baselineskip until vsize line ulcorner q urcorner q shifted 0 i 111 found point line l true rrr found point line r false stopuseMPgraphic Here we divide the available space in lines The first line starts at strutheight from the top We can now finish our graphic by visualizing the lines Both the height and depth of the lines
82. depth discussions on pens Only this far We re still not there Like in a previous example we need to shift over twice the pen width To get good results we should determine the width of the pen at that particular point which is not trivial The more general solution which permits us to specify the amount of shifting is as follows vardef penpoint expr pnt of p save n d numeric n d n d if pair pnt pnt else pnt 1 fi point n of p shifted penoffset direction n of p of currentpen scaled d enddef When the point specification is extended with a distance in which case we have a pair expression the point and distance are derived from this specification First we demonstrate the simple case draw penpoint O of p for i 1 upto length p 1 penpoint i of p endfor cycle withcolor 625red In the next graphic we draw both an inner and and outer path draw penpoint 0 2 of p for i 1 upto length p 1 penpoint i 2 of p endfor cycle withcolor 625red draw penpoint 0 42 of p for i 1 upto length p 1 penpoint i 2 of p endfor cycle withcolor 625yellow Only this far Another case when top and friends cannot be applied in a general way is the following Consider the three paths pathp q r fullcircle scaled 3cm p shifted 7cm 0cm center p center P X5 We draw these paths with
83. edge of 5cm you will get Pens Welcome fol Meta Bose You can define such a pen yourself path p fullcircle xscaled 2cm yscaled 3cm pen doublepen doublepen makepen 0 0 3cm 3cm pickup doublepen draw p Here we define a new pen using the pen command Then we define a path and make a pen out of it using the makepen macro The path should be a relatively simple one otherwise metarost will complain You can use makepen with the previously introduced withpen draw p withpen makepen 0 0 3cm 3cm and pickup pickup makepen 0 0 3cm 3cm draw p You can use makepen and makepath to convert paths into pens and vice versa Pens are very important when defining fonts and METRFONT is meant to be a font creation tool Since METRPOST has a slightly different audience it lacks some features in this area but offers a few others instead Nevertheless one can try to design a font using METRPOST Of course pens are among the designers best kept secrets But even then not every O is a nice looking one 112 Joining lines The way lines are joined or end is closely related to the way POSTSCRIPT handles this By setting the variables linejoin and linecap you can influence the drawing process Figure 1 1 demonstrates the alternatives The gray curves are drawn with both variables set to rounded BiWelcome to MctaPost Joining lines
84. euro 1 offset euro 1 offset euro radius 32 fi if unknown euro l shift euro 1 shift euro offset 2 ds if unknown euro v delta euro v delta euro width 4 save outer circle inner circle hor bar right line right slant top slant bot slant euro circle euro topbar euro botbar path outer circle inner circle hor bar right line right slant top slant bot slant euro circle euro topbar euro botbar outer circle fullcircle scaled euro radius inner circle fullcircle scaled euro radius euro width if trace euro for i outer circle inner circle draw i withpen pencircle scaled ipt withcolor 5white endfor fi right line 1 outer circle urcorner outer circle shifted euro r offset 0 outer circle outer circle cutbefore right line right slant point O of outer circle origin shifted 0 ypart lrcorner outer circle euro circle buildcycle outer circle right line reverse inner circle reverse right slant hor bar euro radius 0 euro radius 0 top slant right slant shifted euro radiusteuro offset euro 1l offset 0 bot slant top slant shifted 0 euro 1 shift if trace euro for i right line right slant top slant bot slant applications The euro symbol draw i withpen pencircle scaled ipt withcolor 5white endfor fi euro topbar buildcycl
85. extreme tensions and show the control points as calculates them sample 21 tension 0 75 z2 23 625red sample zi tension 2 00 z2 z3 625yellow sample z1 z2 z3 625white First we will show the symmetrical tensions Inflection tension and curl The asymetrical tensions are less prominent We use the following values sample zi tension 75 and 10 Z2 23 625red sample zi tension 10 and 75 z2 23 625yellow sample 21 z2 z3 625white What happens when you use the metarosT maximum value of infinity instead of 10 Playing with this kind of graphic can be fun especially when we apply a few tricks def sample expr p c draw p withpen pencircle scaled 2 5mm withcolor white draw p withpen pencircle scaled 2 0mm withcolor c enddef u icm 21 0 0 z2 2u 4u z3 4u 0 for i 0 step 05 until 1 Inflection tension and curl sample zi tension 75 i z2 23 i 625red 625yellow endfor Here we change the color along with the tension This clearly demonstrates that we re dealing with a non linear phenomena We can misuse transparant colors to illustrate how the effect becomes less with growing tension def sample expr p c draw p withpen pencircle scaled 2 0mm withcolor c enddef u 21 0 0 z2 2u 4u z3 4u 0 for i 0 ste
86. figure in any way supported by the macro package that you use Figure 3 8 A silly figure demonstrating that stand alone graphics can be made 3 9 Managing resources A graphic consists of curves either or not filled with a given color graphic can also include text which means that fonts are used Finally a graphic can have special effects like a shaded fill Colors fonts and special effects go under the name resources since they may demand special care or support from the viewing or printing device Special effects like shading are supported by dedicated Metarost modules These are included in the CONTEXT distribution and will be discussed later in chapter 8 Since METRPOST supports color an embedded graphic can be rather colorful However when color support is disabled or set up to convert colors to gray scales CONTEXT will convert the colors in the graphics to gray scales You may wonder what the advantage is of weighted gray conversion Figure 3 9 shows the dif ference between natural colors weighted gray scales and straightforward non weighted gray 565 full color weighted gray linear gray Figure 3 9 The advantage of weighted gray over linear gray Managing resources e When we convert color to gray we use the following formula This kind of conversion also takes place in black and white televisions 30r 59g 11b Section 8 5 introduces the grayed operation that you can us
87. for i PaperHeight 1 step 1 until 1 1 fill p shifted 0 i StrutHeight reverse p shifted 0 i StrutDepth cycle withcolor 85white Graphics and macros draw p shifted 0 1 withpen pencircle scaled 25pt withcolor 5white draw p shifted 0 i ExHeight withpen pencircle scaled 25pt withcolor 5white draw textext origin strut How are those penalty lines called in english I may not steal candies amp decimal n shifted 1 i shifted 0 StrutDepth endfor StopPage stopMPpage stop This code demonstrates the use of LineHeight ExHeight StrutHeight and StrutDepth We set the interline spacing to 1 5 so that we get a bit more loose layout The variables mentioned are set each time a graphic is processed and thereby match the current font settings Graphics and macros 5 Positional graphics In this chapter we will explore some of the more advanced but also conceptually more difficult graphic capabilities of CONTEXT It took quite a few experiments to find the right way to support these kind of graphics and you can be sure that in due time extensions will show up You can skip this chapter if you are no CONTEXT user 5 1 The concept After Tpx has read a paragraph of text it will try to break this paragraph into lines When this is done the result is flushed and after that Tex will check if a page should
88. fullcircle metafun macro Q outerboundingbox path outerboundingbox fullcircle metafun macro x bottomboundary path bottomboundary fullcircle metafun macro WA o c 3 Q A ath leftboundary fullcircle metafun macro 9 WE b e e c H ath topboundary fullcircle metafun macro 7N 4 Transformations rightboundary path rightboundary fullcircle N 2 bbwidth path draw textext decimal bbwidth fullcircle xscaled 100 yscaled 200 190 LWA bbwidth path draw textext decimal bbheight fullcircle xscaled 100 yscaled 200 200 metafun macro x metafun macro metafun macro ath picture xsized numeric currentpicture xsized 5cm metafun macro ath picture ysized numeric currentpicture ysized 2cm metafun macro ath picture xysized numeric currentpicture xysized 3cm 2cm metafun macro Transformations Points ck o air top center fullcircle metapost macro 9 bot center fullcircle g e mm m metapost macro x eh e lft center fullcircle metapost macro bw rt center fullcircle e Lm metapost macro 9 oint numeric of path point 2 of fullcircle metapost primitive NS oint numeric on path point 5 on fullcircle metafun macro
89. fullcircle scaled 5cm withcolor red a graphic endfig end Don t forget the semi colons that end the statements If the file is saved as yourfile mp then the file is processed by mpost mem metafun mem yourfile The results are available in yourfile 1 and can be viewed with GHOSTSCRIPT You don t need to close the file so reprocessing is very convenient Alternatively you can use CONTEXT In that case a simple file looks like starttext startMPpage fill fullcircle scaled 5cm withcolor red stopMPpage startMPpage fill unitsquare scaled 5cm withcolor red stopMPpage stoptext If the file is saved as yourfile tex then you can produce a PDF file with context yourfile This will use LUATEX and CONTEXT MKIV to produce a file with two pages using the built in vEraPosT library with METAFUN When you use this route you will automatically get the integrated text support shown in this manual including OPENTYPE support If one page is enough you can also say startMPpage fill fullcircle scaled 5cm withcolor red stopMPpage So when you have a running CONTEXT on your system you don t need to bother about installing METRPOST and running METAFUN We will use lots of color Don t worry if your red is not our red or your yellow does not match ours We ve made color definitions to match the overall design of this document but you should feel free to use any color of choice in the upcoming examples We assume tha
90. g d n 1 fi 3 enddef vardef drawmidpoints expr p n save a b c pair a b c d for x 0 upto length p 1 a point of p b postcontrol x of p d point 1 of p c precontrol 1 of p dodrawmidpoints a b c d n endfor enddef We apply this macro to a simple shape drawmidpoints fullcircle xscaled 300pt yscaled 50 1 When drawn this results in the points that makes up the curve We now add an extra iteration resulting in the yellow points drawmidpoints fullcircle xscaled 300pt yscaled 50pt 2 Curve construction A ew more detail and get e e LP e o We don t even need that much iterations to get a good result The depth needed to get a good result depends on the size of the pen and the resolution of the device on which the curve is visualized for i 1 upto 7 drawmidpoints fullcircle xscaled 300pt i 1O0pt yscaled 50pt i 10pt i endfor Here we show 7 iterations in one graphic In practice it is not that trivial to determine the depth needed The next example demonstrates how the resolution of the result depends on the length and nature of the segment drawmidpoints fullsquare xscaled 300pt yscaled 50pt randomized 20pt 10pt 5 Inflection tension and curl The MET8POST manual describes the meaning of as choose an infle
91. getbuffer Sometimes it makes sense to collect buffers in separate files In that case we give them names This time we should say typebuffer mfun to typeset the code verbatim Instead of Tex code we can put METRPOST definitions in buffers Buffers can be used to stepwise build graphics By putting code in multiple buffers you can se lectively process this code startbuf fer red drawoptions withcolor 625red stopbuffer startbuffer yellow drawoptions withcolor 625yellow stopbuffer We can now include the same graphic in two colors by simply using different buffers This time we use the special command processMPbuf fer since getbuffer will typeset the code fragment which is not what we want Embedded graphics Graphic buffers startlinecorrection blank processMPbuffer red graphic stoplinecorrection The line correction macros take care of proper spacing around the graphic The blank directive tells CONTEXT to add more space before and after the graphic startlinecorrection blank processMPbuffer yellow graphic stoplinecorrection Which mechanism you use multiple buffers or re usable graphics depends on your preferences Buffers are slower but don t take memory while re usable graphics are stored in memory which means that they are accessed faster 3 6 Communicating color Now that color has moved to the desktop even simple documents ha
92. graphic In the regular dis tributions you will find a module graph mp that provides many ways to accomplish this For the moment METAFUN does not provide advanced features with respect to drawing functions so this section will be relatively short When drawing a functions for educational purposes we need to draw a couple of axis or a grid as well as a shape Along the axis we can put labels For this we can use the package format mp but this does not integrate that well into the way METAFUN deals with text typeset by TEX For those who love dirty tricks and clever macros close reading of the code in format mp may be worthwhile The format macros in there use to typeset the core components of a number and use the dimensions of those components to compose combinations of signs numbers and superscripts In METAFUN we have the module mp form mp which contains most of the code in format mp but in a form that is a bit more suited for fine tuning This permits us to use either the composition method or to fall back on the textext method that is part of METAFUN That way we can also handle fonts that have digits with different dimensions Another change concerns the pattern separator Instead of a we use 6 you can choose to set another separator but for embedded definitions is definitely a bad choice because sees it as a comment and ignores everything following it drawoptions withpen pencircle sc
93. have been made because I would never have thought of them or percelved why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas Hostadter pop M typesetting system has become and around the world By contrast his METAFONT system for designing Tacs of Knuth sets forth for the first time the underlying ceux Uc CIE a Meta Font odd Figure 6 4 A background with enlarged text area we can use the corners of those startuseMPgraphic page StartPage path Main if OnRightPage Main lrcorner llcorner ulcorner urcorner else Main llcorner lrcorner urcorner ulcorner Field OuterMargin Text Field Text Text Field Text Text Field OuterMargin Text Field OuterMargin Text Field Text Text Field Text Text Field OuterMargin Text cycle cycle Crossing borders fi Main Main enlarged 6pt pickup pencircle scaled 2pt fill Page withcolor 625white fill Main withcolor 850white draw Main withcolor 625red StopPage stopuseMPgraphic In this definition we calculate a different path for odd and even pages When done we enlarge the path a bit If you want to use different offsets in all di
94. height stopMPclip To load a buffer we have to specify its name and type as in placefigure here fig clipped text 1 A clipped buffer text clip nx 1 ny 1 mp text clip externalfigure sample type buffer width 4cm METAPOST Clip is 14 the same as a video clip although we can use METAPOST to oduce a video Figure 8 6 A clipped buffer text The next few lines demonstrate that we can combine techniques like backgrounds and clipping startuseMPgraphic clip outline draw fullcircle xscaled overlaywidth yscaled overlayheight Hspeciareitegs _ Clipping withpen pencircle scaled 4mm withcolor 625red stopuseMPgraphic defineoverlay clip outline useMPgraphic clip outline placefigure here fig clipped text 2 A clipped buffer text framed background clip outline offset overlay frame off clip nx 1 ny 1 mp text clip externalfigure sample type buffer width 4cm We could have avoided the framed here by using the clip outline overlay as a background of the sample In that case the resulting linewidth would have been 2 5 mm instead of 5 mm since the clipping path goes through the center of the line METAPOST Clip is the same as a video clip although we can use METAPOST to oduce a video cli Figure 8 7 A clipped buffer text In most cases the clip path will be a rather simple path and defining s
95. in this definition is the fact that we let metaPosT interpolate between the two colors using 5 startuseMPgraphic first numeric size delta size 2 5cm delta size 3 color mainshade topshade bottomshade centershade mainshade MPcolor funcolor topshade 9mainshade bottomshade 5mainshade centershade 5 topshade bottomshade stopuseMPgraphic The color funcolor is provided by CONTEXT and since we want to use this graphic with different colors this kind of mapping is quite convenient The bunch of graphics is packaged in a combi nation with empty captions Note how we set the color before we include the graphic startcombination 5 2 definecolor funcolor red useMPgraphic second definecolor funcolor green useMPgraphic second definecolor funcolor blue useMPgraphic second definecolor funcolor yellow useMPgraphic second definecolor funcolor white useMPgraphic second definecolor funcolor red useMPgraphic third definecolor funcolor green useMPgraphic third definecolor funcolor blue useMPgraphic third definecolor funcolor yellow useMPgraphic third definecolor funcolor white useMPgraphic third stopcombination ir zr ir zr ir We use a similar arrangement for the following graphic where we have replaced the definitions of first second and third by new definitions The definition of the fi
96. it like reversing Close reading of the previous code learns that the macro handles both directions Marking angles IND C Multiples of 90 degrees are often identified by a rectangular symbol We will now extend the previously defined macro in such a way that more types can be drawn numeric anglelength anglelength numeric anglemethod anglemethod 20pt 1 vardef anglebetween expr a b str path path string save pointa pointb common middle offset pair pointa pointb common middle offset save curve path curve save where numeric where if round point 0 of round point 0 of b common point O of a else common a intersectionpoint b fi pointa point anglelength pointb point anglelength on b where turningnumber common pointa pointb cycle middle common pointa rotatedaround pointa where 90 intersectionpoint common pointb rotatedaround pointb where 90 if anglemethod 1 curve pointa unitvector middle pointa pointb middle point 5 along curve elseif anglemethod 2 middle common rotatedaround 5 pointa pointb 180 curve pointa middle pointb elseif anglemethod 3 curve pointa middle pointb elseif anglemethod 4 curve pointa controls middle pointb middle point 5 along curve fi draw thefreelabel str middle common withco
97. manual these four components would have hurt TEX significantly IFI had not Pecan ei literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Knuth has spent the past several years working on a system allowing him to control his forthcoming books from even odd Figure 6 2 A background with combined areas In figure 6 2 you see two pages odd and even with a background spanning the outer margin and the text area You can access an area in two ways The area itself is available as Area StartPage fill Area Text Text withcolor 85white StopPage If you use an area this way you will notice that it is not positioned at the right place An Area is just a rectangle If you want a positioned area you should use the Field array StartPage fill Field Text Text withcolor 85white StopPage The location of an area is available in Location so the previous definition is the same as Crossing borders StartPage fill Area Text Text shifted Location Text Text withcolor 85white StopPage The following definition fills and draws the margin
98. recalcula tion with setupbackgrounds state repeat Multiple overlays You can test this concept yourself with the following code Here we assume that you have a file called tufte tex on your system which is the case if you have CONTEXT installed However you can just as easily use any file having a paragraph of two of text starttext setupinteraction state start setupbackgrounds state repeat def ineoverlay nextpage overlaybutton nextpage setupbackgrounds text text background nextpage dorecurse 20 input tufte par stoptext Note that you can move forward from page to page in the resulting PDF file by clicking on each page with the mouse Now compile this file without setting the background state to repeat and note the difference as you click pages with the mouse Setting the state was not needed when we used the page background setupbackgrounds page background nextpage The dorecurse macro is handy for testing since it saves us typing One can nest this macro as in dorecurse 20 dorecurse 10 Hello World par The current step is available in recurselevel and the depth nesting level in recursedepth 6 4 Crossing borders In many cases the previously mentioned background areas will suffice but in the case of more complicated backgrounds you may wish to use to draw graphics that combine or span these areas At runtime
99. size 6 yscaled size 12 draw halfcircle rotated 90 scaled size pickup pencircle scaled size 4 if MPvar type 1 for i 1 1 draw origin shifted 0 ixsize 4 endfor elseif MPvar type 2 for i 1 1 draw origin shifted size 2 i size 4 endfor pickup pencircle scaled size 6 draw size 4 0 size 4 0 fi stopuniqueMPgraphic We can now change some characteristics of the smilies without the need to redefine the graphic setupMPvariables smile height 1ex color darkred Say it with a or maybe even although seeing too many gt 555555555 in one text may make you cry In order to keep the smilies unique there is some magic involved watch the second argument in the next line startuniqueMPgraphic smile type height color Because unique graphics often are used in backgrounds its uniqueness is determined by the over lay characteristics In our case however the uniqueness is determined by the smilies type height and color By explicitly specifying these we make sure that they count in the creation of the uniqueness stamp midaligned switchtobodyfont 60pt symbol smile Because we use the ex height the previous call works as expected e e 74 Shape libraries Unfortunately it takes some effort to define graphics attach them to an overlay and invoke the background However the good news is that since in many cases we want a consistent layout we only have to do it once
100. spring z1 22 75cm 2 10 is being parsed the macro is expanded the variables are kept invisible for the assignment and the path at the end is considered to be the return value In a def the whole body of the macro is pasted in the text while in a vardef only the last line is visible We will demonstrate this with a simple example n n n nti enddef n 1 m n enddef def one def two Now when we say pair a b numeric n n 10 a one b two we definitely get an error message This is because when macro two is expanded METAPOST sees something 1 By changing the second definition in vardef two n n 1 n n enddef the increment is expanded out of sight for b and the pair n n is returned We can draw a slightly better looking spring by drawing twice with a different pen The following commands use the spring macro implemented by the vardef path p p 0 0 spring 5cm 0 2 5cm 0 5cm 0 10 3cm 0 draw p withpen pencircle scaled 2pt draw p withpen pencircle scaled withcolor 8white This time we get Since the spring macro returns a path you can do whatever is possible with a path like drawing an arrow Simple drawings A few ww Or even watch how we use the neutral unit u to specify the dimensions This was keyed in as drawarrow 0 0 spring 5cm
101. sqrt 2 scaled 3cm shifted 4 5cm 0 withcolor 625yellow draw origin 1 1 1 0 cycle scaled 3cm shifted 9cm 0 withcolor 625white 1 5 Drawing pictures Once a path is defined either directly or as a variable you can turn it into a picture You can draw a path like we did in the previous examples or you can fill it but only if it is closed Drawing is done by applying the draw command to a path as in draw Ocm 1cm 2cm 2cm 4cm 0cm cycle The rightmost graphic was made with fill fill Ocm icm 2cm 2cm 4cm 0cm cycle If you try to duplicate this drawing you will notice that you will get black lines instead of red and a black fill instead of a gray one When drawing or filling a path you can give it a color use all kinds of pens and achieve special effects like dashes or arrows elcomi Drawing pictures These two graphics were defined and drawn using the following commands Later we will explain how you can set the line width or penshape in terms of METAPOST path p p 0cm 1cm 2cm 2cm 4cm 0cm 2 5cm 1cm cycle drawarrow p withcolor 625red draw p shifted 7cm 0 dashed withdots withcolor 625yellow Once we have drawn one or more paths we can store them in a picture variable The straightfor ward way to store a picture is to copy it from the current picture picture pic pic currentpicture The following command effectively cl
102. that the previous definition of the fuzzy counter drawing is not suited to generate the graphics we started with useMPgraphic fuzzycount n 1001 This time we want to limit the width to the current hsize We only need to add a few lines of code Watch how we don t recalculate the bounding box when more lines are used startuseMPgraphic fuzzycount begingroup save height vstep hsize span drift d cp height 3 4 the bodyfontsize currentfontscale span 1 3 height drift 1 10 height hsize the hsize vstep the lineheight xmax hsize div 5span pickup pencircle scaled 1 12 height def d uniformdeviate drift enddef 5 symbols and buttons Random graphics for i 1 upto MPvar n xpos i 1 mod 5 xmax span ypos i 1 div 5 xmax vstep draw if i mod 5 0 d 4 5span d d 0 5span height d else d d d height d fi shifted xpos ypos d drift endfor picture cp cp currentpicture if ypart ulcorner cp ypart llcorner cp lt vstep setbounds currentpicture to 11 cp shifted 0 ypart llcorner cp lrcorner cp shifted 0 ypart lrcorner cp urcorner cp ulcorner cp cycle fi endgroup stopuseMPgraphic 7 3 Graphic variables In the previous sections we have seen that we can pass information to the graphic by means of var
103. that we may not end the vardef with a semi colon So when the content of the vardef is expanded we get something draw some picture Music sheets few Because we are still drawing something we can add transform directives and set attributes like the color The second for loop demonstrates two nice features Instead of repeating the draw operation by copying code we apply it to a list in our case a list of paths This list contains two simple line paths Because an image starts with a fresh currentpicture we can safely use the bounding box data to determine the height of the line The next step in producing the sheets of paper is to put several bars on a page preferable with the width of the current text This time we will use a reusable graphic because each bar is the same startreusableMPgraphic bars includeMPgraphic bar draw MusicBar TextWidth 6pt ipt 2pt withcolor 625yellow stopreusableMPgraphic pd Instead of going trough the trouble of letting metarost calculate the positions of the bars we will use We put 12 bars on a page and let take of the inter bar spacing Because we only want stretchable space between bars called glue in TEX we need to remove the last added glue startstandardmakeup doublesided no page dorecurse 15 reuseMPgraphic bars vfill removelastskip stopstandardmakeup It may add to the atm
104. the chaff and separate the sheep from the goats Donald E Knuth Thus came to the conclusion that the designer of a new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt TEX significantly If I had not participated fully in all these activities literally hundreds of improvements would never have been made because would never have thought of them or perceived why they were important Buta system cannot be successful if it is too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her work Knuth s TEX typesetting system has become well known and available in many countries around the world By contrast his METAFONT system for designing families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some o
105. the redraw and refill macros redraw currentpicture withpen pencircle scaled 4pt withcolor 625yellow refill currentpicture withcolor 625white setbounds currentpicture to boundingbox currentpicture enlarged 2pt 13 10 Killing time Not seldom users want to use this program and its meta relatives as general purpose tools even at the cost of quite some effort or suboptimal results Imagine that you are under way from our planet to Mars After a long period of sleep you wake up and start wondering on what track you are You even start questioning the experts that send you on your way so you pop open your laptop launch your editor and start metaposting First you need to determine the begin and end points of your journey For this it is enough to know the relative angle of the paths that both planets follow as well as the path themselves We assume circular paths path a path b b fullcircle scaled 3cm fullcircle scaled 2cm rotated 120 draw a withpen pencircle scaled imm withcolor 625red ul 2 j Killing time draw b withpen pencircle scaled 1 withcolor 625yellow draw point O of a withpen pencircle scaled 2mm draw point O of b withpen pencircle scaled 2mm The rotation 120 can be calculated from the relative starting points and time the journey will take Alternatively we can use the time along the path but this would be a bit more fuzzy later on After
106. this background shape behind the running text for instance with some inframed background Shape text with a frame some Shaped text with a frame some text with a frame some text with a frame The Shaped macro was defined as def ineframed Shaped background Shape f rame off location low Watch how the graphics are moved to the background while the frame of the first text stays on top since it remains part of the text flow Some text with a frame some text with a frame In the previous instance of the example we have reversed the stacking Reversal can be done with the direction directive setuplayer BackLayer direction reverse You can influence the placement of a background component by using a different anchor point setuplayer BackLayer position no corner bottom height paperheight setlayer BackLayer x 1cm y 10cm location b1 externalfigure somecow pdf width 1cm setlayer BackLayer x 5cm y 8cm location br externalfigure somecow pdf width 1cm setlayer BackLayer x 1cm y 4cm location t1 externalfigure somecow pdf width 1cm setlayer BackLayer x 10cm y 5cm location tr externalfigure somecow pdf width 3cm Instead of using relative positions you can also use absolute ones Of course you need to know how your coordinates relate to the rest of the layout definition setuplayer
107. this three times which is why these curves are classified as third order approximations The first series of graphics demonstrates the process of determining the mid points The third order midpoint is positioned on the final curve The second series focuses on the results new sets of four points that will be used in a next stage The last series only shows the third order midpoints As you can see after some six iterations we have already reached a rather good fit of the final curve The exact number of iterations depends on the resolution needed You will notice that the construction speed density differs per segment The path in these examples is defined as follows path p p 4cm 4cm 6cm Ocm 1cm 2cm If you are playing with graphics like this the METAFUN macro randomize may come in handy p p randomized 1cm 5cm If we apply this operation a couple of times we can see how the control points vary Using the randomizer saves us the troubles of finding nice example values The angle between the tangent as well as the distance from the parent point determine the curve A few more details Curve construction points first order curve second order curve third order curve left side curves right side curves Curve construction points firs
108. to Va b Thus the expression xpart b a ypart b a calculates the length of the vector b a Because the unscaled spring has length n 2h scaling by the expression xpart b a ypart b a n 2h gives the spring the same length as the vector b a Because we have drawn our spring in the vertical position we first rotate it 90 degrees clockwise to a horizontal position and then rotate it through an angle equal to the angle in which the vector b ais pointing After that we shift it to the first point The main complications are that we also want to draw connecting lines at the beginning and end as well as support springs that connect arbitrary points Since no check is done on the parameters you should be careful in using this macro When we want to improve the readability we have to use intermediate variables Since the macro is expected to return a path we must make sure that the content matches this expectation Simple drawings vardef spring expr a b w h pair vec path pat numeric len numeric ang vec b a pat for i 1 upto n 1 if odd i fi w 2 i endfor 0 n pat 0 0 0 h pat shifted 0 h 0 n h 0 n42h len xpart vec ypart vec n42h ang 90 angle vec pat yscaled len rotatedaround origin ang shifted a enddef If you use vardef then the last statement is the return value Here when p
109. to duplicate a graphic this time we show the dark alternatives colorcircle 4cm 5red 5green 5blue This kind of unsafe path calculations are very sensitive to breaking Changing the radius 4 into something else demonstrates this but we will not challenge this macro that much Therefore the 50 color circle shows up as This command is part of METAFUN and can be used to determine nice color combinations by also looking at their complementary colors colorcircle 4cm 7red 5green 3blue Bl Color circles The next circle that we draw shows the three main colors used in this document This circle is not that beautiful colorcircle 4cm 625red 625yellow 625white This definition can be cleaned up a bit by using transform but the fuzzy buildcycle s remain vardef colorcircle expr size red green blue save r g b rr gg bb cc mm yy save radius path r g b rr bb gg cc mm yy numeric radius radius 5cm pickup pencircle scaled radius 25 transform t t identity rotatedaround origin 120 r fullcircle scaled radius shifted 0 radius 4 rotatedaround origin 15 transformed t b transformed t r r rotatedaround center r 90 g rotatedaround center g 90 gg buildcycle buildcycle reverse r b g cc buildcycle buildcycle b reverse g r rr gg transformed t bb rr transformed t yy cc
110. transformed t mm yy transformed t fill fullcircle scaled radius withcolor white fill rr withcolor red fill cc withcolor white red fill gg withcolor green fill mm withcolor white green fill bb withcolor blue fill yy withcolor white blue for i rr gg bb cc mm yy draw i withcolor 5white endfor currentpicture currentpicture xsized size enddef Color circles This rather nice circle is defined as colorcircle 4cm 4 6 8 8 4 6 6 8 4 The final implementation which is part of METAFUN is slightly more efficient vardef colorcircle expr size red green blue save g b c m w save radius path r g b c m y w numeric radius radius 5cm pickup pencircle scaled radius 25 transform t t identity rotatedaround origin 120 fullcircle rotated 90 scaled radius shifted 0 radius 4 rotatedaround origin 135 H ll b r transformed t g b transformed t c buildcycle subpath 1 7 of g subpath 1 7 of b c transformed t m y transformed t w buildcycle subpath 3 5 of r subpath 3 5 of g subpath 3 5 of b pushcurrentpicture fill r withcolor red fill g withcolor green fill b withcolor blue fill c withcolor white red fill m withcolor white green fill y fill w withcolor white blue withcolor white for i r g b c m y draw i withcolor 5white endf
111. using the METAFUN textext macro works well enough but when the typeset text needs to communicate with the typesetting engine for instance because it contains hyperlinks or references you can use the following method define a layer define a reusable graphic put your text into the layer combine the graphic with the text You must be aware of the fact that when the layer is flushed its content is gone You can take advantage of this by using the same graphic with multiple texts definelayer test You don t need to pass the width and height explicitly but when you do so you have access to them later startuseMPgraphic oeps path p fullcircle scaled fill p withcolor 8white draw p withpen pencircle scaled 1mm withcolor 625red register somepos 1 0cm 0cm center currentpicture register somepos 2 3cm 1cm 1cm 1cm register somepos 3 2cm Ocm 2cm 2cm stopuseMPgraphic The METAFUN register macro takes the following arguments register tag width height x offset y offset The width and height are available in the macros MPlayerwidth and MPlayerheight and are equivalent to MPw tag and MPh tag Positional graphics Complex text in graphics setMPlayer test somepos 1 location c Does it work al right setMPlayer test somepos 2 framed width MPlayerwidth height MPlayerheight background color backgroun
112. visual debugging features Nevertheless we provide a few that are all based on visualizing paths 2 e 3 1 e e 4 e e e 5 T e 6 This visualization is achieved by using dedicated drawing commands path p fullcircle scaled 4cm drawpath p drawpoints p drawpointlabels p Since control points play an important role in defining the shape visualizing them may shed some insight in what metarost is doing path p fullcircle xscaled 4cm yscaled 3cm drawpath p drawcontrollines p drawpoints p drawcontrolpoints p drawpointlabels p The pre and post control points show up as small dots and are connected to their parent point with thin lines Libraries You can deduce the direction of a path from the way the points are numbered but using an arrow to indicate the direction is more clear path p fullcircle xscaled 4cm yscaled 3cm drawarrowpath p drawcontrollines p drawpoints p drawcontrolpoints p drawpointlabels p The drawarrowpath is responsible for the arrow Especially when you are in the process of defining macros that have to calculate intersections or take subpaths knowing the direction may be of help The next table summarizes the special drawing commands drawpath the path drawarrowpath the direction of the path drawcontrollines the lines to the control points drawpoints the points that make up the path drawcontrolpoints the co
113. width 4cm Clipping is combined with a matrix as in figure 8 3 The content to be clipped is divided in nx by ny rectangles For instance nx 5 and ny 8 will produce a 40 cell grid with 5 columns of 8 rows 11 3 1 Figure 8 3 A clipped cow Here we have divided the cow in six cells so that we can clip its head and tail This kind of clipping enables you to zoom in or focus on a specific part of a graphic setupclipping nx 3 ny 2 startcombination clip x 1 y 1 externalfigure cow mps width 4cm 1 1 clip x 3 y 1 externalfigure cow mps width 4cm 3 1 stopcombination Alternatively we can specify a width height hoffset and voffset as demonstrated in figure 8 4 1 8 Figure 8 4 Another clipped cow placefigure here fig clipped cow 2 Another clipped cow clip width 2cm height 2cm hoffset 0cm voffset 0cm fNexternalfigure cow mps width 4cm Because METAPOST supports clipping it will be no surprise that both techniques can be combined In the next example we will zoom in on the head of the cow We also use this opportunity to demonstrate how you can package a clip in a figure definition startMPclipfhead clip w Width h height clip currentpicture to O h w h down left 0 0 cycle stopMPclip placefigure here fig circular clipped cowhead A quarter circle applied to a cows head ruledhbox clip n
114. with a gray fill Since METRPOST does not support the CMYK color space and native gray scales although gray colors are reduced to the more efficient POSTSCRIPT setgray operators in the output the macro MPcolor takes care of the translation from CMYK to RGB as well as gray to RGB However there is a fundamental difference between a yellow as defined in CONTEXT using CMYK and a RGB yellow in METRPOST definecolor cmyyellow y 1 definecolor rgbyellow r 1 g 1 definecolor cmydarkyellow y 625 definecolor rgbdarkyellow r 625 g 625 Figure 3 3 demonstrates what happens when we multiply colors by a factor Since we are not dealing with real CMYK colors multiplication gives different results for CMYK colors passed as MPcolor yellow 1 1 0 5 5 0 MPcolor rgbyellow MPcolor rgbdarkyellow 5 MPcolor rgbyellow MPcolor cmyyellow MPcolor cmydarkyellow 5 MPcolor cmyyellow Figure 3 3 All kinds of yellow So 625red is the same as r 5 but 625yellow is not the same as y 5 but matches r 5 g 5 Figure 3 4 shows the pure and half reds red 1 0 0 625 0 0 MPcolor red MPcolor darkred 625 1 Figure 3 4 Some kinds of red edded Braphics B Communicating color Inorder to prevent problems we advise you to stick to RGB color specifications when possible That way you not only prevent conversion problems but also get more predictable resul
115. x NO Points oint numeric alon ath point 1cm along fullcircle metafun macro x 24 recontrol numeric of path precontrol 2 of fullcircle metapost primitive x Sau ostcontrol numeric of path postcontrol 2 of fullcircle metapost primitive 9 directionpoint pair of path directionpoint 2 3 of fullcircle metapost primitive 4 5 Ei pae m H un irpair 5 0 0 1 1 metapost concept 4 ath intersectionpoint path fullcircle intersectionpoint fulldiamond metapost macro UN SZ Points 4 Attributes withcolor rebcolor withcolor 625 0 0 metapost primitive Q z d gt Sg Cy Q rt rx O withrgbcolor 625 0 0 metapost primitive 9 z gt H xs FS H r3 ri withcmykcolor 625 0 0 0 metapost primitive ax NS z gt o 5 oO 2 Cy withgray 625 metapost primitive a NA withcolor cmyk c m y k withcolor cmyk 0 625 625 0 metafun macro a NA withcolor transparent num num color withcolor transparent 1 625 red metafun macro NY withshade numeric f Shades need to be declared before they can be re used ED dashed withdots dashed withdots metapost primitive dashed evenly metapost primitive withpen
116. z0 zi z2 z3 cycle 20 21 22 23 1 20 21 22 23 1 Since there are and it will be no surprise that there is also Constructing paths z0 zi z2 z3 cycle If you compare this graphic with the one using the result is the same but there is a clear differ ence in control points As a result combining with or makes a big difference Here we get a non smooth connection between the curves and the straight line 20 21 22 23 1 As you can see in the next graphic when we use we get a smooth connection between the straight line and the rest of the curve 20 21 22 23 1 So far we have joined the four points as path Alternatively we can constrict subpaths connect them using the ampersand symbol amp 20 21 722 amp z2 z3 z0 amp cycle So far we have created a closed path Closing is done by cycle The following path may look closed but is in fact open Constructing paths 20 21 22 23 20 Only a closed path can be filled The closed alternative looks as follows We will see many exam ples of filled closed paths later on 20 21 22 23 20 1 Here the final will try to make a smooth connection but because we already are at the starting point this is not possible However the cycle command can au
117. 0 z3 625red sample 21 curl infinity z2 curl infinity z3 625yellow sample zi curl 1 z2 curl 1 z3 625white It may sound strange but internally can handle larger values than infinity sample 21 curl infinity z2 curl infinity 23 625red sample 21 curl 4infinity z2 curl 4infinity 23 625yellow sample 21 curl 8infinity z2 curl 8infinity 23 625white Although this is quite certainly undefined behaviour interesting effects can be achieved When you turn off metarost s first stage overflow catcher by setting warningcheck to zero you can go upto 8 times infinity which being some 2 is still far from what today s infinity is supposed to be As the built in MetaPost command accepts the curl and tension directives as described in this section you will now probably understand the following plain mETRPOST definitions def curl i curl 1 enddef def tension infinity enddef def tension atleast 1 enddef These definitions also point out why you cannot add directives to the left or right side of and they are directives themselves Transformations A transform is a vector that is used in what is called an affine transformation To quote the META POST manual If p px py is a pair and T is a transform then p transform T isa pair of the form tx taxPx tyxPx
118. 0 6 Libraries 247 11 Debugging 255 12 Definingstyles 261 121 Adaptivebuttons 261 13 A few applications 271 13 1 Simple drawings 271 132 Free labels 274 13 3 Marking angles 279 134 Color circles 285 13 5 Fool yourself 292 13 6 Growing graphics 296 13 7 Simple Logos 304 13 8 Music sheets 309 13 9 The euro symbol 310 13 10 Killing time 14 METAFUN macros 319 A METAPOST syntax desee ay bon i e 321 1 Syntax diagrams 321 A2 Leftovers 331 B This document 333 C Reference 335 Cal Paths tek vi RM 335 C 2 Transformations 346 C3 Points 2 ERE EAR 357 C4 Attributes 359 CS Text vns ie Red et 364 C 6 Graphics 366 D Literature 367 D 1 METAFONT and METAPOST 367 D2 WX Ie en Ys 367 CONTEXT 367 DA Tools uie 34 be Ds 368 D 5 Distributions 368 Index 22b 369 Conventions When reading this manual you may be tempted to test the examples shown This can be done in several ways You can make a file and process that file by meTaPosT Such a file looks like beginfig 1 fill
119. 1 0 2 0 2 1 2 2 1 2 0 2 0 1 cycle xysized 4cm 2cm drawpath p drawpoints p p simplified p shifted 5cm 0 drawpath p drawpoints p A cousin of the previous operation is unspiked This one removes ugly left overs It works well for the average case path p p 0 0 2 0 3 1 2 0 2 2 1 2 1 3 1 2 0 1 1 xysized 4cm 2cm drawpath p drawpoints p p unspiked p shifted 5cm 0 drawpath p drawpoints p There are a couple of operations that manipulate the path in more drastic ways Take randomized path p p fullsquare scaled 2cm drawpath p drawpoints p Welcome toaMetaPosts Some extensions p shifted 5cm 0 randomized 5 drawpath p drawpoints p Or how about squeezed path p p fullsquare scaled 2cm randomized 5cm drawpath p drawpoints p p p shifted 5cm 0 squeezed 5cm drawpath p drawpoints p A punked path is like a punked font a font with less smooth curves in our case only straight lines path p fullcircle scaled 2cm randomized 5cm drawpath p drawpoints p p punked p shifted 5cm 0 drawpath p drawpoints p A curved path on the other hand has smooth connections Where in many cases a punked path becomes smaller a curved path will be larger path p p fullsquare scaled 2cm randomiz
120. 1 upto n draw pic i shifted len draw boundingbox pic i shifted len withpen pencircle scaled 25pt withcolor red len len xpart urcorner pic i xpart llcorner pic i 0 endfor stopMPdrawing We can call up this drawing with getMPdrawing but first we inform the compiler that our META post drawing is completed MPdrawingdonetrue getMPdrawing This results in o sFun MetaPost Compare this text with the text as typeset by MetaPost is Fun and you will see that the text produced by metarost is not properly kerned When putting charac ters after each other uses the information available in the font to optimize the spacing between characters while metaPosT looks at characters as separate entities But since we have stored the optimal spacing in len we can let do a better job Let s first calculate the correction needed startMPdrawing for i 1 upto n wid i abs xpart urcorner xpart llcorner pic il pos i len il wid i TESTOR ae endfor stopMPdrawing This compares well to the text as typeset by MetaPost is Fun We can now use the values in pos to position the pictures according to what considered to be the best relative position startMPdrawing for i 1 upto n draw pic i sh
121. 3pt 0 Hiding intermediate calculations and manipulations is a very strong point of METRPOST Another important difference between both languages is the way grouping is implemented Be cause is dealing with a flow of information strong grouping is a must and therefore part of 8 This version resulted from a discussion on the METAFONT discussion list and is due to Boguslaw Jackowski In the calculation can be done in less lines using a numexpr versus METAPOST A few more detail the language Occasionally you run into situations where you wished that you could reach over a group for instance in order to pass a value In METAPOST grouping behaves quite different First of all it provides the mechanism that hides processing from the current flow The previously mentioned vardef is implicitly grouped Con trary to in mETRPOST all assignments are global by default even in a group If you assign a variable inside a group it is persistent unless you first save the variable or macro using the save operator So in the next code snippet the value of value inside the box is no but after the box is typeset it will be yes again def value yes hbox def value no value value To make a value local in the following code is needed string value value yes def intermezzo begingroup save value string value value
122. 625 850 withpen pencircle scaled 5pt randomized ipt So randomized can handle a numeric pair path and color and its specification can be a numeric pair or color depending on what we re dealing with In the previous example we also see xyscaled in action Opposite to scaled xscaled and yscaled this is not one of mETRPOST build in features The same is true for the sized operators picture p p image draw fullsquare xyscaled 300 800 withpen pencircle scaled 50 withcolor 625 yellow draw p xysized 3cm 2cm shifted bbwidth currentpicture 5cm 0 draw p xysized 2 shifted bbwidth currentpicture 5cm 0 draw p xsized shifted bbwidth currentpicture 5cm 0 draw p ysized 2cm shifted bbwidth currentpicture 5cm 0 Welcome to MetaPosl Some extensions Here the image macro creates an actually rather large picture The last four lines actually draw this picture but at the given dimensions Watch how the line width scales accordingly If you don t want this you can add the following line redraw currentpicture withpen pencircle scaled 2pt draw boundingbox currenpicture withpen pencircle scaled 5mm Watch how the boundingbox is not affected UL In this example we also used bbwidth which has a companion macro bbheight You can apply this macro to a path or a picture In fact you don t always need to follow th
123. 92bp 95 05238bp 1 77025bp 107 38231bp 6 4069bp 106 13466bp 14 96152bp 89 02438bp 31 50317bp 55 9419bp So reading in this file at the start of a paragraph will setup Tpx to follow this shape The final implementation is a bit more complicated since it takes care of paths that are not centered around the origin and don t start at the top point We achieve this by moving the path to the center Cp center p q p shifted cp The arbitrary starting point is taken care of by a slightly more complicated path cutter First we make sure that the path runs counterclockwise if xpart directionpoint t of lt 0 q reverse q fi Knowing this we can split the path in two using a slightly different splitter cutbefore t if xpart point 0 of q lt 0 amp q fi cutafter b cutbefore b if xpart point 0 of q gt 0 amp q fi cutafter t H H H ll H OF As always when implementing a feature like this some effort goes into a proper user interface In doing so we need some trickery that goes beyond this text like collecting text and splitting of the part needed Also we want to be able to handle multiple shapes at once like the next example demonstrates 10 6 Libraries The macro discussed in the previous section is included in one of the metarost libraries so we first have to say NuseMPlibrary txt We define four shapes They are not really beautiful but they demonstrate what happens in border ca
124. A path can be open or closed The previous path is an example of a closed path An open path looks like this When we close this path and in a moment we will see how to do this the path looks like Paths The open path is defined 1cm 1cm 1 5cm 1 5cm 2cm Ocm The double period connector tells that we want to connect the lines by a smooth curve If you want to connect points with straight line segments you should use Closing the path is done by connecting the first and last point using the cycle command 1cm i1cm 1 5cm 1 5cm 2cm 0cm cycle Feel free to use or at any point in your path 1cm 1cm 1 5cm 1 5cm 2cm 0cm cycle This path when drawn looks like this As you can see in some of the previous examples METRPOST is capable of drawing a smooth curve through the three points that make up the path We will now examine how this is done Q The six small points are the so called control points These points pull their parent point in a certain direction The further away such a point is the stronger the pull Each point has at most two control points As you can see in the following graphic the endpoints of a non closed curve have only one control point e A Paths This time we used the path 1 5cm 1 5cm 2cm Ocm 1cm 1cm When you connect points by a smooth
125. BackLayer position no corner bottom height paperheight More layers Positiqnalgraphics_ setlayer BackLayer 15 5 1 1 1 externalfigure somecow pdf width 3cm setlayer BackLayer x 15cm y 5cm location br externalfigure somecow pdf width 3cm setlayer BackLayer x 15cm y 5cm location t1 externalfigure somecow pdf width 1cm setlayer BackLayer x 15cm y 5cm location tr externalfigure somecow pdf width 2cm setlayer BackLayer x 15cm y 5cm location c externalfigure somecow pdf width 3cm These examples again demonstrate how we can influence the placement by assigning an anchor point to position Here we also put the reference point in the lower left corner bottom This mechanism only works when we also use height One of the reasons for developing the layer mechanism was that we needed to slightly change the position of figures in the final stage of typesetting The previous pages demonstrate how one can position anything anywhere on the page but in the case of figures the position may depend on where the text ends up the page Normally when you manipulate a document this way you are in the final stage of typesetting You may qualify this as desk top publishing without actually using a desktop setlayer BackLayer position yes Figure 5 1 location
126. CONTEXT saves information on the layout that can be picked up by metarost The frame work for a page graphic is StartPage all kind of commands StopPage Between the StartPage and StopPage command you have access to a wide range of variables page PaperHeight PaperWidth PrintPaperHeight PrintPaperWidth PageO0ffset PageDepth margins TopSpace BackSpace text MakeupHeight MakeupWidth vertical TopHeight TopDistance HeaderHeight HeaderDistance TextHeight FooterDistance FooterHeight Crossing borders Page batkgiunds BottomDistance BottomHeight horizontal LeftEdgeWidth LeftEdgeDistance LeftMarginWidth LeftMarginDistance TextWidth RightMarginDistance RightMarginWidth RightEdgeDistance RightEdgeWidth Since using these variables to construct paths is not that handy the areas are available as predefined paths which we will demonstrate here synopsize winnow the wheat from the chaff and separate the sheep from the first large scale user influenced design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Knuth has spent the past several years working on a system allowing him to control his books from winnow the wheat from the chaff and separate the sheep from the ea first large scale user Murus DIA
127. ETRFONT system for designing families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting and clearly well executed but in my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory 1 felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font Edward R Tufte Edward R Tufte We thrive in information thick worlds because of our marvelous and everyday capacity to select edit single out structure highlight group merge harmonize synthesize focus organize condense reduce boil down choose categorize catalog classify list abstract scan look into idealize isolate discriminate distinguish sereen pigeonhole pick over sort integrate blend inspect filter lump skip smooth chunk average approximate cluster ite outline sum marize itemize review dip into flip through browse glance into leaf through skim refine enumerate glean synopsize winnow the wheat from
128. For those who need to be inspired we will demonstrate how metarost can be used to enhance your document with simple graphics In these examples we will try to be not too clever simply because we lack the experience to be that clever The real tricks can be found in the files that come with METAPOST 13 1 Simple drawings In the words of John Hobby the creator of MeTAPosT is particularly well suited for generating figures for technical documents where some aspects of a picture may be controlled by mathematical or geometrical constraints that are best expressed symbolically In other words METAPOST is not meant to take the place of a freehand drawing tool or even an interactive graphics editor An example of such a picture is the following one which is dedicated to David Arnold who asked me once how to draw a spring So imagine that we want to draw a schematic view of a system of four springs A rather natural way to define such a system is 21 23 42cm 0 2cm 0 z2 z4 0 2cm 0 2cm pickup pencircle scaled 1 5pt drawoptions withcolor 625red draw spring z1 draw spring z2 draw spring z3 draw spring z4 z2 z3 24 21 75cm 75cm 75cm 75cm 10 9 8 7 2 draw draw draw draw zi 1 5 z2 1 1 z3 1 5 z4 1 1 21 22 23 5 24 Here the macro spring takes 5 arguments two po
129. In the assignment to 1 we replace 1oc by 1 arclength ori loc unitvector loc ori 13 3 Marking angles A convenient METRPOST macro is unitvector When we draw a line segment from the origin to the point returned by this macro the segment has a length of 1 base point This macro has a wide range of applications but some basic knowlegde of vector algebra is handy The following lines of METRPOST code demonstrate the basics behind unitvectors Marking angles pair uv pickup pencircle scaled imm autoarrows true draw fullcircle scaled 2cm withcolor 625red for i 10 35 40 20 85 15 draw origin i dashed evenly withcolor 625white drawarrow origin unitvector i scaled 1cm withcolor 625yellow endfor draw origin withcolor 625red The circle has a radius of 1cm and the three line segments are drawn from the origin in the direc tion of the points that are passed as arguments Because the vector has length of 1 we scale it to the radius to let it touch the circle By setting autoarrows we make sure that the arrowheads are scaled proportionally to the linewidth of 1 mm An application of this macro is drawing the angle between two lines In the MeTaPosT manual you can find two macros for drawing angles mark angle and mark rt angle You may want to take a look at their definitions before we start developing our own alternatives The pr
130. Margin Text lrcorner Field Text Text urcorner Field Text Text ulcorner Field OuterMargin Text includeMPgraphic draw page StopPage stopreusableMPgraphic The right page text looks similar startreusableMPgraphic right page StartPage path Main Main lrcorner Field OuterMargin Text llcorner Field Text Text cycle Crossing borders ulcorner Field Text Text urcorner Field OuterMargin Text cycle includeMPgraphic draw page StopPage stopreusableMPgraphic Watch how we used a reusable graphic first and a simple usable one next Actually the next graphic is not a stand alone graphic startuseMPgraphic draw page Main Main enlarged 6pt pickup pencircle scaled 2pt fill Page withcolor 625white fill Main withcolor 850white draw Main withcolor 625red stopuseMPgraphic We have seen some predefined paths and locations Apart from the Page path they take two arguments that specify their position on the layout grid path Area an area similar to a CONTEXT one pair Location the position of this area path Field the area positioned at the right place path Page the page itself Some less used and more obscure variables are the following numeric Hstep the horizontal distance to the previous area numeric Vstep the vertical distance to the previous area numeric Hsize the width of an area numeric Vsize the height of an area
131. NNC useMPgraphic fuzzycount n 10 NC MacOS NC 5 7 NC useMPgraphic fuzzycount n 6 NC UNIX NC 51 9 NC useMPgraphic fuzzycount n 55 NC WINDOWS NC 64 2 NC useMPgraphic fuzzycount n 68 HL stoptabulate a dan dan an an NC NR NC NR NC NR NC NR NC NR NC NR NC NR You will notice that we pass a variable to the graphic using a second argument We can access this variable with MPvar The graphic is defined as usable graphic because we want to generate a unique random one each time startuseMPgraphic fuzzycount begingroup save height span drift d cp height 3 5 baselinedistance span 1 3 height drift 1 10 height pickup pencircle scaled 1 12 height def d uniformdeviate drift enddef for i 1 upto MPvar n draw if i mod 5 0 d 4 5span d d 0 5span height d else d d d height d fi shifted span i d drift endfor picture cp cp currentpicture for readability setbounds currentpicture to 11 cp shifted 0 ypart llcorner cp lrcorner cp shifted 0 ypart lrcorner cp urcorner cp ulcorner cp cycle endgroup stopuseMPgraphic The core of the macro is the for loop Within this loop we draw groups of four plus one lines The draw path s look a bit complicated but this has to do with the fact that a mod returns 0 4 while we like to deal with 1 5 The height adapts itself to the height of
132. PT com mands Because METRPOST does all the work this file is efficient and compact The number of distinct POSTSCRIPT operators used is limited which has the advantage that we can postprocess this file rather easily Alternatively meTarost can generate SVG output It does when you say outputformat svg Here we will not go into details about this format Even POSTSCRIPT is not covered in detail as we use METRPOST mostly in embedded form Making graphics few We can view this file in a POSTSCRIPT viewer like GHOSTVIEW or convert the graphic to PDF using mptopdf and view the result in a suitable PDF viewer like ACROBAT Of course you can embed such a file in a CONTEXT document using a command like Nexternalfigure yourfile 7 We will go in more detail about embedding graphics in chapter 3 If you have installed CONTEXT somewhere on your system there resides a file mp too1 mp If you make a stand alone graphic it s best to put the following line at the top of your file input mp tool or input metafun By loading this file the resulting graphic will provide a high resolution bounding box which en ables more accurate placement The file also sets the prologues 1 that viewers like GHOST VIEW can refresh the file when it is changed Next we will introduce some more METAPOST commands From now on we will omit the encapsu lating beginfig and endfig macros
133. RT LHT LT LMY MT H1 MAT LA MET LHT LHET LHAT WT MET HT HT IHT HT LR DAU LA LAT LHT d IHT ME IT LHT HT DT DT MT LHT AE HT LATE HT LHT HT AT MET HE IT reasons why metarost is fun To mention a few you can enhance the layout with graphic or naments you can tune your graphics at runtime and simple high quality graphics can be very effective The previous graphics draws exactly 1001 lines in a scratch numbers in a wall fashion In 1998 the NTG did a survey among its members and in the report we used this fuzzy counter to enhance the rather dull tables system 7o fstusers Atari 104 JW MSDOS 491 JHT Urt utt uu Jut prt wr t uit ti OS 2 9 4 mM MacOS 57 UNIX 51 9 Jf Jtt UHH JH JH VAT T TE UT UT WINDOWS 64 2 Hf LAT HAT HAT IHT JH MAT LHT LHE MT Table 7 1 Operating system n 106 5 symbolstnd buttons Random graphics Table 7 1 demonstrates how scratch numbers be used An interesting side effect is that when you look long enough to these kind of graphics it looks like the lines are no longer horizontal This table is defined as follows Nstarttabulate 1l cl11 HL NC system NC NIC ME users HL NC Atari NC 10 4 NC useMPgraphic fuzzycount n 11 NC MSDOS NC 49 1 NC useMPgraphic fuzzycount n 52 NC 05 2 NC 9 4
134. The current values of the frame color and frame width are passed to the overlay It often makes more sense to use colors defined at the document level if only to force consistency startuniqueMPgraphic super ellipse path p p unitsquare xscaled overlaywidth yscaled overlayheight superellipsed 85 pickup pencircle scaled overlaylinewidth fill p withcolor MPcolor overlaycolor draw p withcolor MPcolor overlaylinecolor stopuniqueMPgraphic defineoverlay super ellipse uniqueMPgraphic super ellipse Foregrounds This background demonstrates that a super ellipse is rather well suited as frame framed background super ellipse frame off width 3cm align middle framecolor darkyellow rulethickness 2pt backgroundcolor darkgray white This is a Super Ellipsed sentence Such a super ellipse looks quite nice and is a good candidate for backgrounds for which the su perness should be at least 85 45 Typesetting graphics I have run into people who consider it kind of strange when you want to use for non mathe matical typesetting If you agree with them you may skip this section with your eyes closed One of the CONTEXT presentation styles number 15 tagged as balls stepwise builds screens full of sentences quotes or concepts packages in balloons and typesets them as a paragraph We will demonstrate that can typeset graphics using t
135. Welcoim o MelaPost startMPdefinitions solvers angle radius 10pt def mark rt angle expr a b c draw 1 0 1 1 0 1 zscaled angle radius unitvector a b shifted b enddef stopMPdefinitions So far most equations are rather simple and in order to solve them metarost did not have to work real hard The only boundary condition is that in order to find a solution must be able to solve all dependencies The actual value of the whatever variable is that it saves us from introducing a slew of variables that will never be used again We could write z0 A zi z3 B z2 z4 and get the same result but the whatever variable saves us the trouble of introducing intermediate variables for which we have no use once the calculation is finished The macro mark_rt_angle draws the angle symbol and later we will see how it is defined First we draw the labels Unfortunately we cannot package btex etex into a macro because it is processed in a rather special way Each btex etex occurance is filtered from the source and converted into a snippet of code When passed through each snippet becomes a page and an auxiliary program converts each page into a METRPOST picture definition which is loaded by METRPOST The limitation lays in the fact that the filtering is done independent from the METAPOST run which means that loops and other code are not s
136. ade fill fullsquare xyscaled 10cm 2cm withcolor 5white fill fullsquare xyscaled 6cm 1 5cm withcolor cmyk 5 5 5 0 fill fullsquare xyscaled 2cm cm withcolor cmyk 0 0 0 5 In figure 3 5 to 3 7 you can see some more colors defined in the CMYK color space When you display the screen version of this document you will notice that the way colors are displayed can differ per viewer This is typical for CMYK colors and has to do with the fact that some assumptions are made with respect to the print medium 1 y 3 k 3 c 9 y 15 25 y 8 c 45 y 1 Figure 3 5 CMYK support disabled conversion to RGB Communicating color Nd c 1 y 3 3 9 y 15 c 25 y 8 45 y 1 Figure 3 6 CMYK support enabled no support METAPOST 1 y 3 k 3 9 y 15 c 25 y 8 45 y 1 Figure 3 7 CMYK support enabled no conversion to RGB support in METRPOST Common definitions When using many graphics there is a chance that they share common definitions Such shared components can be defined by startMPinclusions color mycolor mycolor 625red stopMPinclusions The following is only true for CONTEXT MKII Users of MKIV can skip this section All metarost graphics defined in the document end up in the files mpgraph mp and mprun mp When processed they produce sometimes many graphic files When you use CONTEXT MKII and TEXEXEC to process documents these
137. adius with an r and shift the pictures to the left startMPdrawing numeric r r len n Pi for 1 1 upto picli pic i shifted r 0 endfor stopMPdrawing You can now use the following code to test the current state of the pictures Of course this code should not end up in the final definitions startMPdrawing draw origin withpen pencircle scaled 5pt withcolor red for i 1 upto draw pic i draw boundingbox pic i withpen pencircle scaled 25pt withcolor red endfor stopMPdrawing Later we will write a compact efficient macro to take care of rotation However for the moment so as not to overwhelm you with complicated code we will rotate each individual picture with the following code fragment startMPdrawing numeric delta extra radius rot delta extra radius 0 for i 1 upto rot i extratdelta pos i 5wid i len n 180 2delta endfor stopMPdrawing Here we introduce a few variables that we can use later to tune the result a bit With delta the space between the characters can be increased while extra rotates the whole string around the origin The radius variable can be used to increase the distance to the origin Without these variables the assignment would have been rot i pos i 5wid i len n 180 Typesetting in Placing the pictures is now rather easy startMPdr
138. al horizontal displacement voffset an additional vertical displacement You can position data anywhere in the layer When positioning is turned on the current position will get a placeholder You can change the dimensions of that placeholder when position is set to overlay zero dimensions are used x the horizontal displacement y the vertical displacement width the non natural width height the non natural height location l r t b c lt lb rt rb The location directive determines what point of the data is used as reference point You can keep track of this point and the placement when you enable test mode This is how the rectangles in the previous examples where drawn More layers Positional graphics e option test show positioning information When you are enhancing the final version of a document you can explicitly specify on what page the data will go Use this option with care page the page where the data will go Because layers can migrate to other pages they may disappear due to the background not being recalculated In case of doubt you can force repetitive background calculation by setupbackgrounds state repeat 5 4 Complex text in graphics If you like to embed meTAPosT snippets in CONTEXT you may want to combine text and graphics and let metarost provide the position and the dimensions of the text to be typeset outside by For most applications
139. al paths zi z2 21 tension atleast 1 22 The atleast directive tells to do some magic behind the screens Both the 3 4 and the atleast lead directly to the question What exactly is the influence of the tension directive We will try to demystify the tension specifier through a sequence of graphics u icm z1 0 0 22 2u 4u z3 4u 0 def sample expr p c draw p withpen pencircle scaled 2 5mm withcolor white draw p withpen pencircle scaled 2 0mm withcolor enddef for i 75 step 05 until 1 sample zi tension i z2 z3 625red endfor for i 1 step 05 until 2 sample 21 tension i z2 23 625yellow endfor sample zi z2 z3 625white sample zi z2 z3 625white Indeed values less than 75 give an error message but large values are okay As you can see the two gray curves are the same Here atleast 1 means 1 even if larger values are useful Inflection tension and curl Curves finally are made up out of points and each point has two control points Since the tension specifier finally becomes a control point it is not surprising that you may specify two tension values If we replace the tension in the previous example by tension i and 2i we get the following graphic If we swap both values tension 2i and i we get We mentioned control points We will now draw a few
140. aled 1pt withcolor 625yellow draw hlingrid O 10 1 3cm 3cm draw vlingrid O 10 1 3cm 3cm draw hlingrid O 10 1 3cm 3cm shifted 3 5cm 0 draw vloggrid O 10 1 3cm 3cm shifted 3 5cm 0 draw hloggrid 0O 10 1 3cm 3cm shifted 7 0cm 0 draw vlingrid 0 10 1 3cm 3cm shifted 7 0cm 0 draw hloggrid 0O 10 1 3cm 3cm shifted 10 5cm 0 draw vloggrid O 10 1 3cm 3cm shifted 10 5cm 0 drawoptions withpen pencircle scaled 1pt withcolor 625yellow Grids draw hlingrid 0 draw vlingrid 0 555 555 LIII 10 10 1 3cm 3cm slanted 5 1 3cm 3cm slanted 5 Using macros like these often involves a bit of trial and error The arguments to these macros are as follows hlingrid Min vlingrid Min hloggrid Min vloggrid Min Max Max Max Max Step Step Step Step Length Length Length Length Width Height Width Height The macros take the following text upto the semi colon into account and return a picture We will now apply this knowledge to a more meaningful example First we draw a grid You can use the grid drawing macros to produce your own paper for instance using the following mixed TgX METAFUN code startMPpage StartPage width PaperWidth drawoptions withpen pencircle draw vlingrid 0 width unit draw hlingrid 0 height un
141. alternative numbers which is why we apply a mod The rest of the code is not so much different from the previous definition The hard coded point sizes match the page dimensions 600pt by 450pt quite well t identity if alternative 3 shifted 9pt 9pt fi randomseed seed p Field Text Text enlarged if alternative 1 36pt superellipsed superness elseif alternative 2 36pt squeezed Squeezeness elseif alternative 3 36pt randomized randomness else 36pt fi pickup pencircle scaled 3pt fill Page withcolor MPcolorfyellow fill p withcolor MPcolor white draw p withcolor MPcolorfred randomseed seed p Field Text Text enlarged if alternative 1 48pt superellipsed superness elseif alternative 2 48pt squeezed squeezeness elseif alternative 3 36pt randomized randomness else 48pt fi transformed t def right_menu_button expr nn rr pp xx yy ww hh dd if gt 0 and rr gt 0 q rightsuperbutton p xx yy RightEdgeWidth hh fill q withcolor MPcolor white draw q withcolor if rr 2 MPcolor gray else MPcolor fred fi fi enddef MPmenubuttons right StopPage stopuseMPgraphic When we choose the alternatives 21 and 22 we get this result Defining styles Adaptive buttons page 1 2 page3 page 4 page 5 Adaptive buttons Adaptive buttons 13 few applications
142. an get obscured by this fact Therefore the following series of shapes appear to be the same draw unitsquare xscaled 6cm yscaled 1 5cm withpen pencircle scaled 2mm withcolor 625red draw unitsquare shifted 5 5 xscaled 6cm yscaled 1 5cm withpen pencircle scaled 2mm withcolor 625red unitsquare shifted 5 5 xscaled 6cm yscaled 1 5cm withpen pencircle scaled 2mm withcolor 625red draw unitsquare xscaled 6cm yscaled 1 5cm shifted 1cm 1cm withpen pencircle scaled 2mm withcolor 625red draw unitsquare xscaled 6cm yscaled 1 5cm shifted 1 5cm 1cm withpen pencircle scaled 2mm withcolor 625red Scaling and shifting However when we combine such graphics into one we will see in what respect the scaling and shifting actually takes place draw unitsquare xscaled 6cm yscaled 2cm withpen pencircle scaled 3 0mm withcolor 625yellow draw unitsquare shifted 5 5 xscaled 6cm yscaled 2cm withpen pencircle scaled 3 0mm withcolor 625red draw unitsquare xscaled 6cm yscaled 2cm shifted 1cm 1cm withpen pencircle scaled 3 0mm withcolor 625white draw unitsquare xscaled 6cm yscaled 2cm shifted 1 5cm 1cm withpen pencircle scaled 1 5mm withcolor white draw unitsquare shifted 5 5 xscaled 6cm yscaled 2cm withpen pencircle scaled 1mm withcolor black draw origin withpen pencircle scaled 1mm As you can see the transformations are applied in s
143. ansformation vector with six elements pen pen specification You can achieve interesting effects by using pens with certain shapes For the moment you may consider a pen to be a path itself that is applied to the path that is drawn The numeric data type is used so often that it is the default type of any non declared variable This means that n 10 is the same as numeric n n 10 When writing collections of macros it makes sense to use the second method because you can never be sure if n isn t already declared as a picture variable and assigning a numeric to a picture variable is not permitted Because we often deal with collections of objects such as a series of points all variables can be organized in arrays For instance numeric n n 3 10 n 5 13 An array is a collection of variables of the same type that are assigned and accessed by indexing the variable name asin n 3 5 Multi dimensional arrays are also supported Since you need a bit of imagination to find an application for 5 dimensional arrays we restrict ourselves to a two dimensional example numeric n n 21 3 10 A nice feature is that the bounds of such an array needs not to be set beforehand This also means that each cell that you access is reported as unknown unless you have assigned it a value Behind the screens there are not really arrays It s just a matter of creating hash entries It might not be obvious but the followi
144. ant stretch normal 7 input douglas Douglas R Hofstadter stopshapetext Finally we combine text and shapes Since we also want a background we use framed The macros parwidth and parheight are automatically set to the current shape dimensions The normal result is shown in figure 10 3 startbuffer setupframed offset overlay align normal frame off width parwidth height parheight start combination 2 2 framed background test 1 getshapetext test 1 framed background test 2 getshapetext test 2 framed background test 3 getshapetext test 3 framed background test 4 getshapetext test 4 stopcombination stopbuffer By using a buffer we keep placefigure readable placefigure here fig shapes A continuous text typeset in a non standard shape spread over four areas and right alligned getbuffer Libraries in Donald Knuth has spent the past several thor had anything remotely like this power to con trol the final test 1 Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METRFONT as well as some of its products Not only is the concept exiting and clearly well executed but in my opinion the article is charmingly written as well However despite my over all enthusiasm for Knuth s idea and article there are
145. aphic shows that we need a bit more control over the exact position of the arrow It would be nice if we could start the arrow at the point or end there or center the arrow around the point Therefore the real implementation is a bit more advanced vardef pointarrow expr pat loc len off save 1 r s t path 1 r numeric s pair t t if pair loc loc else point loc along pat fi S len 2 off if s 0 s 0 elseif s gt len s len fi r pat cutbefore t r cutafter point arctime s of r of r S len 2 off if 8 lt 0 s 0 elseif s gt len s len fi l reverse pat cutafter t 1 reverse 1 cutafter point arctime s of 1 of 1 1 enddef This code fragment also demonstrates how we can treat the 1oc argument as pair coordinates or fraction of the path We calculate the piece of path before and after the given point separately and paste them afterwards as 1 r By adding braces we can manipulate the path in expressions without the danger of handling r alone We can now implement left center and right arrows by providing this macro the right parameters The offset the fourth parameter is responsible for a backward displacement This may seem strange but negative values would be even more confusing def rightarrow expr 1 pointarrow p t 1 1 enddef def leftarrow expr p t 1 pointarrow p t 1 1 enddef def centerarrow expr p t l pointarrow p t l
146. aphics again extend the first graphic First we copy the picture constructed so far Watch the double assignment Next we clip the pictures in half and shift the right half down over the width of the circle startuseMPgraphic third includeMPgraphic first picture p q p q currentpicture clip p to unitsquare xscaled width yscaled height clip q to unitsquare xscaled width yscaled height currentpicture p Fool yourself lA few addto currentpicture also q shifted 0 radius 2 stopuseMPgraphic 13 6 Growing graphics Although metarost is not really suited as a simulation engine it is possible to build graphics that are built and displayed incrementally with a sequence of mouse clicks The following example is the result of an email discussion David Arnold and the author had while METAFUN evolved Instead of defining the graphics in a separate metarost file we will incorporate them in the doc ument source in which they are used We can use several methods 1 Define macros and figures in a separate file and include the graphics as external graphics Define everything in the document source as usable graphics and include the graphics using useMPgraphic Package the graphic components in buffers and paste those together as graphics that can be processed at run time The first method is the most independent one which has its advantages if we want to use the
147. apost primitive fullsquare leftenlarged 25 metafun macro Transformations ath topenlarged numeric fullsquare topenlarged 25 metafun macro fullsquare rightenlarged 25 metafun macro fullsquare bottomenlarged 25 metafun macro ath enlarged numeric fullcircle enlarged 25 metafun macro ath enlarged pair fullcircle enlarged 1 25 metafun macro Transformations path llenlarged numeric fullcircle llenlarged 25 metafun macro path lrenlarged numeric fullcircle lrenlarged 25 metafun macro path urenlarged numeric fullcircle urenlarged 25 metafun macro fullcircle ulenlarged 25 metafun macro ath llenlarged pair fullcircle llenlarged 1 25 metafun macro Transformations ath lrenlarged pair fullcircle lrenlarged 1 25 metafun macro fullcircle urenlarged 1 25 metafun macro ath ulenlarged pair fullcircle ulenlarged 1 25 metafun macro ath Ilmoved numeric fullcircle llmoved 25 metafun macro ath Irmoved numeric fullcircle lrmoved 25 metafun macro Transformations ath urmoved numeric fullcircle urmoved 25 metafun macro ath ulmoved numeric fullcircle ulmoved 25 metafun macro ath lImoved pair fullcircle llmoved 1 25 metafun macro ath Irmoved pair fullcircle lrmoved 1 25 metafun macro at
148. are shown startuseMPgraphic text line fill 111 rrr rrr shifted 0 strutheight 111 shifted 0 strutheight cycle withcolor 5white fill 111 rrr rrr shifted 0 strutdepth 111 Talking to Typest ting in MeraPDsT shifted 0 strutdepth cycle withcolor 7white draw lll withpen pencircle scaled 2pt draw rrr withpen pencircle scaled 2pt draw 1ll rrr withpen pencircle scaled 5pt stopuseMPgraphic startuseMPgraphic text done endfor stopuseMPgraphic The result is still a bit disappointing startuseMPgraphic text includeMPgraphic text path includeMPgraphic text vars includeMPgraphic text move includeMPgraphic text split includeMPgraphic text cutoff includeMPgraphic text draw includeMPgraphic text calc includeMPgraphic text step includeMPgraphic text line includeMPgraphic text done stopuseMPgraphic lt In order to catch the overflow at the bottom we need to change the for loop a bit so that the number of lines does not exceed the available space The test that surrounds the assignment of vvsize makes sure that we get better results when we on purpose take a smaller height startuseMPgraphic text step path line pair 111 rrr numeric vvsize if strutheight strutdepth baselineskip vvsize vsize else vvsize vsize div baselineskip baselineskip fi for i topsk
149. aries 180 247 positioning 143 Distributions standalone 117 symbols 182 variables 179 grids 213 i inclusions 122 inflection 81 interfacing 175 interims 110 internals 110 j joining 38 1 labels 226 274 language 321 layers 145 147 layout 155 261 loops 31 m macros 32 arguments 34 metafun 319 outlines 205 overlays 127 160 stack 162 paths 7 14 360 cutting 60 joining 38 pens 36 pictures 63 analyzing 101 points 360 positioning 143 processing 5 111 r randomization 176 rotation 23 running 5 111 5 scaling 73 shading 185 shifting 73 styles 261 symbols 182 syntax 321 t tension 81 text 41 152 225 227 367 outlines 205 transformations 11 90 360 transparency 189 u units 71 v variables 28 179 Distributions This document introduces you in the world of the graphic programming language METRPOST Not only the language itself is covered in detail but also the way to interface with the typographic language We also present the collection of METRPOST graphic that come with the ConTEXt typesetting system This collection goes under the name MetaFun The first chapters focus on the METRPOST language later chapters cover aspects like color graphic inclu sions adding labels and stepwise constructing graph ics We finish with a graphical overview of commands PRAGMA Advanced Document Engine
150. art redpart reverse rightboundary round rt simplified sin sind sinh sar sqrt stroked tan tand textpart textual top topboundary ulcorner uniformdeviate unitvector unknown unspiked urcorner xpart xxpart xypart yellowpart ypart yxpart yypart type boolean color cmykcolor numeric pair path pen picture rgbcolor string transform primary binop and dotprod div infont mod secondary binop gt 4 or intersectionpoint intersectiontimes tertiary binop amp lt lt gt gt cutafter cutbefore cutends of operator arctime direction directiontime directionpoint penoffset point postcontrol precontrol subpath substring variable tag suffix Syntax diagrams suffix empty suffix subscript suffix tag suffix parameter subscript number numeric expression internal variable ahangle ahlength bboxmargin charcode day defaultcolormodel defaultpen defaultscale hour labeloffset linecap linejoin minute miterlimit month outputformat outputtemplate pausing prologues showstopping time tracingoutput tracingcapsules tracingchoices tracingcommands tracingequations tracinglostchars tracingmacros tracingonline tracingrestore
151. as become a viable option Much of what I will discuss here can be realized in DVI using a dedicated postprocessor to extract the information needed Although we believe that the way is the natural way to go CONTEXT also supports the same mechanism in DVI In MKIV we use the built in mechanism or or piece of a word maybe it s best to talk of typographic g instead will end up on Avnanric process The space between words i is flexible xc know in advance when the p ge It might even cross the page boundary In the previous paragraph word and are encircled and connected by an arrow This graphic can be drawn only when the position and dimensions are known Unfortunately this information is only available after the paragraph is typeset and the best breakpoints are chosen Because the text must be laid on top of the graphic the graphic must precede the first word in the typeset stream or it must be positioned on a separate layer In the latter case it can be calculated directly after the The concept paragraph is typeset but in the former case a second pass is needed Because such graphics are not bound to one paragraph the multi pass option suits better because it gives us more control the more we know about he final state the better we can act upon it Think of graphics on the first page that depend on the content of the last pa
152. as example m LEM Libraries Libraries Thi 1 4A e Donald Knuth has m spent the past several years e working on a system allowing him to control many aspects of the design of his lt n forthcoming books from the typesetting and layout down to the very shapes of the letters 3 Seldom has an author had anything remotely like this power to control the final appearance of his 9 her work Knuth s typesetting system has be come well known and available in many countries v around the world By contrast his METAFONT sys x tem for designing families of typefaces has not become as well known or available 2 In his article The Concept of a Meta Font Knuth sets forth for the 2 9 D y time the underlyin a P u P x X Figure 10 5 One more time Hofstadter s quotation Libraries 11 Debugging Those familiar with CONTEXT will know that it has quite some visual debugging features build in So what may you expect of the mETRPOST macros that come with CONTEXT In this chapter we will introduce a few commands that show some insight in what wErePosr is doing to your paths Since the outcome of wETRPOST code is in many respects more predictable than that of Tpx code we don t need that advanced
153. assed as first argument needs to be a valid filename Additionally they need to be given dimensions pseudo procedure externalfigure string expression transformer An external metarost graphic can be loaded by filename and figure number The normal trans formations can be applied pseudo procedure loadfigure string expression figure number transformer figure number number numeric expression A graphic text is normally an outline representation of a snippet of text typeset by This procedure has a couple of dedicated options pseudo procedure graphictext string expression transformer text option list regraphictext transformer text option list text option list empty text drawing option text option list text drawing option drawing option reversefill outlinefill withdrawcolor color expression withfillcolor color expression pseudo procedure resetgraphictextdirective graphictextdirective string expression internal variable graphictextformat Left overs B This document This document is produced in CONTEXT and can serve as an example of how to integrate METAPOST graphics into In this appendix we will discuss some details of producing this document We did not use any special tricks so most of the examples you have seen were coded just as shown We used
154. associated data stored with it From the bounded boolean test we can conclude that the bounding box is part of this data Internally metarost keeps track of two bounding boxes the natural one and the forced one The forced one is actually a component of the picture which applies to all previously added graphics You can calculate the bounding box from the 11corner and urcorner or if you like ulcorner and lrcorner and the METAFUN command boundingbox does so The four corners that make up the bounding box are either the natural ones or the ones forced by setbounds You can force METRPOSrT to report the natural ones by setting truecorners to 1 The next example demonstrates this feature pickup pencircle scaled 2mm path p draw fullcircle scaled 4cm slanted 5 withcolor 625white setbounds currentpicture to boundingbox currentpicture enlarged 5mm interim truecorners 0 p boundingbox currentpicture interim truecorners 1 q boundingbox currentpicture pickup pencircle scaled imm draw p withcolor 625red draw q withcolor 625yellow We use interim because truecorners is an internal METAPOST variable 2 1 Pitfalls When writing macros you need to be careful in what operations apply to what object There is for instance a difference between the following code A few more details Pitfalls pickup pencircle scaled 2pt draw 0 0 0 1 1 1 scaled
155. ast statement It is important to distinguish def macros from those defined with vardef In the latter case vardef macros are not a simple expansion and replacement Rather vardef macros return the value of their last statement In the case of the randomscaledpath macro a path is returned This macro is used in the following manner path mypath mypath randomscaledpath unitsquare 4cm Note that we send randomscaledpath a path unitsquare and a scaling factor 4cm The macro returns a scaled path which is then stored in the path variable mypath The following argument types are accepted expr something that can be assigned to a variable text arbitrary meTAaPosT code ending with suffix a variable bound to another variable An expression is passed by value This means that in the body of the macro a copy is used and the original is left untouched On the other hand any change to a variable passed as suffix is also applied to the original Local variables must be handled in a special manner since they may conflict with variables used elsewhere This is because all variables are global by default The way out of this problem is using grouping in combination with saving variables The use of grouping is not restricted to macros and may be used anywhere in your code Variables saved and declared in a group are local to that group Once the group is exited the variables cease to exist Macros Welcome toliVietaPost_
156. at provides the framed functionality Since this graphic is defined as unique CONTEXT will try to reuse already calculated and embedded graphics when possible framed background demo circle This text is overlayed The background can be set to color screen an overlay identifier like demo circle or comma separated list of those his text is overlayed The framed command automatically draws a ruled box which can be quite useful when debug ging a graphic However in this case we want to turn the frame off framed background demo circle frame off This text is overlayed This text is overlayed Overlays In this case it would have made sense to either set the offset to a larger value or to set backgroundoffset In the latter case the ellipse is positioned outside the frame The difference between the three offsets offset frameoffset and backgroundoffset is demon strated in figure 4 1 While the offset is added to the natural or specified dimensions of the content of the box the other two are applied to the frame and background and don t add to the dimensions In the first row we only set the offset while in the second row the text offset is set to 3pt When not specified the offset has a comfortable default value of 25ex some 25 of the height of an x setupframed width 3Ntextwidth background demo circle startcombination 3 3
157. ated on the fly this is not bad at all Left overs This docunient_ The document style is not that complicated The main complication in such a document is to make sure that MeTAPosT is operating under the same font regime As document font we use the URW Palatino for the running text combined with Computer Modern Typewriter Because this document is available as paper and screen document some large graphics are scaled down in the screen version We don t use any special tricks in typesetting this document but when we added the section about transparency a dirty trick was needed in a few cases order to get the described results Because the screen document has gray backgrounds exclusive transparencies come out wrong In the function drawing example we use the following trick to get a black background behind the graphics only We have a buffer that contains a few lines of code picture savedpicture savedpicture currentpicture currentpicture nullpicture draw savedpicture withcolor black draw savedpicture Since we use buffers for the graphics as well we can now process a buffer with name example as follows processbuffer example This means that the example code is included two times After it is processed we recolor the currentpicture black and after that we add the original picture once again Left overs C R
158. aw pic i shifted wid 2 0 rotated angle ad shifted ap endfor stopMPdrawing MPdrawingdonetrue getMPdrawing resetMPdrawing egroup So how does this compare to earlier results The original full text as typeset by TEX looks like We now follow some arbitrary path In the examples the text is typeset along the path with followtokens We now follow some arbitrary path We now follow some arbitrary path Since we did not set a path a dummy path is used We can provide a path by re defining the graphic followtokens startuseMPgraphic followtokens path RotPath RotPath fullcircle stopuseMPgraphic QE org startuseMPgraphic followtokens path RotPath RotPath reverse fullcircle stopuseMPgraphic rary rary M Do M D 2 gt 2 startuseMPgraphic followtokens path RotPath RotPath 3cm 1cm 0 1cm 3cm 1cm stopuseMPgraphic text SR SR ST Nd C SS 4 go 3 go 3 o b o p ae M qe 24 startuseMPgraphic followtokens path RotPath RotPath 3cm 0 3cm 1cm stopuseMPgraphic arbitrary path et arbitrary path E ow ow 5 We now foll We now foll startuseMPgraphic followtokens path RotPath RotPath 3cm 0 1cm icm 3cm 0 stopuseMPgraphic golow Soe arbitra g
159. awing for i 1 upto n draw pic i shifted radius 0 rotatedaround origin rot i endfor stopMPdrawing The pictures are now positioned on half circle properly kerned This was defined as follows The path variable tcycle is predefined to the top half of a fullcircle startMPdrawing def moved expr i shifted radius 0 rotatedaround origin rot i enddef pickup pencircle scaled 5pt for i 1 upto n draw pic i moved i draw boundingbox pic i moved i withcolor red draw origin center pic i moved i withcolor green endfor draw tcircle scaled 2r withcolor blue stopMPdrawing We will now package all of this into a nice efficient macro using of course the predefined scratch registers MPtoks and MPbox First we define the token processor Note again the expansion inhibition switch def processrotationtoken 1 appendtoks 1 to MPtoks setbox MPbox hbox RotFont the MPtoks startMPdrawing _ Typesetting in yereebe TEX text n n 1 len n the wd MPbox stopMPdrawing startMPdrawing pic n textext RotFont setstrut strut 1 pic n pic n shifted llcorner pic n stopMPdrawing The main macro is a bit more complicated but by using a few scratch numerics we can keep it readable def rotatetokens 1 2 3 4 delta extra radius tokens vbox bgroup MPtoks emptytoks resetMPdrawing star
160. backgrounds background backgraphics foreground foregraphics In this definition the predefined overlay foreground inserts the page data itself so the foreground graphics end up on top This example also demonstrates that you should be well aware of the way CONTEXT builds a page There are six main layers in some cases with sublayers The body text goes into the main text layer which unless forced otherwise lays on top 1 paper background 3 page backgrounds 5 logo areas 2 area backgrounds 4 text areas 6 main text The paper background is used for special sometimes internal purposes There are three page backgrounds left right and both The text areas logo areas and backgrounds form a 5 x 5 matrix with columns containing the leftedge leftmargin text rightmargin and rightedge The rows of the matrix contain the top header text footer and bottom The main text is what you are reading now Since the page background is applied last the previous layers can considered to be the fore ground to the page background layer And indeed it is available as an overlay under the name foreground as we already saw in the example Foregrounds are available in most cases but for the moment not when we are dealing with the text area Since anchoring the graphics is imple mented rather independent of the position of the graphics themselves this is no real problem we can put them all on the page layer if needed in separate o
161. bel lft btex C etex pointC shifted 2w 0 draw dot pointD label lft btex D etex pointD shifted 2w 0 enddef stopbuffer In placing the label we must make sure that the text runs free of the lines and curves Again move the stand_out macro just prior to draw_intersection macro so that this step is highlighted in the drawing color while prior steps are drawn in the default color in this case black startbuffer 3 start_everything draw_basics draw_circles stand_out draw_intersection stop_everything stopbuffer The line drawn through points C and D will be the perpendicular bisector of the line segment con necting points A and B In the next step we will draw a line using the plain Metarost drawdblarrow macro that draws arrowheads at each end of a path startbuffer f def draw_bisector path lineCD lineCD origin origin shifted 2 distance 0 lineCD lineCD rotated 90 shifted 0 5 pointA pointB lineCD lineCD shifted 0 distance drawdblarrow lineCD enddef stopbuffer startbuffer 4 start_everything draw_basics draw_circles draw_intersection stand_out draw_bisector stop_everything stopbuffer Growing graphics The following code draws the intersection of line C D and line segment A B which can be shown to be the midpoint of segment A B start
162. buffer g def draw_midpoint pair pointM pointM lineCD intersectionpoint lineAB draw dot pointM label llft btex M etex pointM enddef stopbuffer startbuf fer 5 start_everything draw_basics draw_circles draw_intersection draw_bisector stand_out draw_midpoint stop_everything stopbuffer Au M As long as we place the graphics as individual insertions in our document everything is fine However if we wish to place them all at once or as we shall see later place them on top of one another in a fieldstack it makes sense to give them all the same bounding box We can do this by completing the start everything and stop everything commands startbuffer a def start_everything path bb JA few applications Growing graphics draw basics draw circles draw intersection draw bisector draw midpoint bb boundingbox currentpicture currentpicture nullpicture enddef def stop_everything setbounds currentpicture to bb enddef stopbuffer In figure 13 5 we demonstrate the effect of this redefinition For this purpose we scale down the graphic to a comfortable 40 of course by using an additional buffer We also visualize the bound ing box startbuffer h def stop_everything setbounds currentpicture to bb draw bb withpen pencircle scaled 5pt withcolor 625yellow currentpicture
163. button frame off hbox button previous previouspage quad button next nextpage Nquad button index index quad button table of contents content The buttons will look like Compare these with Here the graphic was defined as startuniqueMPgraphic wrong or right pickup pencircle scaled 3pt path p p unitsquare xscaled OverlayWidth yscaled OverlayHeight fill p withcolor 8white draw p withcolor 625red stopuniqueMPgraphic The last class of embedded graphics are the runtime graphics When a company logo is defined in a separate file mylogos mp you can run this file by saying startMPrun input mylogos stopMPrun The source for the logo is stored in a file named mylogos mp Integrated graphics beginfig 21 draw fullsquare withcolor 625red draw fullsquare rotated 45 withcolor 625red picture cp cp currentpicture def copy addto currentpicture also cp enddef copy scaled 9 withcolor 625white copy scaled 7 withcolor 625yellow copy scaled 6 withcolor 625white copy scaled 4 withcolor 625red copy scaled 3 withcolor 625white fill fullcircle scaled 2 withcolor 625yellow currentpicture currentpicture scaled 50 endfig end In this example the result is available in the virtual file mprun 21 This file can be included in the normal way using externalfigure mprun 21 width 5cm
164. can also use this operator to harden colors simply by providing a value larger than 1 Keep in mind that colors are clipped at 1 anyway loadfigure gracht mp number 1 scaled 5 addto currentpicture also currentpicture softened 1 2 shifted bbwidth currentpicture 5cm 0 By providing a triplet you can treat each color component independently loadfigure gracht mp number 1 scaled 5 addto currentpicture also currentpicture softened 7 8 9 shifted bbwidth currentpicture 5cm 0 Changing colors 8 6 After these examples your are probably sick of seeing this picture in color so let s turn the colors into a weigthed grayscales in a way similar to the way black and white television treated color loadfigure gracht mp number 1 scaled 5 addto currentpicture also grayed currentpicture shifted bbwidth currentpicture 5cm 0 Outline fonts Outline fonts don t belong to METRPOST S repertoire of features Nevertheless we can simulate this in a reasonable way We will not discuss all details here because most details are covered in the MAKEMPY manual The macro responsible for outline fonts is graphictext The first argument should be a string This string is processed by Tex Additionally you can provide transformation directives and color specifications The next example demonstrates this graphictext bf Fun scaled 4 zscaled 1 1 5 withdrawcolo
165. cause the z variables are used frequently they are reset each figure You can also reset them yourself using the clearxy macro The METAFUN version clears all z variables unless you ex plictly specify what variables to reset If you want to play with this macro see what happens when you run the following code show xO z0 10 10 show x0 x0 whatever yO whatever show x0 z0 20 20 show x0 clearxy 0 show x0 z0 30 30 So the following calls are all legal clearxy clearxy 1 clearxy 1 8 10 Keep in mind that for each figure a full clear is done anyway You should not confuse this command with clearit which clears currentpicture 2 12 versus METRPOST If you are defining your own and meTaPosT macros you will notice that there are a couple of essential differences between the two macro languages In the following code is invalid def fancyplied 1 ifnum 1 0 message zero argument Mi 0 1 multiply NcountO by NcountO count2 1 multiply count2 by 2 count4 1 divide count4 by 2 advance NcountO by count2 advance NcountO by count4 count4 hskip fancyplied 3 pt This is because is very strict in what tokens it expects next In MeTAPosT however you can use vardef d macros to hide nasty intermediate calculations vardef fancyplied expr x if x 0 message x is zero 2 2 enddef a a shifted fancyplied
166. ce after the scaling pair a b c a 2cm 1cm b 3cm 1cm c 1cm 5cm drawarrow c a drawarrow c b drawarrow anglebetween a b c icm withcolor 625red That the results are indeed correct is demonstrated by the output of following example However when we swap the points we get This means that instead of rotating over 90 degrees we have to rotate over 90 or 270 degrees That way the arrow will also point in the other direction There are undoubtedly more ways to determine the direction but the following method also demonstrates the use of turningnumber which reports the direction of a path For this purpose we compose a dummy cyclic path vardef anglebetween expr endofa endofb common length save tn tn turningnumber common endofa endofb cycle Show tn Marking angles unitvector endofa common endofa common rotated tn 90 unitvector endofb common scaled length shifted common enddef Because we use an intermediate variable just to keep things readable we have to use vardef to hide the assignment for the outside world We demonstrate this macro using the following code pair a b c a 2cm 1cm b 3cm 1cm c 1cm 5cm drawarrow c a drawarrow c b drawarrow anglebetween a b c 0 75cm withcolor 625red drawarrow anglebetween b a c 1 50cm withcolor 625red Watch how both arrows po
167. ce of graphs depicting the construction of the midpoint of segment A So in fact we are dealing with a manual simulation The definition of such a stack is as follows definefieldstack midpoint construction step 1 step 2 step 3 step 4 step 5 frame on offset 3pt framecolor darkyellow rulethickness 1pt The first argument is to be a unique identifier the second argument takes a list of symbols while the third argument accepts settings More on this command can be found in the CONTEXT manuals The stack is shown as figure 13 6 Its caption provides a button which enables the reader to cycle through the stack We call this a stack because the graphics are positioned on top of each other Only one of them is visible at any time placefigure here fig steps Bisecting a line segment with compass and straightedge Just click goto here JS Walk_Field midpoint construction to walk through the construction This stack is only visible in a PDF viewer that supports widgets fieldstack midpoint construction At the start of this section we mentioned three methods When we use the first method of putting all the graphics in an external metarost file the following framework suits We assume that the file is called step mp and that it is kept by the user along with his document source We start with the definitions of the graphic steps These are the same as the ones shown previously def draw_basics enddef
168. ction free path between these points unless the endpoint directions make this impossible To use the words of David Arnold a point of inflection is where a path switches concavity from concave up to concave down for example Inflection tension and curl It is surprisingly difficult to find nice examples that demonstrate the difference between and as it is often impossible to honour the request for less inflection We will demonstrate this with a few graphics In the four figures on the next pages you will see that is not really suited for taming wild curves If you really want to make sure that a curve stays within certain bounds you have to specify it as such using control or intermediate points In the figures that follow the gray curves draw the random path using on top of yellow curves that use the connection As you can see in only a few occasions do the yellow inflection free curves show up For those who asked for the code that produces these pictures we now include it here We use a macro sample which we define as a usable graphic nearly all examples in this manual are coded in the document source startuseMPgraphic sample def sample expr rx ry path p numeric n m r a b color c c MPcolor lightgray a b 2mm r 2cm n 7 m 5 unitsquare scaled xyscaled n m shifted 5r 5r draw q withpen pencircle scal
169. cture as well as increment the shift counter currentpicture nullpicture n n 1 The drawfill macro is one of the METAFUN macros Another handy macro is boundingbox When used instead of bbox you don t have to set the margin to zero Figure 2 2 The influence of pens on fill Bounding boxes There is a subtle point in filling a shape In figure 2 2 you see the influence of the pen on fill operation An indirect specification has no influence and results in a filled rectangle with sharp corners The third rectangle is drawn with a direct pen specification which results in a larger shape with rounds corners However the bounding box is the same in all three cases The graphic is defined as follows This time we don t use a complicated macro drawoptions withcolor 625white path p p unitsquare scaled 2cm fill p shifted 3cm 0 pickup pencircle scaled 5cm fill p shifted 6cm 0 fill p shifted 9cm 0 withpen pencircle scaled 5cm When a graphic is constructed its components end up in an internal data structure in a more or less layered way This means that as long as a graphic is not flushed you may consider it to bea stack of paths and texts with the paths being drawn or filled shapes or acting as clipping paths or bounding boxes When you ask for the dimensions of a graphic the lower left and upper right corner are calculated using this stack Because you can explicitly set bounding
170. curve wEraPosr will calculate the control points itself unless you specify one or more of them This path is specified as 1cm 1cm 1 5cm 1 5cm controls 3cm 2cm 2cm 0cm In this path the second and third point share a control point Watch how the curve is pulled in that direction It is possible to pull a bit less by choosing a different control point 1cm 1cm 1 5cm 1 5cm controls 2 75cm 1 25cm 2cm 0cm Now we get We can also specify a different control point for each connecting segment This path is defined as 1cm 1cm controls 5cm 2cm and 2 5cm 2cm 2cm 5cm Paths 1 2 Transformations We can store a path in a path variable Before we can use such a variable we have to allocate its memory slot with path path p p 1cm 1cm 1 5cm 2cm 2cm Ocm Although we can manipulate any path in the same way using a variable saves us the effort to key in a path more than once In this graphic the path stored in p is drawn twice once in its displaced form The displacement is defined as p shifted 4cm 2cm In a similar fashion you can rotate a path You can even combine shifts and rotations First we rotate the path 15 degrees counter clockwise around the origin p rotated 15 Os This rotation becomes more visible when we also shift the path to the right by saying rotated 15 shifted 4cm 0c
171. d by The operator gives you exponentiation The nature of the metarost language is such that you can easily define interesting functions using such symbols The logarithmic functions are based on bytes This makes them quite accurate but forces you to think like a computer mexp x expential function with base 256 mlog x logarithm with base 256 The basic goniometric functions operate on degrees which is why they have a d in their name cosd x cosine of x with x in degrees sind x sineofx with x in degrees There are three ways to truncate numbers The round function can also handle pairs and colors ceiling x the least integer greater than or equal to x floor x the greatest integer less than or equal to x round x round each component of x to the nearest integer Of course we have x mod y the remainder of x y x div y the integer part of x y abs the absolute value of x sqrt x the square root of x x dotprod y the dot product of two vectors What would life be without a certain randomness and uncertainty normaldeviate a number with mean 0 and standard deviation 1 uniformdeviate x number between zero and x The following functions are actually macros Overview decr x n decrement x by incr x n increment x by n max a b return the maximum value in the list min a b return the minimum value in the list The min and max f
172. dcolor white It Works setMPlayer test somepos 3 externalfigure cow mps width 2cm Combining the graphic and the text is handled by the macro getMPlayer getMPlayer test useMPgraphic oeps Does it work al right It Works The macro getMPlayer is built on top of framed The settings passed in the optional second argument are the same as those to framed getMPlayer test frame on offset 5pt useMPgraphic oeps As you see you need a bit of a twisted mind to handle graphics this way but at least the function ality is there to create complex graphics in a declarative way Complex text in graphics Positional graphics _ Complex text in graphics 6 Page backgrounds Especially in interactive documents adding backgrounds to the page and text areas not only enhances read ability but also makes it more convenient to identify header footers and navigational areas In this chapter we will demonstrate that with meTAPosT we can go beyond the based features present in CONTEXT section is dedicated to graphics and printing especially bleeding 6 1 The basic layout In the CONTEXT manual you can find many details on the composition of the page When 1x type sets text crossing the page boundary triggers output routine This routine is responsible for pasting the body text that goes onto a pa
173. define circular shade is fed with two pairs points two radius and two colors The shade is distributed between the colors according to the radius Shading can hardly be called an easy issue The macros that we provide here are in fact simpli fications which means that at a lower level one can do more advanced things Here we limit ourselves to the more common cases In the previous examples we used an arrow to indicate the Shading ia direction and magnitude of the shade The next macro demonstrates the principles in a different way def test shade expr a b ra rb pickup pencircle scaled imm color ca ca MPcolorfa color cb cb MPcolor b color cc cc MPcolor c path pa pa fullcircle scaled 2ra shifted a path pb pb fullcircle scaled 2rb shifted b sh define circular shade a b ra rb ca cb fill pb withshade sh draw pb withcolor cc draw pa withcolor cc enddef The shade is distributed between two circles each with a radius and center point four can be set but as the next calls demonstrate we can normally do with less which is why we provided the macro with less parameters test shade origin origin Ocm 1cm test shade origin origin 25cm test shade origin origin 50cm test shade origin origin shifted 25cm 0 Ocm icm test shade origin origin shifted 25cm 0 25cm 1cm
174. draw p withpen pencircle scaled 10pt withcolor 625red draw q withpen pencircle scaled 10pt withcolor 625yellow draw r withpen pencircle scaled 20pt withcolor 625white The line is drawn from center to center and since the line has a non zero width and a round line cap it extends beyond this point If we want to line to stop at the circular paths we can cut off the pieces that extend beyond those paths pair pr qr pr p intersectionpoint r qr q intersectionpoint r r cutbefore pr cutafter qr This time we get Only this far Due to the thicker line width used when drawing the straight line part of that line is still visible inside the circles So we need to clip off a bit more r r cutbefore point 5pt on r r r cutafter point 5pt on r The point on operation is a METAFUN macro that takes a dimension In order to save you some typing METAFUN provides a macro cutends that does the same job r r cutends 5pt This time we draw the path in a different order draw r withpen pencircle scaled 20pt withcolor 625white draw p withpen pencircle scaled 10pt withcolor 625red draw q withpen pencircle scaled 10pt withcolor 625yellow That way we hide the still remaining overlapping part of the line Only this far m 2 9 Directions Quite often you have to tell in what direction line should be drawn A direction is
175. e top slant hor bar shifted 0 euro v delta right slant hor bar shifted 0 euro v delta euro width 2 euro botbar buildcycle bot slant hor bar shifted 0 euro v delta right slant hor bar shifted 0 euro v delta euro width 2 for i euro circle euro topbar euro botbar draw i withpen pencircle scaled 0 endfor for i euro circle euro topbar euro botbar fill i withpen pencircle scaled O endfor if trace euro drawpoints euro circle withcolor red drawpoints euro topbar withcolor green drawpoints euro botbar withcolor blue fi 3 enddef end of euro We only set a parameter when it is not yet set This has the advantage that we don t have to set them when we change one This way of manipulating paths cutting and building does not always work well because of rounding errors but here it does work euro radius 4cm trace euro true draw euro symbol For educational purposes we have added a bit of tracing When enabled the euro shows up as The euro symbol A few applications Of course it would be best to define the euro as one shape but we won t go though that process right now By packaging the combined paths in an image we can conveniently color the euro symbol draw euro symbol withcolor 625red You may wonder why we both draw and fill the euro using a pen with zero width We ve done this in order to demonstrate
176. e labels Again we use a macro which we feed with a picture generated by Since these pictures are filtered from the source and pre processed we cannot embed the btex etex in the macro do it and pass a string It has to be done this way def do it expr yy tt path p unitsquare xyscaled w 1 hlyy shifted x 1 ylyy label lft tt center p shifted w 1 2 u 25cm 0 enddef do it 1 btex bottom etex do it 2 btex footer etex do it 3 btex text etex do it 4 btex header etex do it 5 btex top etex In the horizontal direction we have edges margins and text There are left and right edges and margins which are swapped on even pages when you typeset a double sided document def do it expr xx tt path p p unitsquare xyscaled w xx h 1 shifted 1 label tt center p shifted O height h 1 2 enddef do it 1 btex edge tex do it 2 btex margin etex do it 3 btex text etex do it 4 btex margin etex do it 5 btex edge Since we want the graphic to match the dimensions of the text area of the current page we have to make sure that the bounding box is adapted accordingly By this action the labels will fall outside the bounding box When we directly embed a graphic this works ok but when we start scaling and reusing due to the object reuse mechanism the graphic will be clipped to the bounding box setbounds currentpicture to units
177. e ones demonstrated in this document These transforma tions are not part of standard METRPOST but come with METAFUN A very handy extension is enlarged Although you can feed it with any path it will return a rectangle larger or smaller than the boundingbox of that path You can specify a pair or a numeric path p fullsquare scaled 2cm drawpath p drawpoints p p shifted 3cm 0 enlarged 5cm 25cm drawpath p drawpoints p There are a few more alternatives like bottomenlarged rightenlarged topenlarged and leftenlarged The cornered operator will replace sharp corners by rounded ones we could not use rounded because this is already in use path p p 1 0 2 0 2 2 1 2 0 1 cycle xysized 4cm 2cm drawpath p drawpoints p p p shifted 5cm 0 cornered 5cm drawpath p drawpoints p Some extensions Welcoime to MetaPost_ The smoothed operation is a less subtle one since it operates on the bounding box and thereby can result in a different shape path p p 1 0 2 0 2 2 cycle xysized 4cm 2cm drawpath p drawpoints p p shifted 5cm 0 smoothed 5cm drawpath p drawpoints p The next one simplified can be applied to paths that are constructed automatically Instead of testing for duplicate points during construction you can clean up the path afterwards path p p 0 0
178. e scaled 200pt withcolor 625yellow stopreusableMPgraphic This definition is accompanied by reuseMPgraphic name Imagine that we use a graphic as a background for a button We can create a unique and reusable graphic by saying def MyGraphic startreusableMPgraphic name overlaywidth overlayheight path p p unitsquare xscaled OverlayWidth yscaled OverlayHeight fill p withcolor 625yellow draw p withcolor 625red stopreusableMPgraphic reuseMPgraphic name overlaywidth overlayheight Notice the use of OverlayWidth and OverlayHeight These variables are set for each call to META POST After this we can say Integrated graphics Embedded graphics defineoverlay my graphic MyGraphic button background my graphic frame off Go Home firstpage Say that we have a 30pt by 20pt button then the identifier will be name 30pt 20pt Different dimensions will lead to other identifiers so this sort of makes the graphics unique We can bypass the ugly looking def by using a third class of embedded graphics the unique graphics startuniqueMPgraphic name path p p unitsquare xscaled OverlayWidth yscaled OverlayHeight fill p withcolor 625yellow draw p withcolor 625red stopuniqueMPgraphic Now we can say defineoverlay my graphic uniqueMPgraphic name button background my graphic frame off Go Home firstpage You may wonder why un
179. e to convert a colored picture into a gray one This macro uses the same conversion method as mentioned here Managing resources Embedded graphics Managing resources 4 Enhancing the layout One of the most powerful and flexible commands of CONTEXT is N ramed We can use the background features of this command to invoke and position graphics that adapt themselves to the current situation Once understood overlays will become a natural part of the CONTEXT users toolkit 4 1 Overlays Many CONTEXT commands support overlays The term overlay is a bit confusing since such an overlay in most cases will lay under the text However because there can be many layers on top of each other the term suits its purpose When we want to put METRPOST graphic under some text we go through a three step process First we define the graphic itself startuniqueMPgraphic demo circle path p fullcircle xscaled overlaywidth yscaled overlayheight fill p withcolor 85white draw p withpen pencircle scaled 2pt withcolor 625red stopuniqueMPgraphic This graphic will adapt itself to the width and height of the overlay Both overlaywidth and overlayheight are macros that return a dimension followed by a space The next step is to register this graphic as an overlay defineoverlay demo circle uniqueMPgraphic demo circle We can now use this overlay in any command th
180. ea E m E m M MI O l NEM W o lg Em wm NM EH uu NM O mw m m NV For them I owe much inspiration to both my parents My mother Jannie constantly demonstrates me that computer graphics will never improve nature She also converted one of my first METAPOST graphics into a patchwork that will remind me forever that handcraft is more vivid than computer artwork My father Hein has spent a great deal of his life teaching math and I m sure he would have loved metarost I inherited his love for books I therefore dedicate this document to them Colofon This manual is typeset with CONTEXT MKIV No special tricks are used and everything you see in here is available for CONTEXT users The text is typeset in Palatino and Computer Modern Typewriter We used LUATEX as processing engine Since this document is meant to be printed in color some examples will look sub optimal when printed in black and white Graphics The artist impression of one of Hasselts canals at page 202 is made by Johan Jonker The CDROM production process graphic at page 199 is a scan of a graphic made by Hester de Weert Copyright Hans Hagen PRAGMA Advanced Document Engineering Hasselt NL copyright 1999 2010 version 2 October 8 2010 Publisher publisher Boekplan NL isbn ean
181. ears the picture memory and allows us to start anew currentpicture nullpicture We can shift rotate and slant the picture stored in pic as we did with paths We can say draw pic rotated 45 withcolor red A picture can hold multiple paths You may compare a picture to grouping as provided by drawing applications draw Ocm O0cm 1cm icm draw 1 1 picture pic pic currentpicture draw pic shifted 3cm 0cm draw pic shifted 6cm 0cm pic currentpicture draw pic shifted 0cm 2cm We first draw two paths and store the resulting cross in a picture variable Then we draw this picture two times so that we now have three copies of the cross We store the accumulated drawing again so that after duplication we finally get six crosses Nh Nh Nh N Nh NL NL ZN ZN You can often follow several routes to reach the same solution Consider for instance the following graphic Drawing pictures Welcome to MetaPost fill 0 0 ww 0 ww hh w hh w h 0 h cycle fill ww 0 w 0 w hh cycle The points that are used to construct the paths are defined using the constants w h ww and hh These are defined as follows 4cm h 2cm ww 1cm hh 1 5cm In this case we draw two shapes that leave part of the rectangle uncovered If you have a back ground this technique allows the background t
182. ed framed background screen backgroundscreen 8 framed background circle framed background color cow backgroundcolor red framed background color cow grid backgroundcolor red In the last three cases of course you have to define circle cow and grid as overlay These items are packed in a comma separated list which is to be surrounded by Overlay variables BEhhan ing the layout 44 Foregrounds The overlay system is actually a system of layers Sometimes we are confronted with a situation in which we want the text behind another layer This can be achieved by explicitly placing the foreground layer as in figure 4 3 Gre two two ree frame on top layer frame on bottom layer 4 Figure 4 3 Foreground material moved backwards The graphic layer is defined as follows startuniqueMPgraphic backfore draw fullcircle xscaled overlaywidth yscaled overlayheight withpen pencircle scaled 2pt withcolor 625yellow stopuniqueMPgraphic defineoverlay backfore uniqueMPgraphic backfore The two framed texts have a slightly different definition The leftmost graphic is defined as framed background backfore backgroundoffset 4pt fone two three unknown The rightmost graphic is specified as framed background foreground backfore backgroundoffset 4pt fone two three unknown
183. ed 5cm drawpath p drawpoints p p curved p shifted 5cm 0 drawpath p drawpoints p Some extensions Probably less usefull although we use it in one of the OPENTYPE visualizers is laddered path p fullcircle scaled 3cm drawpath p drawpoints p p laddered p shifted 5cm 0 drawpath p drawpoints p When writing that can be used to draw chemical structure formulas I needed a paral lelizing macro so here it is path p fullcircle scaled 3cm drawpath p drawpoints p p p paralleled icm drawpath p drawpoints p If you use a negative argument like 1cm the parallel line will be drawn at the other side The blownup operation scales the path but keeps the center in the same place path p p fullsquare xyscaled 4cm icm randomized 5cm drawpath p drawpoints p p p blownup 5cm drawpath p drawpoints p The shortened operation also scales the path but only makes it longer or shorter This macro only works on straight paths WelcometoMetabosl Some extensions path p p 0 0 2cm 3cm drawpath p drawpoints p p p shortened icm drawpath p drawpoints p p p shortened 1cm drawpath p drawpoints p Here are a few more drawing helpers Even if you don t need them you might at some point take a look at the
184. ed b 4 withcolor 625yellow for i 1 upto n for j 1 upto m fullcircle scaled randomized r rx r ry shifted i j scaled r pickup pencircle scaled a draw for k 0 upto length p point of p endfor cycle withcolor draw for k 0 upto length p point k of p endfor cycle withcolor c pickup pencircle scaled b draw for k 0 upto length p point of p endfor cycle withcolor 625yellow draw for k 0 upto length p point k of p endfor cycle withcolor 625white for k 0 upto length p draw point k of p withcolor 625red endfor endfor endfor setbounds currentpicture to q enddef stopuseMPgraphic As you see not so much code is needed The graphics themselves were produced with a couple of commands like placefigure Circles with minimized inflection and 25 randomized points startMPcode includeMPgraphic sample sample 4 4 stopMPcode JA few more details Inflection tension and curl The tension specifier can be used to influence the curvature To quote the 5 manual once more The tension parameter can be less than one but it must be at least 3 4 The following paths are the same zi z2 zi tension 1 z2 21 tension 1 and 1 22 The triple dot command is actually a macro that makes the following commands equivalent Both commands will draw identic
185. ed we can also use backgrounds def processword 17 noindent framed frame off background lions 1 We can add a supperellipsed frame using the following definition startuniqueMPgraphic lions a path p p fullsquare xyscaled overlaywidth overlayheight superellipsed 85 pickup pencircle scaled ipt fill p withcolor 850white draw p withcolor 625yellow stopuniqueMPgraphic defineoverlay lions uniqueMPgraphic lions a startuseMPgraphic lions b path p p fullsquare xyscaled overlaywidth overlayheight randomized 5pt pickup pencircle scaled ipt fill p withcolor 850white draw p withcolor 625yellow stopuseMPgraphic defineoverlay lions uniqueMPgraphic lions b startuniqueMPgraphic lions path p p fullsquare xyscaled overlaywidth overlayheight squeezed 2pt pickup pencircle scaled ipt fill p withcolor 850white draw p withcolor 625yellow stopuniqueMPgraphic defineoverlay lions uniqueMPgraphic lions c Typesetting graphics youl know 3 pmbassado H X H epresented H Jioness JK jis 5 unclear Xf havd H elationship but nd pom Jarl N These paragraphs were typeset with the following settings EE Ei Hd setupalign broad right Nveryraggedright setupalign broad middle veryraggedcenter setupalign broad left veryraggedleft The
186. ed areas Edward R Tufte We thrive in information thick worlds because of our marvelous and everyday capacity to select organize into leaf refine eerie pen eee a user the designer should also write the first user IET dq eT US participated fully in al these activities hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial design is complete and fairly robust the eal test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system books from has become TERR y tem for desing families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying even withcolor 625white Edward We thrive in information thick worlds because of our marvelous and everyday capacity to select the wheat from the chaff and separate the sheep from the ase eet br ee ey Di first large scale user the designer should also write the first user i os Far omer wa Der Prt Te ent TP participated fully in these activities literally hundreds of improvements would never
187. ed on many paths pictures pens or other transforms However in most cases you will use the predefined commands scaled shifted rotated and alike We will now demonstrate the most common transformations in a text example draw btex bfd MetaFun etex draw boundingbox currentpicture withcolor 625yellow Before a METRPOST run the btex etex s are filtered from the file and passed on to Af ter that the DVI file is converted to a list of pictures which is consulted by METRPOST We can manipulate these pictures like any graphic as well as draw it with draw MetaFun We show the transformations in relation to the origin and make the origin stand out a bit more by painting it a bit larger in white first draw origin withpen pencircle scaled 1 5mm withcolor white draw origin withpen pencircle scaled imm withcolor 625red The origin is in the lower left corner of the picture This is no longer the case in LUATEX where we use MPLIB Transformations few MetaFun Because the transformation keywords are proper english we let the pictures speak for themselves currentpicture currentpicture 4 I ll currentpicture currentpicture currentpicture shifted 0 1cm currentpicture rotated 180 currentpicture rotatedaround origin 30 currentpicture scaled 1 75 currentpicture I I currentpicture currentpicture scaled
188. een at all Later we will introduce the METAFUN way around this In order to get all the labels typeset we have to put a lot of code here The macro dotlabel draws a dot and places the typeset label startMPdefinitions solvers def draw_problem_labels pickup pencircle scaled 5pt dotlabel 11ft Z_ 11 211 dotlabel ulft Z_ 12 212 dotlabel ulft Z_ 13 z13 dotlabel 11ft Z_ 14 214 dotlabel lrt Z_ 21 z21 dotlabel 11ft Z_ 22 z22 dotlabel urt Z_ 23 223 dotlabel ulft Z_ 24 224 dotlabel urt Z_ 31 231 dotlabel ulft Z 32 z32 dotlabel urt Z_ 33 z33 dotlabel urt Z_ 34 z34 dotlabel lrt Z_ 41 241 dotlabel urt Z 42 z42 dotlabel 11ft Z_ 43 243 dotlabel 1rt Z 44 244 dotlabel urt Z_ 0 20 dotlabel lft Z_ 1 z1 dotlabel top Z_ 2 22 Welcome to Metabast Linear equations dotlabel rt Z_ 3 z3 dotlabel bot Z_ 4 z4 enddef stopMPdefinitions Watch out as we are in CONTEXT we can pass regular code to the label macro In a standalone METAPOST run you d have to use the btex variant We are going to draw a lot of pictures so we define an extra macro This time we hard code some values The fractions i and j are responsible for the visual iteration process while s determines the labels We pa
189. eference In this chapter we will demonstrate most of the drawing related primitives and macros as present in plain METRPOST and METAFUN extensions If a path is shown and or a transformation is applied we show the original in red and the transformed path or point in yellow The small dark gray crosshair is the origin and the black rectangle the bounding box In some drawings in light gray we show the points that makeup the path This list describes traditional Metarost and the stable part of METAFUN As METAPOST evolves new primitives are added but they are not always that relevant to us If you browse the METAFUN sources you will for sure notice more functionality then summarized here Most of that is meant for usage in CONTEXT and not exposed to the user Other macros are still somewhat experimental but might become more official at some point When metarost version 2 is ready this reference will be updated accordingly C 1 Paths air 1 5 metapost concept air pair ty gobs metapost macro CO 0 aC D ca Cb ou tel metapost macro air pair 0 0 75 0 1 25 1 1 metapost macro Paths air pair 0 005 44 65 0 01 25 24005 1 metapost macro OO 800 dottjoim GL 25 0154 metapost macro controls pair 0 0 controls 75 0 1 1 metapost primitive controls pair and pair 0 0 controls 75 0 and 1 25
190. efore we set the position variable to yes setupinteractionmenu right frame off position yes align middle topoffset 75cm bottomoffset 75cm Defining styles Adaptive buttons 1 contrastcolor gray style bold before after The menu content is rather sober just a list of topics and a close button Later we will define the command that generates topic entries The alternative right lets the topic list inherit its charac teristics from the menu startinteractionmenu right placelist Topic alternative right vfill but CloseDocument close stopinteractionmenu We have now arrived at the more interesting part of the style definition the graphic that goes in the page background Because this graphic will change we define a useable Metarost graphic Page backgrounds are recalculated each page opposite to the other backgrounds that are calculated when a new background is defined or when repetitive calculation is turned on setupbackgrounds page background page def ineoverlay page useMPgraphic page setupMPvariables page alternative 3 We will implement three alternative backgrounds First we demonstrate the relatively simple su per ellipsed one The main complication is that we want the button shapes to follow the right edge of the curve that surrounds the text We don t know in advance how many lines of text there will be
191. elineskip vvsize vsize else vvsize vsize div baselineskip baselineskip fi for i topskip step baselineskip until vvsize line ulcorner q urcorner q shifted 0 i 111 found point line l true rrr found point line r false 1 indent n abs xpart 111 xpart llcorner q width n abs xpart rrr xpart 111 endfor stopuseMPgraphic startuseMPgraphic text save write parshape amp decimal n to mfun mp data txt for i 1 upto n write decimal indent i amp bp amp decimal width i amp bp to mfun mp data txt endfor write EOF to mfun mp data txt stopuseMPgraphic We can call this macro using the part we used in the previous examples startuseMPgraphic text includeMPgraphic text macro path p p 0 1 1 0 1 0 cycle scaled 65pt provide parshape p shape path 5 baselinedistance offset baselinedistance distance between lines strutheight height of a line strutdepth 4 depth of a line Typesetting in Talking to strutheight height of first line stopuseMPgraphic After we called useMPgraphic text the resulting file looks as follows You can call up this file by its anonymous name MPdatafile since this macro gets the value of the graphic at hand parshape 8 21 25648bp 46 39665bp 16 79666bp 54 3987bp 6 52979bp 77 31822bp 1 447
192. eoffset 6pt backgroundoffset 9pt background screen backgroundscreen 85 Welcome in the hall of frame Welcome in the hall of frame Figure 4 2 The three offsets 4 2 Overlay variables The communication between Tex and embedded metarost graphics takes place by means of some macros overlay status macro meaning overlaywidth the width of the graphic as calculated from the actual width and back ground offset overlayheight the height of the graphic as calculated from the actual height depth and background offset overlaydepth the depth of the graphic if available overlaycolor the background color if given overlaylinecolor color of the frame overlaylinewidth the width of the frame The dimensions of the overlay are determined by dimensions of the background which nor mally is the natural size of a framed When a background offset is specified it is added to overlayheight and overlaywidth Colors can be converted by MPcolor and in addition to the macros mentioned you can use all macros that expand into a dimension or dimen register prefixed by the primitive the this and other primitives are explained in The TgXbook by Donald Knuth 4 3 Stacking overlays A background can be a gray scale screen a color color a previously defined overlay identifier or any combination of these The next assignments are therefore legal framed background color backgroundcolor r
193. ep 5 externalfigure step 5 Growing graphics A few applications Which method is used depends on the way the graphics are used In this example we wanted to change the definition of everything so here the third method was quite useful 13 7 Simple Logos Many company logos earn their beauty from their simplicity One of the logos that most Dutch people have imprinted in their mind is that of the Dutch Railway Company NS An interesting feature of this logo is that although it is widely known drawing it on a piece of paper from mind is a task that many people fail This logo makes a good candidate for demonstrating a few fine points of drawing graphics like using linear equations setting line drawing characteristics clipping and manipulating bounding boxes The implementation below is quite certainly not according to the official specifications but it can nevertheless serve as an example of defining such logos As always we need to determine the dimensions first Here both the height and line width depend on the width of the graphic Instead of calculating the blue shape such that it will be a filled outline we will draw the logo shape using line segments This is why we need the line parameter numeric width width 3cm numeric height height width 2 numeric line line height 4 We want sharp corners which can be achieved by setting linej
194. er files meta tex definition and managing mlib tex processing and conversion The last category will certainly grow Some of these modules are preloaded others can be loaded using the command useMPlibrary like useMPlibrary clp txt for loading the predefined clipping paths and text tricks The code is organized in files named mp mp The core file is mp tool mp and this file can comfortably be used in stand alone graphics The file metafun mp is used to load the collection of modules into a format The collection of Metarost code files will grow in due time but as long as you use the METAFUN format you don t have to keep track of the organization of files Most files relate to subsystems and are loaded automatically like the files that implement page layout support and flow charts Although this document is the main source of information occasionally the source code of META FUN and in many cases the source code of CONTEXT may contain additional information and ex amples Killing time METAFUN macros 320 Killing time A METAPOST syntax In the METAFONT book as well as the wErePosr manual you can find the exact specification of the language Below you find the full werePosr syntax to which we add the basic METAFUN extensions If this page looks too cryptic you can safely skip to the next chapter 1 Syntax diagrams The following
195. er to be typeset in an outline font The quality of the output depends on how the glyphs are constructed For instance in math symbols are sometimes composed of glyph fragments and rules graphictext sqrt 1 x scaled 8 Outline fonts E withdrawcolor 625red withpen pencircle scaled 1 5pt This is not really a problem because we can also fill the shapes It is the reason why the fill is applied after the draw and in such case the effective line width is half the size specified graphictext left Nsqrt 14x J Nover Nsqrt 2 x 2 Nright scaled 4 dashed evenly withdrawcolor 625red withfillcolor 850white withpen pencircle scaled 1 5pt In this example we also use a dashed line Instead of normal colors we could have used shades or transparent colors D U DOES GI EXE Pea ee MS 4f 2 E 9 44 D T fv A d T a enm pd ar TUB T l F g 1 t alba n tA D 7 SAS 1 3 it um 1 ty a il ia 1 V datana a DES a e 3 Ka T weg g a T fF 1 1 L1 Sage 7n a A rj 4 GW dui T t 7 p SEED 11 X a YA y 4 44 Ny Now eae UAM Pj Ny y ez Instead of supplying the text directly you can use the indirect method This permits you
196. eren 32 110 Arguments 34 Lll Pens a4 RE RE 36 112 Joining lines 38 118 Colors i RR RERRDRRERS 40 114 Dashes 40 T5 41 116 Linear equations 42 117 Clipping 49 1 18 Some extensions 51 1 19 Cutting and pasting 60 120 Current picture 63 2 Afew more details 65 21 Making graphics 65 2 2 Bounding boxes 67 2 3 I 71 24 Scaling and shifting 73 2 5 Curve construction 75 2 6 Inflection tension and curl 81 2 7 Transformations 90 2 8 Only this far 93 2 9 Directions 100 2 10 Analyzing pictures 101 241 Pitfalls 106 2 12 versus METRPOST 109 2 13 Internals and Interims 110 3 Embeddedgraphics 111 3 31 Getting started 111 3 2 External graphics 111 33 Integrated graphics 112 3 4 3 5 3 6 3 7 3 8 3 9 4 1 4 2 4 3 4 4 4 5 4 6 5 1 5 2 5 3 5 4 8 1 8 2 8 3 8 4 8 5 8 6 Using METAFUN but not 117 Graphic buffers 118 Communicating color 119 Common definitions 122 One page graphics 123 Managing resources 124 Enhancing the layout
197. eric or pair primary enlarged numeric or pair primary leftenlarged numeric primary rightenlarged numeric primary topenlarged numeric primary bottomenlarged numeric primary randomized numeric or pair or color primary cornered numeric or pair smoothed numeric or pair Sqeezed numeric or pair primary superellipsed numeric primary randomshifted numeric or pair primary uncolored color primary softened numeric or color primary numeric or pair primary numeric primary pair primary numeric or pair or color primary numeric primary pair primary color primary numeric or color primary numeric primary color primary Syntax diagrams nullary op false normaldeviate nullpen nullpicture pencircle true whatever unary op type abs acos acosh angle arclength ASCII asin asinh atan bbox blackpart bluepart bot bottomboundary bounded boundingbox ceiling center char clipped colormodel condition cosd cos cosh cot cotd cyanpart cycle dashpart decimal ddecimal dddecimal dir exp filled floor fontpart fontsize grayed greenpart greypart hex innerboundingbox inv invcos inverse inverted invsin known leftboundary length 1ft llcorner 1n log lrcorner magentapart makepath makepen mexp mlog not oct odd outerboundingbox pathpart penp
198. eries Sometimes this is not what we want in which case we can use parentheses to force the desired behaviour The lesson learned is that scaling and shifting is not always the same as shifting and scaling draw origin origin shifted 4cm 0cm shifted 4cm 0cm withpen pencircle scaled icm withcolor 625white draw origin origin shifted 4cm 0cm shifted 4cm 0cm withpen pencircle scaled 8mm withcolor 625yellow draw origin origin shifted 4cm 0cm shifted 4cm 0cm withpen pencircle scaled 6mm withcolor 625red draw origin origin shifted 4cm 0cm shifted 4cm 0cm withpen pencircle scaled 4mm withcolor white Scaling and shifting Especially when a path results from a call to a macro using parentheses around a path may help as in the following example def unitslant origin origin shifted 1 1 enddef draw unitslant xscaled 5cm yscaled icm withpen pencircle scaled 1cm withcolor 625red draw unitslant xscaled 5cm yscaled 1cm withpen pencircle scaled 5mm withcolor 625yellow The next definition of unitslant is therefore better def unitslant origin origin shifted 1 1 enddef draw unitslant xscaled 5cm yscaled icm withpen pencircle scaled 5mm withcolor 625red An even better alternative is path unitslant unitslant origin origin shifted 1 1 draw unitslant xscaled 5cm yscaled icm withpen pencircle scaled 5mm withcolor
199. ering Hasselt NL 2010 All aspects of the METAPOST language are covered
200. erlayDepth overlayheight current depth often zero OverlayColor MPcolor overlaycolor background color OverlayLineWidth overlaylinewidth width of the frame OverlayLineColor MPcolor color of the frame BaseLineSkip the baselineskip main line distance LineHeight the baselineskip idem BodyFontSize the bodyfontsize font size of the running text StrutHeight strutheight space above the baseline StrutDepth strutdepth space below the baseline ExHeight lex height of an x EmWidth 1em width of an m dash startuseMPgraphic FunnyFrame picture p numeric o path a b pair c p textext rt MPstring FunnyFrame o BodyFontSize unitsquare xyscaled OverlayWidth OverlayHeight shifted 2o 0verlayHeight ypart center p pickup pencircle scaled OverlayLineWidth b a fill b draw b b fill draw superellipsed 95 withcolor OverlayColor withcolor OverlayLineColor boundingbox p superellipsed 95 b withcolor OverlayColor b withcolor OverlayLineColor p withcolor black setbounds currentpicture to a stopuseMPgraphic draw Many people are just fascinated by their PC s tricks and think that a widely praised pro gram called up on the screen will make everything automatic from now on We used the following command to pass the settings setupframedtexts FunnyText backgroundcolor lightgray framecolor darkred rulethickness 2pt of fset bodyfontsize before blan
201. evious graphic demonstrates what we want to accomplish a circular curve indicating the angle between two straight lines The lines and curve are drawn with the code pair a b a 2cm 1cm b 3cm 1cm drawarrow origin a drawarrow origin b drawarrow anglebetween a b scaled 1cm withcolor 625red where anglebetween is defined as def anglebetween expr a b Cunitvector a a rotated 90 unitvector b enddef Both unitvectors return just a point on the line positioned 1 unit later scaled to 1cm from the origin We connect these points by a curve that starts in the direction at the first point If we omit thea rotated 90 direction specifier we get E Marking angles f These definitions of anglebetween are far from perfect If we don t start in the origin we get the curve in the wrong place and when we swap both points we get the wrong curve The solution for the displacement is given in the MeTAPosT manual and looks like this we package the macro a bit different def anglebetween expr endofa endofb common length unitvector endofa common endofa common rotated 90 unitvector endofb common scaled length shifted common enddef As you can see we compensate for the origin of both vectors This macro is called with a few more parameters We need to pass the length since we want to add the shift to the macro and the shift takes pla
202. expression point number list suffix point number list suffix label suffix empty 1ft rt top bot ulft urt 11ft 1rt raw origin Syntax diagrams command clip picture variable to path expression interim internal variable right hand side let symbolic token symbolic token pickup expression randomseed numeric expression save symbolic token list setbounds picture variable to path expression shipout picture expression special string expression addto command drawing command font metric command newinternal command message command mode command show command special command tracing command show command show expression list showvariable symbolic token list showtoken symbolic token list showdependencies symbolic token list symbolic token symbolic token symbolic token list expression list expression expression list expression addto command addto picture variable also picture expression option list addto picture variable contour path expression option list addto picture variable doublepath path expression option list option list empty drawing option option list Syntax diagrams drawing option withcolor
203. f its products Not only is the concept exiting and clearly well executed but in my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory 1 felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font Edward R concept copyright Figure 6 1 Two examples of annoying backgrounds If you really want to add such texts to a document in CONTEXT we don t have to use the page back ground but can use one of the layout areas instead like text text or text 1eftmargin setupframedtexts FunnyText backgroundcolor lightgray framecolor darkred rulethickness 2pt Setting up backgrounds of fset bodyfontsize before blank big medium after blank big width textwidth There is one drawback when your left and right margin have different dimensions the text will be scaled differently on odd and even pages Normally this is no problem for a draft As an alternative you can use the setuptexts command and wrap the graphic in a box with the right dimensions using code like startuniqueMPgraphic copyright picture p
204. finished drawing the graphic we can anchor the result with anchor_box This macro automatically handles positioning on specific layers The position macro MPpos returns the current characteristics of a position The previously defined G positions return position page x y width G 1 149 182 84163pt 287 9047pt 31 97 G 2 149 110 1036pt 275 33267pt 21 15999pt G 3 149 228 85555pt 275 33267pt 27 68001pt G 4 149 368 61012pt 262 76065pt 16 46999pt height 7 26pt 4 69pt 7 26pt 6 21pt depth 2 83pt 2 83pt 0 2pt 0 2pt The numbers represent the real pagenumber p the current position x y and the dimensions of the box w h d if known These values are fed directly into mMetarost graphics but the individual components can be asked for by MPp MPx MPy MPw MPh and MPd In the previous definition of the graphic we saw another macro MPvar When we invoke a graphic or attach a graphic to a layer we can pass variables We can also set specific variables in other ways as we will see later setMPpositiongraphic G 1 mypos circle setMPpositiongraphic G 1 mypos line to G 2 In the second definition we let the variable to point to another position When needed we can ask for the value of to by MPvar to For reasons of convenience the current position is assigned automatically to from and self This means that in the line we saw in the graphic initialize_box MPpos MPvar self MPvar self will retur
205. fluenced by a single person Once the initi lesign is complete and fairly robust the real test begins as people with many different viewpoint own experiments ther own experiments uglas R Hostadter ce they are po agen and eei they Pt spelled io make same cn a Meta For important issues raised by The Concept of a Meta Font E Edward R Tu ad E Tufte H even odd Figure 6 6 A quick way to draw all used areas In figure 6 6 we see all used areas Areas that are not used are not drawn which saves some testing This background was defined as startuseMPgraphic page StartPage for i Top Header Text Footer Bottom for j LeftEdge LeftMargin Text a cities RightEdge draw Field il j withpen pencircle scaled 2pt withcolor 625red endfor endfor StopPage stopuseMPgraphic We use two nested for loops to step over the areas A for loop with a step of 1 will fail because the indices are defined in a rather special way On the other hand the mechanism is rather tolerant in the sense that i j and j i are both accepted 6 5 Bleeding If you want to share your document all over the world it makes sense to use a paper format like letter or A4 In that case the layout often matches the paper size Bleeding
206. following command to reflect the square about a line through the given points p reflectedabout 2 4cm 5 2 4cm 3cm The line about which the path is mirrored Mirroring does not have to be parallel to an axis p reflectedabout 2 4cm 5 2 6cm 3cm The rectangle now becomes The table also mentions zscaled Transformations zscaled specification takes a vector as argument p zscaled 2 5 The result looks like a combination of scaling and rotation and conforms to the formula in the previous table Transformations can be defined in terms of a transform matrix Such a matrix is stored in a trans form variable For example transform t t identity scaled 2cm shifted 4cm 1cm We use the associated keyword transformed to apply this matrix to a path or picture p transformed t In this example we ve taken the identity matrix as starting point but you can use any predefined transformation The identity matrix is defined in such a way that it scales by a factor of one in both directions and shifts over the zero vector Transform variables can save quite some typing and may help you to force consistency when many similar transformations are to be done Instead of changing the scaling shifting and other trans formations you can then stick to just changing the one transform variable 1 3 Constructing paths In most cases a path will have more points than the few sho
207. for bitmaps but the next macro offers a way out This macro permits you to include graphics in PNG PDF and JPG format or more precise those formats supported by PDFTEX externalfigure hacker png scaled 5cm shifted 6cm 0 externalfigure hacker png scaled 5cm slanted 5 You can apply the usual transformations but only those applied directly will be taken into ac count This means that you currently cannot store external figures in picture variables in order to transform them afterwards Although you are limited in what you can do with such graphics you can include them multiple times with a minimum of overhead Graphics are stored in objects and embedded only once numeric s pair d for i 1 upto 5 S 3cm randomized 1cm 4 size of picture C x 5 s s center of picture d 2cm i 5cm randomized 5cm displacement externalfigure hacker png scaled s rotatedaround c 0 randomized 30 shifted d endfor Because we cannot store the graphic in a picture and scale afterwards we calculate the scale in advance so that we can rotate around the center Including graphics SpedaLeff ets As long as you don t mess around with a stored external figure you re safe The following example demonstrates how we can combine two special driven features figure inclusion and shading picture p p image externalfigure hacker png scaled 150pt clip p to unitcirc
208. ften have need of a little macro that will put an arrow of requested length anchored at a point on the curve and bending with the curve in the direction of motion When David Arnold asked me how this could be achieved the fact that a length was requested meant that the solution should be sought in using the primitives and macros we introduced a few paragraphs before Say that we want to call for such an arrow as follows path p fullcircle scaled 3cm pair q point 4 along p pickup pencircle scaled 2mm draw P withcolor 625white drawarrow somearrow p q 2cm withcolor 625red draw q withcolor 625yellow Because we want to follow the path we need to construct the arrow from this path Therefore we first reduce the path by cutting off the part before the given point Next we cut off the end of the resulting path so that we keep a slice that has the length that was asked for Since we can only cut at points we determine this point using the arctime primitive vardef somearrow expr pat loc len save p path p p pat cutbefore loc p cutafter point arctime len of p of p enddef Cutting and pasting Weltome ta MetaPost By using a vardef we hide the intermediate assignments Such vardef is automatically sur rounded by begingroup and endgroup so the save is local to this macro When processed this code produces the following graphic This gr
209. ftert bot The command thelabel returns the typeset label as picture that you can manipulate or draw afterwards pair a a 3cm 3cm pickup pencircle scaled 1mm drawdot a withcolor 625yellow draw thelabel rt the right way a withcolor 625red Text Welche to Metast You can of course rotate slant and manipulate such a label picture like any other picture ethe right way The font can be specified in the string defaultfont and the scale in defaultscale Labels are defined using the low level operator infont The next statement returns a picture draw this string will become a sequence of glyphs MP infont defaultfont scaled defaultscale By default the infont operator is not that clever and does not apply kerning Also typesetting math or accented characters are not supported The way out of this problem is using btex etex draw btex this string will become a sequence of glyphs TeX etex The difference between those two methods is shown below The outcome of infont depends on the current setting of the variable defaultfont this string will become a sequence of glyphs MP this string will become a sequence of glyphs When you run inside CONTEXT as we do here there is no difference between infont and the TEx methods This is because we overload the infont operator and also pass its content to Tex Both infont and btex use the macro textext whic
210. g the same thing but it is a nice introduction to METRPOST s point operation In order to use this command effectively you need to know how many points make up the path z0 zi z2 z3 cutbefore point 2 of 20 21 22 23 As with subpath you can use fractions to specify the time on the path although the resulting point is not necessarily positioned linearly along the curve Constructing paths 20 21 22 23 cutbefore point 2 5 of 20 21 22 23 If you really want to know the details of where fraction points are positioned you should read the METRFONT book and study the source of METAFONT and meTAPosT where you will find the compli cated formulas that are used to calculate smooth curves 20 21 1 Like any closed path this path has points where the tangent is horizontal or vertical Early in this chapter we mentioned that a pair or point can specify a direction or vector Although any angle is possible we often use one of four predefined directions right 1 0 up 0 1 left 1 0 down 0 1 We can use these predefined directions in combination with directionpoint and cutafter The following command locates the first point on the path that has a tangent that points vertically upward and then feeds this point to the cutafter command 20 21 1 cutafter directionpoint up of z0 z1 cycle You are not limited to predefined direct
211. ge as in this paragraph backgrounds that depend on the typeset text It may be clear now that we need some positional information in order to provide features like the ones shown here The fact that we will act upon in a second pass simplifies the task although it forces us to store the positional information between runs in some place This may look uncom fortable at first sight but it also enables us to store some additional information Now why is that needed A position has no dimensions it s just a place somewhere on the page In order to do tricks like those shown here we also need to know the height and depth of lines at a specific point as well as the width of the box es we re dealing with In the encircled examples the dimensions of the box following the positional node are stored along with the position In the background example we store the current height and depth of the strut an imaginary character with maximum height and depth but no width along with the current text width In order to process the graphics we tag each point with a name so that we can attach actions to those points In fact they become trigger points As we will demonstrate we also need to store the current page number This brings the data stored with a point to lt identifier gt lt pagenumber gt lt x gt lt y gt lt width gt lt height gt lt depth gt The page number is needed in order to let the graphics engine determ
212. ge in the correct area A simple representation of such a page is The red areas are the header and footer while the yellow areas contains the text flow We can turn headers on and off and or hide them For this reason the header text and footer areas together make up the height of the text A close look at the left picture will reveal that the two arrows point to the center of the lines This is achieved by the top and 1ft directives If we would not have clipped the picture the arrow would have stuck half a line width outside the gray area that represents the page When constructing such pictures one should really pay attention to such details since it pays off in the overall look and feel of the document The vertical arrow represents the top space while the horizontal arrow denotes the distance to the back of the cover back space By changing their values you can shift the main body text on the page In a double sided layout scheme the back space is automatically mirrored on even pages The basic layout Since we want to teach a bit of mETRPOST now and then we will also show how these graphics were drawn An advanced wErePosr user may wonder why we hard code the dimensions and avoid metarost s powerful mechanisms for defining relations Our experience has taught us that in pictures like this providing a general solution seldom pays large dividents or savings in time startuseMPgraphic layout 1 pickup
213. graphics in other applications too The second method works well in graphics where parts of the definitions change between invocations of the graphic This method follows the template startuseMPgraphic whatever Neton ssMParabhie startuseMPgraphic result ee te useMPgraphic result The disadvantage of this method is that it cannot be combined with btex etex since it is nearly im possible to determine when how and to what extent the content of a graphic should be expanded before writing it to the temporary meTaPosT file Therefore we will demonstrate how buffers can be used This third method closely parallels the first way of defining graphics A nice side effect is that we can easily typeset these buffers verbatim which we did to typeset this document We are going to do a classic compass and straightedge construction the bisection of a line segment joining two arbitrary points We will construct five graphics where each one displays one step of the construction We will embed each graphic in a start stop command Later we will see the advantage of this strategy A few applications Growing graphics startbuffer def start everything enddef def stop everything enddef stopbuffer We are going to draw a few dots and to force consistency we first define a macro draw_dot The current step will be highlighted in red using stand_out startb
214. grated graphic is defined in the document source or in a style definition file The most primitive way of doing this is just inserting the code Embedded graphicss Integrated graphics startMPcode fill fullcircle scaled 200pt withcolor 625white stopMPcode Such a graphic is used once at the spot where it is defined In this document we also generate graphics while we finish a page so there is a good chance that when we have constructed a graphic which will be called on the next page the wrong graphic is placed For this reason there are are more convenient ways of defining and using graphics which have the added advantage that you can predefine multiple graphics thereby separating the definitions from the usage The first alternative is a usable graphic Such a graphic is calculated anew each time it is used An example of a usable graphic is startuseMPgraphic name fill fullcircle scaled 200pt withcolor 625yellow stopuseMPgraphic When you put this definition in the preamble of your document you can place this graphic any where in the file saying useMPgraphic name As said this graphic is calculated each time it is placed which can be time consuming Apart from the time aspect this also means that the graphic itself is incorporated many times Therefore for graphics that don t change CONTEXT provides reusable graphics startreusableMPgraphic name fill fullcircl
215. h is intercepted and redirects the task to TX This happens in the current run so there is no need to pass extra information about fonts Instead of passing strings to infont you can also pass characters using char for example char 73 When you use infont you normally expect the font to be ASCII conforming If this is not the case you must make sure that the encoding of the font that you use matches your ex pectations However as we overload this macro it does not really matter since the string is passed to TEX anyway For instance UTF encoded text should work fine as CONTEXT itself understands this encoding 1 16 Linear equations In the previous sections we used the assignment operator to assign a value to a variable Al though for most of the graphics that we will present in later chapters an assignment is appropriate specifying a graphic in terms of expressions is not only more flexible but also more in the spirit of the designers of METAFONT and METAPOST The METAFONT book and manual provide lots of examples some of which involve math that we don t consider to belong to everyones repertoire But even for non mathematicians using expressions can be a rewarding challenge The next introduction to linear equations is based on my first experiences with and involves a mathematical challenge posed by a friend I quickly ascertained that a graphical proof was far more easy than some proof with a lo
216. h urmoved pair fullcircle urmoved 1 25 metafun macro Transformations c ath ulmoved pair fullcircle ulmoved 1 25 metafun macro fullcircle slanted 5 metapost primitive ath rotated numeric fullsquare rotated 45 metapost primitive ath rotatedaround pairnumeric fullsquare rotatedaround 25 5 45 metapost macro ath reflectedabout pair pair fullcircle reflectedabout 25 1 25 1 metapost macro Hl Referen Transformations eat al O MES reverse path reverse fullcircle shifted 5 0 metapost primitive counterclockwise fullcircle shifted 5 0 metapost macro tensepath fullcircle metapost macro subpath 1 5 of fullcircle metapost primitive fullcircle cutbefore point 3 of fullcircle metapost macro path cutafter pair fullcircle cutafter point 3 of fullcircle metapost macro Transformations ath cutends 1 fullcircle cutends 5 metapost macro path llcorner fullcircle metapost primitive Ircorner path lrcorner fullcircle metapost primitive urcorner path urcorner fullcircle metapost primitive O ulcorner path ulcorner fullcircle metapost primitive center path center fullcircle metapost macro Transformations boundingbox path boundingbox fullcircle Va metafun macro Va innerboundingbox path innerboundingbox
217. h using a non standard pen In the mMetaront manual you will find methods to draw shapes with similar pens where the pen is also turning as it does in real calligraphy Here we stick to a more simple one We construct the inner path from the points that make up the curve Watch how we use a for loop to compose the new path When used this way no semi colon may be used to end the loop since it would isolate the color directive draw point O of p for i 1 upto length p point i of p endfor withcolor 625red The points are still located on the original path We can move the points to the inside by shifting them over the penwidth in the direction perpen dicular to the point Because we use this transformation more than once we wrap it into a macro This also keeps the code readable vardef inside expr pnt of p point pnt of p shifted penoffset direction pnt of p of currentpen enddef draw inside 0 of p for i 1 upto length p inside i of p endfor withcolor 625red Whenever you define stores its characteristics in some private variables which are used in the top and alike directives The penoffset is a built in primitive and is defined as the point on the pen furthest to the right of the given direction Deep down in METAPOST pens are actually simple paths and therefore metarost has a notion of a point on the penpath In the METRFONT book and manual you can find in
218. hade of red This is because the attributes are collected and applied to each of the components that make up the arrow Because for each component the attribute code is expanded again we get two random colors One way around this is to apply the color afterwards draw image drawarrow 0 0 10 0 withpen pencircle scaled 2pt scaled 8 withcolor red randomized 4 9 Here the image macro creates a picture and as you can see this provides a way to draw within a draw operation Once you see the benefits of image you will use it frequently Another handy at first sight strange macro is hide You can use this in situations where you don t want code to interfere def mydraw text t boolean error error false def withpencil expr p hide error true enddef draw t if error message pencils are not supported here fi enddef mydraw fullcircle scaled 10cm withpencil sharp Here setting the boolean normally interferes with the draw operation but by hiding the assign ment this code becomes valid This code will bring the message to your terminal and log file Once you start using expressions you have a good chance of encountering messages with regards to redundant expressions The following code is for instance a recipe for problems zi 1 0 21 2 0 Changing the into helps but this may not be what you want A few more detail Pitfalls Be
219. hat is not explicitly saved migrates to the outer level In order to prevent all successive graphics to have butt d linecaps we have to change this line characteristic locally Because linecap is defined as an internal variable we have to use interim to overload its value Because uis a rather commonly used scratch variable we don t save its value Watch how we use u as the loop step In spite of what your eyes tell you this graphic only has two explicit color directives both being 5076 black In the next example we will use some real colors Figure 13 3 The simultaneous contrast effect In figure 13 3 the small squares in the center of each colored pair of big squares have the same shade but the way we perceive them are influenced by their surroundings Both sets of squares are defined using usable graphics The top squares are defined as startuseMPgraphic second includeMPgraphic first fill fullsquare scaled size withcolor topshade fill fullsquare scaled delta withcolor centershade stopuseMPgraphic and the bottom squares are coded as Fool yourself few applica ons p startuseMPgraphic third includeMPgraphic first fill fullsquare scaled size withcolor bottomshade fill fullsquare scaled delta withcolor centershade stopuseMPgraphic Because both graphics share code we have defined that code as a separate graphic that we include The only point of interest
220. have to fall back on a few tricks For the moment shading is only supported in PDF In the following examples we will use the next three colors definecolor a darkyellow definecolor b s 8 definecolor c darkred A shade is a fill with a stepwise change in color In POSTSCRIPT level 2 the way this color changes can be circular linear or according to a user defined function Circular and linear shades look like this there I m Circuli Whow this is Li As you can see the shade lays behind the text as a background overlay These overlays are unique METRPOST graphics so they will adapt themselves to the dimensions of the foreground defineoverlay circular shade uniqueMPgraphic CircularShade defineoverlay linear shade uniqueMPgraphic LinearShade The two framed texts are defined as framed background circular shade frame off bf white Hi there I m Circular and framed background linear shade frame off bf white Whow this is Linear Shading We still have to define the graphics Here we use a macro that takes four arguments a path number identifying the center of shading and the colors to start and end with startuniqueMPgraphic CircularShade path p unitsquare xscaled overlaywidth yscaled overlayheight circular_shade p 0 MPcolor a MPcolor b stopuniqueMPgraphic startuniqueMPgraphic LinearShade path p un
221. hbox bfd the MPtoks startMPdrawing n n 1 len n the wd MPbox stopMPdrawing startMPdrawing pic n textext bfd setstrut strut 1 pic n pic n shifted llcorner pic n stopMPdrawing handletokens MetaPost is Fun with whatever T t text We use the low level CONTEXT macro appendtoks to extend the token list MPtoks The handletokens macro passes each token character of MetaPost is Fun to the macro whatever The tokens are appended to the token register MPtoks already defined Then we typeset the content of MPtoks in MPbox also already defined The width of the box is passed to METAPOST and stored in len By default the content of the drawing is expanded which means that the macro is replaced by its current meaning so the current width ends up in the metarost file The next part of the drawing starting with btex puts the token in a picture This time we don t expand the drawing since we want to pass font information Here the suppresses expansion of btex bfd 1 etex The process is iterated by handletokens for each character of the text MetaPost is Fun Before we typeset the text now available in pieces in pic in a circle we will first demonstrate what they look like You may like to take a look at the file mpgraph mp to see what is passed to METAPOST startMPdrawing pair len len origin for i
222. he following command Watch the use of line correction commands They optimize the white space around the graphic startlinecorrection blank hbox useMPgraphic layout 1 hskipicm useMPgraphic layout 2 stoplinecorrection Page backgrounds The basic layout As soon as you want to make an electronic document you will want to use different areas of the screen for different purposes text menus buttons etc For this reason CONTEXT provides not only left and right margins but also additional left and right edge areas and top and bottom margins These areas are shown in the figure on the next page When defining this graphic all areas have related dimensions Here it makes sense to let METAPOST calculate these dimensions as much as possible First we define the five by five matrix of areas We pass the width and height of the main text area Because they are stored in dimension registers we have to prefix them by Nthe pickup pencircle scaled 2pt numeric w xf yO u u 5cm numeric width width numeric height height the textwidth the textheight We now specify the lower left corners using instead of the which means that vEraPosr will calculate 3 and h 3 for us w 1 h 1 2u w 2 iu h 2 w 1 w 2 w 3 w 4 w 5 4u h 1 h 2 h 3 h 4 h 5 4u x 1 1u x 2 x 1 w 1 x 3 x 2 w 2 x
223. he end points are not calculated due to rounding errors In such case you can use the epsed value which gives slightly more playroom draw function 1 x sin 2x 1 10 01 scaled 1 5cm withpen pencircle scaled 1mm withcolor transparent 1 5 red draw function 1 x sin 2x x 1 10 01 scaled 1 5cm withpen pencircle scaled imm withcolor transparent 1 5 green draw function 1 x sin 2x xt x 1 10 01 scaled 1 5cm withpen pencircle scaled imm withcolor transparent 1 5 blue Of course you can do without a grid The next example demonstrates a nice application of trans parencies Drawing functions Figure 9 3 By using transparent colors we don t have to calculate and mark the common points they already stand out Drawing functions If we use the exclusion method for the transparencies combined with no transparency we get the following alternative draw function 2 x sin x O 2pi pi 40 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 red draw function 2 x sin 2x 0 2pi pi 40 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 green draw function 2 x
224. he following statement As you may know TgX s ambassador is a lion while METAFONT is represented by a lioness It is still unclear if they have a relationship but if so and if a baby is born may it enjoy METAFUN The low level CONTEXT macro processwords provides a mechanism to treat the individual words of its argument The macro is called as follows processwords As you may know TEX s ambassador is a lion while METAFONT is represented by a lioness It is still unclear if they have a relationship but if so and if a baby is born may it enjoy METAFUN In order to perform a task you should also define a macro processword which takes one argu ment The previous quote was typeset with the following definition in place def processword 1 1 A slightly more complicated definition is the following def processword 1 noindent framed 1 space We now get Typesetting graphics As you may know TEX s ambassador is a lion while mETRFONT jis represented a lioness It jis still unclear if they have a relationship but if so land baby is may it enjoy METAFUN If we can use fram
225. her large This style is the 19 presentation style Those numbered styles are internally mapped onto more meaningful names like y P y y y mapp 5 in this case pre organic Adaptive buttons E edge distance By setting the header and footer dimensions to zero we automatically get rid of page body ornaments like the page number setuplayout topspace 48pt backspace 48pt cutspace 12pt width 400pt margin 0cm rightedge 88pt rightedgedistance 48pt header 0cm footer Ocm height middle We use a moderate about a line height inter paragraph white space setupwhitespace big Of course we use colors since on computer displays they come for free setupcolors state start definecolor red r 75 definecolor yellow r 75 g 75 definecolor gray s 50 definecolor white s 85 Because it is an interactive document we have to enable hyperlinks and alike However in this style we disable the viewer s highlight a hyperlink when it s clicked on feature We will use a menu so we enable menus Later we will see the contrast color hyperlinks gets that color when we are already on the location in action setupinteraction state start click off color red contrastcolor gray menu on The menu itself is set up as follows Because we will calculate menu buttons based on their position on the page we have to keep track of the positions Ther
226. his point or touching that point In this section we will spend some time on this touchy aspect drawarrow reverse Only this far A few This rectangle is a scaled instance of the predefined METAFUN path fullsquare which is centered around the origin pickup pencircle scaled 2mm path p p fullsquare scaled 2cm draw p withcolor 625white On this path halfway between two of its corners we define a point q pair q 5 11 p lrcorner We draw this point in red using draw q withcolor 625red As you can see this point is drawn on top of the path There are four of those midpoints and when we connect them we get Because path p is centered around the origin we can simply rotate point q a few times draw q q rotated 90 q rotated 180 q rotated 270 cycle withcolor 625red There are situations where you don t want the red path to be drawn inside another path or more general where you want points to touch instead of being overlayed E Only this far We can achieve this by defining point q to be located on top of the midpoint pair q top 5 11 p lrcorner p The predefined macro top moves the point over the distance similar to the current pen width Because we are dealing with two drawing operations and since the path inside is drawn through the center of points
227. hpen pencircle scaled 4pt withcolor 625red drawpath p drawpoints p resetdrawoptions When stretched is applied to a path it is scaled but the starting point point 0 keeps its location The specification is a scale path p p 0cm 0 3cm icm 4cm 0 5cm icm drawpath p drawpoints p p p stretched 1 1 drawpathoptions withpen pencircle scaled 2 5pt withcolor 625yellow drawpointoptions withpen pencircle scaled 4 0pt withcolor 625red drawpath p drawpoints p resetdrawoptions We can scale in two directions independently or even in one direction by providing a zero value In the next example we apply the stretch two times path p p 0cm 0 3cm icm 4cm 0 5cm i1cm drawpath p drawpoints p p p stretched 75 1 25 drawpathoptions withpen pencircle scaled 2 5pt withcolor 625yellow drawpointoptions withpen pencircle scaled 4 0pt withcolor 625red Some extensions drawpath p drawpoints p p p stretched 0 1 5 drawpathoptions withpen pencircle scaled 4 0pt withcolor 625red drawpointoptions withpen pencircle scaled 2 5pt withcolor 625yellow drawpath p drawpoints p resetdrawoptions We already met the randomize operator This one is the chameleon under the operators draw fullsquare xyscaled 4cm 2cm randomized 25 shifted origin randomized 1cm 2cm withcolor red randomized
228. iable halfcircle halfcircle metapost variable D uartercircle quartercircle metapost variable llcircle llcircle metafun variable d lrcircle lrcircle metafun variable urcircle urcircle metafun variable D ulcircle ulcircle metafun variable D tcircle tcircle metafun variable D Paths bcircle bcircle metafun variable d lcircle lcircle metafun variable am rcircle rcircle metafun variable V lltriangle lltriangle metafun variable 4 Irtriangle lrtriangle metafun variable iangle urtriangle H ec H metafun variable V ultriangle ultriangle metafun variable N Paths flex pair pair pair flex 0 00 01 0 1 00 metapost macro erellipse pair p p p num superellipse 1 5 5 1 0 5 5 0 75 metapost macro ath smoothed numeric pair unitsquare scaled 1 5 smoothed 2 metafun macro ath cornered numeric pair lltriangle scaled 1 5 cornered 2 metafun macro ath superellipsed numeric unitsquare scaled 1 5 superellipsed 75 metafun macro Paths ath randomized numeric pair unitsquare scaled 1 5 randomized 2 2 metafun macro _ ath squeezed numeric pair unitsquare scaled 1 5 squeezed 2 1 metafun macro unked path punked unitcircle scaled 1 5 metafun macro curved 10 0 7 2 1 1 2
229. iables How exactly does this mechanism work A nice application of setting up variables for a specific graphic or class of graphics is the follow ing In an email message the author can express his own or the readers expected emotions with so called smilies like 2 If you want them in print you can revert to combinations of characters in a font but as a user you may want to include nicer graphics A convenient way to implement these is to make them into symbols one reason being that in that case they will adapt themselves to the current font size Say it with a symbol smile or maybe even a symbol smilemore although seeing too many dorecurse 10 symbol smile Nunskip in one text may make you cry Say it with gt or maybe even 2 although seeing too many 2222222222 one text may make you cry Because we want an efficient implementation we will use unique graphics because these will only be generated when the circumstances change def inesymbol smile uniqueMPgraphic smile type 1 def inesymbol smilemore uniqueMPgraphic smile type 2 The definition itself then becomes setupMPvariables smile type 1 height 1 25ex color darkred startuniqueMPgraphic smile type height color numeric size size MPvarfheight drawoptions withcolor MPvar color Graphic variables bol t pickup pencircle xscaled
230. ic Each method has its advantages and disadvantages In the previous chapter we were still assuming that the graphic was defined in its own file In this chapter we will introduce the interface between CONTEXT and and demonstrate how the definitions of the graphics can be embedded in the document source 3 1 Getting started From now on we will assume that you have CONTEXT running on your platform Since PDF has full graphics support we also assume that you use LUATEX in combination with CONTEXT MKIV although most will also work with other engines and MKII Since this document is not meant as a CONTEXT tutorial we will limit this introduction to the basics needed to run the examples A simple document looks like starttext Some text stoptext You can process this document with the LUA based command line interface to CONTEXT If the source code is embedded in the file mytext tex you can say context mytext We will use color and in color is enabled by default If you don t want color you can tell CONTEXT so setupcolors state stop starttext Some color blue text and or color green graphics stoptext comes out in black and white In later chapters we will occasionally see some more CONTEXT commands show up If you want to know more about what CONTEXT can do for you we recommend the beginners manual and the reference manual as well as the wiki pages 3 2 External graphics Since
231. ifted 0 1 250 ypart urcorner two setbounds currentpicture to boundingbox currentpicture enlarged 3pt stopuseMPgraphic Outline fonts In this graphic we have two text fragments the first one is a text the second one the name of the author We combine the quotation and author into this graphic using the following definitions setMPtext text vbox hsize 8 5cm input zapf setMPtext author hbox sl Hermann Zapf These definitions assume that the file zapf tex is present on the system which is the case when you have installed CONTEXT The graphic can now be typeset using the following call placefigure A text does not need to be an outline in order to be typeset in an outline font useMPgraphic quotation Coming back to the use of typefaces in elec tronic publishing many of the new typogra phers receive their knowledge and information about the rules of typography from books from computer magazines or the instruction manu als which they get with the purchase of a PC or software There is not so much basic in struction as of now as there was in the old days showing the differences between good and bad typographic design Many people are just fascinated by their PC s tricks and think that a widely praised program called up on the screen will make everything automatic from now on Hermann Zapf Figure 8 9 A text does not need to be an outline in ord
232. ifted pos i 0 draw boundingbox pic i shifted pos i 0 withpen pencircle scaled 25pt withcolor red endfor stopMPdrawing That this correction is adequate is demonstrated in the next graphic If you look closely you will see that for instance the o is moved to the left under the capital P MetaPost is Fun When we want to position the pictures along a circle we need to apply some rotations especially because we want to go clockwise Since we don t want to use complicated math or more advanced METRPOST code yet we will do it in steps startMPdrawing for i 1 upto n pic i pic i rotatedaround origin 270 endfor stopMPdrawing gt ataca e We will now center the pictures around the baseline Centering comes down to shifting over half the height of the picture This can be expressed by ypart 5 ulcorner pic i llcorner pic il but different ways of calculating the distance are possible too startMPdrawing for i 1 upto pic i shifted 0 ypart 5 ulcorner pic i llcorner pic i endfor stopMPdrawing So now we have gt When we typeset on a half circle we should map the actual length onto a partial circle We denote the r
233. ile the decimal operator converts a number into a string The result has no typographic beauty keep in mind that here we use meTaPosT to typeset the text but the result serves its purpose an redpart 0 625 d greenpart 0 I bluepart 0 2 We can also ask for the path itself pathpart the pen penpart and the dashpattern dashpart but these can only be assigned to variables of the corresponding type A path can be stroked or filled in which case it is a cyclic path It can have a non natural bounding box be a clip path consist of line segments or contain text All these characteristics can be tested label rt filled amp condition filled p 4cm 1 25cm label rt stroked amp condition stroked p 4cm 0 75cm label rt textual amp condition textual 4cm 0 25cm label rt clipped amp condition clipped 4cm 0 25cm label rt bounded amp condition bounded 4cm 0 75cm label rt cycle amp condition cycle pathpart p 4cm 1 25cm filled false XN stroked true textual false x clipped false 9 4 bounded false cycle true In this code snippet condition is a macro that takes care of translating a boolean value into a string like decimal does with a numeric value def condition primary b if b true else false fi enddef Clip paths and bounding boxes are kind of special in the sense that they can obscure com
234. in a button and we also don t know at what height it will end up Therefore we need to calculate each button shape independently and for that purpose we need to know its position see chapter 5 In figure 12 1 you can see what lines we need in order to be calculate the button shapes We separate the calculation of the button shape from the rest by embedding it in its own usable graphic container The StartPage StopPage pair takes care of proper placement of the whole graphic startuseMPgraphic page includeMPgraphic rightsuperbutton StartPage path p q pickup pencircle scaled 3pt p Field Text Text enlarged 36pt superellipsed 90 fill Page withcolor MPcolorfyellow fill p withcolor MPcolor white draw p withcolor MPcolor red p Field Text Text enlarged 48pt superellipsed 90 Adaptive buttons Deliningsgyles jdez uueurloH SAU tal uqnuwy preuoq J93pe3sJoH se 3no q 000c 3snSny uosepy suey e A3g op durg Figure 12 1 The auxiliary lines used to calculate the button shapes Adaptive buttons def right menu button nn rr pp xx yy ww hh dd if gt 0 and rr gt 0 q rightsuperbutton p xx yy RightEdgeWidth hh fill withcolor MPcolor white draw q withcolor if rr 2 MPcolor gray else MPcolor fred fi fi enddef MP
235. ine boundary conditions Backgrounds like those shown here can span multiple pages In order to calculate the right back grounds some additional information must be available like the top and bottom of the current text area In fact these are just normal points that can be saved while processing the split off page So apart from positioning anchors in the text we need anchors on crucial points of the layout This means that this kind of support cannot be fully integrated into the kernel unless we also add extensive support for layout definitions and that is probably not what we want As soon as something like x y shows up a logical question is where 0 0 is located Although this is a valid question the answer is less important than you may expect Even if we know that 0 0 is officially located in the bottom left corner of the page the simple fact that in CONTEXT we are dealing with a mixed page concept like paper size and print paper size or left and right pages forces us to think in relative positions instead of absolute ones Therefore graphics even those that involve multiple positions are anchored to a position on the layer on which they are located The MPanchor macro takes care of this Users who simply want to use these features may wonder why we go into so much detail The main reason is that in the end many users will want to go beyond the simple cases and when dealing with these issues you must be aware not onl
236. int in the direction of the line that is determined by the second point t We now have the framework of an angle drawing macro ready and can start working placing the label vardef anglebetween expr endofa endofb common length str save curve where path curve numeric where where turningnumber common endofa endofb cycle curve unitvector endofa common endofa common rotated where 90 unitvector endofb common scaled length shifted common draw thefreelabel str point 5 of curve common withcolor black curve enddef The macro thefreelabel is part of METAFUN and is explained in detail in section 13 2 This macro tries to place the label as good as possible without user interference pair b drawarrow 2cm 1cm drawarrow origin a 3cm drawarrow origin b anglebetween a b origin icm btex alpha etex withcolor 625red Instead of a picture we may also pass a string but using by means of btex etex often leads to better results fe applications _ Marking angles Because in most cases we want the length to be consistent between figures and because passing two paths is more convenient than passing three points the final definition looks slightly different numeric anglelength anglelength 20pt vardef anglebetween expr a b str path path string save endofa endofb c
237. ints the width of the winding the length of the connecting pieces and the number of elements half windings The definition of spring is less complicated than readable Simple drawings def spring expr a b w h n C 0 0 0 h for i 1 upto n 1 if odd i fi w 2 i h endfor 0 n h 0 n 2h yscaled xpart b a ypart b a n 2h rotatedaround origin 90 angle b a shifted a enddef First we build a path starting in the origin going left or right depending on the counter being an odd number pat 0 0 for i 1 upto n 1 if odd i pat pat w 2 i else pat pat w 2 i fi endfor pat pat 0 1 Once you are accustomed to the way meTAPosT interprets specialists may say expand the source code you will start using if and for statements in assignments The previous code can be con verted in a one liner using the pattern pat for i 1 upto n 1 x y endfor 0 n The loop splits out a series of x y but the last point is added outside the loop Otherwise pat would have ended with a dangling Of course we need to replace x y by something meaningful so we get pat for i 1 upto n 1 if odd i fi w 2 i endfor 0 n We scale this path to the length needed The expression b a calculates a vector starting at a and ending at b In Metarost the expression a b is identical
238. ion vectors You can provide a pair denoting a direction In the next example we use the following cyclic path Constructing paths 20 21 1 Using is not mandatory but makes the expression look less complicated 20 21 1 cutafter directionpoint 1 1 of 20 21 1 We will apply these commands in the next chapters but first we will finish our introduction in METRPOST We have seen how a path is constructed and what can be done with it Now it is time to demonstrate how such a path is turned into a graphic 1 4 Angles You can go from angles to vectors and vice versa using the angle and dir functions The next example show both in action pickup pencircle scaled 2mm draw origin scaled 3cm draw origin scaled 3cm draw origin scaled 3cm dir 45 dir 0 cycle withcolor 625red dir angle 1 1 dir angle 1 0 cycle shifted 3 5cm 0 withcolor 625yellow 1 1 1 0 cycle shifted 7cm 0 withcolor 625white AA Angles The dir command returns an unit vector which is why the first two shapes look different and are smaller than the third one We can compensate for that by an additional scaling pickup pencircle scaled 2mm draw origin dir 45 dir 0 cycle scaled sqrt 2 scaled 3cm withcolor 625red draw origin dir angle 1 1 dir angle 1 0 cycle scaled
239. ions at the TUG 2000 conference in Oxford UK This style exploits a few tricks like graphics calculated using positional information It also demonstrates how you can make menu buttons that dynamically adapt their shapes to the rest of the page layout page 1 page2 page3 page4 page 5 Later we will see an instance with some more randomness in the graphics While writing this style the random alternative made me think of those organic buildings with non equal windows we have a few of those in The Netherlands so I decided to label this style as pre organic If you use CONTEXT you can load this style with usemodule pre organic At the end of this file there is a small test file so when you process the file s pre 19 tex with the options mode demo and pdf you will get a demo document We use one of the standard screen paper sizes and map it onto the same size so that we get a nicely cropped page Other screen sizes are 54 and S5 setuppapersize s6 56 Like in this METAFUN manual we use the Palatino as main bodyfont This font is quite readable on even low resolution screens although I admit that this style is developed using an 1400 x 1050 pixel LCD screen so the author may be a little biased setupbodyfont ppl The layout specification sets up a text area and a right edge area where the menus will go see chapter 6 for a more in depth discussion on the layout areas Watch how we use a rat
240. ip step baselineskip until vvsize line ulcorner q urcorner q shifted 0 i 111 found point line l true rrr found point line r false stopuseMPgraphic Talking to We can manipulate the heigth and depth of the lines to give different and maybe better results startuseMPgraphic text vars baselineskip 8pt strutheight 4pt strutdepth 2pt offset Apt topskip Spt stopuseMPgraphic This kind of graphic trickery in itself is not enough to get into typesetting within the bounds of a closed curve Since METAPOST can write information to a file and Tpx can read such a file a natural way to handle this is to let MeTaPosT write a parshape specification startuseMPgraphic text macro def provide_parshape expr p offset baselineskip strutheight strutdepth topskip includeMPgraphic text includeMPgraphic text includeMPgraphic text includeMPgraphic text includeMPgraphic text includeMPgraphic text includeMPgraphic text enddef stopuseMPgraphic Talking to move split cutoff draw calc loop save We have to adapt the for loop to register the information about the lines After the loop we write those values to a file using another loop startuseMPgraphic text loop path line pair 111 rrr numeric vvsize n n 0 if strutheight strutdepth bas
241. ique graphics are needed when a single graphic might be used multiple times by scaling it to fit the situation Since a unique graphic is calculated for each distinctive case we can be sure that the current circumstances are taken into account Also scaling would result in incomparable graphics Consider the following definition startuseMPgraphic demo draw unitsquare xscaled 5cm yscaled icm withpen pencircle scaled 2mm withcolor 625red stopuseMPgraphic Since we reuse the graphic the dimensions are sort of fixed and because the graphic is calculated once scaling it will result in incompatible line widths C C These graphics were placed with hbox bgroup scale width 5cm height 1cm useMPgraphic demo quad scale width 8cm height 1cm useMPgraphic demo egroup Imagine what happens when we add some buttons to an interactive document without taking care of this side effect All the frames would look different Consider the following example Embedded Integrated graphics startuniqueMPgraphic right or wrong pickup pencircle scaled 075 fill unitsquare withcolor 8white draw unitsquare withcolor 625red currentpicture currentpicture xscaled OverlayWidth yscaled OverlayHeight stopuniqueMPgraphic Let s define this graphic as a background to some buttons def ineoverlay button uniqueMPgraphic right or wrong setupbuttons background
242. ir definitions to see what happens there First we give a square round corners with roundedsquare path p p roundedsquare 2cm 4cm 25cm drawpath p drawpoints p Next we draw a square like circle or circle like square using tensecircle path p p tensecircle 2cm 4cm 25cm drawpath p drawpoints p Some extensions Welcome to MetaPost Often I make such helpers in the process of writing larger drawing systems Take crossed path p p origin crossed 1cm drawpath p drawpoints p p origin crossed fullcircle scaled 2cm crossed 5cm shifted 3cm 0 drawpath p drawpoints p These examples demonstrate that a path is made up out of points something that you probably already knew by now The metarost operator of can be used to access a certain point at a curve path p p fullsquare xyscaled 3cm 2cm randomized 5cm drawpath p drawpoints p drawpointlabels p draw point 2 25 of p withpen pencircle scaled 5mm withcolor 625red e 2 0 e 4 1 To this we add two more operators on and along With on you get the point at the supplied distance from point 0 with along you get the point at the fraction of the length of the path pathp q r fullsquare xyscaled 2cm 2cm randomized 5cm p shifted 3cm 0 r q shifted 3cm 0 drawpath p drawpoints p drawpointlabels p drawpath q drawpoints q dra
243. is complex route if you want to simply redraw a path with another pen or color draw fullcircle scaled icm withcolor 625red withpen pencircle scaled imm draw currentpicture withcolor 625yellow withpen pencircle scaled 3mm draw boundingbox currentpicture withpen pencircle scaled 5mm This is what you will get from this If you want to add a background color to a picture you can do that afterwards This can be handy when you don t know in advance what size the picture will have fill fullcircle scaled withcolor 625 addbackground withcolor 625 yellow The background is just a filled rectangle that gets the same size as the current picture that is put on top of it A Some extensions 1 19 Cutting and When enhancing or building a graphic often parts of already constructed paths are needed The subpath cutbefore and cutafter operators can be used to split paths in smaller pieces In order to do so we must know where we are on the path that is involved For this we use points on the path Unfortunately we can only use these points when we know where they are located In this section we will combine some techniques discussed in previous sections We will define a few macros manipulate some paths and draw curves and points 6 This circle is drawn by scaling the predefined path fullcircle This path is constructed using 8 points As you ca
244. it drawoptions withpen pencircle draw vlingrid 0 width unit draw hlingrid 0 height unit StopPage stopMPpage height PaperHeight unit cm scaled 2pt withcolor 8white 1 10 width height 1 10 height width scaled 5pt withcolor 4white 1 width height 1 height width This produces a page as in figure 9 1 with a metric grid If you re hooked to the inch you can setunit 1in If you want to process this code you need to wrap it into the normal document producing commands setupoutput pdftex Nsetupcolors state start starttext definitions stoptext Grids Figure 9 1 Quick and dirty grid paper i Fi i Grids ictions 9 3 Drawing functions Today there are powerful tools to draw functions on grids but for simple functions you can com fortably use Let s first draw a simple log linear grid drawoptions withpen pencircle scaled 25pt withcolor 5white draw hlingrid draw vloggrid 0 20 0 10 2 20cm 10cm 5 10cm 20cm drawoptions withpen pencircle scaled 50pt draw hlingrid draw vloggrid 0 20 0 10 To this grid we add some labels fmt pictures textextoffset false draw hlintext lft 0 20 draw vlogtext bot 0 10 1 20cm 10cm 1 10cm 20cm use TeX as formatting engine 5 20cm 9 10cm ExHeight a variable
245. itsquare xscaled overlaywidth yscaled overlayheight linear_shade p 0 MPcolor a MPcolor b stopuniqueMPgraphic The METAPOST macros circular shade and linear shade add information to the METAPOST out put file which is interpreted by the converter built in CONTEXT Shading comes down to interpo lation between two or more points or user supplied ranges A poor mans way of doing this is to build the graphics piecewise with slightly changing colors But instead of manually stepping through the color values we can use the more efficient and generalized POSTSCRIPT level 2 and PDF level 1 3 shading feature circular 0 circular 1 circular 2 circular 3 circular 4 b b linear 1 linear 2 linear 3 linear 4 linear 5 linear 6 linear 7 linear 8 Shading is not a METRPOST feature which means that it has to be implemented using so called specials directives that end up in the output file Unfortunately these are not coupled to the spe cific path which means that we have to do a significant amount of internal bookkeeping Also in PDF we have to make sure that the graphics and their resources being the shading functions are packaged together Shading Because of this implementation shading may behave somewhat unexpected at times A rather normal case is the next one where we place 5 shaded circles in a row path p fullcircle scaled for i 0 step 2cm until 8cm circular shade p shifted i 0 0
246. k big medium after blank big width textwidth In a real implementation we should also take care of some additional spacing before the text which is why we have added more space before than after the framed text Graphics and macros Enhan ing the Jayout_ We demonstrated that when defining graphics that are part of the layout you need to have access to information known to the typesetting engine Take figure 4 4 The line height needs to match the font and the two thin horizontal lines should match the x height We also need to position the baseline being the lowest one of a pair of lines in such a way that it suits the proportions of the line as specified by the strut A strut is an imaginary large character with no width You should be aware of the fact that while works its way top down in mMetarost the origin is in the lower left corner Figure 4 4 Penalty lines usetypescript serif chorus definefont SomeHandwriting TeXGyreChorus MediumItalic at 12pt start SomeHandwriting setstrut startMPpage StartPage path p numeric 1 n 1 1 5LineHeight n 0 origin shifted 1 0 origin shifted PaperWidth 1 0
247. l fullcircle scaled 2cm reverse fullcircle scaled icm cycle withcolor 625 yellow The inner circle is indeed not filled Variables At this point you may have noted that vETRPOST is a programming language Contrary to some of today s languages Metarost is a simple and clean language Actually it is a macro language Although metarost and are a couple the languages differ many aspects If you are using both you will sometimes wish that features present in one would be available in the other When using both languages in the end you will understand why the conceptual differences make sense Being written in PASCAL it will be no surprise that has some PASCAL like features al though some may also recognize features from ALGOL68 in it Welcome toavtetaPast Variables First there is the concept of variables and assignments There are several data types some of which we already have seen numeric real number in the range 4096 4096 boolean a variable that takes one of two states true or false pair point or vector in 2 dimensional space path a piecewise collection of curves and line segments picture collection of stroked or filled paths string sequence of characters like metapost color vector of three rgb or four cmyk numbers There are two additional types transform and pen but we will not discuss these in depth transform tr
248. le scaled 150pt circular shade boundingbox p enlarged 10pt 0 2red 9red addto currentpicture also p We end this section with a few more words to METRPOST inclusion It may seem that in order to use the features discussed here you need to use CONTEXT as typesetting engine This is not true First of all you can use the small TEX package MPTOPDF described in another manual or you can make small CONTEXT files with one page graphics The advantage of the last method is that you can manipulate graphics a bit Nsetupcolors cmyk yes rgb no state start starttext startMPpage offset 6pt loadfigure niceone mp number 10 stopMPpage stoptext Including graphics The resulting PDF file be included any other graphic and has the advantage that it is self contained 8 5 Changing colors One of the advantages of graphics is that it is rather easy to force consistency in colors and line widths You seldom can influence third party graphics that way but we can use some METAFUN trickery to get around this limitation Say that we want a red cow instead of a black one The following code does the trick loadfigure mycow mp number 1 scaled 35 refill currentpicture withcolor 625red In a similar way we can influence the width and colors of the lines loadfigure mycow mp number 1 scaled 35 refill currentpicture withcolor 625red redraw currentpicture
249. linejoin beveled metapost variable C Attributes inverted picture inverted currentpicture 9 metafun macro icture uncolored color currentpicture uncolored green v y icture softened numeric currentpicture softened 8 vw icture softened color currentpicture softened 7 8 9 metafun macro metafun macro metafun macro rayed picture grayed currentpicture metafun macro C Text label label MetaFun origin metapost macro Metarun Text label to label top MetaFun origin Metarun label bot label bot MetaFun origin metapost macro metapost macro label lft label 1ft MetaFun origin metapost macro label rt label rt MetaFun origin metapost macro label lft label 11ft MetaFun origin metapost macro label lrt label 1rt MetaFun origin metapost macro label urt label urt MetaFun origin metapost macro V MetaFun label ulft label ulft MetaFun origin metapost macro M 0 btex text etex draw btex MetaTeX etex metapost primitive textext string draw textext MetaFun MetaFun raphictext string graphictext MetaFun MetaFun C 6 Graphics loadfigure string number numeric loadfigure mycow mp number 1 scaled 25 metafun macro metafun macro externalfigure string externalfigure myco
250. lor black curve enddef applications Marking angles method 1 method 2 method 3 Figure 13 1 Three ways of marking angles Figure 13 1 shows the first three alternative methods implemented here Instead of using unitvectors we now calculate the points using the arctime and arclength primitives Instead of complicated expressions we use the METAFUN operators along and on The following expressions are equivalent pointa point anglelength on a middle point 5 along curve pointa point arctime anglelength of a of a middle arctime 5 arclength curve of curve of curve The third method can be implemented in different more math intensive ways but the current implementation suits rather well and is understood by the author 13 4 Color circles In chapter 3 we showed a few color circles Drawing such a graphic can be done in several ways and here we will show a few methods First we will demonstrate how you can apply cutafter and cutbefore next we will show how the metarost macro buildpath can be used and finally we will present a clean solution using subpath We will assume that the circle is called with the macro colorcircle 4cm red green blue We need to calculate seven paths The first implementation does all the handywork itself and thereby is rather long complicated and unreadable It does not really use the strenghth of
251. lors Most dashpatterns be defined in terms of on and off This simple on off dashpattern is pre defined as picture evenly Because this is a picture you can and often need to scale it draw 0 0 10cm 0 dashed evenly scaled 1mm withpen pencircle scaled 1m Opposite to a defaultpen there is no default color and default dash pattern set The macro drawoptions provides you a way to set the default attributes drawoptions dashed evenly withcolor red 1 15 Text Since METAFONT is meant for designing fonts the only means for including text are those that permit you to add labels to positions for the sole purpose of documentation Because is derived from METAFONT it provides labels too but in order to let users add more sophisticated text like a math formula to a graphic it also provides an interface to Because we will spend a whole chapter on using text in METRPOST we limit the discussion here to a few fundamentals pair a a 3cm 3cm label top top a label bot bot a label lft lft a label rt rt a These four labels show up at the position stored in the pair variable a anchored in the way speci fied after the period top lft rt bot The command dot1label also typesets the point as rather visible dot pair a a 3cm 3cm dotlabel top top a dotlabel bot bot a dotlabel lft lft a dotlabel rt rt a top l
252. lse bounded setbounds currentpicture to fullcircle draw fullcircle withpen pencircle scaled 3mm clip currentpicture to fullcircle B The description lines were generated by the following loop n 0 5 for i within currentpicture n n 1 label n amp decimal n amp length amp decimal length i amp stroked amp condition stroked i amp clipped amp condition clipped i amp bounded amp condition bounded i 0 endfor 1 length 0 stroked false clipped false bounded 2 length 1 stroked true clipped false bounded n 5cm true false false true false false false true false If we have a textual picture we can also ask for the text and font Take the following picture Analyzing pictures picture p pes MetaFun normalinfont rm 1mr 10 p shifted 0 ypart center p currentpicture Here we can ask for Scaled 2 rotated 30 slanted 5 label rt textpart amp textpart p 4cm 0 25cm label rt fontpart amp fontpart p 4cm 0 25cm and get pu Met We use normalinfont instead of infont because in METAFUN this operator is overloaded and fol lows another route for including text textpart fontpart MetaFun rm lmr10 If we re dealing with a path the transformati
253. m Now we get Transformations Note that rotated 15 is equivalent to p rotatedaround origin 15 It may make more sense to rotate the shape around its center This can easily be achieved with the rotatedaround command Again we move the path to the right afterwards rotatedaround center p 15 shifted 4cm 0cm Yet another transformation is slanting Just like characters can be upright or slanted a graphic can be p slanted 1 5 shifted 4cm 0cm The slant operation s main application is in tilting fonts The x coodinates are increased by a per centage of their y coordinate so here every x becomes x 1 5y The y coordinate is left untouched The following table summarizes the most important primitive transformations that sup ports METRPOST code mathematical equivalent x y shifted a b x ay b x y scaled s sx sy x y xscaled s sx y x y yscaled s x sy Transformations x y zscaled u v xu yo xv yu x y slanted s x sy y x y rotated r x cos r ysin r x sin r y cos r The previously mentioned rotatedaround is not a primitive but a macro defined in terms of shifts and rotations Another transformation macro is mirroring or in METRPOST terminology reflectedabout The reflection axis is specified by a pair of points For example in the graphic above we used the
254. menubuttons right StopPage stopuseMPgraphic The macro MPmenubuttons expands into a list of in this case four calls to the METAPOST macro right menu button This list is generated by CONTEXT when it generates the menu Because the page background is applied last this list is available at that moment expr nn rr pp xx yy ww hh dd This rather long list of arguments represents the following variables number referred page cur rent page x coordinate y coordinate width height and depth The last six variables originate from the positioning mechanism Because the variables are only available after a second pass we only draw a button shape when the test for the page numbers succeeds startuseMPgraphic rightsuperbutton vardef rightsuperbutton expr pat xpos ypos wid hei save p ptop pbot t b edge shift width height path p ptop pbot pair t b numeric edge shift width height edge xpos wid shift ypos hei p rightpath pat ptop infinity shift edge shift pbot infinity shift hei edge shift hei t p intersectionpoint ptop b intersectionpoint pbot subpath 0 xpart intersectiontimes ptop of p subpath xpart p intersectiontimes pbot length p of p p t point 1 of ptop amp point 1 of ptop point 1 of pbot amp point 1 of pbot b cycle Adaptive buttons Defining styles
255. n pencircle scaled imm withcolor 625red currentpicture currentpicture slanted 5 Current picture i Sometimes it s handy to temporarily set aside the current picture draw fullcircle scaled 1cm withpen pencircle scaled 1mm withcolor 625red currentpicture currentpicture slanted 5 pushcurrentpicture draw fullcircle scaled 1cm withpen pencircle scaled imm withcolor 625yellow currentpicture currentpicture slanted 5 popcurrentpicture CS SZ These METAFUN commands but metarost itself comes with a variant image and you explicitly have to draw this picture or otherwise add it to the currentpicture draw fullcircle scaled withpen pencircle scaled imm withcolor 625red currentpicture currentpicture slanted 5 draw image draw fullcircle scaled 1cm withpen pencircle scaled imm withcolor 625yellow currentpicture currentpicture slanted 5 ij NZ Each graphic starts fresh with an empty current picture In METAFUN we make sure that we also reset some otherwise global variables like color pen and some line properties Current picture 2 A few more details In this chapter we will see how to define a METAPOST graphic and how to include it in a document Since the exact dimensions of graphics play an important role in the placement of a graphic we will explore the way a bounding
256. n see these points are not distributed equally along the path In the following graphic the second and third point of the curve are colored red and point 2 5 is colored yellow Point 0 is marked in black This point is positioned halfway between point 2 and 3 It is clear that unless you know exactly how the path is constructed other methods should be available A specific point on a path is accessed by point strates two more alternatives path p p fullcircle scaled 3cm xscaled 2 pickup pencircle scaled 5mm p withcolor 625white p withcolor 625red draw point 6 along p withcolor 625yellow draw draw point 3 of draw point 3cm on of but the next example demon Cutting and pasting So in addition to on to specify a point by number in metarost terminology called time we have along to specify a point as fraction of the path and on to specify the position in a dimension The on and along operators are macros and can be defined as primarydef len on pat arctime len of pat of pat enddef primarydef pct along pat arctime pct arclength pat of pat of pat enddef These macros introduce two new primitives arctime and arclength While arctime returns a number denoting the time of the point on the path arclength returns a dimension When mathematicians draw parametric curves they frequently need to indicate the direction of motion I o
257. n the current position which fed to MPpos will return the list of posi tional numbers We already warned the reader this is not an easy chapter 5 3 More layers Overlays are one of the nicer features of CONTEXT and even more nice things can be build on top of them Overlays are defined first and then assigned to framed boxes using the background variable You can stack overlays which is why they are called as such You can use the special overlay called foreground to move the topmost often text layer down in the stack More layers background overlay a text graphic hyperlink or widget position overlay a series of macros triggered by positions background layer a box that can hold boxes with offsets The last kind of layer can be used in other situations as well but in most cases it will be hooked into a background overlay definelayer MyLayer option test setupbackgrounds text leftmargin background MyLayer setlayer MyLayer x 5cm y 5cm rotate framed This goes to the background In this case the framed text will be placed in the background of the current page with the given offset to the topleft corner Instead of a fixed position you can inherit the current position using the position directive Say that we have a layer called YourLayer which we put in the background of the text area definelayer YourLayer setupbackgrounds text text background
258. name macro communicates the running font from to MeTAPosT Instead of such low level code one can of course also use the textext macro However as we do the typesetting in Tpx in MKIV this is the way to go vardef SampleText expr t draw textext t scaled 5 enddef Transparency SampleText colored a 1 t 5 r 1 Much Of This SampleText colored a 1 t 5 g 1 Functionality SampleText colored a 1 t 5 b 1 Was Written SampleText colored a 1 t 5 c 1 While Listening SampleText colored a 1 t 5 m 1 To the CD s Of SampleText colored a 1 t 5 y 1 Tori Amos As expected we get Currently the 12 in PDF available transparency methods are supported You can use both numbers and names As you may expect both CONTEXT and METAFUN support transparency in the same way Figure 8 1 shows how the method affects the result normal multiply Screen overlay softlight hardlight colordodge colorburn lighten difference exclusion Figure 8 1 The 12 transparancy alternatives by name In CONTEXT a transparent color is defined in a similar way as normal colors The transparency method is specified with the a key either by number or by name and the factor t 13 In the future we may also support more control over the individual methods m 18 fect Transparency E definecolor tred r 1 t 5 a exclusion defi
259. nce between the point given and the content of the label When we set the offset to zero we get the following output upper left upper right lef lower left ower right This kind of positioning works well as long as we know where we want the label to be placed However when we place labels automatically for instance in a macro we have to apply a few clever tricks There are fore sure many ways to accomplish this goal but here we will follow the mathless method ower right The previous graphic visualizes the bounding box of the labels This bounding box is rather tight and therefore the placement of labels will always be suboptimal Compare the alignment of the left and rightmost labels The btex etex method is better since then we can add struts like btex strut right etex to force labels with uniform depths and heights The next graphic demonstrates that this looks better indeed Also as does the typesetting we get the current text font instead of the label font and the content will be properly typeset for instance kerning will be applied when applicable Spending some time on such details pays back in better graphics pper right lower left bottom Free labels few Now what happens when we want to place labels in other positions In the worst case given that we place the labels manually we end up in vague argument
260. necolor tgreen g 1 t 5 a exclusion definecolor tblue b 1 t 5 a exclusion Both keys are needed You can define your own symbolic names using definetransparency myowndefault 1 The MPcolor macro passes a color from CONTEXT to MeTAPOST including the transparency speci fication definecolor tred r 1 t 5 a exclusion definecolor tgreen g 1 t 5 a exclusion definecolor tblue b 1 t 5 a exclusion Of course this also works well for CMYK colors definecolor tred c 1 k 2 t 5 a 1 definecolor tgreen m 1 k 2 t 5 a 1 definecolor tblue y 1 k 2 t 5 a 1 Gray scales work as well definecolor ta s 9 t 7 a 11 definecolor tb s 7 t 7 a 11 definecolor tc s 5 t 7 a 11 We apply this to some text By using an overlay we can conveniently explore the difference in fonts draw textext color ta tf Hello scaled 5 draw textext color tb bf Hello scaled 5 draw textext color tc sl Hello scaled 5 Transparency Hello 8 3 Clipping In this section we will use the graphic representation although simplified of a Dutch cow to demonstrate clipping Figure 8 2 A cow Since this cow is defined as a mETRPOST graphic we use the suffix mps instead of eps or a number although CONTEXT will recognize each as being mMetarost output The placement of the cow is defined as placefigure A cow externalfigure cow mps
261. ng assignments are all equivalent Variables 17 i 111 222 icm i 111 222 i 111 222 draw image draw Ocm i 111 222 draw 1cm i 111 222 draw 2cm i 111 222 withpen pencircle scaled 5mm withcolor 625 red Sometimes METRPOST Ways are mysterious Conditions The existence of boolean variables indicates the presence of conditionals Indeed the general form of METRPOST s conditional follows if n 10 draw p else draw q fi Watch the colons after the if and else clause They may not be omitted The semi colons on the other hand are optional and depend on the context You may say things like draw if n 10 p else q fi Here we can omit a few semi colons draw if n 10 p else q fi withcolor red Adding semi colons after p and q will definitely result in an error message since the semi colon ends the draw operation and withcolor red becomes an isolated piece of nonsense There is no case statement available but for most purposes the following extension is adequate draw p withcolor if n lt 10 red elseif n 10 green else blue fi There is a wide repertoire of boolean tests available if picture p if known n if odd i if cycle q Of course you can use and or not and to construct very advanced boolean expressions If you have a bit of programming experience you will appreciate the exte
262. nsive support of conditionals in METAPOST Welcomto MetaPast Conditions 1 8 Loops Yet another programming concept present in mETaPOST is the loop statement the familiar for loop of all programming languages for i 0 step 2 until 20 draw 0 i endfor As explained convincingly in Niklaus Wirth s book on algorithms and datastructures the for loop is the natural companion to an array Given an array of length n you can construct a path out of the points that make up the array draw for i 0 step 1 until n 1 pli endfor pin If the step increment is not explicitly stated it has an assumed value of 1 We can shorten the previous loop construct as follows draw for i 0 upto n 1 p i endfor p n After seeing if in action the following for loop will be no surprise draw origin for i 0 step 10 until 100 down i 0 endfor This gives the zig zag curve a a al av au n a a a You can use a loop to iterate over a list of objects A simple 3 step iteration is for i p q r fill i withcolor 8white draw i withcolor red endfor Using for in this manner can sometimes save a bit of typing The list can contain any expression and may be of different types In the previous example the i is an independent variable local to the for loop If you want to change the loop variable itself you need to use forsuffixes In the next loop the paths p q and
263. nt we use the string as string and by means of scantokens as a point or vector A few more adtsils Directions up left right down The previous definition is a stepping stone to the next one This time we don t use points but the dir command This command converts an angle into an unitvector pair destination for whereto 0 step 30 until 330 destination dir whereto 1 5cm freedotlabel decimal whereto destination origin drawarrow origin destination withpen pencircle scaled 25mm withcolor 625 red endfor In the angles go counter clockwise which is not that illogical if you look at it from the point of view of vector algebra 120 90 60 150 30 180 210 330 240 270 300 2 10 Analyzing pictures Unless you really want to know all details you can safely skip this section The METAPOST features discussed here are mainly of importance when you write advanced macros We can decompose METRPOST pictures using a within loop You may wonder if such a within loop construct has any real application and as you can expect it has In section 13 4 a macro is defined that draws a colored circle If you want the inverted alternative you can pass the inverted color specification but wouldn t it be more convenient if there was an operator that did this for you automatically Unfortunately there isn t one so we have to define one ourselves in
264. ntrol points of the points drawpointlabels the numbers of the points You can set the characteristics of these like you set drawoptions The default settings are as follows drawpathoptions withpen pencircle scaled 5 withcolor 8white drawpointoptions withpen pencircle scaled 4 withcolor black drawcontroloptions withpen pencircle scaled 2 5 withcolor black drawlineoptions withpen pencircle scaled 1 withcolor 5white drawlabeloptions Two more options are draworiginoptions and drawboundoptions which are used when visual izing the bounding box and origin swappointlabels true path p p fullcircle xscaled 4cm yscaled 3cm drawarrowpath p drawcontrollines p drawpoints p drawcontrolpoints p drawpointlabels drawboundingbox p draworigin In this example we have set swappointlabels to change the place of the labels You can set the variable originlength to tune the appearance of the origin Libraries Here we used the options x path p p fullcircle xscaled 6cm yscaled 3cm rotated 15 drawarrowpath p drawcontrollines p drawpoints p drawcontrolpoints p drawpointlabels p drawboundingbox draworigin withcolor withcolor withcolor withcolor withcolor 625 625yellow 625yellow 625yellow 625 Sometimes it makes sense to draw a simple coordinate system and for that purpose we have three more macros
265. o Hasselt Oxford The Luar follow up provided a more tight integration and runtime is now virtually zero The METRPOST 2 project is done alongside LUATEX development LuaTEX development team 2006 Lua TEX Reference www luatex org As we aim at upward compatibility as much as possible the older manuals still apply In MKIV much of the action is hidden for the user and installation is no issue Therefore no additional manuals need to be consulted Hagen J 1999 explained Hasselt NL Pragma ADE Hagen J 1999 MakeMPY Hasselt NL Pragma ADE Hagen J 2000 Making Stand Alone MetaPost graphics Amsterdam NL NTG Maps Distributions Information about installing can be found on the websites of user groups A convenient way to start with CONTEXT is to use the installer from contextgarden net The TEX Live distribition as well as the MikTEX windows distribution come with CONTEXT Tools Index a anchoring 143 145 angles 23 279 arguments 34 attributes 40 360 axis 213 b backgrounds 160 163 bleeding 170 boundingbox 67 buffers 118 dipping 49 194 color 40 119 285 manipulating 201 common definitions 122 conditions 30 curl 81 curves 75 cutting 60 d dashes 40 debugging 255 definitions 32 directions 100 drawing 24 e environments 225 equations 42 expressions 42 f functions 211 8 graphics 65 367 buffers 118 embedded 112 external 111 including 198 libr
266. o show through the graphic A not uncommon practice when making complicated graphics is to use unfill operations Since METAPOST provides one let us see what happens if we apply this command fill 0 0 w 0 w h 0 h cycle unfill ww 0 w hh ww hh cycle This does not always give the desired effect because METRPOST s unfill is not really an unfill but a fill with color background Since this color is white by default we get what we just showed So if we set background to black using background black we get Of course you can set the variable background to a different color but this does not hide the fact that metarost lacks a real unfill operation Drawing pictures Since we don t consider this unfill a suitable operator you may wonder how we achieved the above result fill 0 0 0 h Gw h w 0 ww 0 w hh ww hh ww 0 cycle This feature depends on the POSTSCRIPT way of filling closed paths which comes down to filling either the left or the right hand side of a curve The following alternative works too fill 0 0 0 h w h w hh ww hh ww 0 Cw hh w 0 cycle The next alternative will fail This has to do with the change in direction at point 0 0 halfway through the path Sometimes changing direction can give curious but desirable effects but here it brings no good fill 0 0 0 h w h w 0 0 0
267. o graphics Graphics and macros enhancing the layout defineoverlay FunnyFrame useMPgraphic FunnyFrame defineframedtext FunnyText frame off background FunnyFrame def StartFrame startFunnyText def StopFrame stopFunnyText def FrameTitle 1 setMPtext FunnyFrame hbox spread 1tem hss strut 1 hss setMPtext FunnyFrame initialize the text variable There is a little bit of low level code involved like a horizontal box hbox that stretches one em space beyond its natural size spread 1em with a centered text two times hss Instead of applying this spread we could have enlarged the frame on both sides In the previous graphic we calculated the big rectangle taking the small one into account This was needed because we don t use a background fill The next definition does so there we can use a more straightforward approach by just drawing and filling the small rectangle on top of the big one startuseMPgraphic FunnyFrame picture p numeric o path a b pair p textext rt MPstring FunnyFrame a unitsquare xyscaled OverlayWidth OverlayHeight o BodyFontSize shifted 2o 0verlayHeight ypart center p drawoptions withpen pencircle scaled 1pt withcolor 625red b a randomized 0 2 fill b withcolor 85white draw b b boundingbox p randomized 0 8 fill b withcolor 85white draw
268. oin to mitered linejoin mitered pickup pencircle scaled line The colors are rather primary blue and yellow At the time of writing this manual Dutch trains are still painted yellow so we will use that shade as background color color nsblue nsblue 0 0 1 1 1 0 color nsyellow nsyellow We will now describe the main curves Although these expressions are not that advanced they demonstrate that we can express relationships instead of using assignments A few applications Simple Logos zi 0 height 2 22 width 2 height 4 y1 23 width 2theight 4 y4 24 width 0 path p p 21 22 23 24 Although it is accepted to consider z to be a variable it is in fact a vardef macro that expands into a pair This means that the previous definitions internally become x1 y1 0 height 2 x2 y2 width 2 height 4 y1 x3 y3 width 2 height 4 y4 x4 y4 width 0 These 8 relations can be solved by metarosr since all dependencies are known 1 0 yl height 2 x2 width 2 height 4 y2 yl x3 width 2 height 4 y3 y4 4 width 4 0 Since we express the variables and y in terms of relations we cannot reuse them because that would mean that inconsistent relations occur So the following lines will lead to an error message zi 10 20 z1 30 50 For similar
269. olor white fill rr withcolor red fill cc withcolor white red fill gg withcolor green fill mm withcolor white green fill bb withcolor blue fill yy withcolor white blue for i rr gg bb cc mm yy draw i withcolor 5white endfor currentpicture currentpicture xsized size enddef In determining the right intersection points you need to know where the path starts and in what direction it moves In case of doubt drawing the path as an arrow helps If you want to see the small paths used you need to comment the lines with the i11 s and uncomment the lines with draw s Due to the symmetry and the fact that we keep the figure centered around the origin we only need to calculate two paths since we can rotate them Color circles There are for sure more efficient ways to draw such a figure but this one demonstrates a few new tricks like grouping We use grouping here because we want to use mm to indicate the magenta path and mm normally means millimeter Within a group you can save variables These get their old values when the group is left With for we process multiple paths after each other In this case it hardly saves tokens but it looks more clever One of the more efficient methods is using the buildcycle macro This macro takes two or more paths and calculates the combined path Although this is a rather clever macro you should be prepared to help it
270. olow arbitra o L o L S 36 FC S 3f startuseMPgraphic followtokens path RotPath RotPath 3cm 0 1cm icm Ocm 2cm 3cm 0 stopuseMPgraphic WwW WwW a d T 2 7 5 2 lt 3 3 gt Q Q 2 When turned on tracing will produce bounding boxes as well as draw the path Tracing can be turned on by saying startMPinclusions boolean TraceRot TraceRot true stopMPinclusions The next example is dedicated to Giuseppe Bilotta who wants to handle multiple strings and uses a patched version of followtokens To avoid a complicated explanation we will present an alternative here that uses overlays This method also avoids complicated path definitions ETRPOST TEX text startoverlay startuseMPgraphic followtokens draw fullcircle scaled 5cm withpen pencircle scaled 1pt withcolor 625yellow draw fullsquare scaled 5 25cm withpen pencircle scaled 1pt withcolor 625red drawoptions withcolor 625red path RotPath RotPath halfcircle scaled 5cm setbounds currentpicture to boundingbox fullcircle scaled 5 25cm stopuseMPgraphic followtokens Met a superiore startuseMPgraphic followtokens drawoptions withcolor 625red path RotPath RotPath halfcircle rotated 90 scaled 5cm setbounds currentpicture to boundingbox fullcircle scaled 5 25cm s
271. ommon curve where pair endofa endofb common path curve numeric where endofa point length a of a endofb point length b of b if round point 0 of a round point O of b common point 0 of a else common a intersectionpoint b fi where turningnumber common endofa endofb cycle curve unitvector endofa common endofa common rotated where 90 unitvector endofb common scaled anglelength shifted common draw thefreelabel str point 5 of curve common withcolor black curve enddef This macro has a few more if s than its predecessor First we test if the label is a string and if so we calculate the picture ourselves otherwise we leave this to the user path a b c d e f a C e origin 1cm 2cm origin 2cm 1cm origin 2cm 1cm b origin 2cm 2cm d origin 1cm 2cm f origin 1cm 2cm for i a b c d e f drawarrow i endfor anglelength 1 0cm drawoptions withcolor 625red drawarrow anglebetween a b btex alpha etex drawarrow anglebetween c d btex gamma etex drawarrow anglebetween e f btex epsilon etex anglelength 1 5cm drawoptions withcolor 625yellow drawdblarrow anglebetween b c btex beta etex drawarrow reverse anglebetween d e btex delta etex drawarrow anglebetween a f btex zeta etex Because anglebetween returns a path you can apply transformations to
272. on a system al lowing him to control many as pects of the design of his forthcom ing books from the typesetting and layout down to the very shapes of the letters Seldom has an au thor had anything remotely like this power to con trol the final test 1 Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METRFONT as well as some of its products Not only is the concept exiting and clearly well executed but in my opinion the article is charmingly written as well However despite my over all enthusiasm for Knuth s idea and article there are some test 3 ap pearance of his or her work Knuth s typeset ting system has become well known and available in many countries around the world By contrast his METRFONT system for designing families of typefaces has not become as well known or available In his ar ticle test 2 points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt com pelled to make some com ments to clarify certain important issues raised by Ihe Concept of a Meta Font test 4 Figure 10 4 A continuous text typeset in a non standard shape spread over four areas tracing on We can combine all those tricks although the input is somewhat fuzzy First we define a qu
273. only more portable but also less sensitive for misinterpretation vardef ColorCircle expr method factor ca cb cc save p path p p fullcircle shifted 1 4 0 image fill p rotated 90 withcolor transparent method factor ca fill p rotated 210 withcolor transparent method factor cb fill p rotated 330 withcolor transparent method factor cc enddef draw ColorCircle normal 5 red green blue xsized 3cm currentpicture currentpicture shifted 4cm 0 draw ColorCircle exclusion 5 red green blue xsized 3cm currentpicture currentpicture shifted 4cm 0 draw ColorCircle exclusion 1 red green blue xsized 3cm 8 9 color xcyan xcyan cmyk 1 0 0 0 color xmagenta xmagenta cmyk 0 1 0 0 color xyellow xyellow cmyk 0 0 1 0 draw ColorCircle exclusion 5 xcyan xmagenta xyellow xsized 3cm You can be tempted to use transparency as a convenient way to achieve soft colors In that case you should be aware of the fact that rendering transparent colors takes more time than normal colors Fortunatey METAPOST provides a similar mechanism The last circle in the following row demon strates how we can trigger colors proportionally to other colors Normally background is white but you can set predefined color variables to another value path p fullcircle scaled 2cm fill p shifted 0cm 0 withcolor blue 7 When your printer does not suppor
274. ons have ended up in the path specification If we have a text picture we can explicitly ask for the transform components label label label label label label rt xpart rt ypart rt xxpart rt xypart rt yxpart rt yypart pu Met We will now define the inverted macro using these primitives Because we have to return a picture we cannot use draw and fill but need to use the low level operators Because a picture can consist of more than one path we need a temporary picture pp amp decimal amp decimal amp decimal amp decimal amp decimal amp decimal xpart 0 xpart ypart p xxpart p xypart p yxpart p yypart p ypart 25 93834 xxpart 2 23206 xypart 0 13397 yxpart 1 yypart 1 73206 vardef inverted expr p save pp picture pp for i within p addto pp if stroked i or filled i if filled i dashed dashpart i withpen penpart i else Analyzing pictures contour else 4cm 1 4cm 0 4cm 0 4cm 0 4cm 0 4cm 1 nullpicture 25cm 75cm 25cm 25cm 75cm 25cm doublepath fi pathpart i also i fi withcolor white redpart i greenpart i bluepart i endfor PP enddef We probably need to handle a few more border cases but for general purposes this macro works as expected From the previous examples it may be clear that each picture has some
275. op path r r 1x ly ux ly ux uy 1ux uy cycle A few applications Simple Logos The clipping path is applied by saying clip currentpicture to r The result is quite acceptable But if you watch closely to how this graphic extends into to left margin of this document you will see that the bounding box is not yet right setbounds currentpicture to r We use the same path r to correct the bounding box There are a few subtle points involved like setting the 1inejoin variable If we had not set it to mitered we would have got round corners We don t set the linecap because a flat cap would not extend far enough into the touching curve and would have left a small hole The next example shows what happens if we set these variables to the wrong values In fact we misuse the fact that both curves overlay each other Simple Logos A few applications The complete logo definition is a bit more extensive because we also want to add a background Because we need to clip the blue foreground graphic we must temporarily store it when we fill the background numeric width height line delta width 5cm height width 2 line height 4 delta line linejoin mitered pickup pencircle scaled line color nsblue nsblue 0 0 1 color nsyellow nsyellow 1 1 0
276. op edge of q s bounding box by topskip then cut any part of the left and right pieces of q that lie above it Similarly we raise the bottom edge and cut off the pieces that fall below this line startuseMPgraphic text cutoff path tt bb tt ulcorner q urcorner q shifted 0 topskip bb 11 q lrcorner q shifted 0 strutdepth l 1 cutbefore 1 intersectionpoint tt l 1 cutafter 1 intersectionpoint bb r cutbefore intersectionpoint bb r r cutafter intersectionpoint tt stopuseMPgraphic Because we use includeMPgraphic to construct the graphic we can redefine text draw to show the result of this effort startuseMPgraphic text draw drawarrow p withpen pencircle scaled ipt withcolor red drawarrow 1 withpen pencircle scaled ipt withcolor green drawarrow r withpen pencircle scaled 1pt withcolor blue stopuseMPgraphic The text graphic now becomes startuseMPgraphic text includeMPgraphic text path includeMPgraphic text vars includeMPgraphic text move includeMPgraphic text split includeMPgraphic text cutoff includeMPgraphic text draw stopuseMPgraphic Or as graphic BiTypesetting in ereepsr Talking to We are now ready for an attempt to calculate the shape of the text For each line we have to calculate the left and right intersection points and since a line has a height and
277. or currentpicture currentpicture xsized size Color circles popcurrentpicture enddef Here we first fill the primary circles next we fill the secondary ones These also cover the center which is why finally we fill the center with white The circle uses the following colors colorcircle 4cm 2 5 8 8 2 5 5 8 2 The next graphic demonstrates how the subpaths look that build the shapes We did not mention what the push and pop commands are responsible for Scaling the current picture is well defined as long as we deal with one graphic However if the current picture already has some content this content is also scaled The push and pop commands let us add content to the current picture as well as manipulating the picture as a whole without any side effects The final result is put on top of the already drawn content Instead of the sequence pushcurrentpicture Color circles currentpicture currentpicture transformations popcurrentpicture you can say pushcurrentpicture popcurrentpicture transformations Both are equivalent to draw image transformations For larger sequences of commands the push pop alternative gives a bit more more readable code 13 5 Fool yourself When doing a literature search on the human perception of black white edges I ran into several articles with graphics that
278. ors like or the path and string concatenation operator amp have tertiary macros as companions More details can be found in the MeTAFONT book When it comes to taking precedence metarost tries to be as natural as possible in the sense that you need to provide as few s as possible When in doubt or when surprised by unexpected results use parentheses 1 10 Arguments The metarost macro language is rather flexible in how you feed arguments to macros If you have only one argument the following definitions and calls are valid def test expr a enddef test a test a def test expr a enddef test a test a A more complex definition is the following As you can see you can call the test macro in your favorite way def test expr a b expr c d enddef Arguments test a b c test a b c d test a b c d test a b c d The type of the arguments is one of expr primary or suffix When fetching arguments METAPOST uses the type to determine how and what to grab A fourth type is text When no parenthesis are used a text argument grabs everything upto the next semicolon def test expr a text b enddef test a test a b You can use a text to grab arguments like withpen pencircle scaled 10 withcolor red Be cause text is so hungry you may occasionally need a two stage definition dotext a enddef enddef def
279. osphere of handy work if you slightly randomize the lines We leave it up to the reader to figure out how the code should be changed to accomplish this The complete result is shown on the next page 13 9 Theeuro symbol When Patrick Gundlach posted a nice version of the euro symbol to the CONTEXT dis cussion list he added the comment The official construction is ambiguous how thick are the horizontal bars How much do they stick out to the left Is this thing a circle or what Are the angles on the left side of the bars the same as the one on the right side The alternative below is probably not as official as his but permits a finetuning You are warned whatever you try the euro is and will remain an ugly symbol We use a couple of global variables to control the euro shape within reasonable bounds Then we define two circles Next we define a vertical line that we use in a couple of cut and paste operations Watch how the top left point of the outer circle determines the slant of the line that we use to slice the vertical bars A few ications The euro symbol boolean trace euro trace euro false vardef euro symbol image begin of euro if unknown euro radius euro radius 2cm vog s if unknown euro width euro width Seuro radius 16 fi if unknown euro r offset euro r offset euro width sed s if unknown
280. ote typeset in a circular paragraph shape startuseMPgraphic center build_parshape fullcircle scaled 8cm 0 0 0 baselinedistance strutheight strutdepth strutheight stopuseMPgraphic startshapetext center input douglas stopshapetext def ineoverlay center useMPgraphic center Libraries We will surround this text with a circular line that we define as follows By using a buffer we keep things organized startbuffer circle startuseMPgraphic followtokens path RotPath RotPath reverse fullcircle rotatedaround origin 90 xscaled overlaywidth yscaled overlayheight drawoptions withcolor 625red stopuseMPgraphic followtokens This is just a dummy text kerned by T kern 1667em lower 5ex hbox E kern 125emX and typeset in a circle using setMFPfont M setMFPfont E setMFPfont T setMFPfont A setMFPfont P setMFPfont O setMFPfont S setMFPfont T quad stopbuffer defineoverlay edge getbuffer circle The text and graphics come together in a framed text startbuffer quote framed offset 6pt background edge frame off getshapetext stopbuffer placefigure One more time Hofstadter s quotation getbuffer quote Here also I will rewrite things a bit so that we can avoid startMPdrawing outside the macro and thereby avoid problems I can also add the maps cdrom cover
281. p 05 until 1 1 21 tension 75 i z2 23 transparent 1 1 i 625red endfor A third magic directive is curl The curl is attached to a point between like curl 2 Any thing between curly braces is a direction specifier so instead of a cur1 you may specify a vector like 2 3 a pair of numbers as in 2 3 or a direction like dir 30 Because vectors and angles are straightforward we will focus a bit on curl Inflection tension and curl z0 z1 22 20 curl 1 z1 curl 1 z2 So a cur1 of 1 is the default When set to 1 the begin and or end points are approached Given the following definitions u 1cm 21 0 0 22 2u 4u z3 4u 0 def sample expr p c draw p withpen pencircle scaled 2 5mm withcolor white draw p withpen pencircle scaled 2 0mm withcolor c enddef We can draw three curved paths sample zi curl 0 z2 curl 0 z3 625red sample z1 curl 2 z2 curl 2 z3 625yellow sample zi curl 1 z2 curl 1 z3 625white The third gray curve is the default situation so we could have left the cur1 specifier out of the expression The curly specs have a lower bound of zero and no upper bound When we use METAPOST maxi mum value of infinity instead of 2 we get These curves were defined as Inflection tension and curl 2 7 sample zi 1 O z2 curl
282. page is covered completely Where in desk top printing you can get away with imperfection simply because the printing engines have their limitations in professional output you need to be more considerate B Slightly enlarging a graphic so that it exceeds the natural page limits is called bleeding Because quite often layout elements have a rectangular nature METAFUN provides a couple of operations that can save you some work in defining bleeding boxes Bleeding This graphic is generated as follows path p q def ShowPath fill p withcolor transparent 1 5 625yellow fill q withcolor transparent 1 5 625yellow currentpicture currentpicture shifted 25mm 0 enddef fullsquare xyscaled 2cm 3cm ShowPath p leftenlarged 2mm ShowPath p topenlarged 2mm ShowPath p rightenlarged 2mm ShowPath p bottomenlarged 2mm ShowPath The trick is in the last couple of lines In addition to the general enlarged operator we have 4 op erators that enlarge a rectangle in a certain direction This means that we can define the original path using dimensions related to the layout and add bleed strips independently fullsquare xyscaled 4cm icm p leftenlarged 2mm topenlarged 2mm pathp p path fill withcolor transparent 1 5 625yellow fill q withcolor transparent 1 5 625yellow draw boundingbox currentpicture withcolor 625red
283. pencircle scaled 1m fill unitsquare xyscaled 7cm 8cm withcolor 85white fill unitsquare xyscaled 5cm 5cm shifted 1cm 1 5cm withcolor 625yellow fill unitsquare xyscaled 5cm icm shifted 5cm withcolor 625red fill unitsquare xyscaled 5cm icm shifted 1cm 6 5cm withcolor 625red draw unitsquare xyscaled 5cm 7cm shifted 1cm 5cm withcolor 25white drawarrow 2cm 8cm top 2cm 7 5cm drawarrow Ocm 7cm lft 1cm 7cm clip currentpicture to unitsquare xyscaled 7cm 8cm stopuseMPgraphic As you can see the left graphic is defined as a series of rectangles The xyscaled macro is part of the CONTEXT files and saves some typing and space It is defined as a primary requiring both left and right operands primarydef p xyscaled q p xscaled xpart q yscaled ypart q enddef Zooming in on the top left corner only takes a few lines First we clip the correct part next we scale it up and finally we let the bounding box suit the left picture startuseMPgraphic layout 2 includeMPgraphic layout 1 clip currentpicture to unitsquare scaled 3cm shifted 0 5cm currentpicture currentpicture scaled 2 shifted 0 8cm setbounds currentpicture to unitsquare xyscaled 6cm 8cm stopuseMPgraphic This code demonstrates how you can reuse a graphic inside another one This strategy can easily be used to stepwise build or extend graphics The two graphics were put side by side with t
284. pencircle transform withpen pencircle scaled 2mm metapost macro 5 V Du withpen pensquare transform withpen pensquare scaled 2mm P dii metapost macro 7 U withpen penrazor transform withpen penrazor scaled 2mm metapost macro withpen penspeck transform withpen penspeck metapost macro Attributes draw fullcircle es S metapost macro 9 fill fill fullcircle metapost macro filldraw fullcircle metapost macro drawfill drawfill fullcircle metapost macro b drawdot drawdot origin metapost macro drawarrow fullcircle em S z o R H 5 metapost macro N undraw fullcircle metapost macro unfill fullcircle c 3 im metapost macro c S S 5 unfilldraw fullcircle metapost macro e undrawfill fullcircle metapost macro undrawdot origin metapost macro origin 1 1 metapost macro E mm gt 2 ME c 11 butt metapost variable lt Attributes rounded linecap rounded metapost variable amp squared linecap squared metapost variable lt H em linejoin mitered metapost variable K H c Q linejoin rounded metapost variable amp 2
285. phic is shown From the previous examples you can conclude that the following alternative results in a proper bounding box pickup pencircle scaled 5cm path p p unitsquare xscaled 8cm yscaled icm fill p withcolor 625white draw p withcolor 625white path bb bboxmargin Opt bb bbox currentpicture draw bb withpen pencircle scaled withcolor 625red draw origin withpen pencircle scaled 5pt withcolor 625yellow The CONTEXT distribution comes with a set of METAPOST modules one of which contains the drawfill macro which provides the outer bounding box Next we demonstrate its use in an other more complicated example picture finalpicture finalpicture nullpicture numeric n n 0 bboxmargin Opt pickup pencircle scaled 5cm def shape unitsquare scaled 2cm withcolor 625white draw bbox currentpicture withpen pencircle scaled 5mm withcolor 625red addto finalpicture also currentpicture shifted n 3cm 0 currentpicture nullpicture n ntl enddef Old versions of wErePosr calculated the boundingbox differently for a filldraw through the middle of the penpath Starting from version 1 0 metarost calculates the boundingbox differently and the distinction between drawfill and filldraw is gone We keep them around both for compatibility Bounding boxes fill shape draw shape filldraw shape drawfill shape currentpicture finalpictu
286. phic it is dealing with When enabled CONTEXT will call either wErRPOsrT or when the graphic contains btex etex commands call TEXEXEC which in turn makes sure that the right aux iliary programs are executed In CONTEXT MKIV you won t notice this at all as there everything is tightly integrated with LUATEX s MPLIB TEXEXEC CONTEXT TEXEXEC METRPOST METRPOST Figure 10 1 How and metarost work together 10 2 Environments In case you want to pass code that is shared by all btex etex pictures METAPOST provides verbatimtex DefineSomeCommands etex However in CONTEXT one has a better mechanism available In CONTEXT MKII the advised method is passing environments The best way to pass them is the following As an example we switch to the 15 basic POSTSCRIPT fonts The process Iypesetting METRPOST startMPenvironment usetypescript palatino texnansi mkii has encodings setupbodyfont palatino stopMPenvironment This means that in code like the following a Palatino font will be used startMPcode draw btex Meta is a female lion etex xysized the textwidth the textheight stopMPcode However in CONTEXT MKIV this method is no longer recomended as all processing happens in the same run anyway startMPcode numeric w h w the textwidth h w 2 picture p w h picture wh
287. ponents The following examples demonstrate this In case of a clip path or bounding box the pathpart operator returns this path In any case that asking for a value does not make sense a clipping path for instance has no color a zero null value is returned draw fullcircle withpen pencircle scaled 3mm clip currentpicture to fullcircle setbounds currentpicture to fullcircle n 1 length 1 stroked false clipped true bounded false Analyzing pictures _ few more details draw fullcircle withpen pencircle scaled 3mm setbounds currentpicture to fullcircle clip currentpicture to fullcircle n 1 length 1 stroked false clipped false bounded clip currentpicture to fullcircle draw fullcircle withpen pencircle scaled 3mm setbounds currentpicture to fullcircle 1 length 0 stroked false clipped true bounded 2 length 1 stroked true clipped false bounded clip currentpicture to fullcircle setbounds currentpicture to fullcircle draw fullcircle withpen pencircle scaled 3mm 1 length 1 stroked false clipped false bounded 2 length 1 stroked true clipped false bounded setbounds currentpicture to fullcircle clip currentpicture to fullcircle draw fullcircle withpen pencircle scaled 3mm 1 length 1 stroked false clipped true bounded 2 length 1 stroked true clipped fa
288. quare xyscaled width height In the following sections we will demonstrate how you can put graphics behind these 25 areas as well as behind the left and right page 11 This is true only in a regular METAPOST In CONTEXT MKIV we follow a different route The basic layout Page badkgtoundse 6 2 Setting up backgrounds One way of protecting a document for unwanted usage is to put an annoying word in the back ground If you like this you may try the following The macro ysized is part of the macros that come with CONTEXT and scales a picture to a specific size startuniqueMPgraphic concept draw btex colored s 8 bf CONCEPT etex rotated 60 currentpicture currentpicture ysized overlayheight 5cm stopuniqueMPgraphic defineoverlay concept uniqueMPgraphic concept You can now put this graphic in the page background by saying setupbackgrounds page background concept You may consider the next alternative a bit better but still it renders the text unreadable Like xysized the macro enlarged is not part of standard metarost but comes with CONTEXT startuniqueMPgraphic copyright picture p p btex colored s 8 COPYRIGHT etex rotated 90 setbounds p to boundingbox p enlarged draw p currentpicture currentpicture xysized overlaywidth overlayheight stopuniqueMPgraphic defineoverlay copyright uniqueMPgraphic copy
289. r are all shifted forsuffixes i p q r i i shifted 3cm 2cm endfor Sometimes you may want to loop forever until a specific condition occurs For this METAPOST provides a special looping mechanism Loops EWelcome ta numeric done i 0 forever i round uniformdeviate 10 j round uniformdeviate 2 if unknown done i j drawdot i cm j cm n n 1 done il j n fi exitif n 10 endfor Here we remain in the loop until we have 10 points placed We use an array to keep track of placed points The mETRPOST macro uniformdeviate n returns a random number between 0 and n and the round command is used to move the result toward the nearest integer The unknown primitive allows us to test if the array element already exists otherwise we exit the conditional This saves a bit of computational time as each point is drawn and indexed only once The loop terminator exitif and its companion exitunless can be used in for forsuffixes and forever 1 9 Macros In the previous section we introduced upto Actually this is not part of the built in syntax but a sort of shortcut defined by def upto step 1 until enddef You just saw a macro definition where upto is the name of the macro The counterpart of upto is downto Whenever you use upto it is replaced by step 1 until This replacement is called expansion There are se
290. r blue withfillcolor 5white withpen pencircle scaled 5pt Once the text is typeset by it is converted to POSTSCRIPT and converted into by the PSTOEDIT program The resulting graphic is imported analyzed and processed conforming the specifications of graphictext Outline fonts By default the shapes are filled after they are drawn This has the advantage that in characters built out of pieces disturbing lines fragments are covered The drawback is that you get only half the linewidth You can reverse the drawing order by adding the reversefill directive The previous graphic then comes out as graphictext bf Fun scaled 4 zscaled 1 1 5 reversefill withdrawcolor blue withfillcolor 5white withpen pencircle scaled 5pt The reversefill directive can be countered by outlinefill The next example is taken from the MAKEMPY manual It demonstrates that you can combine TgX s powerful line breaking with metarost s graphic capabilities startuseMPgraphic quotation picture one one image graphictext MPstring text scaled 1 5 withdrawcolor 625blue withfillcolor 625white withpen pencircle scaled 1pt picture two two image graphictext MPstringfauthor scaled 2 withdrawcolor 625red withfillcolor 625white withpen pencircle scaled 2pt currentpicture one addto currentpicture also two shifted lrcorner one shifted 1 125 lrcorner two sh
291. raphic are for experts only and fooling around with them can interfere with existing features 3 8 One page graphics An advantage of using CONTEXT to make your graphics is you don t have to bother about specials font inclusion and all those nasty things that can spoil a good day An example of such a graphic is the file mf un 888 that resides on the computer of the author 4 output pdftex copyright pragma ade readme readme pdf licence cc by nc sa setupcolors state start setupMPpage offset 1pt background color backgroundcolor gray definecolor gray s 625 definecolor red r 625 definecolor yellow r 625 g 625 startuseMPgraphic test fill fullsquare rotated 45 scaled 4cm withcolor MPcolorf yellow stopuseMPgraphic starttext startMPpage includeMPgraphic test fill fullcircle scaled 3cm withcolor 1 stopMPpage stoptext Given that CONTEXT is present on your system you can process this file with context mfun 888 You can define many graphics in one file Later you can include individual pages from the result ing PDF file in your document Mplacefigure A silly figure demonstrating that stand alone graphics can be made externalfigure mfun 888 page 1 One page graphics Embedded graphics In this case the page 1 specification is not really needed You can scale and manipulate the
292. re Here we introduce a macro definition shape In METRPOGST the start of a macro definition is in dicated with the keyword def Thereafter you can insert other variables and commands even other macro definitions The keyword enddef signals the end of the macro definition The result is shown in figure 2 1 watch the bounding boxes Close reading of the macro will reveal that the fill draw filldraw and drawfill macros are applied to the first unitsquare path in the macro Figure2 1 A fill draw filldraw and drawfill applied to the same square In this macro bbox calls a macro that returns the enlarged bounding box of a path By setting bboxmargin we can influence how much the bounding box is enlarged Since this is an existing variable we don t have to allocate it like we do with numeric n Unless you take special precau tions variables are global by nature and persistent outside macros picture finalpicture finalpicture nullpicture Just as numeric allocates an integer variable the picture primitive allocates a picture data struc ture We explicitly have to set this picture to nothing using the built in primitive nullpicture Later on we will add the drawn paths as accumulated in currentpicture to this finalpicture in the following manner addto finalpicture also currentpicture shifted n 3cm 0 Since we want to add a few more and don t want them to overlap we shift them Therefore we have to erase the current pi
293. re are a few helpers built in and more might follow For example draw ctxlua metapost metafun topath x 1 y 1 x 1 y 3 4 1 cycle xysized 4cm 3cm withpen pencircle scaled 1mm withcolor 625 red The topath function takes a table of points or strings You can pass a connector so draw ctxlua metapost metafun topath x 1 y 1 x 1 y 3 4 1 cycle xysized 4cm 3cm withpen pencircle scaled imm withcolor 625 red gives Drawing functions Writing such LUA functions is no big deal For instance we have available function metapost metafun interpolate f b e s c tex write for i b e e b s do local d loadstring string format return function x return s end f if d then d dO if i gt b then tex write c or end tex write string format 4s 4s i d i end end tex write end An example of usage is draw ctxlua metapost metafun interpolate math sin x72 2 x math sqrt math abs x math pi 2 math pi 2 100 xysized 6cm 3cm withpen pencircle scaled imm withcolor 625 red And indeed we get some drawing Let s see what happens when we use less accuracy and a different connector draw ctxlua metapost metafun interpolate math sin x72 2 x math sqrt math abs x math pi 2 math pi 2 10 xysized 6cm 3cm withpen pencircle scaled imm withcolor 625 red
294. re several ways to use the power of METAFUN either or not using CONTEXT 1 You can create an independent mp file and process it with the program or MPTOPDF Depending on what features you use the succes of a run depends on the proper set up of the programs that take care of running for btex 2 You can embed the graphic in a startMPpage construct and process it with CONTEXT MKIV which is the future anyway In that case you have the full METAFUN functionality available If for some reason you still want to use you need to use TEXEXEC as before processing the file it will do a couple of checks on the file It will also make sure that the temporary files mpt for textext s and mpo for outline fonts are taken care of too You can integrate the graphic in the document flow using buffers mMETRPOST code sections or reusable graphic containers In that case the graphics are processed runtime or between runs This happens automatically Unless you want to write low level CONTEXT code yourself there is no real reason to look into the modules that deal with support The traditional partly generic code is collected in supp mps tex low level inclusion macros and housekeeping supp mpe tex experimental extensions like specials supp pdf tex METAPOST to PDF conversion Especially the last two can be used in other macro packages However in CONTEXT we have re grouped the code plus more in oth
295. reasons we may not assign a value using to such a z variable Within a METRPOST figure z variables are automatically saved which means that they can be reused for each figure So far we have defined the following segment of the logo 2 3 The next expressions are used to define the second segment The third expression determines 27 to be positioned on the line z5 z6 where we extend this line by 50 25 x4 height 2 y1 26 x4 2y1 z7 1 5 z5 z6 path q z3 z4 zb zT 2 Simple Logos A few applications If we combine these two segments we get 3 e e e 2 0 1 20 31 However when we draw them using the right linewidth and color you will notice that we re not yet done The second curve is similar to the first one but rotated over 180 degrees addto currentpicture also currentpicture rotatedaround 5 z2 z3 180 shifted height 4 height 2 In order to get the sharp edges we need to clip off part of the curves and at first sight we may consider using a scaled bounding box However when we show the natural bounding box you will notice that a more complicated bit of calculations is needed The right clip path is calculated using the following expressions Watch how we use rt and top to correct for the linewidth numeric d 1 ly ux uy d line 2 1 3d 4 3 ly d ux rt x5 d 3 uy t
296. rections you can use moved corner points startuseMPgraphic page StartPage def somewhere uniformdeviate icm uniformdeviate 1cm enddef path Main Main Field Text Text lrmoved somewhere Field Text Text llmoved somewhere Field Text Text ulmoved somewhere Field Text Text urmoved somewhere cycle pickup pencircle scaled 2pt fill Page withcolor 625white fill Main withcolor 850white draw Main withcolor 625red StopPage stopuseMPgraphic Here we displace the corners randomly which leads to backgrounds like figure 6 5 The following definition would have worked as well startuseMPgraphic page StartPage path Main Main Field Text Text randomized 1cm pickup pencircle scaled 2pt fill Page withcolor 625white fill Main withcolor 850white draw Main withcolor 625red StopPage stopuseMPgraphic The previous graphics are defined as usable ones which means that they will be recalculated each page This is rather inefficient when the shapes don t change But using a reusable graphic instead would result in only one graphic for both pages Since the layout for the left and right page differs another method is needed Instead of putting the same graphic on the page layer we put two different ones on the left and right page layer Crossing borders M RUP M first large scale u
297. references for using CONTEXT in combination with metarost were the following Otten amp Hagen J 1998 ConTgXt an Excursion Hasselt Pragma ADE Hagen J 1999 ConTEXt the Manual Hasselt Pragma ADE Hagen J 1999 Charts Uncovered mp flowcharts Hasselt Pragma ADE Hagen J 1997 Steps mp stepcharts and tables Hasselt Pragma ADE As we moved on more resources became available but in the perspective of moving from CONTEXT MKII to MKIV the following make most sense as they introduce the new concepts Hagen J 2006 ConTgXt MKII MKIV The history of LUATEX 2006 2009 Hasselt Pragma ADE Hagen J 2009 Hybrid Technology The history of LUATEX 2009 Hasselt Pragma ADE METAFONT and METAPOST D 4 There are more manuals You can use the showcase document on the website and wiki aka con textgarden to browse all the documentation The show pdf files demonstrate a bit of combined TEX METAPOST trickery Quite some articles have been written in user group journals and a lot of styles that come with CONTEXT or are published by users demonstrate how metarost can be used Tools DS Convenient use of mETRPOST became possible when PDFTEX came around Its machinery made it possible to process graphics at runtime and embed them by parsing the result H n Th Th nh amp Rahtz S P Q amp Hagen J 1998 The pdfTgX manual Brn
298. resent in METAFONT and vice versa With METAFUN I will demonstrate that mETaPOST can also be used or misused for less technical drawing purposes We will see that METRPOST can fill in some gaps in especially its lack of graphic capabilities We will demonstrate that graphics can make a document more attractive even if it is processed in a batch processing system like Tex Most of all we will see that embedding METRPOST definitions in the TEX source enables a smooth communication between both programs The best starting point for using METRPOST is the manual written by its author John Hobby You can find this manual at every main repository Also a copy of the book from Donald Knuth is worth every penny if only because it will give you the feeling that many years of graphical fun lays ahead In this METAFUN manual we will demonstrate how you can embed graphics in a document but we will also introduce most of the features of mETRPOST For this reason you will see a lot of METRPOST code For sure there are better methods to solve problems but I have tried to demonstrate different methods and techniques as much as possible I started using metarost long after I started using and I never regret it Although I like Tex very much I must admit that sometimes using METRPOST is even more fun Therefore before we start exploring both in depth I want to thank their creators Donald Knuth and John Hobby for
299. right Again we put this graphic in the background By using a unique graphic we make sure that it s rendered only once and reused when possible setupbackgrounds text rightmargin background copyright In both cases we slightly scale down the graphic We do so because otherwise a small portion of the text if clipped off This is unrelated to or mETRPOST but a characteristic of the font Compare the following Pagella Latin Modern and Termes gi s the Pagella is the body font of this text showboxes hbox bgroup hbox def inedfont file texgyrepagella regular at 6cm git hbox def inedf ont file 1mromani0 regular at 6cm git hbox definedfont file texgyretermes regular at 6cm git egroup Page Setting up backgrounds Watch how the bounding boxes differ and sometimes cross the shape So in order not to loose part of a glyph when clipping you need to add a bit of space Figure 6 1 shows the two backgrounds in action Edward R Tufte We thrive in information thick worlds because of our marvelous and everyday capacity to select edit single out structure highlight group pair merge harmonize synthesize focus organize e down choose categorize catalog classify list abstract scan look into discriminate distinguish screen pigeonhole pick over sort integrate blend inspect filter l
300. rkred darkred 625 0 0 You can now use this color as withcolor darkred Given that red is already defined we also could have said withcolor 625red Because for 5 colors are just vectors you can do things similar to points A color halfway red and green is therefore accomplished with withcolor 5 red green Since only the RGB color space is supported this is about all we can tell about colors for this mo ment Later we will discuss some nasty details 1 14 Dashes A dash pattern is a simple picture that is build out of straight lines Any slightly more complicated picture will be reduced to straight lines and a real complicated one is rejected and in this respect METAPOST considers a circle to be a complicated path The next example demonstrates how to get a dashed line First we built picture p that we apply to a path Here we use a straight path but dashing can be applied to any path picture p p nullpicture addto p doublepath 0 0 3mm 3mm shifted 6mm 6mm draw 0 0 10cm 0 dashed p withpen pencircle scaled 1m This way of defining a pattern is not that handy especially if you start wondering why you need to supply a slanted path Therefore provides a more convenient mechanism to define a pattern picture p p dashpattern on 3mm off 3mm draw 0 0 10cm 0 dashed p withpen pencircle scaled 1mm Pweleome to MetaPosts Co
301. rograms claim the pt to be a bp This confusion can lead to interesting discussions with desktop publishers when they have to use They often think that their demand of a baseline distance of 13 4 is met when we set it to 13 4pt while actually they were thinking of 13 4bp which of course in other programs is specified using a pt suffix Therefore when embedding graphics in CONTEXT we strongly recommend that you use pt as the base unit instead The main reason why we spend so many words on this issue is that when neglected large graphics may look inaccurate Actually when taken care of it is one of the many reasons why documents always look so accurate Given that the eye is sensitive to distortions of far less than 1pt you can be puzzled by the fact that many drawing programs only provide a bounding box in rounded units Thereby they round to the next position to prevent unwanted cropping For some reason this low resolution has made it into the high end POSTSCRIPT standard In CONTEXT we try to deal with these issues as well as possible A few more details Units 2 4 Scaling and shifting When we draw a shape will adapt the bounding box accordingly This means that a graphic has its natural dimensions unless of course we adapt the bounding box manually When you limit your graphic to a simple shape say a rectangle shifting it to some place c
302. rst row of figure 13 4 is used in the second and third and therefore is the most complicated We use quite some scratch variables to reach a high level of abstraction The xyscaled operator is a METAFUN macro startuseMPgraphic first numeric height width radius gap gap imm height 2 5cm width height 2 radius height 2 5 color mainshade leftshade rightshade centershade mainshade MPcolor funcolor leftshade 9mainshade rightshade 5mainshade centershade 5 leftshade rightshade fill unitsquare xyscaled width height withcolor leftshade Fool yourself Figure 13 4 Koffka s examples of manipulating contrast by changing the spatial configuration fill unitsquare xyscaled width height withcolor rightshade draw fullcircle scaled radius shifted 0 height 2 withpen pencircle scaled radius 2 withcolor centershade stopuseMPgraphic The graphics of the second row extend those of the first by drawing a white line through the middle In this example setting the linecap is not really needed because rounded top and bottoms in white are invisible and the part that extends beyond the points does not count in calculating the bounding box startuseMPgraphic second includeMPgraphic first interim linecap butt pickup pencircle scaled gap draw 0 0 O height withcolor white stopuseMPgraphic The third row gr
303. rutheight strutdepth strutheight draw p withpen pencircle scaled ipt stopuseMPgraphic Contrary to the first three shapes here we use a different path for the calculations and the drawing Watch carefully If instead of an offset we pass a path wErRPosr is able to calculate the right dimensions and offsets This is needed since we need these later on startuseMPgraphic test 4 numeric w h def shape 0 0 w 0 0 amp w 0 0 75w o 5h w 20 h 0 amp w 20 h 0 cycle enddef T pa Libraries w h w h 6cm o 6pt path p p shape 6cm o Opt path q q shape build parshape p q 6pt 6pt baselinedistance strutheight strutdepth strutheight draw q withpen pencircle scaled ipt stopuseMPgraphic Since we also want these graphics as backgrounds we define them as overlays If you don t want to show the graphic you may omit this step defineoverlay test 1 useMPgraphic test 1 defineoverlay test 2 useMPgraphic test 2 defineoverlay test 3 useMPgraphic test 3 defineoverlay test 4 useMPgraphic test 4 As text we use a quote from Douglas R Hofstadter s book Metamagical Themas Questing for the Essence of Mind and Pattern Watch how we pass a list of shapes startshapetext test 1 test 2 test 3 test 4 forgetall as it says setupalign verytoler
304. s symbolic token suffix list forever progression numeric expression upto numeric expression numeric expression downto numeric expression numeric expression step numeric expression until numeric expression for list expression forlist expression suffix list suffix suffixlist suffix Left overs There are a few more concepts and commands available in METAFUN like color remapping shad ing and graphic inclusion Because they have their own small syntax world we present them here You may consider shades to be internally represented by a hidden datastructure The end user has access to a shade by means of a pointer expressed in a numeric pseudo procedure linearN shade path expression numeric expression color expression color expression circularN shade path expression numeric expression color expression color expression Left overs pseudo function defineN linearN shade pair expr pair expr color expr color expr defineN circularN shade pair expr pair expr path expr path expr color expr color expr predefinedN linearN shade path expr numeric expr color expr color expr predefinedN circularN shade path expr numeric expr color expr color expr External figures are just files so the string p
305. s that determine the central quadrilateral All of them are expressions startMPdefinitions solvers def draw problem expr q r s show labels begingroup save x a b c d e f g h 211 242 p 221 212 q 231 x12 x11 b 12 yil 32 x31 f 32 y31 211 x11 711 212 x12 213 x12 b yi2 a 214 x11 b 221 x21 21 222 x22 223 x22 d 22 224 21 231 x31 731 232 32 233 32 y32 e 234 x31 f 241 x41 741 242 x42 243 x42 h y42 g 244 x41 h pickup pencircle scaled 5pt draw 211 212 213 214 1 draw draw z21 z22 z23 z24 cycle draw z31 z32 z33 z34 cycle draw z41 z42 z43 z44 cycle 21 z3 0 5 z11 z13 z2 0 5 z31 z33 z4 0 5 z21 z23 0 5 z41 z43 222 r 241 232 8 22 x21 d 42 x41 h y22 y21 y42 y41 y12 yiita 22 y21 c y32 P y3ite y42 y4itg 211 213 draw 212 214 z21 z23 draw z22 z24 z31 z33 draw z32 z34 241 243 draw z42 z44 draw 21 23 dashed evenly draw z2 z4 dashed evenly 20 whatever zi z3 whatever z2 z4 mark rt angle zi 20 z2 4 22 is not used at all if show labels gt O draw problem labels fi endgroup enddef stopMPdefinitions
306. s become pictures The MPbetex macro returns a btex etex construct The MPstring returns the text as a METAPOST string between quotes The raw text can be fetched with MPtext Graphics and macros Enhancing the layout startMPcode picture p p MPbetex 1 picture q q textext MPstring 2 3 picture r r thelabel MPtext 3 origin for i p boundingbox p draw i withcolor 625red endfor for i q boundingbox q draw i withcolor 625yellow endfor for i r boundingbox r draw i withcolor 625white endfor currentpicture currentpicture scaled 2 draw origin withpen pencircle scaled 5 0mm withcolor white draw origin withpen pencircle scaled 2 5mm withcolor black draw boundingbox currentpicture withpen pencircle scaled imm dashed evenly stopMPcode The first two lines return text typeset by while the last line leaves this to If you watch closely you will notice that the first red alternative is positioned with the baseline on the origin startMPcode picture p p MPbetex 1 textext origin MPstring 2 thelabel origin MPtext 3 origin picture picture r for i p boundingbox p draw i withcolor 625 endfor for i q boundingbox q draw i withcolor 625yellow endfor for i r boundingbox r draw i withcolor 625white endfor currentpicture c
307. s in favour for one or the other placement lower left Although any automatic mechanism will be sub optimal we can give it a try to write a macro that deals with arbitrary locations This macro will accept three arguments and return a picture thefreelabel some string or picture a position the origin Our testcase is just a simple for loop that places a series of labels The freedotlabel macro is derived from thefreelabel pickup pencircle scaled imm path p fullcircle scaled 3cm draw p withcolor 625yellow for i 0 step 5 until 7 5 freedotlabel text point i of p center p endfor As a first step we will simply place the labels without any correction We also visualize the bound ing box vardef thefreelabel expr str loc ori save s picture s s thelabel str loc draw boundingbox s withpen pencircle scaled 5pt S enddef To make our lives more easy we also define a macro that draws the dot as well as a macro that draws the label vardef freedotlabel expr str loc ori drawdot loc draw thefreelabel str loc ori enddef vardef freelabel expr str loc ori draw thefreelabel str loc ori enddef Now we get A few applications Free labels The original label macros permits us to align the label at positions 4 corners and 4 points halfway the sides It happens that circles
308. s tracingspecs tracingstats tracingtitles truecorners warningcheck year symbolic token defined by newinternal pseudo function min expression list max expression list incr numeric variable decr numeric variable dashpattern on offlist interpath numericexpression pathexpression pathexpression buildcycle path expression list thelabel labelsuffix expression pairexpression thefreelabel expression pairexpression pair expression anglebetween pathexpression pathexpression expression pointarrow path expression numeric or pair primary numeric expression numeric expression leftarrow path expression numeric or pair primary numeric expression centerarrow path expression numeric or pair primary numeric expression rightarrow pathexpression numericor pair primary numeric expression paired numeric or pair tripled numeric color remappedcolor color expression path expression list path expression path expression list path expression on off list on off list on off clause on off clause Syntax diagrams E on off clause on numeric tertiary off numeric tertiary boolean expression expression cmykcolor expression expression color expression expression numeric atom
309. se we want to run METAPOST as less times as possible so we need to use unique graphics Let s start with the graphic setupMPvariables EnglishRule height 1ex width localhsize color darkgray startuniqueMPgraphic EnglishRule height width color numeric height height MMPvar height 1 0 x3 MPvar width x2 x4 5 3 yl y3 0 y2 y4 height 2 fill zi z2 z3 amp z3 z4 z1 amp cycle withcolor MPvar color stopuniqueMPgraphic As you can see we pass two arguments to the graphic definition The first argument is the name the second argument is a comma separated list of variables This list serves two purposes First this list is used to create a unique profile for the graphic This means that when we change the value of a variable a new graphic is generated that reflects the change A second purpose of the list is to convert data structures into METRPOST ones especially dimensions and colors The graphic itself is not that spectacular We use amp because we don t want smooth connections defineblank EnglishRule medium def EnglishRule fNstartlinecorrection EnglishRule setlocalhsize noindent reuseMPgraphic EnglishRule stoplinecorrection When setting the variables we used localhsize This variable is set by setlocalhsize We need to use noindent a rather familiar primitive that we use here to start a non indented Interfacing to
310. sed shapes instead of random ones We need a high degree of superness 95 in order to make sure that the curves don t touch the texts startuseMPgraphic FunnyFrame picture p numeric o path a b pair p textext rt MPstring FunnyFrame o BodyFontSize a unitsquare xyscaled OverlayWidth OverlayHeight shifted 2o 0verlayHeight ypart center p drawoptions withpen pencircle scaled 1pt withcolor 625red b superellipsed 95 fill b withcolor 85white draw b b boundingbox p superellipsed 95 fill b withcolor 85white draw b draw p withcolor black setbounds currentpicture to a stopuseMPgraphic Many people are just fascinated by their PC s tricks and think that a widely praised program called up on the screen will make every thing automatic from now on There are quite some hard coded values in these graphics like the linewidths offsets and col ors Some of these can be fetched from the framed environment either by using macros or dimensions or by using their METAFUN counterparts In the following table we summarize both the available variables and their counterparts They may be used interchangeably METAPOST variable command meaning OverlayWidth overlaywidth current width Graphics and macros Bhhancingthellayout_ OverlayHeight overlayheight current height Ov
311. ser the designer should also write the first user etui 16 Thad not i of improvements would in certain important issues raised by The Concept of a Meta Font even Figure 6 5 Edward R Tufte We thrive in information thick m earch eer synopsize winnow the wheat from the chaff and separate the sheep from the eens first large scale user the designer should also write the first user Ie em fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter por E certain important issues raised by The Concept ofa Meta Font odd A random text area defineoverlay left page useMPgraphic left pagel defineoverlay right page useMPgraphic right page setupbackgrounds leftpage background left page setupbackgrounds rightpage background right page Now we only have to split the previously defined graphic into two parts In order to force consis tency we isolate the code that fills and draws The left page code looks like startreusableMPgraphic left page StartPage path Main Main llcorner Field Outer
312. ses For instance too small first lines are ignored First we define a circle Watch how the dimensions are set in the graphic The arguments passed to build parshape are path an offset Libraries an additional horizontal and vertical displacement the baseline distance the height and depth of the line and the height of the first line topskip in terminology The height and depth of a line are often called strut height and depth with a strut being an invisible character with maximum dimensions startuseMPgraphic test 1 path p p fullcircle scaled 6cm build_parshape p 6pt 0 0 baselinedistance strutheight strutdepth strutheight draw p withpen pencircle scaled ipt stopuseMPgraphic The second shape is a diamond This is a rather useless shape unless the text suits the small lines at the top and bottom startuseMPgraphic test 2 path p p fullsquare rotated 45 scaled 5cm build_parshape p 6pt 0 0 baselinedistance strutheight strutdepth strutheight draw p withpen pencircle scaled ipt stopuseMPgraphic The third and fourth shape demonstrate that providing a suitable offset is not always trivial startuseMPgraphic test 3 numeric w h w h 6cm path p p 5w h 0 h 0 0 w 0 amp w 0 75w 5h w h amp w h cycle build parshape p 6pt 0 0 baselinedistance st
313. set by ConTeXt The arguments to the text placement macros are similar to the ones for drawing the axes Here we provide a format string hlintext vlintext hlogtext vlogtext Min Min Min Min Max Max Max Max Step Step Step Step Length Length Length Length Format Format Format Format When drawing a smooth function related curve you need to provide enough sample points The function macro will generate them for you but you need to make sure that for instance the max imum and minimum values are part of the generated series of points Also a smooth curve is not always the right curve Therefore we provide three drawing modes method result 1 a punked curve drawn using 2 a smooth curve drawn using 3 a tight curve drawn using If method 2 or 3 do not give the desired outcome you can try a smaller step combined with method 1 draw function 1 log x x 1 10 1 xyscaled 10cm 2cm withpen pencircle scaled 5mm withcolor transparent 1 5 yellow draw Drawing functions 10
314. some test 3 years working on a system al lowing him to control many as pects of the design of his forthcom ing books from the typesetting and layout down to the very shapes of the letters Seldom has an au countries around the world By contrast ap pearance of his or her work Knuth s typeset ting system has become well known and available in many his METRFONT system for designing families of typefaces has not become as well known or available In his ar ticle test 2 points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt com pelled to make some com ments to clarify certain important issues raised by Ihe Concept of a Meta Font test 4 Figure 10 3 A continuous text typeset in a non standard shape spread over four areas and right alligned The traced alternative is shown in figure 10 4 This one is defined as Mplacefigure here fig traced shapes A continuous text typeset in a non standard shape spread over four areas tracing on startMPinclusions boolean trace_parshape trace_parshape true stopMPinclusions getbuffer Libraries Donald Knuth has spent the past several years working
315. ss these variables to the graphic using an extra argument When you define the useable graphic you need to tell what variables it can expect startuseMPgraphic one i j s draw_problem 400pt 400pt 300pt 600pt MPvariit 300pt 600pt 550pt 800pt MPvar j 400pt 400pt 550pt 500pt MPvar s stopuseMPgraphic Of course we could have used a loop construct here but defining auxiliary macros probably takes more time than simply calling the drawing macro directly The results are shown on a separate page figure 1 3 We will use a helper macro that saves us typing def MyTest 1 2 scale width 25 textwidth useMPgraphic solvers one i 1 j 2 s O We now can say startcombination 3 4 MyTest 1 0 1 0 1 0 1 0 MyTest 0 8 1 0 0 8 1 0 MyTest 0 6 1 0 0 6 1 0 MyTest 0 4 1 0 0 4 1 0 MyTest 0 2 1 0 0 2 1 0 MyTest 0 0 1 0 0 0 1 0 MyTest 0 0 1 0 0 0 1 0 MyTest 0 0 0 8 0 0 0 8 MyTest 0 0 0 6 0 0 0 6 MyTest 0 0 0 4 0 0 0 4 MyTest 0 0 0 2 0 0 0 2 MyTest 0 0 0 0 0 0 0 0 stopcombination Watch how we pass the settings to the graphic definition using an extra argument We force using the solvers instance by prefixing the name It does not need that much imagination to see the four sided problem converge to a three sided one which itself converges to a two sided one In the two sided alternative it
316. suffix macro de nition macro heading replacement text enddef macro heading def Symbolic token delimited part undelimited part vardef generic variable delimited part undelimited part vardef generic variable delimited part undelimited part binary def parameter symbolic token parameter delimited part empty delimited part parameter type parameter tokens parameter type expr suffix text Syntax diagrams parameter tokens parameter parameter tokens parameter parameter Symbolic token undelimited part empty parameter type parameter precedence level parameter expr parameter of parameter precedence level primary secondary tertiary binary def primarydef secondarydef tertiarydef pseudo procedure drawoptions option list label labelsuffix expression pairexpression dotlabel label suffix expression pair expression labels labelsuffix point number list dotlabels label suffix point number list textext label suffix expression freelabel expression pair expression pair expression freedotlabel expression pair expression pair expression remapcolor colorexpression color expression resetcolormap recolor picture
317. syntax diagrams are derived from the diagrams in the wErePosr manual The gt represents means and the symbol stands for or The diagrams describe the hard coded metarost syntax as well as most of the macros and variables defined in the plain format that belongs to the core of the system They also include some of the more fundamental METAFUN commands atom variable argument number or fraction internal variable expression begingroup statement list expression endgroup nullary op btex typesetting command etex pseudo function primary atom numeric expression numeric expression numeric expression numeric expression numeric expression numeric expression numeric expression numeric expression numeric expression of operator expression of primary of operator expression along primary of operator expression on primary unary op primary str suffix z suffix numeric atom expression expression scalar multiplication op primary secondary primary secondary primary binop primary secondary transformer tertiary secondary tertiary secondary binop secondary Syntax diagrams METAPOST subexpression tertiary path expression path join path knot expression
318. t inside this circle we need to know where a line starts and ends Given that lines are horizontal and straight we therefore need to calculate the intersection points of the lines and the path As a first step we calculate the top and bottom of the path and after that we split off the left and right path startuseMPgraphic text split grap P pair t b path 1 t ulcorner p urcorner p intersectionpoint b 11 p lrcorner p intersectionpoint l p cutbefore t 1 1 cutafter b r cutbefore b r cutafter t stopuseMPgraphic The intersectionpoint macro returns the point where two paths cross If the paths don t cross an error is reported when the paths cross more times just one point is returned The cutafter and cutbefore commands do as their names say and return a path Inthetext split code fragment t and b are the top points of the main path while 1 and r become the left and right half of path p We now draw the original path using a thick pen and both halves with a thinner pen on top of the original The arrows show the direction Talking to MITT ME startuseMPgraphic text draw draw p withpen pencircle scaled 3pt withcolor red drawarrow 1 withpen pencircle scaled 1pt withcolor green drawarrow withpen pencircle scaled 1pt withcolor blue stopuseMPgraphic We use includeMPgraphic
319. t of sin this and cos that and long forgotten formulas I was expected to prove that the lines connecting the centers of four squares drawn upon the four sides of a quadrilateral were perpendicular see figure 1 2 Welcome to MetaPosl Linear equations Figure 1 2 The problem This graphic was generated with the following command placefigure here fig problem The problem scale width Ntextwidth useMPgraphic solvers one i 0 6 j 1 0 s 1 We will use this example to introduce a few new concepts one being instances Ina large document there can be many graphics and they might fall in different categories In this manual we have graphics that are generated as part of the style as wel as examples that show what METAFUN do As definitions and variables in Metarost are global by default there is a possibility that we end up with clashes This can be avoided by grouping graphics in instances Here we create an instance for the example that we re about to show Linear equations Welcome to MetgPost defineMPinstance solvers format metafun extensions yes initializations yes We can now limit the scope of definitions to this specific instance Let s start with the macro that takes care of drawing the solution to our problem The macro accepts four pairs of coordinate
320. t order points second order points left side points right side points Curve construction e first iteration second iteration e o e e e 9 e e gt e e e ua 9 third iteration fourth iteration 9000 e H H P e P 9 e e e p 600000099 fifth iteration Curve construction sixths iteration 27 7 Just in case you are interested in how such graphical simulations can be organized we show sim plified versions of the macros used here In the previous examples we minimized the complexity of the code by using buffers but describing this mechanism is out of the scope of this section We need to loop over all segments of a curve where for each segment the left and right side sub curves are handled recursively upto the requested depth denoted as n For this we define the following macros vardef dodrawmidpoints expr a b c d n save e f g h i j pair e f g h i j e 5 a b f 5 b c g 5 c d h 5 e f i 5 f g j 5 h i draw j if mi dodrawmidpoints a e h j n 1 dodrawmidpoints j i
321. t this feature natively the intermediate POSTSCRIPT file send to the printing engine is also larger Transparency fill p shifted 3cm 0 withcolor 5blue fill p shifted 6cm 0 withcolor transparent 1 0 5 blue fill p shifted 9cm 0 withcolor 5 blue white The next series demonstrates that we use the complementary factor 7 in the mETRPOST soft color to achieve the same softness as the 3 transparency path p fullcircle scaled 2cm fill p shifted 0cm 0 withcolor red fill p shifted 3cm 0 withcolor 7red fill p shifted 6cm 0 withcolor transparent 1 0 3 red fill p shifted 9cm 0 withcolor 7 red white So far we have applied transparent colors to shapes but text can also be the target The following works okay in MKII vardef SampleText expr t c save p picture p p image draw t infont truefontname Regular draw p shifted xpart center p 0 scaled 5 withcolor c enddef SampleText Much Of This transparent 1 5 red SampleText Functionality transparent 1 5 green SampleText Was Written transparent 1 5 blue SampleText While Listening transparent 1 5 cmyk 1 0 0 0 SampleText To the CD s Of transparent 1 5 cmyk 0 1 0 0 SampleText Tori Amos transparent 1 5 cmyk 0 0 1 0 The source code of this example illustrates that the CMYK color space is also supported The truefont
322. t you are using CONTEXT MKIV otherwise you need to run texexec with the mptex flag Comenius By default CONTEXT has turned its color mechanism on If you don t want your graphics to have color you should say setupcolors state stop 1 Welcome to MetaPost In this chapter we will introduce the most important METAPOST concepts as well as demonstrate some draw ing primitives and operators This chapter does not replace the METAFONT book or MeTAPOST manual both of which provide a lot of explanations examples and dirty tricks As its title says the METAFONT book by Donald E Knuth is about fonts Nevertheless buying a copy is worth the money because as a METAPOST user you can benefit from the excellent chapters about curves algebraic expressions and linear equations The following sections are incomplete in many aspects More details on how to define your own macros can be found in both the METAFONT book and MeTAPOST manual but you will probably only appreciate the nasty details if you have written a few simple figures yourself This chapter will give you a start A whole section is dedicated to the basic extensions to METAPOST as provided by METAFUN Most of them are meant to make defining graphics like those shown in this document more convenient Many of the concepts introduced here will be discussed in more detail in later chapters So you may consider this
323. tMPdrawing picture pic numeric wid len rot numeric delta extra radius n r len 0 n 0 delta 41 extra 2 radius 3 stopMPdrawing handletokens 4 with processrotationtoken startMPdrawing r len n Pi for i 1 upto n wid abs xpart lrcorner pic i xpart llcorner pic i rot extra delta len i 5wid len m 180 2delta draw pic i rotatedaround origin 270 shifted r radius ypart 5 ulcorner pic i llcorner pic ill rotatedaround origin rot endfor stopMPdrawing MPdrawingdonetrue getMPdrawing resetMPdrawing egroup We can use this macro as follows startcombination 3 1 rotatetokens 0 0 0 Does it work ok A rotatetokens 20 0 0 Does it work ok B rotatetokens 20 30 0 Does it work ok C stopcombination text The previous macro is not really an example of generalization but we used it for demonstrating how to build graphics in a stepwise way If you put the steps in buffers you can even combine steps and replace them at will This is how we made the previous step by step examples We put each sub graphic in a buffer and then called the ones we wanted We now present a more general approach to typesetting along a given path This method is not only more robust and general it is also a more compact definition especially if we omit the tracing and tes
324. ternal unit of length is the scaled point sp something on the nanometer range Because METAPOST is focused on POSTSCRIPT output its internal unit is the big point bp All other units are derived from this unit and available as numeric instead of hard coded m mm 2 83464 pt 28 34645 pc 0 99626 dd 11 95517 cc 1 06601 bp 12 79213 in 72 cm Careful reading reveals that only the bp and in are fixed while the rest of the dimensions are scalar multiples of bp Since we are dealing with graphics the most commonly used dimensions are pt bp mm cm and in Pm Lg h 4 rN b dh dh dh A The text in the center of the leftmost graphic is typeset by METRPOST as a label fill fullsquare scaled 72 27pt withcolor 625yellow fill fullcircle scaled 72 27pt withcolor white label 72 27pt center currentpicture In metarost the following lines are identical i Normally you will use grouping to keep the interim local In METAFUN each figure restores this variable at the beginning Units 8 i Ki draw fullcircle scaled 100 draw fullcircle scaled 100bp You might be tempted to omit the unit but this can be confusing particularly if you also program a language like meTAFONT where the pt is the base unit This means that a circle scaled to 100 in METPPOST is not the same as a circle scaled to 100 in
325. test expr a def dotest expr a text b test a test a b This definition permits arguments without parenthesis which is something you want with com mands like draw The vardef alternative behaves in a similar way It always provides grouping You need to gener ate a return value and as a result may not end with a semicolon You may consider the whole vardef to be encapsulated into parenthesis and thereby to be a self contained variable Adding additional parenthesis often does more harm than good vardef test expr a do tricky things with a manipulated_a enddef Here the tricky things become part of the return value which quite certainly is something that you don t want The three operator look alike macro definitions are less flexible and have the definition scheme primarydef x test y enddef secondarydef x test y enddef tertiarydef x test y enddef When defining macros using this threesome you need to be aware of the associated priorities When using these definitions you also have to provide your own grouping In the plain Metarost macro collection plain mp you can find many examples of clever defini tions The following simplified version of min demonstrates how we use the argument handler to isolate the first argument from the provided list simply by using two arguments vardef min expr u text t save min u min u u for uu t if uu lt u min u uu fi endfor
326. the line The bounding box correction at the end ensures that the baseline is consistent and that the random vertical offsets fall below the baseline Random graphics Shapes gymbolsand Because we want to be sure that n has a value we preset it by saying setupMPvariables fuzzycount n 10 In the table it makes sense to adapt the drawing to the lineheight but a more general solution is to adapt the height to the fontsize height 3 4 the bodyfontsize currentfontscale In the table we called the graphic directly but how about making it available as a conversion macro In CONTEXT this is not that hard def fuzzycount 1 tx useMPgraphic fuzzycount n 1 defineconversion fuzzy fuzzycount Because such a counter should not be that large we use tx to switch to a smaller font This also demonstrates how the graphic adapts itself to the font size We can now use this conversion for instance in an itemize To save space we use three columns and no white space between the lines The 2 broad directive makes sure that we have enough room for the number l one IIl four seven li two Hf five eight III three six nine startitemize fuzzy pack 2 broad columns three item one item two 1 three item four item five item six item seven Mtem eight item nine stopitemize A careful reader will have noticed
327. ting code We use a familiar auxiliary definition The Nsetstrut and Nstrut commands ensure that the lines have the proper depth and height def processfollowingtoken 17 appendtoks 1 to MPtoks setbox MPbox hbox RotFont setstrut strut the MPtoks startMPdrawing n 1 len n the wd MPbox stopMPdrawing startMPdrawing pic n btex RotFont setstrut strut 1 etex pic n pic n shifted llcorner pic n stopMPdrawing The definition of followtokens is as follows Keep in mind that RotFont is defined in the META POST environment You may notice that we have added a directive to include the graphic called followtokens Storing the path in a graphic container instead of using startMPdrawing is less sensitive for interference with other drawing processes def followtokens 1 vbox bgroup MPtoks emptytoks resetMPdrawing startMPdrawing includeMPgraphic followtokens picture pic numeric len n n 0 stopMPdrawing handletokens 1 with processfollowingtoken startMPdrawing numeric al pl at wid pos pair ap al arclength RotPath pl al len n n 1 for i 1 upto n wid abs xpart lrcorner pic i xpart llcorner pic il pos len i wid 2 i 1 pl at arctime pos of RotPath _ Typesetting in METRPOST text ap point at of RotPath ad direction at of RotPath dr
328. to achieve this is as follows path p fullcircle scaled icm draw p draw p scaled 2 withpen pencircle draw p scaled 3 withpen pencircle scaled 1mm draw p scaled 4 withpen pencircle xscaled 2mm yscaled 4mm rotated 30 If this were the only way of specifying a pen we would be faced with a considerable amount of typing particularly in situations where we use pens similar to the fourth specification above For that reason METRPOST supports the concept of a current pen The best way to set this pen is to use the pickup macro pickup pencircle xscaled 2mm yscaled 4mm rotated 30 This macro also stores some characteristics of the pen in variables so that they can be used in the more complicated calculations that are involved in situations like drawing font like graphics If we substitute pencircle by pensquare we get a different kind of shapes In the non rotated pens the top bottom left and right parts of the curve are thinner You should look at pens in the way an artist does He follows a shape and in doing so he or she twists the pen and thereby the nib and puts more or less pressure on it The chance that you have an appropriate pen laying at your desk is not so large but you can simulate the following metarost s pen by taking two pencils and holding them together in one hand If you position them in a 45 degrees angle and draw a circle you will get something like If you take a calligraphic pen with a thin
329. to assemble the components startuseMPgraphic text includeMPgraphic text path includeMPgraphic text split includeMPgraphic text draw stopuseMPgraphic This graphic is typeset with useMPgraphic text Before we are going to use them we define some variables that specify the text We use a baseline distance of 8 points The part of the line above the baseline is 7 2 points while the maximum depth is 2 8 points These ratios are the ones we use in CONTEXT Because we don t want the text to touch the circle so we define an offset too also startuseMPgraphic text vars baselineskip 8pt strutheight 7 2 10 baselineskip strutdepth 2 8 10 baselineskip offset baselineskip 2 topskip strutheight stopuseMPgraphic We more of less achieve the offset by scaling the path In doing so we use the width and height which we call hsize and vsize thereby conforming to the naming scheme First we calculate both dimensions from the bounding box of the path Next we down scale the path to compensate for the offset When done we recalculate the dimensions startuseMPgraphic text move pair t b path q 1 r hsize xpart lrcorner p xpart llcorner p Typesetting in wETRPDST Talking to vsize ypart urcorner p ypart lrcorner p q 7 p xscaled hsize 2offset hsize yscaled vsize 2offset vsize hsize
330. to process rather complex data without messing up your METRPOST code setMPtext some math usemodule mathm1 xmlprocessdata main lt math xmlns http www w3c org mathml version 2 0 gt lt apply gt lt log gt lt logbase gt lt cn gt 2 lt cn gt lt logbase gt lt apply gt lt plus gt lt ci gt x lt ci gt lt cn gt 1 lt cn gt Sp cial effects Outline fonts lt 1 gt lt 1 gt lt math gt Here we feed some MATHML into which in turn shows up as a METRPOST graphic graphictext MPstring some math scaled 4 withdrawcolor 625red withfillcolor 625white withpen pencircle scaled 1 5pt Outline fonts Outline fonts 9 Functions METRPOST provides a wide range of functions like sind and floor We will discuss most of them here and define a few more We will also introduce a few methods for drawing grids and functions 9 1 Overview What follows is a short overview of the functions that can be applied to numeric expressions and strings Functions that operate on pairs colors paths and pictures are discussed in other chapters First of all we have and For as far as is reasonable you can apply these to numerics pairs and colors Strings can be concatenated by amp Pythagorean addition is accomplished by while Pythagorean subtraction is handle
331. tomatically connect to the first point Watch the difference between the previous and the next path 20 21 22 23 1 It is also possible to combine two paths into one that don t have common head and tails First we define an open path Constructing paths m 20 21 22 ERN 0 umm 2 5 buildcycle z0 z1 z2 20 23 21 1 We would refer readers to the METAFONT book and the manual for an explanation of the intricacies of the buildcycle command It is an extremely complicated command and there is just not enough room here to do it justice We suffice with saying that the paths should cross at least once before the buildcycle command can craft a combined path from two given paths We encourage readers to experiment with this command In order to demonstrate another technique of joining paths we first draw a few strange paths The last of these three graphics demonstrates the use of soft join z0 z1 z2 z3 E 3 Constructing paths 20 21 22 23 Watch how soft join removes a point in the process of smoothing connection The smoothness is accomplished by adapting the control points of the neighbouring points in the appropriate way 20 21 softjoin z2 z3 Once a path is known you can cut off a slice of it We will demons
332. topuseMPgraphic followtokens star startuseMPgraphic followtokens drawoptions withcolor 625red path RotPath RotPath halfcircle rotated 180 scaled 5cm setbounds currentpicture to boundingbox fullcircle scaled 5 25cm stopuseMPgraphic followtokens Met a inferiore startuseMPgraphic followtokens drawoptions withcolor 625red path RotPath RotPath halfcircle rotated 270 scaled 5cm setbounds currentpicture to boundingbox fullcircle scaled 5 25cm stopuseMPgraphic followtokens star stopoverlay In order to fool the overlay macro that each graphic has the same size we force a bounding box text Typesetting in 10 5 Talking to TEX Sometimes others may say oftentimes we are in need for some fancy typesetting If we want to typeset a paragraph of text in a non standard shape like a circle we have to fall back on parshape Unfortunately is not that strong in providing the specifications of more complicated shapes unless you are willing to do some complicated arithmetic Tpx Given that MeTaPosT knows how to deal with shapes the question is Can METRPOSrT be of help In the process of finding out how to deal with this we first define a simple path Because we are going to replace pieces of code we will compose the graphic from components First we create the path startuseMPgraphic text path path p
333. tr POST representation of the text typeset by Tpx Before METRPOST processes a graphic definition file it first calls another program that filters the btex commands from the source file and generates a TX file from them This file is then processed by Tpx and after that converted to a mpx file In CONTEXT we let TEXEXEC take care of this whole process Because the btex etex commands are filtered from the raw METRPOST source code they can not be part of macro definitions and loop constructs When used that way only one instance would be found while in practice multiple instances may occur This drawback is overcome by METAFUN s textext command This command still uses btex etex but writes these commands to a separate job related file each time it is used After the first METRPOST run this file is merged with the original file and meTaPosT is called again So at the cost of an additional run we can use text typeset by in a more versatile way Because METAPOST runs are much faster than runs the price to pay in terms of run time is acceptable Unlike btex 10 It took the author a while to find out that there is a 5 module called tex mp that provides a similar feature but with the disadvantage that each text results in a call to x Each text goes into a temporary file which is then included and results in METRPOST triggering TEX Graphics and macros Enhancig thelayout_
334. trate a few alternative ways of doing so but first we show one more time the path that we take as starting point 20 21 22 23 1 This path is made up out of five points where the cycle duplicates the first point and connects the loose ends The first point has number zero We can use these points in the subpath command which takes two arguments specifying the range of points to cut of the path specified after the keyword of subpath 2 4 of z0 z1 z2 z3 cycle Constructing paths The new sub path is a new path with its own points that start numbering at zero The next graphic shows both the original and the subpath from point 1 upto 3 z0 zi z2 z3 cycle subpath 1 3 In spite of what you may think a point is not fixed This is why in mMetarost a point along a path is officially called a time The next example demonstrates that we can specify any time on the path z0 zi z2 z3 cycle subpath 2 45 3 85 Often we want to take a slice starting at a specific point This is provided by cutafter and its companion cutbefore Watch out this time we use a non cyclic path zO zi z2 z3 When you use cutafter and cutbefore it really helps if you know in what direction the path runs Constructing paths z0 zi z2 z3 cutafter z2 20 21 22 23 cutbefore z1 Here is a somewhat silly way of accomplishin
335. ts on printing and viewing devices However reality demands that sometimes CMYK colors are used so how can we deal with that In the METAFUN macro collection there is a macro cmyk that takes four arguments representing the cyan magenta yellow and black component fill fullsquare xyscaled 10cm icm withcolor cmyk 1 0 3 3 If you take a close look at the numbers you will notice that the cyan component results in a 10076 ink contribution You will also notice that 30 black ink is added This means that we cannot safely convert this color to RGB r 1 c k lt 0 without losing information Nevertheless the previous blue bar is presented all right This is due to the fact that in METAFUN the CMYK colors are handled as they should even when metarost does not support this color model If you use this feature independent of CONTEXT you need to enable it by setting cmykcolors to true You have to convert the resulting graphic to PDF by using for instance the mptopdf suite In CONTEXT you can influence this conversion by changing parameters related to color handling setupcolors cmyk yes mpcmyk no Unless you know what you are doing you don t have to change the default settings both yes In the CONTEXT reference manual you can also read how color reduction can be handled Special care should be paid to gray scales Combining equal quantities of the three color inks will not lead to a gray scale but to a muddy brown sh
336. two files are processed automatically after a run so that ina next run the right graphics are available When you are using the web2c distribution CONTEXT can call Metarost at runtime and thereby use the right graphics instantaneously In order to use this feature you have to enable write18 in the file texmf cnf Also in the file cont sys tex that holds local preferences or in the document source you should say runMPgraphicstrue This enables runtime generation of graphics using the low level command write18 First make sure that your local brand of supports this feature A simple test is making a file with the following line immediate write18 echo It works If this fails you should consult the manual that comes with your system locate an expert or ask around on the CONTEXT mailing list Of course you can also decide to let TEXEXEC take care of pro cessing the graphics afterwards This has the advantage of being faster but has the disadvantage that you need additional runs If you generate the graphics at run time you should consider to turn on graphic slot recycling which means that you often end up with fewer intermediate files recycleMPslotstrue Common definitions There are a few more low level switches and features but these go beyond the purpose of this manual Some of these features like the option to add tokens to everyMPg
337. uch a path every time you need it can be annoying Figure 8 8 shows a collection of predefined clipping paths These are available after loading the metarost clipping library NuseMPlibrary 1 We already saw how the circular clipping path was defined The diamond is defined in a similar way using the predefined path diamond startMPclip diamond clip currentpicture to unitdiamond xscaled width yscaled height stopMPclip The definition of the negated ellipse negellipse uses the primary peepholed This primary is defined in one of the 5 modules that come with CONTEXT startMPclip negellipse clip currentpicture to unitcircle peepholed unitsquare xscaled width yscaled height stopMPclip Gigping Special eft cis The definition of peepholed is rather dirty and using peepholed is restricted to well defined sit uations like here It s called a primary because it acts as an operator at the same level as and scaled Eb A Qe urellipse ulellipse llellipse lrellipse ellipse E db n E gt tellipse bellipse lellipse rellipse ib d SP 5 urtriangle ultriangle Iltriangle Irtriangle diamond negdiamond Figure 8 8 A collection of predefined clipping paths 8 4 Including graphics This document demonstrates that it is no big problem to include metarost graphics in doc ument But how about including graphics in a METRPOST pict
338. ue Killing time startMPcode includeMPgraphic gamble Gamble 120 aa 0 1 bb stopMPcode According to when we leave the Earth straight upwards and want a smooth trajectory we have to pass through outer space startMPcode Given that we want a smooth path as well as a short journey we can best follow Mars path Here we face the risk that when we travel slower than Mars does we have a problem startMPcode includeMPgraphic gamble Gamble 120 aa dir 90 precontrol 0 of b rotated 90 bb stopMPcode We can even travel a shorter path when we leave Earth at the surface that faces the point of arrival Killing time startMPcode includeMPgraphic gamble Gamble 120 aa precontrol 0 of b rotated 90 bb stopMPcode In the end we decide that although the trajectories look impressive we will not trust our lives to METRPOST A beautiful path is not neccessarily a good path But even then this macro provides a nice way to experiment with directions controls and tensions Killing time 318 Killing time 14 METAFUN macros CONTEXT comes with a series of METAPOST modules In this chapter we will summarize the most important and METAPOST macros More information can be found in the documentation of the modules There a
339. uf fer b numeric u w u 5cm w ipt pickup pencircle scaled w def draw dot expr p draw p withpen pencircle scaled 3w enddef def stand out drawoptions withcolor 625red enddef stopbuffer First we construct the macro that will plot two points A and B and connect them with a line segment startbuf fer def draw_basics pair pointA pointB path lineAB pointA origin pointB pointA shifted 5u 0 lineAB pointA pointB draw lineAB draw dot pointA label lft btex A etex pointA draw dot pointB label rt btex B etex pointB enddef stopbuffer The code in this buffer executes the preceding macros The everything commands are still undefined but later we can use these hooks for special purposes startbuffer 1 start_everything stand_out draw_basics stop_everything stopbuffer This graphic can now be embedded by the CONTEXT command processMPbuffer This command like the ordinary buffer inclusion commands accepts a list of buffers startlinecorrection blank ruledhbox processMPbuffer a b c 1 stoplinecorrection Growing graphics laCfewlapplications We ruledhbox to show the tight bounding box of the graphic The line correction takes care of proper spacing around non textual content like graphics This is only needed when the graphic is part of the text flow Ac _
340. ump skip smooth chunk average approximate cluster aggregate outline sum marize itemize review dip into flip through browse glance into leaf through skim refine enumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the goats Donald E Knuth Thus I came to the conclusion that the designer of a new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt significantly If I had not participated fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her work Knuth s TEX typesetting system has become well known and available in many countries around the world By contrast his M
341. untions can be applied to numerics as well as strings The following functions are related to strings oct s string representation of an octal number hex s string representation of a hexadecimal number str s string representation for a suffix ASCII s ASCII value of the first character char x character of the given ASCII code decimal x decimal representation of a numeric With substring i j of s youcan filter the substring bounded by the given indices from the given string In METAFUN we provide a few more functions you can take a look in mp tool mp to see how they are defined You need to be aware of very subtle rounding errors Normally these only show up when you reverse an operation This is a result from mapping to and from internal quantities sqr x x log x log x 1n x In x exp x e pow x p inv x 1 x The following sine and cosine functions take radians instead of angles in degrees sin x asin x invsin x cos x acos x invcos x There are no tangent functions so we provide both the radian and degrees versions tan x tand x cot x cotd x Here are a couple of hyperbolic functions sinh x asinh x cosh x acosh x We end with a few additional string converters ddecimal x decimal representation of a pair dddecimal x decimal representation of a color condition x string representation of a boolean Overview 92 Grids Some day you may want to use METRPOST to draw a function like
342. ure In this section we will explore a couple of macros that provide you this feature Before we go into details we introduce a very impressive program called PSTOEDIT by Wolfgang Glunz This program runs on top of GHOSTSCRIPT and is able to convert POSTSCRIPT code into other formats among them metarost that part of the PSTOEDIT code is due to Scott Pakin Some of the graphics that we use in this section are produced that way For us the next call works well but the exact call may differ per version or platform pstoedit ssp dt f mpost yourfile ps newfile mp We have converted the Dutch cow that shows up in many CONTEXT documents into METRPOST using this program The resulting file encapsulates the cow in 5 figure 1 beginfig 1 Of course you can process this file like any other but more interesting is to use this code in an indirect way loadfigure mycow mp number 1 scaled 5 This call will load figure 1 from the specified Metarost file in such a way that there is no interfer ence with the current encapsulating figure Spatialieifects Including graphics Because this graphic is the result from a conversion there are only paths If you want to import more complex graphic you need to make sure that the variables used in there do not conflict with the one currently in use METAPOST is good in drawing vector graphics but lacks natural support
343. urrentpicture scaled 2 draw origin withpen pencircle scaled 5 0mm withcolor white draw origin withpen pencircle scaled 2 5mm withcolor black draw boundingbox currentpicture withpen pencircle scaled imm dashed evenly stopMPcode This draws This picture demonstrates that we can also position textext s and label s on the baseline For this purpose the repertoire of positioning directives top 1ft etc is extended with an origin directive Another extra positioning directive is raw This one does not do any positioning at all picture q q textext origin MPstring 2 2s picture r r thelabel origin MPtext 3 origin FEnhancingetig layouts Graphics and macros We will now apply this knowledge of text inclusion in graphics to more advanced example The next definitions are the answer to a question on the CONTEXT mailinglist with regards to framed texts with titles Coming back to the use of typefaces in electronic publishing many of the new typographers receive their knowledge and information about the rules of typography from books from computer magazines or the instruction manuals which they get with the purchase of a PC or software In this example the title is positioned on top of the frame Title and text are entered as FrameTitle Zapf 1 StartFrame Coming back to the use of typefaces in electronic publishing many of the new t
344. using symbols is that you can redefine them depending on the situation So definesymbol yes Nem Yes creates a symbol that lets symbol yes expand into Yes Since nearly anything can be a symbol we can also say definesymbol yes mathematics star or even the already defined symbol x by saying definesymbol yes symbol star It may be clear that we can use a graphic as well def metabuttonsymbol 1 uniqueMPgraphic meta button type 1 definesymbol menu definesymbol menu definesymbol menu definesymbol menu definesymbol menu definesymbol menu definesymbol menu definesymbol menu definesymbol menu definesymbol menu a left metabuttonsymbol 101 right metabuttonsymbol 102 list metabuttonsymbol 103 index metabuttonsymbo1 104 person metabuttonsymbol 105 stop metabuttonsymbo1 106 info metabuttonsymbo1 107 down metabuttonsymbol 108 up metabuttonsymbol 109 print metabuttonsymbol 110 Symbol collections Since we have collected some nice buttons in a meTaPosT file already we can use a rather simple definition startuniqueMPgraphic meta button type size linecolor fillcolor if unknown context_butt input mp butt fi some_button MPvar type MPvar size MPvar linecolor MPvar fillcolor stopuniqueMPgraphic This lea
345. ve become more colorful so we need a way to consistently apply color to text as well as graphics In CONTEXT colors are called by name The next definitions demonstrate that we can define a color using different color models RGB or CMYK Depending on the configuration CONTEXT will convert one color system to the other RGB to CMYK or vice versa The full repertoire of color components that can be set is as follows definecolor color one r 1 g 2 b 3 definecolor color two c 4 m 5 y 6 k 7 definecolor color three s 8 The numbers are limited to the range 0 1 and represent percentages Black is represented by definecolor black 1 r 0 g 0 b 0 definecolor black 2 c 0 m 0 y 0 k 1 definecolor black 3 s 0 Predefined colors are passed to MeTAPOST graphics via the MPcolor First we define some colors def inecolor darkyellow 625 4 a CMYK color def inecolor darkred r 625 a RGB color definecolor darkgray s 625 a gray scale These are the colors we used in this document The next example uses two of them startuseMPgraphic color demo pickup pencircle scaled 1mm path p fullcircle xscaled 10cm yscaled icm fill p withcolor MPcolor darkgray draw p withcolor MPcolor darkred stopuseMPgraphic useMPgraphic color demo Communicating color Embedded graphite The previous example uses a pure RGB red shade combined
346. veral types of macros A primary macro is used to define your own operators For example primarydef p doublescaled s p xscaled s 2 yscaled s 2 enddef Once defined the doublescaled macro is implemented as in the following example draw somepath doublescaled 2cm withcolor red When this command is executed the macro is expanded Thus the actual content of this command becomes draw somepath xscaled icm yscaled 4cm withcolor red Macros e If in the definition of doublescaled we had added a semi colon after s 2 we could not have set the color because the semicolon ends the statement The draw expects a path so the macro can best return one A macro can take one or more arguments as in def drawrandomscaledpath expr p s draw p xscaled s 2 yscaled s 2 enddef When using this macro it is expected that you will pass it two parameters the first being a path the second a numeric scale factor drawrandomscaledpath fullsquare 3cm Sometimes we want to return a value from a macro In that case we must make sure that any calculations don t interfere with the expectations Consider vardef randomscaledpath expr p s numeric r r round 1 uniformdeviate 4 p xscaled s r yscaled s r enddef Because we want to use the same value of r twice we have to use an intermediate variable By using a vardef we hide everything but the l
347. verlays How is such a graphic defined In fact these graphics are a special case of the already present mechanism of including metarost graphics The circles are defined as follows NstartMPpositiongraphicimypos circle initialize_box MPpos MPvar self path p llxy lrxy urxy ulxy cycle pickup pencircle scaled ipt fill p withcolor 800white draw p withcolor 625yellow anchor_box MPanchor MPvar self stopMPpositiongraphic Drawing the lines is handled in a similar fashion startMPpositiongraphic mypos line path pa pb pab numeric na nb initialize_box MPpos MPvar from na pa llxy lrxy urxy ulxy cycle initialize_box MPpos MPvar to nb pb llxy lrxy urxy ulxy cycle if na nb pab center pa center pb pab pab cutbefore pab intersectionpoint pa Anchors and layers pab pab cutafter pab intersectionpoint pb pickup pencircle scaled ipt draw pab withcolor 625yellow anchor_box MPanchor MPvar from fi stopMPpositiongraphic The command startMPpositiongraphic defines a graphic in this example we have called it mypos circle The METAPOST macro initialize_box returns the characteristics of the box as identified by MPpos After this call the corners are available in 11xy 1rxy urxy and ulxy The center is defined by cxy and the path stored in pxy When we are
348. ves a few settings setupMPvariables meta button type 1 size 2 bodyfontsize fillcolor gray linecolor darkred These symbols are collected in table 7 4 and are called up with the CONTEXT commands like symbol menu left If needed we can collect these button symbols in a so called symbol set which permits us to instantly switch between sets with similar symbols I E E AKO v A B left right list index person stop info down print Table7 4 collection of button symbols Symbol collections Shapes symbols and buttons Symbol collections 8 Special effects Sometimes we want to go beyond mErRPOsT s native features Examples of such an extension are CMYK colors shading and transparency Although features like this should be used with care sometimes the doc uments look and feel can profit from it If you don t want the whole graphic but only a part of it clipping comes into play In addition to the standard clipping features we can use METRPOST fo provide a decent clipping path In this chapter we will uncover the details We will also introduce ways to include externally defined graphics and outline fonts We will demonstrate that within reasonable bounds you can manipulate such graphics 8 1 Shading In this section we introduce different kinds of shading Since does not support this feature directly we
349. w draws a path the 2111 macro fills one In order to be filled a path should be closed which is accomplished by the cycle primitive as we saw in constructing the unitsquare path pickup pencircle scaled 5cm fill unitsquare xscaled 8cm yscaled 1cm withcolor 625white path bb bboxmargin Opt bb bbox currentpicture draw bb withpen pencircle scaled 1pt withcolor 625red draw origin withpen pencircle scaled 5pt withcolor 625yellow This example demonstrates that when we fill the path the resulting graphic is smaller Where draw follows the center of a path 2111 stays inside the path A third alternative is the filldraw macro From the previous examples we would expect a bound ing box that matches the one of the drawn path Bounding boxes a jew pickup pencircle scaled 5 filldraw unitsquare xscaled 8cm yscaled 1cm withcolor 625white path bb bboxmargin Opt bb bbox currentpicture draw bb withpen pencircle scaled withcolor 625red draw origin withpen pencircle scaled 5pt withcolor 625yellow The resulting graphic has the bounding box of the fill Note how the path because itis stroked with a 5cm pen extends beyond the border of the previous bounding box The way this image shows up depends on the viewer settings you use to render the graphic For example in GHOSTVIEW if you disable clipping to the bounding box only the positive quadrant of the gra
350. w pdf scaled 3cm N metafun macro addbackground text addbackground withcolor 625 yellow metafun macro image text draw image draw fullcircle xscaled 4cm yscaled 1cm metapost macro Graphics D Literature There is undoubtly more literature about meTaPosT and the tools described in this document than is men tioned below More information on METRFONT and METAPOST can be found at the internet sites of the local TEX user groups When this document was written METAPOST was not used that widely Nowadays it is the natural companion to and more macros have been written The next list reflects the state when we started with METAFUN and for completeness only a few entries were added When the development of mMetarost was transfered from the original author to a larger team the maintaince of the manual also became more dynamic The relevant documents can be found in Knuth D E 1986 The Metafont book Reading MA Addison Wesley Hobby J D 1997 A User s Manual for Metapost Murray Hill NJ AT amp T Bell Laboratories Reading the book is not needed in order to work with metarost but it will give you a good Knuth D E 1986 The Reading MA Addison Wesley D 1 METAFONT and METRPOST TEX distributions and at CTAN D2 perspective in what atmosphere it evolved D 3 CONTEXT At the time the first version of this document was written the main
351. wEra POST yet vardef colorcircle expr size red green blue save r g b rr gg bb cc mm yy savebr bg gr gb save radius path r g b rr bb gg cc mm yy Color circles mro pair br bg gr gb numeric radius radius 3cm pickup pencircle scaled radius 20 r b fullcircle scaled radius shifted 0 radius 4 r r rotatedaround origin 15 drawarrow r withcolor red g g rotatedaround origin 135 drawarrow g withcolor green b b rotatedaround origin 255 drawarrow b withcolor blue br b intersectionpoint r draw b_r bg b intersectionpoint g draw b g reverse intersectionpoint r draw gr g_b reverse g intersectionpoint b draw g b bb b cutafter bb bb cutbefore b_g drawarrow bb gg g cutbefore b g gg gg cutafter drawarrow gg rr r cutbefore gr amp r cutafter b r drawarrow rr cc b cutbefore b r cc cc cutafter g b drawarrow br yy g cutbefore g r yy yy cutafter gb drawarrow rg mm r cutbefore g r amp r cutafter b r drawarrow gb bb gg rr reverse bb cycle gg bb rotatedaround origin 120 rr bb rotatedaround origin 240 cc mm cc reverse yy cycle yy cc rotatedaround origin 120 mm cc rotatedaround origin 240 fill fullcircle scaled radius withc
352. wing code demonstrates startusableMPgraphic bar vardef MusicBar expr width gap linewidth barwidth image interim linecap butt for i 1 upto 5 draw 0 0 width 0 shifted 0 i 1 gap withpen pencircle scaled linewidth endfor for i llcorner currentpicture ulcorner currentpicture lrcorner currentpicture urcorner currentpicture draw i withpen pencircle scaled barwidth endfor enddef stopusableMPgraphic We can define the sidebars a bit more efficient using two predefined subpaths for i leftboundary currentpicture rightboundary currentpicture We define a macro MusicBar that takes four arguments The first two determine the dimensions the last two concern the line widths Now watch how we can use this macro includeMPgraphic bar draw MusicBar 200pt 6pt ipt 2pt draw MusicBar 300pt 6pt ipt 2pt shifted 0 30pt p p As you can see in this example the bar is a picture that can be transformed shifted in our case However a close look at the macro teaches us that it does a couple of draws too This is possible because we wrap the whole in an image using the image macro This macro temporary saves the current picture and at the end puts the old currentpicture under the new one We wrap the whole in a vardef This means that the image is returned as if it was a variable Actually the last thing in a vardef should be a proper return value in our case a picture This also means
353. withpen pencircle scaled 2pt withcolor 625yellow Of course we can also use the more fancy features of METAFUN like transparency and shading loadfigure mycow mp number 1 scaled 35 numeric sh sh define linear shade 11 currentpicture urcorner currentpicture 625red 625yellow refill currentpicture withshade sh redraw currentpicture withpen pencircle scaled 2pt withcolor 5white Before we show a next trick we draw a few circles E N Changing colors fill fullcircle scaled 2cm withcolor yellow fill fullcircle scaled 2cm shifted 3cm 0 withcolor red The yellow and red color do not match the main document colors but this is no problem we can remap them without spoiling the original definition fill fullcircle scaled 2cm withcolor yellow fill fullcircle scaled 2cm shifted 3cm 0 withcolor red remapcolor yellow 625yellow remapcolor red 625red recolor currentpicture resetcolormap We can combine the inclusion technique with remapping colors This time using an artist impres sion of one of Hasselts Canals gracht in Dutch loadfigure gracht mp number 1 scaled 5 If you think that the sky is too bright in this picture and given that you also know which color is used you can fool the reader by remapping a few colors loadfigure gracht mp number 1 scaled 5 color skycolor Skycolor 0 8 0 90 1 0
354. wn here Take for instance a so called super ellipse 6 These graphics provide a lot of information In this picture the crosshair in the center is the origin and the dashed rectangle is the bounding box of the super ellipse The bounding box specifies the position of the graphic in relation to the origin as well as its width and height In the graphic on the right you can see the points that make up the closed path as well as the control points Each point has a number with the first point numbered zero Because the path is closed the first and last point coincide We ve used the commands and as path connecting directives In the next series of examples we will demonstrate a few more However before doing that we define a few points using the predefined z variables Welcome to MetaPosl Constructing paths 20 22 0 5cm 1 5cm zi 6 5cm 0 5cm z3 2 5cm 2 5cm 3 0cm 1 5cm Here z1 is a short way of saying x1 y1 When a z variable is called the corresponding x and y variables are available too Later we will discuss Metarost capability to deal with expressions which are expressed using an instead of In this case the expression related to 20 is expanded into 20 0 0 0 5cm 1 5cm But for this moment let s forget about their expressive nature and simply see them as points which we will now connect by straight line segments
355. wpointlabels q drawpath r drawpoints r drawpointlabels r pickup pencircle scaled 5mm draw point 2 25 of p withcolor 625red draw point 2 50cm on q withcolor 625yellow draw point 45 along withcolor 625white Beware the length of a path is the number of points minus one The shapes below are constructed from 5 points and a length of 4 If you want the length as dimension you should use arclength 0 b fo e 0 Y 1 1 1 4 4 4 We will now play a bit with simple lines With cutends you can indeed cut off the ends of a curve The specification is a dimension Welcome to MetaPasl Some extensions path p 4cm icm path q 5cm 0cm right 9cm icm drawpath p drawpoints p drawpath q drawpoints q p cutends 5cm q q cutends 5cm drawpathoptions withpen pencircle scaled 5pt withcolor 625yellow drawpointoptions withpen pencircle scaled 4pt withcolor 625red drawpath p drawpoints p drawpath q drawpoints resetdrawoptions 1 7 As with more operators cutends accepts a numeric or a pair Watch the subtle difference between the next and the previous use of cutends path p p 0cm 0 4cm 0 8cm 0 4cm 0 cycle drawpath p drawpoints p p p cutends 2cm 1cm drawpathoptions withpen pencircle scaled 5pt withcolor 625yellow drawpointoptions wit
356. x 2 ny 2 x 1 y 1 mp head clip externalfigure cow mps width 4cm A more advanced clip is demonstrated in figure 8 5 We added ruledhbox to demonstrate the dimensions of the resulting graphic Putting something in such a ruled box is often a quick way to test spacing Figure 8 5 A quarter circle applied to a cows head Although a clip path definition can contain any MeTAPOST command even graphics it must con tain at least one clipping path The first one encountered in the resulting graphic is used In the example we used a path that is built out of three subpaths 0 h w h down left 0 0 cycle Clipping We start in the top left corner and draw a straight line Next we draw a curve to the origin Di rectives like down and right force the curve in a certain direction With cycle we close the path Because we use this path as a clipping path we use clip instead of draw or 2111 Clipping as such is not limited to graphics Take for instance the text buffer startbuffer sample framed align middle width 4cm background screen frame off A METAPOST clip is not the same as a video clip although we can use METAPOST to produce a video clip stopbuffer We can call up such a buffer as if it were an external figure Figure 8 6 shows the result This time we use a different clip path startMPclip text clip clip currentpicture to fullcircle shifted 5 5 xscaled width yscaled
357. y of height depth and width but also of the crossing of a page boundary and the height and depth of lines In some cases your graphics may have to respond to layout characteristics like differences between odd and even pages Given that unique identifiers are used for anchor points in CONTEXT you can have access to all the information needed The concept and connected by an As with from declaring what to de with those In a previous section we saw that some hpos X 1 words were hpos X 2 circled and connected by an hpos X 3 arrow As with most things in CONTEXT marking these words is separated from declaring what to do with those words This paragraph is keyed 5 2 Anchors and layers In a previous section we saw that some most things in CONTEXT marking these words This paragraph is keyed in as in as We see three position anchors each marked by an identifier X 1 X 2 and X 3 Each of these anchors can be associated with a series of graphic operations Here we defined setMPpositiongraphic X 1 mypos arrow to X 2 setMPpositiongraphic X 2 mypos arrow to X 3 These examples clearly demonstrate that we cannot control to what extent graphics will cover text and vice versa A solution to this problem is using position overlays We can define such an overlay as follows startpositionoverlay backgraphics setMPpositiongraphic G 1 mypos
358. ypographers receive their knowledge and information about the rules of typography from books from computer magazines or the instruction manuals which they get with the purchase of a PC or software StopFrame The implementation is not that complicated and uses the frame commands that are built in CONTEXT Instead of letting draw the frame we use MeTAPOST which we also use for handling the title The graphic is defined as follows startuseMPgraphic FunnyFrame picture p numeric w h o p textext rt MPstring FunnyFrame w OverlayWidth h OverlayHeight o BodyFontSize p shifted 2o h ypart center p draw p drawoptions withpen pencircle scaled 1pt withcolor 625red draw 2o0 h 0 h 0 0 w 0 w h xpart urcorner p h draw boundingbox p setbounds currentpicture to unitsquare xyscaled w h stopuseMPgraphic Because the framed title is partly positioned outside the main frame and because the main frame will be combined with the text we need to set the boundingbox explicitly This is a way to create so called free figures where part of the figure lays beyond the area that is taken into account when positioning the graphic The shift shifted 20 h ypart center p ensures that the title is vertically centered over the top line of the main box The macros that use this graphic combine some techniques of defining macros using predefined CONTEXT classes and passing information t

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