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1. A DATA 254 qwords 4k y next ADDR A1 QWC 0 W call ADDR A QWC 0 A1 cnt ADDR QWC 254 end ADDR QWC 0 DATA 254 qwords 4k next ADDR A2 QWC 0 y A2 cnt ADDR QWC 100 A Each call tag transfers the pre compiled data DATA 100 qwords lt 4k ret ADDR QWC 0 y Figure 4 On reading the first call tag from the call chain the DMAC pushes the following qword which in this case is the next call tag onto the call stack and reads the qword pointed to by the ADDR field in the call tag as the next tag This action is carried out since the qword count QWC field of the call tag is set to zero DMAC control then passes to the first ent tag in the data section which is the first qword of the stitched data to be transferred When the DMAC reads the ret tag at the end of the data it transfers the number of qwords following this tag which in this case is zero then reads the qword popped from the call stack as the next tag The next tag will thus be the second call tag in the call chain This process repeats until the final end tag is reached in the call chain and the transfer is ended Using Call Chains in Games Programming Now that the process of creating and transferring pre compiled data chains has been describes the use of such techniques in the writing of games programs will be discussed Consider the situation of a game consisting of several animated 3D models which must be sent down the graphics pipeli2. NEXT texture while it is still in use by geometry Finally to get the benefit of MSKPATHS the key is to have your NEXT texture s being uploaded while your CURRENT geometry is being used As soon as I mention CURRENT and NEXT you should be thinking to yourself well that sounds like double buffering to me Because it sure is For simplicity I ll assume we have two addresses to which we want to send textures address 0 and address 128 Here s a simple timeline of what should happen PSynergy Issue 3 April 2004 Page 13 psynergy pakl net Transfer texture 1 to address 0 through PATH 3 or 2 Wait for texture 1 to complete Flush textures amp activate texture 1 Start transfer of texture 2 to address 128 through PATH 3 Draw geometry using texture at address 0 Wait for texture 2 to complete Flush textures amp activate texture 2 Start transfer of texture 3 to address 0 through PATH 3 Draw geometry using texture 2 at address 128 Wait for texture 3 to complete 10 Flush textures amp activate texture 3 11 Draw geometry using texture 3 at address 0 OMAANDNMBWNFK CO If you skip step 0 as an initialization step you could put that in PATH 2 for simplicity for instance you ll notice a pattern in steps 1 3 and steps 4 6 The pattern says Wait for CURRENT texture in address A start upload of the NEXT texture to address B and draw using the CURRENT texture in address A Of course A and B swap every
3. a sequence of GIF primitives terminated by a GIF primitive that has EOP 1 In other words a GS packet is any number of GIF codes data with EOP 0 plus one GIF code data at the end with EOP 1 So the magic part here is that to get a texture to go through completely we just need to make sure that all GIF primitives for a texture upload except for the last one have EOP 0 and the last one has EOP 1 When we d like to Start transfer of texture n 1 from VIF1 what we re basically adding to our sequence of VIF commands is PSynergy Issue 3 April 2004 Page 14 psynergy pakl net a MSKPATH3 0 to start the transfer b NOPs in order to wait long enough to ensure that the transfer has started c MSKPATH3 0x8000 to suspend PATH 3 at the end of the current transfer The only particularly tricky part is answering how many NOPs do we put in If you put in too many NOPs there s the possibility that if texture n 1 is very small it ll get transferred immediately and texture n 2 will also get started If you put in too few NOPs there s the possibility that texture n 1 will never even get started because the GIF won t have had a chance to even start transferring that first GIF code with EOP 0 indicating the beginning of the GS packet Understanding that too many NOPs could make two transfers go through instead of one is fairly simple but you may wonder why would it take so long for a transfer to start Why would I ever suffer the too few NOP
4. into console programming Then I heard about the ps2linux kit about a year ago and ordered it When I got it and started to read the manuals I got a bit hesitant so I used ps2g the first six months or so before I started to program it on a lower level PSynergy What do you like and dislike about the PS2 hardware Ola It s a fun piece of hardware with several processors and all very versatile On the downside is the fact that they completely crippled vu0 by giving it only 4 kb of memory Peter Obviously I m a big fan of the VU units Comparing them to vertex shaders on a PC it s really nice to be able to actually generate geometry on the fly and to have branching Another thing I really like is that you can access the frame buffer in a more direct way than you normally can on a PC I m not particularly impressed with the pixel pipeline A few extra texture units and an extra VU unit for pixel processing would have been nice And of course you can never have enough memory PSynergy Issue 3 April 2004 Page 18 psynergy pakl net PSynergy How is your development environment set up both physically and on your machine Peter I got a small network set up with one Windows PC and one PS2linux box using samba I do all the source code editing on my PC running Visual Studio NET 2003 Telnet is used to compile and run the programs In fact it s just like Henry described in the PlayStation2 in Higher Education article in the February i
5. of data to be transferred and the transfer process is ended by inserting an appropriately configured end tag after the final data section PSynergy Issue 3 April 2004 Page 7 psynergy pakl net AO cnt ADDR QWC 254 A DATA 254 qwords 4k next ADDR A1 QWC 0 A1 cnt ADDR QWC 254 gt lt DATA 254 qwords 4k next ADDR A2 QWC 0 l A2 cnt ADDR QWC 100 DATA 100 qwords lt 4k end ADDR QWC 0 y Figure 2 It is interesting to note that the final end tag could be replaced with a ret tag if the data packet is part of a call chain but this will be described in more detail later in this article Organisation of data with ref tags is illustrated in figure 3 In this case the 4k block contain only the data to be transferred and there are no embedded DMATags within the data A separate area of memory is required to build the DMAC command chain which is constructed using ref tags and ended with a refe tag The tag at address A3 is the first to be read and this instructs the DMAC to transfer the 4k block starting at address AO then read the tag after the one at A3 as the next tag This process continues until the final refe tag is reached this transferring the final section of data then ending the transfer In this case if the DMA chain is part of a call chain the final refe tag can be replaced by an appropriately configured ret tag PSynergy Issue 3 April 2004 Pag
6. understanding that when using MSKPATH3 you re basically going to have two long chains One chain will be sent through DMA channel 1 it s a VIF1 chain The other chain will be sent through DMA channel 2 the GIF The GIF channel will be used only to send textures so basically the chain is a sequence of textures Thorough VIF1 you ll be sending your geometry matrices whatever else you want and a special sequence of MSKPATH3 VIF codes So in short VIF1 gets geometry and MSKPATHS instructions while the GIF through PATH 3 gets textures What MSKPATHS is used for is to actually block the GIF from getting data through PATH 3 You can still send data First of all we should all to the GIF through PATH 1 amp PATH 2 i e through VU1 or start by understanding that VIF1 but PATH 3 will be blocked when using MSKPATHS3 you re basically going to So now we have a sequence of geometry going to VIF1 and have two long chains a sequence of textures going to the GIF through PATH 3 and a tool that allows us to suspend resume PATH 3 transfers Having said all that let s consider the diagram that Hikey has posted Ed See Hikey s comment at the end of this article for this diagram You ll notice that he s using 3 sets of geometry with 3 different textures It s important of course that the CURRENT texture is already loaded by the time the geometry goes to draw It s also important that the CURRENT texture is not over written by the
7. PSynergy Issue 3 April 2004 Page 1 psynergy pakl net PSynergy An Independent Journal for PlayStation 2 Linux Developers and Enthusiasts Issue 3 April 27 2004 Table of Contents EDITORIA d essssscssscodscccssscscscssscccsscssssctsssscsstsosecosssssscesesesscesscasecosseesedecesasscsaseasscostssseabcdsassesassssscossecssaesdsassces ssssceses 2 THIS MONTH IN THE FORUM csccsssssssssccsssssscssccsccssssssccscsssscssccssssssescessssncesscescsssesscenssensesscenssensesssenss 3 IBA TURES siccistccscesctsttessatsescessacavacsstsetcosctssecsstsetacssesesteustsubcesstesssevcasencacsessbecssasessavsaseucuscteusessseceusevsasencacstenseessceeee 5 FEATURE USING THE DMAC IN GAMES PROGRAMMING cccsssseccceccesessnsecceeccssessnscceeececessnsseseeeeecessnaaeess 5 Using Call Chains in Games Programming o cscscsscsssscessessessesseseeseeeeseeseeseeseeseeseeseeseeseeaeeseeaeesesseeseeeeaeeaeeas 9 Foue Die aE EE E O ERRE EE a E T E R E E ERE OE ATES 10 CONCLU ON S er ARR ENARE RRON RAAR A REREN ARREA REN A ARRAREN AAR ee RERA AA Il Acknowledment S correia CERAR ERA CAR RR CERERE RRO NA CARO CR ORRE RRC OCC RTER Il Dr TLENI YS FOTLUING serina r aE RRR RE R ARERR ARERR RRR R ER RRR ARER REER RR ER E ERER E ERA Il FEATURE MSKPATH3 TUTORIAL AND COMMENT c cccssscssssessscessecessecessecssecessecesecessecsseecsseeesseceeeceseeesaes 12 INTERVIEW cies scssecessccdscssscstscesccstvessseciecsssccescascossvcsnsestssssssceseuccassscs
8. all the appropriate model data needed for a specific animation frame For example the call chain for frame 0 may call the model data sections 0 1 2 7 9 and 12 the call chain for frame 6 may call the model data sections 0 1 5 7 10 and 11 Given that the data is pre compiled into the correct format it is thus possible to quickly render a specific animation frame for a model at run time with minimal processing overheads Conclusions This article has illustrated the use of DMATags for the organisation of precompiled data within a computer game application Pre compiling and efficiently organising data prior to run time is essential in order to achieve effective application performance Acknowledgements Much of the information presented here has been gleaned from various post on the Playstation2 linux com developer forum The author is grateful to the many contributors to this forum Dr Henry S Fortuna Lecturer in Computer Games Technology University of Abertay Dundee Scotland UK h s fortuna abertay ac uk 27 April 2004 PSynergy Issue 3 April 2004 Page 12 psynergy pakl net Features Feature MSKPATHS Tutorial and Comment Steven Osman Sauce sauce users playstation2 linux com Department of Computer Science Carnegie Mellon University This article is based on a an earlier post from Sauce at the end of March https playstation2 linux com forum message php msg_id 42234 First of all we should all start by
9. e 8 psynergy pakl net DMA Chain DATA A3 ref ADDR A0 QWC 256 AO A ref ADDR A1 QWC 256 refe ADDR A2 QWC 100 DATA 256 qwords 4k gt lt A1 DATA 256 qwords 4k A2 I DATA 100 qwords lt 4k Figure 3 There are relative advantages to both of these methods of memory stitching The use of ent and next tags requires only one area of memory to be configured whist the use of ref tags requires two areas of memory but only about half the number of tags Using Call Chains Each of the DMAC channels to VIFO VIF1 and the GIF contain tag address save registers which can be used to facilitate the creation of data subroutines Data subroutines are similar to normal program subroutines in that once called the subroutine performs it s function then returns control back to the main line of execution An example of a call chain is illustrated in figure 4 The data section at the right of the figure is stitched together into as large a packet as required and is ended with a return ret tag The organisation of the data into this format would be undertaken prior to run time The transfer is initiated when the DMAC reads the first call tag from the start of the call chain shown on the left hand side of figure 4 PSynergy Issue 3 April 2004 Page 9 psynergy pakl net Call Chain DATA call ADDR A0 QWC 0 AO cnt ADDR QWC 254
10. e not available through sps2 and MSKPATHS which Sparky has implemented and is provided in the sps2 samples I knocked up a programmer s art diagram to illustrate PATH1 Gi G2 G3 PATH2 TT 72 J fT GS A 12 units PATH1 cen G2 Gy PATH3 Ti WY iy T2 W T3 TB GS a 4 VY Lot 9 units http www scee sony co uk lionel cfyc path123 gif As you can see already with three objects the speed difference is significant Hikey Lionel Lemarie SCEE PSynergy Issue 3 April 2004 Page 17 psynergy pakl net Interview This month s interview is with the creators of the recently released VUC C like compiler for the Vector Processing Units on the Playstation 2 You may contact them through peterp users playstation2 linux com PSynergy Where do you live We both live in Gothenburg Sweden PSynergy How old are you We re both 28 years old PSynergy What do you do for a living Ola I m a student at the University of Gothenburg currently working on my masters thesis previously I ve worked as a games programmer in Brisbane Australia Peter I ve been working as a games programmer since 1995 never on a PS2 game though PSynergy When did you get started on developing under PS2 Linux Ola In fact I haven t I did some PS2 while working professionally but I haven t got a Linux kit or indeed a PS2 even we re doing all testing on Peters kit Peter I ve always wanted to get
11. e of those things you need to read about a few times before the magic is somewhat understandable Sauce did a great job in the forums go check out this article for another read MinRay for SPS2 At http playstation2 linux com forum message php msg_id 42061 lives an ideal candidate for a code snippet if I ever saw one a Minimal Ray Tracer for SPS2 Print it out in a small enough font and the source would probably fit on a business card MIPS1 Compilation Issues A discussion at https playstation2 linux com forum message php msg_id 41740 shows some problems that vliw hit when he tried using inline MIPS asm Sparky verified that the code works on his T10k at work so the problem was narrowed down to GCC and the MIPS1 barrier Any potential compiler hackers should read this thread and maybe write an article about the MIPs1 limitations Higher level library wanted The discussion at https playstation2 linux com forum message php msg_id 42332 centers around the creation of a higher level library for programming the PS2 The general consensus seems to be that a general higher level library is not the way to go to PSynergy Issue 3 April 2004 Page 4 psynergy pakl net get maximum performance but what do you think Can a higher level library reach an acceptable performance level for people who don t want to mess with ASM and VU coding Do have the desire to write such a library Would you use it if it were created Answe
12. iteration as this is a double buffering scheme Now remember that only the texture transfers are happening through PATH 3 Everything else including the Start transfer of texture are happening through VIF1 Some of the texture transfer amp geometry drawing can happen at the same time which is where the speed benefit comes from If you re still with me at this point you have a conceptual understanding of how interleaving the texture transfer with the geometry drawing can be used to give a performance benefit Now we should consider how MSKPATH3 works for a minute so we can get to the details that Sparky was trying to cover As I mentioned earlier MSKPATH3 allows you to suspend amp resume PATH 3 transfer So trivially whenever I say Start transfer of texture n 1 that simply means using MSKPATHS3 to re enable PATH 3 The problem is when do we disable it again so that texture n 2 texture n 3 and so on don t also get uploaded If we disable it too soon would we disrupt the transfer of texture n 1 the texture we really wanted to transfer Well we re fortunate in that when you use MSKPATHS disabling PATH 3 doesn t abruptly terminate the PATH 3 transfer Instead of saying Suspend PATH 3 transfers IMMEDIATELY what MSKPATHS is really saying is Suspend PATH 3 transfers AT THE END OF THIS CURRENT GS PACKET For a brief review we see from page 150 of our EE User s Manual that a GIF primitive is a GIF code data and a GS packet is
13. ndependent processors and between main memory and scratchpad RAM e 129 VUO vu1 Path 1 FPU lt P EE Core lt P 4k lt P 16k i i GIF GS y y Path 2 I D SP 16k 8k 16k t E aa i me pe 128 bit Data Bus gt i 2 4Gb sec i p Timer DMAC Main Vsync Memory Hsync Figure 1 During the execution of typical game code the DMAC is responsible for transferring vertex data and transformation lighting matrices to Vector Unit 1 VU1 and image data PSynergy Issue 3 April 2004 Page 6 psynergy pakl net for primitive texturing to the Graphics Synthesiser GS In order to maintain an effective frame rate it is important that as much of this data as possible is pre compiled and efficiently organised prior to run time Such organisation frees up the main processor from this mundane task and allows it to perform other important game related functions such as AI and game logic during game execution Image Data Transfer Image data used for texturing is normally sent to the GS via path 2 or 3 Path 3 is a direct path to the GIF whilst Path 2 is through VIF1 to the GIF There are a few additional overheads associated with sending data via Path 2 but Path 2 has the advantage of providing inherent synchronisation between texture and vertex data Typical image data may be many KiloBytes in size and generally larger than the 4 kByte mem
14. ne for rendering It is advisable in such situations to cull as many objects as possible from the pipeline as early as possible within the pipeline thus saving valuable processing time A simple first approximation method might be to generate bounding spheres round each model and test each sphere against the view PSynergy Issue 3 April 2004 Page 10 psynergy pakl net frustum Models inside or partly inside the frustum will require further processing whilst models fully outside the frustum can be culled Consider therefore the pseudo code shown in figure 5 Figure 5 In the main chain the visibility of each model is checked and the appropriate sub chain is only called if the model is visible thus requiring further processing Another use of call chains in games programming is in the rendering of animated models in either 2 or 3 dimensions Consider that the data for an animated model is precompiled and organised in the manner shown in figure 6 PSynergy Issue 3 April 2004 Page 11 psynergy pakl net Call Chains Model Data Call Chain Frame 0 Model Data 0 Call Chain Frame 1 Call Chain Frame 2 Model Data 1 Call Chain Frame m Model Data 2 Model Data n Figure 6 All of the data necessary to render any animation frame for the model is contained within the model data section Various call chains are configured within the call chain section to c
15. nergy Issue 3 April 2004 Page 15 psynergy pakl net uploaded through PATH 2 or some other method as part of initialization your sequence would look like this Of course make sure you re stitching this chain as needed What has this achieved Well if you look closely you ll see that the transfer IMMEDIATELY begins with a GS packet Similarly every time a GS packet ends which is the GIFtag with EOP 1 the next GS packet begins immediately after it This helps to give us a much more predictable and short amount of time that will be required to start the next GS packet when MSKPATH3 temporarily re enables PATH 3 transfers helping to avoid the problem of the transfer getting missed because there aren t enough NOPs in the VIF1 sequence Two other details before I end this discussion 1 The magic number of NOPs to put in your VIF1 sequence that appears to work well is 24 Don t ask just learn it love it and use it Keep in mind that really really small textures may transfer faster than that but it s not safe to reduce the 24 NOPs because you risk missing a texture entirely The solution is to pad really small textures with other stuff for instance you could always add a bunch of GIF NOPs at the end of your texture 2 When I mentioned wait for texture n 1 to complete the VIF tag you want to use is FLUSHA FLUSHA makes sure that the path 3 transfer which is texture n 1 has finished Don t forget to put the appropriate i
16. nsessevcssanessunsesessaesesesscasesesevasseesssascssdecasustseoss 17 PS2 DEVELOPMENT TIES wiccsiscscecsssossossdsesenccteeseoaassescoseesesescscdesceacesedsosaeseseesdusedseadesescosseseseesscdescesdesessesdosesase 19 NEXT MONTH IN PSYNERGY sessisscsssssesctcssssscssscdasessssdescssantesussecteacsvesssscdsasteosdsacbesesssssessdsestessdsssbescascessessess 20 End Reader License You my freely reproduce and redistribute this publication in its entirety through any means You may freely redistribute any article contained herein in its entirety as long as the name of the original author and the text as per The PSynergy Journal are placed both at the beginning and the end of the article Also this license paragraph must be copied and appended to the article to ensure that it continues to apply to the redistributed article Article Submission Guidelines You may submit a copy of your article manuscript to patryk pakl net For your article to even be considered it must be related to development for the Playstation 2 Linux kit Please note that this includes programming for the RTE so long as anyone with the Kit can learn from use it All submissions will be edited for content clarity and brevity and the author is given at least 3 days to approve final copy A suggested template for articles will be provided at http psynergy pakl net template html Finally by submitting your article you agree that it can be redistributed freely only in it
17. nstructions to activate the texture If anyone has any questions about this please let me know If any pros out there want to jump down my throat for any gross errors I ve made please do so but do it gently Sauce PSynergy Issue 3 April 2004 Page 16 psynergy pakl net I would like to add a comment on the typical chain I gave in the mentioned post This was if you use only PATH1 2 which is the easiest way to go When this is sorted out the next step is to use PATH 1 3 instead The reason for this is that using PATH1 and 2 the data goes through the VIF typically for both PATHs So while you are uploading a texture you cannot draw anything on the screen If you have many textures you might be slowing down the rendering unnecessarily The PATH 1 3 technique is a lot more complicated But it means that only the 3D geometry is going through the VIF and that in the gaps between rendering the polys you could be sending the next texture to use This means you need adouble buffer in the VRAM in your case 128k each one for the texture that is currently used and one for the next texture abetter VRAM manager that can send the texture before you need it otherwise you will still be waiting for it and this is all pointless It needs to group the textures into batches too it s useless to send only a tiny texture a geometry texture synchronisation technique There are two main ones Interrupts which at the moment ar
18. ory block allocation size provided under SPS2 It is therefore necessary to split the image data into 4 kByte blocks and stitch these blocks together with appropriate DMATags As discussed above such organisation of the texture data should be undertaken prior to run time Achieving this with memory stitching is outlined below Memory Stitching The process of pre compiling image data will be demonstrated using two different methods of memory stitching The first method uses cnt and next tags and the second uses ref tags Organising data with cnt and next tags is illustrated in Figure 2 A ent tag with it s qword count field QWC set to 254 is inserted at the start of each full 4k block The value in the address field ADDR is not used with ent tags and can be cleared to zero The ent tag instructs the DMAC to transfer QWC of data following the tag and read the quad word after that data as the next DMATag which in this case is a next tag The purpose of the next tag is to direct the DMAC to the start of the next 4k block to be transferred This is achieved by setting the ADDR field of the next tag to point to address A1 which is the start of the next 4k block and the QWC field of the tag to zero to indicate that no data is to be transferred with this tag The DMAC therefore reads the ent tag at address A1 as the next instruction and this process repeats until the last block is reached The QWC of the ent tag in the last block is set to the amount
19. rs on a postcard to the PSynergy mailbox perhaps there s an article in this for a future issue Other news in brief Win32 Cygwin cross compiler in CFYC If you want to compile on Cygwin whilst your PS2 is playing games you need this https playstation2 linux com files cfyc gcec 2 95 2 ps2linux win32 zip Developers Wanted for a hardware benchmarking suite for the PS2 http playstation2 linux com projects psb Kazan Jonathan Hobson has released some excellent SPS2 demos with source Yay Metaballs http www jhobson co uk ps2section htm PSynergy Issue 3 April 2004 Page 5 psynergy pakl net Features Feature Using the DMAC in Games Programming Dr Henry S Fortuna h s fortuna abertay ac uk University of Abertay Dundee Scotland UK Introduction Background information on the general operation and characteristics of the Direct Memory Access Controller DMAC was provided in the article The PS2 Direct Memory Access Controller published in PSynergy Issue 2 March 2004 This article will describe how the various Direct Memory Access Control Tags DMATags can be used to help manage the transfer of model and texture data through the graphics pipeline of the PlayStation2 in a typical Computer Game application Background The internal structure and main data paths within the PS2 are shown in figure 1 The DMAC is responsible for transferring data between main memory and each of the i
20. s entirety as long as your name is placed at the beginning and the end of it Sony is a registered trademark of Sony Inc PlayStation PlayStation2 the PlayStation PS logo and all associated logos are trademarks of Sony Computer Entertainment Inc PSynergy and is NOT associated in ANY way with Sony Computer Entertainment Inc PSynergy Issue 3 April 2004 Page 2 psynergy pakl net Editorial Readers Here finally is Issue 3 The combination of tax day and final exams made this one particularly late Happy Spring Summer Patryk Laurent Editor in Chief PSynergy patryk playstation2 linux com PSynergy Issue 3 April 2004 Page 3 psynergy pakl net This Month in the Forums A Monthly Column by Eratosthenes Apologies for my recent total absence from the PS2 scene I ve been a busy guy However there s nothing like a good browse through the Developer s forum to catch up on the latest VU C Compiler In what sounds to me like the most significant step in PS2Linux tools since the creation of SPS2 we now have a C compiler for the VUs Yes that s right create VU code in C This deserves an entire article of its own hopefully you ll find one elsewhere in this very issue of PSynergy Sauce s MSKPATHS Pseudo Tutorial With any luck you ll also find Sauce s Pseudo Tutorial on the MSKPATH3 technique in this issue This technique is used to manage your textures frame by frame and is on
21. s problem There are a couple of reasons for that First remember that only one thing can read from the EE memory at once This means that if you ve got a number even just the VIF1 and GIF transfers from the EE memory going and using the EE memory in your own program it could take a little bit of time Second remember that if you use many CALL and NEXT DMA tags in your GIF transfer the DMAC may take a little time processing and following all those DMA tags that it never gets to transfer that first GIF code The magic then is to try to put the GIF primitive with EOP 1 from texture n as close as possible to a GIF code with EOP 0 for texture n 1 This means that once texture n ends the very next thing to be transferred by the DMAC is the first GIF code of the next texture not a bunch of CALL tags or anything else Sparky proposed a pretty good solution to that in his post I ll give a slightly different example that may waste a tiny bit of memory more but is simpler to understand Let s say we want to pre build our textures so that they can either upload to address 0 or address 128 We d create sequences in memory as in Snippet B 1 Note first that I didn t have anything in there with EOP 1 You d create one of these sets for tex1 one for tex2 and so on Now as you re creating your PATH 3 chain to upload these textures let s assume that we start with texture 2 at address 128 since we said that texture 1 may have been PSy
22. ssue Ola I run Visual Studio too and a CVS server since I ve got a fixed IP Then since I don t have a PS2 PSynergy What do you foresee as the future for the PS2 and Linux development Ola Don t really have a great deal of a clue about the future but it seems clear to me that the PS3 isn t gonna be out for another 2 years or so and that s not the immediate end for PS2 either Peter I read in a recent magazine that Sony said that even though they sold a lot of units they figure that they ve sold less than half of what they expect to sell during its lifetime I guess that means that when the PS3 is released we re going to see the same thing that happened to the PS1 when the PS2 was released All the early adopters buy the latest and greatest and then give away their PS2 to some younger relative And the PS2 will get smaller and so cheap that any impulse buyer not normally buying games might pick one up The gaming population will grow and the PS2 games are going to be more mainstream and probably targeted to a younger audience As for the future of the ps2linux environment I think and hope that it will get easier to develop for the kit as we get more and better documentation Henrys sps2 and Eratos VU tutorials PSynergy etc libraries and tools e g Sauces SPS2 amp Visual VU Debugger Maybe the next step is to build more high level libraries or rather components for people to pick from when putting together their own game bj
23. t s kiss renderer sparky s intmd etc PSynergy Anything else you would like to add Ola Don t you have any questions about VUC at all PSynergy Yes maybe next time Thank you for taking the time to respond to these questions PSynergy Issue 3 April 2004 Page 19 psynergy pakl net PS2 Development Tips Tip Triangle Strip Stitching posts from jawadx sparky sauce and hikey To draw a mesh or object with multiple vertices it is useful to use Triangle Strips specifically because they can be stitched together to make polygons But doing so successfully requires correct usage of the PRIM tag and ADC bits See GS User s Guide Incorrect usage results in broken strips as brought up by jawadx in a post You don t need to add extra vertices or anything like that but the first two vertices of every strip should be delivered with ADC enabled which means drawing kick disabled Now we only have the problem limited to from one chunk to the next between deliveries mscalls If when you kick your vertices you don t set the PRIM register in your GIFtag then it will be the same PRIM as it was for the previous kick and the vertex queue as it s called will remain intact Of course you ll have to set the PRIM register once perhaps at the start of a mesh This means you will not obtain split strips and you will NOT have to add any extra dummy vertices or anything like that You can just process the vertices So if you ne
24. ver send the PRIM register along with your gif packet that contains vertices you should set ADC on the first two vertices of a strip This is so when you move from one strip on to a second strip it won t draw a triangle that spans the last one or two vertices of the first strip and the first one or two of the second strip If on the other hand you send PRIM whenever you re starting a new strip then setting the ADC bit is optional because nothing would get drawn until the third vertex anyway So to make it 100 clear you always set the ADC bits at the 2 first vertices of every actual strip if the next batch takes over a strip from the previous batch and it s processing somewhere after the first two vertices of this strip then it would not set the ADCs until the next strip PSynergy Issue 3 April 2004 Page 20 psynergy pakl net Next Month in PSynergy Look for PSynergy Next Month
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