On 2 Feb 2003, Sergey V. Oudaltsov wrote: > > According to the docs, mach64 implements 4:1 VQ de-compression, but > > there's no other info. Rage 128 also has a VQ texture format bit, > > according to the register header file. Sega dreamcast used a form of VQ > > compression also, I think. > Sorry for my ignorance, are these compression methods supported in any > way by DRI now? Which apps would benefit of them?
No they aren't supported in DRI. For existing apps, they would probably only be useful for apps supplying uncompressed textures and requesting generic compression through ARB_texture_compression. The textures would have to be compressed in software and then passed to the card to de-compress as it applies the textures. There is no GL extension (vendor-specific or otherwise) that I know of for these formats, so it would require a new extension spec. and a software implementation of compression/de-compression as well as the support for hardware de-compression (that's the easy part). Since there's no existing extension, there wouldn't be any existing apps supplying pre-compressed textures to the GL in this format, and afaik, very few existing apps would ask for generic compressed formats either. This limits the utility of implementing it, as VQ compression is much more time consuming than S3TC/DXTC compression, as I understand it. It's better for offline compression and real-time de-compression (de-compression could be faster than with S3TC). So it would require detailed specs on the compression format as implemented in the hardware (e.g. block and codebook sizes) to write the spec. and software support, or some trial and error reverse engineering. Quite frankly, it seems like it's probably more trouble than it's worth. Does anyone know if these formats were ever supported in ATI's drivers? I'm assuming it would have to have been in the DX drivers, since I can't find any GL extension supporting them. But I can't find any reference to DX supporting VQ except for the WinCE DirectX SDK for the Sega Dreamcast. I think Microsoft made DX 5 and 6.1 sdks for the dreamcast, and DXTC/S3TC was introduced in the PC version of DX6. According to ATI's site, later Rage 128 chips (Rage Fury Pro, Rage Mobility) support DX6 texture compression, which I assume means S3TC, but I don't see any relevant register defines in the headers and I don't have specs for Rage 128. -- Leif Delgass http://www.retinalburn.net ------------------------------------------------------- This SF.NET email is sponsored by: SourceForge Enterprise Edition + IBM + LinuxWorld = Something 2 See! http://www.vasoftware.com _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
