LPFG user`s manual - Algorithmic Botany
Contents
1.2. ERO ERE 39 244 ise e au ue ene 39 24 2 Maternal filen ec oem euet aet 39 DAS 3 Surjace ilex cea noe begs Devs Dd tos E a amet 39 24 42 Funen set files e EE CE e Use 39 2457 Contour set aee nO TS eddie qoe eu a eds 39 3 450 e NE 39 4 APPENDIX HOW PRODUCTIONS ARE MATCHED eeeeeeee enean tn toon sna nene tatu 40 1 Introduction Ipfg is a plant modeling program Models are expressed using a formalism based on L systems the L C modeling language adds L system specific constructs to the C programming language 1 1 Hardware requirements Ipfg does not have any specific hardware requirements It uses OpenGL to generate images therefore a graphics card capable of accelerated 3D graphics with a display resolution of at least 1024x768 with a color depth of at least 24 bits is strongly recommended A mouse or equivalent pointing device is also required 1 2 Software requirements Ipfg runs under Microsoft Windows operating systems 95 98 Me NT4 2000 XP It requires a C compiler capable of generating Windows Dynamic Link Libraries DLLs Ipfg was originally developed and tested with Microsoft Visual C A version of pfg is also available for Linux 1 3 Installation Ipfg is distributed with L studio refer to the
3. When the statement decomposition is present in the L system it specifies that all the following rules are decomposition rules until the end of the source file or until a production interpretation statement is encountered The statement maximum depth specifies the maximum decomposition depth It must be placed in the global scope after the decomposition statement The syntax of the maximum depth statement is maximum depth expression The default maximum decomposition depth is 1 An L system may contain many decomposition sections but only one instance of the maximum depth statement is allowed it is applied to all decomposition rules in the program Decomposition rules can be recursive the module in the strict predecessor can appear in the successor For example decomposition maximum depth 6 length if length gt 0 produce 1 A age length 1 Note decomposition is internally implemented by a recursive call to a function If the maximum depth 15 a very large number the thread stack might overflow causing Ipfg to crash 2 2 7 Interpretation rules Interpretation rules are syntactically very similar to decomposition rules To specify interpretation rules the interpretation statement must be given Like decomposition rules interpretation rules must have exactly one module in the strict predecessor and must be context free A maximum depth definition may be given after the interpretatio
4. orientation The float xscale surface is scaled independently along the X Y and Z axes float yscale by xscale yscale and zscale respectively float zscale BSurface Draws the predefined B spline surface identified by the Cunt identifier id at the current location and orientation The float scale surface is uniformly scaled by the factor scale B spline surfaces are specified in the view file with the command bsurface see below SetUPrecision Sets the drawing precision of bicubic surfaces in the U float precsn direction If set to an invalid value such as zero the U precision resets to the surface default defined in the view file SetVPrecision Sets the drawing precision of bicubic surfaces in the V float precsn direction If set to an invalid value the V precision resets to the surface default InitSurface Initializes the L system defined surface with id id PS int id Currently there is only one surface allowed so the parameter is ignored SurfacePoint Sets the p q control point with 0 lt p q lt 4 of the L PC int id system defined surface with id id to the current turtle int p position The first parameter is ignored int q DrawSurface Draws the L system defined surface with id id PD int id parameter 1s currently ignored DSurface Draws the given SurfaceObj See the section on SurfaceObj s Dynamic Surfaces above Drawing gener
5. q starts pfg in quiet mode All messages including warnings and errors suppressed The only mandatory item is the L system file Command line parameters can appear in any order All the input file types are recognized based on their extension If no colormap file or material file is specified then default colormap is used 1 5 User interface 1 5 1 Multiple views More than one output window or view can be opened within the main Ipfg window The views can be opened by the user using a command from the popup menu or by calling functions from the L system The user is free to open and close views at will however when the last view is closed by the user or from the L system Ipfg will exit 1 5 2 View manipulation e Rotation pfg uses XY rotation interface based on the continuous XY rotation The model is rotated around the Y axis when the mouse is moved horizontally and around the X axis when the mouse is moved vertically To start rotating hold the left mouse button e Roll to roll the model around the Z axis hold Shift middle mouse button Moving the mouse to the right rotates the model clockwise moving the mouse to the left rotates the model counter clockwise Zoom to zoom hold Ctrl left mouse button or the middle mouse button Moving the mouse up zooms in moving down zooms out Pan to pan hold Shift left mouse button e Change frustum angle hold Ctrl middle mouse button Movin
6. roll Reset gt Frustum Resets frustum not implemented yet Show axes Turns on or off display of coordinate system axes in the lower left corner Output gt BMP Creates image file filename bmp containing the current state of the window where filename is the name of the L system file Output gt Rayshade Creates a rayshade file Output gt POV Ray Creates a POV ray file Output gt Postscript Creates a postscript file filename ps where filename is the name of the L system file All modules F are drawn as lines even if line style is set to cylinder If line style is polygon then modules F are drawn as lines of properly scaled width The only other modules supported are Circle and 0 No other modules are visualized Output gt Obj Creates output file in the Alias Wavefront obj format Output gt View Creates a file called viewid vw where vw is the numeric id of the current view window The file contains a single view command as used in the view file see section 3 2 describing the current view parameters View gt view name Opens the specified view window View gt Save arrangement Creates a file called winparams cfg This file contains a series of window commands as used in the view file see section 3 2 one for every active view with their current arrangement 2 L C modeling language L system input files to pf
7. the fset file is named 1 then the following macro is defined define Funcl 1 Consequently it is possible to call func using the identifier Funci instead of the integer literal 1 float y func Funcl 0 5 float curveX int id float t float curveY int id float t float curveZ int id float t V2f curveXY int id float t curveXYZ int id float t These functions return the coordinates of the curve defined in a contour set file id is the number of the curve and t is the arc length parameter When calling the pre processor pfg will define numerical values for the names of the curves just as for functions see above void curveScale int id float x float y float z Scales the curve identified by id by the factors x y and z void curveSetPoint int id int p float x float y float z Assigns the pth control point of curve id the position x y z After this function is used the curve must be recalculated by a call to void curveRecalculate int id in order for the curveX Y Z functions to return the proper values void curveReset int id Resets the curve to the state defined in the cset file The file is not re read 2 3 6 Dynamic surfaces LPFG makes it possible to create and use dynamic surfaces Dynamic surfaces are single patch Bezier surfaces that can be manipulated from within the L system They are 26 useful for example when creating an animation wi
8. the second production will be tried following the usual application order for L system productions The second production will only be applied if the first parameter is greater or equal to 10 2 2 6 2 1 Alternative successors It is important to note that a produce statement may be found anywhere in the production body where a C statement is valid and causes the production to be applied with the given successor Just as it is possible in C to have alternative return values it is possible in L C to choose between alternative successors length if lt 10 produce A aget 1 length dl else produce B length In this single production both productions shown in the last section have been combined into one If the first parameter is less than 10 the first successor will be produced otherwise the second successor will be produced 2 2 6 2 2 Empty successor A produce statement may be issued without a sequence of modules produce If this statement is reached in executing the production body the production will be applied with an empty successor the strict predecessor will be removed from the string and will not be replaced Note the difference between ending with a return statement 16 which case the production will not be applied and an empty produce statement in which case the production is applied but produces nothing 2 2 6 2 3 The nproduce statement It is sometimes useful
9. to build a production s successor incrementally The nproduce statement specifies part of a successor but critically does not end the production It syntax is like that of the produce statement nproduce module_list The nproduce statement adds the listed modules to the currently defined successor but does not end execution of the production A subsequence produce statement will add its own argument to the successor then produce that successor If the production body ends without a produce statement the production is not applied and the partial successor is ignored For instance A age length for int i 0 i lt age itt nproduce B produce 1 length An empty produce statement adds no more modules to the successor but will still produce the successor specified by nproduce statements 2 2 6 3 Decomposition rules While productions specify how a structure evolves over time decomposition rules specify how a structure is composed of substructures After the axiom and every derivation step a decomposition step is performed Decomposition is performed as long as the string does not contain any modules that can be further decomposed or the maximum decomposition depth is reached Syntactically decomposition rules are very similar to regular productions except for the following differences e only one module is allowed in the strict predecessor and e decomposition rules are always context free 17
10. wireframe or shaded Default is filled light command command Each command must be one of the following y z origin of point light source y z vector of directional source g bambient g bambient b specular x y z e c spotlight with the direction x y z exponent e cutoff angle c T c 1 qattenuation factors Up to 8 lights can be specified 8 is the minimum number of lights that must be supported according to the OpenGL specifications O Pao HH HX X contour sides sides Specifies the number of sides that will be drawn on generalized cylinders This command affects all generalized cylinders in the model however it is overridden by either the ContourSides module or the contour specific samples parameter Other commands surface filename scale s div t div txid Declares a predefined Bezier surface The surface command can be used with 1 2 4 or 5 parameters The required parameter filename is the filename of a surface s file scale which defaults to 1 is a file specific scaling parameter which is multiplied by the scaling parameter specified in the Surface module to produce the total scaling factor s div and t div specify the number of subdivisions to draw along the s and t axes txid if present specifies the identifier of the texture associated with the surface See the description of the module Surface in Predefined modules Note this command may be dropped in a f
11. 2 GetLeft float x float y float z Queries the current turtle left vector L X Y Z GetUp float x float y float z Queries the current turtle up vector 2 U X Y Z En float zal lt Communication modules used to send and receive environmental information There are different modules for different numbers of parameters El float E2 float float E3 float float float and so on MouseIns When the user holds Ctrl and Shift and left clicks on a module in the simulator window the MouseIns module is inserted immediately before the clicked on module in the string MouseInsPos float xr float yr When the user holds Ctrl and Alt and left clicks on a module in the simulator window the MouseInsPos module is inserted immediately before the clicked on module in the string The parameters give the relative position of the mouse on the screen while clicking xr is 0 at the left edge of the screen increasing to 1 and the right edge yr is O at the top of the screen increasing to 1 at the bottom Miscellaneous Label Text str Prints the string str in the drawing window at the current L str turtle location Text is a datatype defined lintrfc hasconst char 3 Other input files 3 1 Animation parameters file Command Comments first frame n Derivation step to be interpreted as
12. 2 3 Predefined functions There are many functions and structures predefined by pfg for controlling the derivation of the L system accessing the system and for general convenience 2 3 1 Vector structures Ipfg provides four structures that represent vectors The structures are truc flo truc flo truc u 8 8 8 8 t V2f at x t V3f at x t V2d t V3d double x Ys 2 33 Vin 2220 FS These structures are used as parameters for some predefined modules They can also be used in the user s code in the L system Additionally if the preprocessor symbol NOAUTOOVERLOAD is not defined before include lt lpfgall h gt these structures receive additional functionality operators for addition subtraction of two structures of 22 the same type unary negation multiplication and division of vector by a scalar dot product and assignment operators and In addition cross product is defined on v3f and v3d with operator V2t a 1 5 2 0 b Q 0 5 V2f c 2 5 b float x b Two further methods are defined f Length returns the vector s length as float or double depending on the structure void Normalize normalizes the vector This function s behaviour is undefined if the vector s Length 1s zero void Set x y sets the x and y components of a v2f or 24 v3f and v3d have a corresponding method set x y z Refer to th
13. D mE 12 2 2 4 Igp ore and considern iadasngn WR e PE a Ms 12 2 2 0 Control Statements a v nere erased et eec ee nti en eret fe uites RES 12 22 6 Producton setae i ee RR C e tae red e ey ree RDUM 13 2 2 7 3nt rpret tion rules iiie Ree rp RB ele gh a ee Revives atone 18 2 2 8 Production blocks RR Weiden 19 2 2 0 TeSys lem ext nsiohy sie eec eee pe etg eter te ee step nece epe cet ts 20 2 3 PREDEFINED FUNCTIONS ecciccieo tierce entier nite enin o ait e reed 22 Zu Vector SUTUCTUTES uS o rp pe De ise Revive 22 2 3 2 Controlling L system derivation eese i nennen rennen 23 2 53 Manipulating VIEWS s nee em p n e ee er ue gene 24 ZRA Exe hal Q6 COSS es s tee eei eee ue to ete 25 2 3 9 Curves and functions isse re a ear e RESUME E RR Ute Mee AERE 25 2 56 Dynamic Surfaces uoa e a Ree E CREE Se ceed ree e etd cea 26 2 3 7 Other predefined functions eet et eer Pe 29 24 PREDEFINED MODULES tue desee 29 Table of contents OTHER INPUT 35 3 1 ANIMATION PARAMETERS FILE enne nenenetene tren 35 32 DRAW VIEW PARAMETERS FILE eeeeeeee teens trennt 36 3 3 ENVIRONMENT PARAMETERS FILE n elitu aeo p RENE 38 3 4 MISCELLANEOUS INPUT FILES
14. L studio documentation for installation instructions 1 4 Running Ipfg Ipfg is designed to be used as a single element of a modeling environment such as L studio or Vlab Usually it will be invoked by the environment rather than directly by the user 1 4 1 Command line options The following command line options are supported by Ipfg lpfg a d b cn wnb wnm wr w h wpr x yl wp x y w w h out filename lp path c dll filename dll colormap file map material file mat animation file a functionset_file fset drawparameters_file dr viewparameters_file v contourset_file cset environmentfile e Lsystemfile l wnb no borders The Ipfg window is created without borders or title bar Also the output console window is not shown Used for demonstration purposes wnm no message window The output console window is not shown w wandh specify the window s size in pixels wr specify relative window size w and h parameters are numbers between 0 and 1 and specify the relative size of the Ipfg window with respect to the screen wp x and y specify window s top left corner position in pixels relative to the top left corner of the screen wpr specify relative window position x and y parameters specify the position of the top left corner relative to the top left corner of the screen out specifies the output string filename 1p path is the pat
15. LPFG user s manual Radek Karwowski and Brendan Lane July 4 2006 TABLE OF CONTENTS 2 1 INTRODUCTION Pere 4 1 1 HARDWARE REQUIREMENTS E pe pe eie atre 4 1 2 SOFTWARE REOUIREMENT Srecna he 4 1 3 een 4 1 4 RUNNING TPE Gi ER 4 141 ES Rent 4 1 5 USERINTERFACE ote er AR AD n D TR RR A D TR I OONN R 6 1541 Multiple viewssi ioca rH RYE REIR des 6 1 5222 View manipulation i dts E EEE EEEE res 6 13 3 Menu Commands i t FUERTES REF ORTA 7 2 THE L C MODELING LANGUAGE e eeeeeeee teen seen ense ta senten sesto seta suse ta sensn stata sen tus 9 2 1 L SYSTEMCEIBE Rent p bee RIED NODI emet e ee 9 Z IT Mandatory elements uo galette e E E 9 DAD Bcludefileszi 9 22 LTCELANGUAGECONSTRUCTS ete 10 2 24 10 2 2 2 Module declarations eee eese eese eene eene tenete entente entente entente 11 pP SU
16. RE The following interpretation rule could be used to render the leaf by interpolating between the two predefined surfaces interpretation Leaf age SurfaceObj young GetSurface L YOUNG SurfaceObj mature GetSurface L MATURE SurfaceObj leaf surface young 1 produce DSurface leaf surface 2 3 7 Other predefined functions float ran float range mature age Generates a pseudorandom number uniformly distributed in the range 0 range void sran long seed Seeds the pseudorandom number generator used by ran You can use sran in the Start control block for instance to ensure that every run is identical even after rewinding void SeedGillespie long seed Seeds the pseudorandom number generator used by the Gillespie engine You can use SeedGillespie in the start control block for instance to ensure that every run 18 identical even after rewinding 2 4 Predefined modules The following table lists all of the predefined modules Module Description Equivalent in cpfg 29 Modeling branching structures SB Starts a new branch by pushing the current state of the turtle onto the turtle stack EB Ends a branch by popping the state of the turtle from the 1 turtle stack Cut Cuts the remainder of the current branch If the derivation direction is from left to right forward then when this module is detect
17. aceObj Get int id const 21 set explicitly coordinates of a control point use one of the Set methods void SurfaceObj Set int id const float arr void SurfaceObj Set int id const V3f amp v The scalar multiplication operator allows the scaling of the surface object by a real number const SurfaceObj amp SurfaceObj operator float To scale the surface non uniformly by different factor in every direction make the scaling factors coordinates of a V3f vector and use the method void SurfaceObj Scale V3f scale The addition operator combines two surfaces by pointwise adding their control points friend SurfaceObj operator const SurfaceObj amp 1 const SurfaceObj amp r The addition operator along with the scalar multiplication operator defines a vector space over Bezier patches This can be used to interpolate between surfaces For example SurfaceObj 51 s2 float weight SurfaceObj interpolated sl weight sl 1 weight Drawing dynamic surfaces To draw a dynamic surface use the DSurface module module DSurface SurfaceObj Example Let us consider a developmental model of a plant In the model individual leaves are represented by module L float The parameter specifies the age of the leaf The values of age in range 0 11 28 Let us also assume that the Ipfg model contains two one patch surfaces commands surface in the view file named L YOUNG and L MATU
18. ach module A production definition has two parts the predecessor declaring which module is being changed the strict predecessor and what context it must be found in and the production body declaring how it changes in the next derivation step predecessor production body 2 2 6 1 The predecessor The predecessor of a production contains at a minimum the strict predecessor This is the module or sequence of modules which if the production is applied will be replaced 13 by new modules at the next derivation step Valid productions containing only strict predecessor include F x feat A age length B 3 Any parameters must be listed and given unique names even if they are not used in the production body Also unlike the axiom and produce statements a module with no parameters must be followed by parentheses In addition to the strict predecessor a production may also list a context to its left or right or both These contexts must also be matched within the string for the production to be applied although only the strict predecessor will be replaced The left context 15 set to the left of the strict predecessor and separated by a the right predecessor is to the right separated by gt Some examples include A ageL lengthL lt A age length gt lengthR 1 B B gt B BO Note that again all parameters must be given unique names Fina
19. alized cylinders CurrentContour Sets the contour specified by id as the current contour for id int id generalized cylinders If id equal to 0 is specified then the default contour circle is used StartGC Starts a generalized cylinder at the current turtle position Gs 33 PointGC Specifies a control point on the central line of the generalized Gc n but li not exactly EndGC Ends a generalized cylinder Ge CurrentContours Sets the current contour to be an interpolated contour int id1 between 141 and id2 with blending coefficient blend At Int 1d2 blend 0 the contour is id1 at blend 1 the contour is float blend id2 ScaleContour Scales the contour independently by p left and up float p float q ContourSides Specifies how many sides generalized cylinders will be int sides drawn with If this module is interpreted outside a generalized cylinder that is before StartGC and after EndGC if any then it affects all subsequent generalized cylinders If it is interpreted within a generalized cylinder it is ignored CurrentTexture Specifies which texture should be used to texture map int txtid generalized cylinders Calling this function with txtid 0 will turn off texture mapping of generalized cylinders TextureVCoeff Sets the texture s v coordinate scaling fa
20. be mixed with groups For example interpretation group 0 vgroup 0 Interpretation vgroup 1 Interpretation group 1 Interpretation vgroup 0 Interpretation rules rules rules rules 2 2 8 Production blocks here here here here belong to belong to belong to belong to group 0 group 0 group 1 group 1 vgroup 0 vgroup 1 vgroup 1 vgroup 0 Nf Ny It is possible to specify regular productions after decomposition and interpretation rules To specify regular productions use the production statement This possibility leads to another way to organize models Instead of dividing the model into 19 production decomposition interpretation sections all rules that apply to one type of module can be grouped together For example production decomposition interpretation A production BO gt AQ decomposition Be fo ae 2 2 9 L systems extensions 2 2 9 1 Ring L systems A ring L system provides an alternate topology for the L system string The derivation is performed as if the last module in the string and the first module in the string are adjacent so that the string forms a ring Productions which are applied to the beginning of the string have their left contexts matched against the end of the string and productions which are applied to the end of the string have their right cont
21. cess of determining the applicable production is called production matching For every module in the string productions are checked for matching The productions are checked in the order in which they are specified in the L system For a production to match all three components of the predecessor left context strict predecessor and right context must match The rules for matching each of these components are different This is because the L system string is a means of representing branching structures and symmetric operations on the string do not in general correspond to symmetric operations on the branching structure This section contains a detailed explanation of rules that control the process of production matching The notation used here utilizes symbols and to denote beginning of branch and end of branch modules sB and EB in Ipfg When the strict predecessor is compared with the contents of the string in the current position in order for it to match the modules in the strict predecessor have to match exactly the modules in the string When matching the right context and a module in the context is not the same as module in the string the following rules apply e Ifa module in the string is and the module expected is not then the branch is skipped This rule reflects the fact that modules may be topologically adjacent even though in the string representation of the structure the two modules may be separated by modules repre
22. cifies the way the frames are numbered when the Recording menu command is checked If consecutive the default each file s number reflects the frame number not the derivation step If this parameter is set to stepno the number in the filename is the derivation step number 3 2 Draw view parameters file Drawing and viewing parameters are stored in the view file This file can have extension v or dr The view file is preprocessed by the C preprocessor therefore the use of comments both C style and C style as well as defines ifs and all other standard preprocessor directives are allowed The commands are interpreted in the order in which they appear in the file If there are two or more commands that specify the same parameter the last one takes precedence This does not apply to commands that specify new set of parameters every time they appear e g lights tropisms Every command must be contained on a single line Command Comments Setting the view projection Default is parallel parallel perspective scale factor s scale s s specifies the size of the final image on the screen 1 0 corresponds to full size Default is 0 9 Either scale or scale factor may be used they are equivalent min zoom v v specifies the minimum value of zooming factor see Interactive view manipulation Default is 0 05 max zoom v v specifies the maximum value of zoom
23. ctor If v 1 then float v when the turtle moves forward by one unit the generalized cylinder will be textured by the entire texture If for instance you want to texture a cylinder 10 units long then setting the v scaling factor to 0 1 will map the texture exactly onto the cylinder If the texture s v coordinate exceeds one then the texture wraps sets v to 0 Tropism SetElasticity Sets the elasticity parameter of tropism id to v Ts int id float v IncElasticity Increments the elasticity parameter of tropism id by the Ti int id elasticity step parameter of the tropism DecElasticity Decrements the elasticity parameter of tropism id by the int id elasticity step parameter of the tropism Simple tropism Elasticity Sets the elasticity to v float v underscore Query and communication modules GetPos Queries the current turtle position If any query module is 2 float x float y float z present in the predecessor of any production in the L system a special interpretation step is performed after each generate step when productions are applied The string is interpreted even if no drawing occurs During the interpretation the three parameters of the module are set to the x y and z coordinates of the current turtle position 34 GetHead float x float y float z Queries the current turtle heading vector
24. d Same as LineTo2f 2 p LineRel3f Draws a line from the current turtle position to the point p2 turtle position p After the interpretation of the module the turtle position is equal to p2 Heading left and up vectors are not changed If the length of vector p is less than e the module is ignored V2d p LineRel3d Same as LineRel3f V3d p LineRel2f Same as LineRe13f except that z coordinate is assumed V2f p to be 0 LineRel2d Same as LineRel2f Turtle rotations float a Left Turns left by angle a around the U axis a float a Right Turns right by angle a around the U axis a float a Up float a Pitches up by angle around the L axis a Down Pitches down by angle a around the L axis amp a float a RollL Rolls left by angle around the H axis a float a RollR Rolls right by angle around the H axis a TurnAround Turns around 180 degrees around the U axis This is 31 equivalent to Left 180 or Right 180 It does not roll or pitch the turtle SetHead float hx float hy float hz float ux float uy float uz Sets the heading vector of the turtle to hx hy hz and the up vector to ux uy uz The left vector is set to the cross product of the new H and U The values do not need to specify normalized vectors The modu
25. e file 1intrfc h in the 1pfg include directory to see full definition of these structures 2 3 2 Controlling L system derivation void Forward This function specifies that the derivation of the string should be performed forward from left to right This is the default void Backward This function specified that the derivation of the string should be performed backward from right to left Forward and Backward can be used anywhere in the code where it is legal to call a function They take effect on the next derivation step In particular if called in the StartEach statement they affect the immediately succeeding derivation step bool IsForward Returns the last derivation direction as set by Forward Or Backward Note this function returns a variable set by Forward and Backward Consequently it may not reflect the current derivation direction if it is changed during a derivation step 23 void Environment void NoEnvironment These functions specify whether or not the interpretation for environment step should be performed after the current derivation step NoEnvironment turns the environment off unconditionally void UseGroup int Specifies current group of productions that should be used See Table L systems int CurrentGroup Returns the number of the current group See Table L systems void DisplayFrame Displays a frame of the animation at the current derivation step when disp
26. eading left and up vectors are not changed MoveRel3d V3d p Same as MoveRel3f MoveRel2f V2f p Same as MoveRe13f except that z coordinate is assumed to be 0 MoveRel2d V2d p Same as MoveRel2f Affine geometry support Line3f pl Draws a line from the point p1 to the point p2 After the interpretation of the module the turtle position 1s equal to 30 V3f p2 p2 Heading left and up vectors are not changed If the distance between 1 and p2 is less than e a constant set to 10 the module is ignored Line3d V3d p1l V3d p2 Same as Line3f Line2f V2f pl V2f p2 Same as Line3f except that the z coordinate is assumed to be 0 Line2d V2d p1 V2d p2 Same as Line2f LineTo float x float y float z Draws a line from the turtle s current position to the point 2 LineTo3f p Draws a line from the current turtle position to the point p After the interpretation of the module the turtle position is equal to p Heading left and up vectors are not changed If the distance from the current position to p is less than e the module is ignored p LineTo3d Same as LineTo3f V3d p LineTo2f Same as LineTo3f except that z coordinate is assumed to 2 be 0 LineTo2
27. ed in the string during a derivation it and all following modules up to the closest unmatched EB module are ignored for derivation purposes If no unmatched EB module can be found symbols are ignored until the end of the string This symbol has no effect if the derivation direction is from right to left backward Changing position and drawing Turtle commands F float d Moves forward a step of length d and draws a line segment F d from the original position to the new position of the turtle If the polygon flag is on see modules SP PP and EP the final position is recorded as a vertex of the current polygon f float d Moves forward a step of length d No line is drawn If the F d polygon flag is on the final position is recorded as a vertex of the current polygon G float d Same as F except that it does not create polygon vertices G d g float d Same as f except that it does not create polygon vertices g d MoveTo Sets the turtle s position to x y 2 GM 2 float x float y float z MoveTo3f Moves the turtle to point p QM p MoveTo3d Same as MoveTo3f p MoveTo2f Moves the turtle to point p z coordinate is assumed to V2f p be 0 MoveTo2d Same as MoveTo2f 2 p MoveRel3f p Move the turtle to the point p2 turtle position p The h
28. exts matched against the beginning of the string For example Axiom A A lt A gt A produce B will yield the string B and Axiom A C lt A gt B produce D will yield the string BCD To specify a ring L system include the statement ring L system value where value 1s some nonzero value or an expression returning a nonzero value 2 2 9 2 Groups of productions It is possible to specify alternate groups of productions and switch between them when generating the model By default all productions decompositions and interpretation rules belong to the default group numbered 0 To specify productions for another group use the group statement 20 group number where number is an integer constant You can switch between groups any number of times The statement endgroup is equivalent to group 0 it ends the definition of the current group and returns to defining the default group When pfg is started the default group of productions is used The function void UseGroup int grpid changes which group of productions is currently in use it can be called at any time but will only take effect on the next derivation step The default group has a special property if no production in the current group can be applied to a symbol the productions in the default group will be tried even if it is not the current group 2 2 9 3 Interaction with the model Lpfg makes it possible to i
29. f f f verbose on off Verbose mode generates additional information about the details of the communication 38 3 4 Miscellaneous input files All of these file formats are described in the CPFG User s Manual 3 4 1 Colourmap file Specifies 256 colours Colourmap mode is used to create schematic images See also material file 3 4 2 Material file Specifies 256 materials Materials are specified by the following components ambient colof diffuse color specular color emission color specular exponent and transparency See the OpenGL documentation for further explanation Material mode is used to create realistic images 3 4 3 Surface file Specifies surfaces composed of one or more B zier patches 3 4 4 Function set file Specifies functions of one variable The functions are defined as B spline curves constrained in such a way that they assign exactly one y to every x in the normalized function domain 0 1 3 4 5 Contour set file Specifies contours defined as planar B spline curves The curves are considered as cross sections of generalized cylinders 3 4 6 Textures Currently the only supported format of textures is SGI RGB Textures in the RGB format may contain Alpha transparency channel 39 4 Appendix How productions are matched When rewriting the string it is necessary to determine which production must be applied to each module in the string The pro
30. g the mouse up increases the angle moving down decreases the angle This operation has effect only in perspective projection mode 1 5 3 Menu commands To display the menu click the right mouse button inside the pfg window Step Ctrl F Step Ctrl F Run Ctrl R Run Ctrl R Forever Ctrl V Forever Ctrl Stop Ctrl S Stop Ctrl S Rewind Chl Rewind Ctra Don t animate Don t animate Restore view Restore view Rotation Reset gt Show axis Zoom Show axis BMP Roll Exit Frustum Exit E E POV Ray Postscript Figure 1 Lpfg menu Advances simulation to the next step This may correspond to Step more than one derivation step if parameter step in the animate file is present and specifies a value greater than 1 Run Starts or resumes the animation Forever Starts or resumes the animation After the last frame is reached the animation returns to the first frame and continues Stop Stops the animation Rewind Resets the animation to the first frame Don t animate Stops the animation and generates the image in the still mode performs the number of derivation steps as specified in the derivation length statement Restore view Resets rotation zoom pan frustum and roll to the default values Reset gt Rotation Resets rotation Reset gt Zoom Resets zoom Reset gt Pan Resets pan Reset gt Roll Resets
31. g use a new L system based modeling language L C It is a declarative language which combines L system constructs notably modules and productions with the general purpose programming language C L system constructs have syntax which is similar to the traditional notation of L systems used for instance in cpfg however this syntax is also not too different from that of C The principle advantage of this hybrid approach is that the expressive power of C can be used in L C programs experience has shown that developing complex models is substantially easier in L C than in traditional L system notation 2 1 L system file A typical L system program file has the following format finclude lt lpfgall h gt derivation length declarations of data structures declarations of functions module declarations derivation length n axiom module list productions All elements of a program can appear in any order except for the following restrictions 1 all elements referred to in a statement must be declared beforehand Types used as parameters of a module must be declared before the module is declared Modules that appear in an ignore or consider statement must be declared beforehand 2 Productions are matched in the order in which they are declared 2 1 1 Mandatory elements Every L system must include the statements derivation length and axiom 2 1 2 Include files The first line in the L system is
32. h to be used instead of LPFGPATH environment variable c compile the L system to the file 1sys d11 only do not run the simulation dll causes Ipfg not to generate 1Sys d11 but instead use DLL filename dll There is no translation of L C to C and the C compiler is not invoked c and d11 are useful when a simulation is run many times for instance from a batch file and the L system doesn t change but some other input file does cn check for numerical errors in the arguments of turtle movement modules When this option is included Ipfg checks that the arguments to modules like F and Right are valid numbers It is useful to track down division by zero errors and similar numerical mistakes in your models a starts Ipfg in animate mode first frame as specified in the animation file steps are performed as opposed to derivation length starts in debug mode some information about the execution of the program is sent to the standard output This mode is intended to be used by the developers of Ipfg b starts in batch mode no window is created The simulation is performed and the final contents of the string is stored in the file specified by the out option Only module names are stored in the file This mode cannot be combined with the switch s starts Ipfg in silent mode currently no effect v starts Ipfg in verbose mode displays additional information warning messages
33. ing factor see Interactive view manipulation Default is 50 line style style style must be one of the following pixel polygon or cylinder Default is pixel front distance x x specifies the distance to the front clipping plane 36 back distance x x specifies the distance to the back clipping plane Defaults to off If on the L system string is regenerated the simulator rewinds to the axiom and performs derivations again every time the view changes through rotation zoom or pan If triggered the string is regenerated after the user completes each view change after the user releases the mouse button triggered is currently the same as on regenerate view on off triggered view id rotx roty roll scale panx pany panz Defines the view transform to be used for the view window with id id window name left width height top Declares that the window with the given name should be placed with its top left corner at relative position left top within the main Ipfg window with relative width and height width and height The views will be numbered in the order in which they appear in the view file and the name name will be defined as the view number so that the L system can contain commands like UseView Plant vgroup Graph Rendering parameters z buffer on off Default is of f render mod mode Mode must be one of the following filled
34. lay on request is on in the animation file If display on request is of f this function has no effect void Stop Stops the simulation The End statement is executed after the current derivation step 2 3 3 Manipulating views To manipulate multiple views use the following functions void UseView int vid opens or activates view identified by vid void CloseView int vid closes the view identified by vid If the view is not open a warning message will be printed The L system can also access some of the current view parameters float vvXmin int id float vvYmin int id float vvZmin int id float vvXmax int id float vvYmax int id float vvZmax int id return the coordinates of bounding box of view number id float vvScale int id returns the current projection scaling factor of view number id 24 2 3 4 External access void Printf const char This function is similar to the standard C function printf Its use is recommended over the printf for the following reasons Output generated by printf is not stored in the 1p g 10g file e In the future releases pfg might not be connected to any console but instead provide its own output window like cpfg s message log In that case output of printf would not be visible anywhere void Run const char cmnd This function works like standard C system function except that it does not wait for the called process to terminate It is equivalent
35. le is ignored if any of the following is true a hx hy hz specify vector of length less than b ux uy uz specify a vector of length less than c Length of the cross product of new H and U is less than e GR hx hy hz ux uy uz RollToVert Rolls the turtle around the H axis so that H and U line in a v common vertical plane with U closer to up than down Changing turtle parameters IncColor Increases the current colour index or material index by one DecColor Decreases the current colour index or material index by one i SetColor Sets the current colour index or material index to n If n is n int n less than 1 or greater than 255 the module is ignored n SetWidth Sets the current line width to v If lt 0 the module is float v ignored n Drawing circles and spheres Circle Draws a circle in the HL plane centered at the current turtle 8o d float r position and with radius r The number of sides in the approximation is controlled by the contour sides parameter in the view file and the ContourSides module as for generalized cylinders Sphere Draws a sphere of radius r at the current turtle position d float r CircleO0 Draws a circle of diameter equal to the current line width in Go the HL plane SphereO0 Draws a sphere of diameter equal to the current line width CircleFront Draws a circle
36. lly pfg executes the production body This is a block which may contain any valid C statement In the production body the names given to the module parameters in the predecessor act akin to function parameters in a C function Normally the production body will end with a produce statement The produce statement ends execution of the production body like a return statement in a C function and tells pfg what the successor is Its syntax is produce module string where the module string is a sequence of modules For instance produce A newAge newLength produce A x length 12 B As with the axiom if a module has no parameters the parentheses may be omitted produce B A x length 12 B In general it is possible for a production to end in one of two ways First a produce statement may be reached In this case the production is applied with the given successor Second the production body may end execution in some other way by reaching the end of the block or by a return statement In this case the production is considered not applied and Ipfg will continue to look for a production that does apply to the predecessor For instance A age length 15 if age lt 10 produce A aget 1 length dl length if age gt 10 produce B length The first production will only be applied if the first parameter of the module A is less than 10 otherwise it will not be applied and
37. lly a production may list either a right or left new context The new context is an L system construct new to Ipfg It lets you take advantage of the fact that the actual computation of L system derivations happens sequentially from one end of the string to the other to transfer information from end to end in a single derivation step Normally the direction of derivation is from left to right forward the statements Forward and Backward let you control this derivation direction If the derivation direction is from left to right the new left context can be used if the derivation direction is from right to left the new right context can be used These new contexts are set off from the strict predecessor by a lt lt for left context or gt gt for right context For example the production B lt lt D ss 14 will match if the module B exists in the new left context of the module D The new and old contexts can be combined as in A age length lt B gt gt B Tena which matches an A x y in the old left context and a in the new right context Finally note that a new context production will never match if the derivation is going in the wrong direction a new right context will not match if the direction is left to right forward and a new left context will not match if the direction is right to left backward 2 2 6 2 Production body If a production predecessor is matched successfu
38. n statement As with decomposition rules there may be only one maximum depth definition which applies to all of the interpretation rules in the program The default maximum depthis 1 Interpretation rules are equivalent to homomorphisms in cpfg They are executed only during the interpretation of the string Modules produced by interpretation rules are 18 not inserted into the string used in the next derivation step they are used as commands for the turtle when interpreting the string The interpretation step is performed in the following cases 1 2 3 4 When redrawing the model in the window When generating output file rayshade POVray postscript When calculating the view volume After axiom and each derivation step if any of the productions predecessors contain query or communication modules Interpretation rules can be helpful in properly expressing visual models They are especially useful in separating the functional aspect of a model from its graphical display 2 2 7 1 Visual groups Ipfg allows multiple view windows to be open simultaneously Each view window has its own interpretation section called a visual group To specify a visual group use the following syntax vgroup nn where nn is a numerical identifier Visual groups are somewhat similar to groups of productions section 2 2 9 2 By default no vgroup command interpretation rules belong to vgroup 0 Visual groups can
39. nt If the name consists of more than one word e g Times New Roman it should be enclosed in the quotation marks Times New Roman Size specifies the font size in pixels Optional b and i flags specify bold and italic respectively stropism x y z e Specifies the direction and elasticity of the tropism This is the old style tropism or simple tropism as introduced in cpfg by Jim Hanan 3 3 Environment parameters file The environment parameters file has extension e It is read in by both pfg and the environmental program and defines how they should communicate Command Remarks executable command Specifies the environmental process s executable together with its optional command line parameters communication type pipes sockets memory files Ignored The only communication supported in the current version is files following module Defines whether the module following the communication module is sent to the environmental process Default is of f If the following module has parameters they must all be floats turtle position format turtle heading format turtle left format turtle up format turtle line width format turtle scale factor format printf like format string used when sending turtle parameters are optional but most environmental programs will require at least the turtle position For example Turtle position P oo
40. nteract with a running L system model The user can point to an element of the model on the screen and click to insert a predefined module MouseIns or MouseInsPos in the string immediately before the module pointed to by the user For example if the current string is F 1 SB Left 30 F 1 EB SB Right 30 F 1 EB then the Ipfg window will show a Y shape Click here If the user clicks on the line as shown the string will be modified F 1 SB Left 30 F 1 EB SB Right 30 MouseIns F 1 EB Now if the L system contains the production MouselIns produce F 0 2 Cut then it will be applied in the next derivation step and the string will become F 1 SB Left 30 F 1 EB SB Right 30 F 0 2 EB 21 This interaction thus simulates pruning To insert the module MouseIns press Ctrl and Shift and click with the left mouse button There is also MouseInsPos module that can be inserted by holding Alt and Ctrl while left clicking MouseInsPos has two parameters module MouseInsPos float float The values of these parameters are the relative horizontal and vertical position of the mouse on the screen when clicking The first parameter has a value of 0 if the mouse is at the left edge of the screen increasing to 1 at the right The second parameter has a value of 0 at the top of the screen increasing to 1 at the bottom 2 2 9 4 Gillespie groups Gillespie groups are as yet undocumented
41. ntroduction to C syntax see a standard C textbook the L system specific constructs are described here 2 2 1 Derivation length The derivation length must be defined in all files It specifies the number of derivation steps for the L system derivation length expression The expression must evaluate to an integer though other than that there are no restrictions on it However some care should be taken that the value is constant the expression may be evaluated more than once and Ipfg s behaviour is undefined if the value changes 10 2 2 2 Module declarations L C requires that all modules which are to be used in an L system be declared Many standard modules are predefined see section 2 3 the syntax for declaring new modules is module name parameters Here name is the module s name and parameters is a list of the types of the module s parameters For instance module A int int module B module C float data The module A has two parameters both with type int B has no parameters and C has two parameters the first with type float the second with some previously defined type data If a module has no parameters it can also be declared omitting the parentheses module B All types such as data above must be defined before being used in the module declaration In addition each type must be a single identifier compound types such as char or unsigned int are not allowed If you want to use
42. of radius r in the screen plane float r CircleFrontO Draws a circle of diameter equal to the current line width in the screen plane Note that in cpfg the parameters of the modules Qo and O specify the diameter not the radius Drawing other shapes Rhombus float length float width Draws a rhombus in the HL plane Triangle float width float height Draws an isosceles triangle 32 SP Starts a polygon EP Ends a polygon PP Sets a polygon vertex There may be at most 16 vertices in a polygon Orient Draws three lines of unit length at the turtle s current position The red line represents the heading vector the green line represents the left vector and the blue line represents the up vector This module is useful for model debugging Drawing bicubic parametric surfaces Surface Draws the predefined Bezier surface identified by the xut identifier id at the current location and orientation The float scale surface is uniformly scaled by the factor scale Surfaces are specified in the view file The first surface specified in the view file has id 0 Like functions and contours surface names are de fined by Ipfg Surface3 Draws the predefined Bezier surface identified by the int id identifier id at the current location and
43. senting the lateral branch B see Figure 2 e When a branch in the right context ends with a right bracket then the rest of the branch in the string is ignored by skipping to the first unmatched This rule also reflects the topology of the branching structure not its string representation For example in Figure 3 module is closer to a than D e If multiple lateral branches start at a given branching point then the predecessor in Figure 3 would check the first branch see Figure 4 To skip a branch it is necessary to specify explicitly which branch at the branching point should be 40 tested see Figure 5 This notation is simple consequence of the rule presented in Figure 3 In the current L system notation there is no shortcut to specify the second third etc lateral branch in a branching point without explicitly including pairs in the production predecessor There is also no way to specify any of the lateral branches Strict Right Skipped predecessor context branch gt A 4 CM String A C Right Se context Skipped branch A predecessor Current position Figure 2 Matching right context lateral branches are implicitly ignored Ignored part fthe branch of the branch Right A context ho JA String A B C s Rest of the branch ignored A Current position Figure 3 Matching right context remainder of lateral branch is implicitly ignored 41 A g
44. t B D 44 i x No match B Stings A C B D Current position Figure 4 Problem with multiple lateral branches when matching the right context gt 4 D String B D b Branch explicitly ignored A Current position Figure 5 Explicit enumeration of lateral branches in the right context When matching the left context the following rules apply e Module is always skipped since the preceding module will be topologically adjacent see Figure 6 e Ifthe module in the string indicates the end of a branch then the entire branch is skipped Figure 7 lt d B String C A B 44 b r4 Y Left context Ignored module Current position Figure 6 Matching left context beginning of the branch implicitly ignored 42 Ignored branch lt B String Ignored branch Left context Current position Figure 7 Matching left context lateral branches implicitly ignored The rule illustrated in Figure 6 is a pronounced manifestation of asymmetry in the left context right context relationship module c is left context of both a and B But c s right context is B unless delimiters are used explicitly The relation of the left context can be thought of as the parent module the module before below the branching point It is then natural to say that c is parent module for both a and B 43
45. t If a consider statment is used only those modules listed are considered in context matching SB and EB modules are always considered Listing them in an ignore or consider statement has no effect 2 2 5 Control statements There are four control statements which are called by pfg while performing L system derivation The statement Start is called before the string is initialized to the axiom the statement StartEach is called before each derivation step the statement EndEach is 12 called after each derivation step and the statement End is called after the final derivation step Any of these four control statements can be defined in the L C program as procedures and they may contain any valid C statements For instance to maintain a global variable steps equal to the current derivation step you could define the control statements int steps Start steps 0 EndEach Note the statement End is called after the final derivation step This means that if you are in Animate mode and stop or rewind the animation before it reaches the final derivation step the End statement is never called If the End statement runs a vital command for instance to close an output file you should make sure that you let the animation reach the final frame 2 2 6 Productions Productions define the way the structure defined by the L system string develops over time by specifying the fate of e
46. th the use of keyframe surfaces or when building a family of similar surfaces that are modifications of a predefined set of base surfaces The manipulations that can be performed on dynamic surfaces include Non uniform scaling e Linear interpolation between surfaces e Manipulation of individual control points defining the surface The central point in the manipulation of the dynamic surfaces is the class SurfaceObj defined in 1intrfc h Creating dynamic surfaces There are two basic ways of initializing a dynamic surface object for further manipulation e Using a predefined surface surface loaded into the object using the surface command in the view file e Creating a surface from scratch by initializing coordinates of individual control points To use a predefined surface use the GetSurface function SurfaceObj GetSurface int id This function takes the numerical identifier of the surface and returns a SurfaceObj object that contains the control points of the predefined surface If the predefined surface contains more than one patch only the first patch is returned For the numeric identifier you can use the same symbolic identifiers that are available for the Surface and Surface3 modules To create a surface by initializing its control points individually use the SurfaceObj Set method described below Manipulating dynamic surfaces To get the coordinates of a control point use the Get method Surf
47. the first frame Default 1s 0 Note in cpfg the first frame defaults to 1 This is why Rewind in cpfg rewinds to the first derivation step while pfg Rewind rewinds to axiom last frame n Derivation step to be interpreted as the last frame Default is the number of derivation steps swap interval t Minimum time interval between frames step n Number of derivation steps between drawing of frames Default is 1 35 double buffer on off Specifies if the double buffer mode should be used Default is on clear between frames on off Specifies whether to clear the screen between frames Default is on hcenter between frames on off Specifies whether model should be horizontally centered between frames Default is off Scale between frames on off Specifies whether the model should be scaled to fit in the pfg window between frames Default 1s off New view betw on off n frames Currently has no effect display on request on off If on then when running an animation only the first and last frame are displayed automatically To display a frame the L system must call the function DisplayFrame This makes it possible to skip drawing frames which do not advance time but perform other calculations If off the default then frames are displayed according to the step parameter frame numbers consecutive stepno Spe
48. the include statement The 1p ga11 n include file includes the following header files and stdlib h are standard C header files They are required by the code generated by the L2C translator e lparams h This file contains the declarations and definitions of parameters used by the L2C translator and the C code generated by the translator such as the maximum number of parameters per module the maximum number of modules in a production predecessor and so on e lintrfc h This file contains declarations and definitions that are used by Ipfg and the C code generated by the L2C translator such as types used for communication between the L system and lpfg predefined vector types and internal types relating to productions and context e isys h This file contains declarations and definitions required by the C code generated by the L2C translator These include definitions of some predefined functions Forward Backward etc e stdmods h contains the declarations of predefined modules Ipfg standard header files should be treated the same way as the standard C header files they should never be changed or edited in any way If they are altered models might not compile stop working or pfg may hang or crash 2 2 L C language constructs A typical L C program consists of standard C declarations such as data structures global variables or function definitions and L system constructs For an i
49. these types use a typedef statement to give them single names typedef char string typedef unsigned int uint Note also that unlike function arguments module parameters have no names thus the declaration module A int id int age is illegal However it is often useful to note the parameter names module A int id int age Unlike cpfg a module name cannot be used twice even with different types or numbers of parameters 11 2 2 3 The axiom statement defines the L system s axiom Its syntax is axiom module string where the module string is a sequence of modules Some valid axioms are axiom A 1 2 B 0 0 axiom A idx 2 int sin x M PI If a module has no parameters you may omit the parentheses axiom A 1 2 B A 0 0 2 2 4 ignore and consider These statements have the following syntax ignore module names or consider module_names where module_names is a sequence of module names Valid ignore or consider statements include ignore F P RollR consider G A Circle Only one of ignore or consider may be used in an L C program They affect which modules are considered in context matching when applying productions By default all modules are considered when matching contexts More or less see the Appendix How productions are matched When an ignore statement is used all modules listed in it are ignored for the purposes of matching contex
50. to adding a amp at the end of the command in a Unix shell void OutputString std string filename void LoadString std string filename These functions write the current string to a file and overwrite the current string with a saved string respectively At the moment it is not checked if LoadString is called during a production or a control block If it is called during a production then Ipfg will probably crash Calling during a control block is safe Note also that it 1s only the string that is saved and loaded not any global variables that you may have created 2 3 5 Curves and functions float fune int id float x This function returns the value of function id in the function set file if one is specified on the command line The parameter id must be in the range 1 num of functions The second parameter is the x value whose y value is requested x must be in the range 0 1 If the parameter id is incorrect outside the range the value 0 is returned and a warning message is printed If the parameter x has invalid value then 25 e ifx lt 0 then func id 0 is returned or e ifx gt 1 then func id 1 is returned In the case of invalid value of x a warning message is printed in Verbose mode only When calling the pre processor pfg defines macros with the names of the functions in the fset file The values correspond to the numerical identifiers of the functions For example if the first function in
51. uture version when the surface gallery is introduced bsurface filename scale Declares a predefined B spline surface The bsurface command 37 s div t div txid can be used with 1 2 4 or 5 parameters The required parameter filename is the filename of a surface s file scale which defaults to 1 is a file specific scaling parameter which is multiplied by the scaling parameter specified in the Surface module to produce the total scaling factor s div and t div specify the number of subdivisions to draw along the s and t axes txid if present specifies the identifier of the texture associated with the surface See the description of the module BSurface in Predefined modules texture filename filename specifies the image file that contains the texture Both width and height of the image must be powers of 2 Textures are indexed starting at 0 Currently only SGI RGB files are supported tropism command Each command must be one of the following 2 tropism vector required a angle Default is 0 x Intensity Default is 1 e elasticity Default is 0 de elasticity step Default is 0 Any number of tropisms can be specified in the view file QU rp H PH torque command Each command must be one of the commands valid for tropism except for A winfont font size bi Specifies the font to be used for the module Label Font is the name of the fo
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