On 28.01.2009 01:50, Ian Romanick wrote: > I'd like to propose a couple changes to our current GL and GLX extension > policies. > > GL > == > > There are a few GL extensions that I believe should just be made > mandatory. Doing so would allow us to remove a ton of extension tests > sprinkled throughout the code. The proposed extensions all provide ways > to expose the extension without requiring additional hardware > functionality. Enabling the extension just makes the API available. > Here is my proposed list:
... > > - GL_ARB_vertex_program - For hardware that uses software for TNL, Mesa > does all the work. For hardware that has only fixed-function TNL, > vertex programs act like a TNL software fallback. Only i810, mach64, > r128, radeon, savage, and sis do not support this extension. I believe > that GL_NV_vertex_program and GL_NV_vertex_program1_1 should also be > enabled. The expose nearly the same feature set as the ARB extension. I think the concerns for enabling ARB_vp on radeons was that this might cause programs to use a vertex program instead of using fixed function even though they'd support the latter just fine, and the former would be a software fallback whereas the radeon accelerates fixed function tnl. This isn't an issue on all other chips mentioned (and it's no issue with the tnl-less 7000/igp radeons), except performance may still be much worse even though both tnl/vertex shaders are running in software (and apps probably don't gain much if the chips don't support ARB_fp too). The problem with NV_vertex_program I have is that there are subtle differences to ARB_vertex_program, specifically the need to initialize registers to some defined values which ARB_vp leaves undefined. Not sure if apps are really relying on this, but this adds quite some complexity to drivers for very little gain (some generic dead code elimination would sure help), unless this requirement is just ignored. I just don't see much point in this extension anyway nowadays. Roland ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword _______________________________________________ Mesa3d-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
