-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Since the discussion on sale2x touched the topic of texture compression and Timothy stated that he wants to stay away from it for now because of patents I'd like to give an overview about the interesting texture compression algorithms. I think texture compression is important since it helps with the bottleneck of memory throughput.
GL_EXT_texture_compression_s3tc: The most common algorithm today. Many OpenGL applications (mostly games) will only work when this extension is present or assume it's presence while only checking for GL_ARB_texture_compression. This algorith is implemented by nearly all PC graphics hardware. It has been patented by S3 in 1999. Via won't even talk to Mesa when they ask about a license. GL_3DFX_texture_compression_FXT1: A competitor to S3TC created by 3DFX a year later. IP status in the extension specification says: "A royalty-free license is available from 3dfx Interactive". The extension did not gain widespread vendor support though. It is supported by all 3Dfx and Intel graphics cards. GL_ATI_texture_compression_3dc: A texture compression algorithm optimized for normal maps. Created by ATI, supported by their 9800 cards and above. They state that in their documentation 3Dc is an "Open standard", but there isn't that much documentation available, the extension isn't even in the extension registry. NV_texture_compression_vtc: Very similar to S3TC, so inherits the S3TC patent issue, furthermore, IP status in the extension documentation states: "Nvidia Proprietary". GL_EXT_texture_compression_dxt1: Simplified version of S3TC, inherits the S3TC patent issue. GL_EXT_texture_compression_latc: A new texture compression algorithm implemented in the GeForce 8 series. I do not know about the patent situation. GL_EXT_texture_compression_rgtc.txt: A new texture compression algorithm implemented in the GeForce 8 series. I do not know about the patent situation. GL_OES_compressed_paletted_texture: Just some formats for paletted textures. Paletted textures aren't a new thing, so no patent problems here. GL_OES_compressed_ETC1_RGB8_texture: A new texture compression algorithm developed by Ericsson, documented in the OpenGL ES 2.0 spec. As far as I remember it's either patent-free or Ericsson gives free licenses to anyone. GL_MESA_texture_compression_s2x: THis could be the future extension for the scale2x algorithm. I think making it a texture compression algorith is the right thing to do, since this makes it available for texture compression and those using it to make old games look better will use emulators. Those emulators that use OpenGL for acceleration are licely to render their images into textures (by emulated graphics hardware) and then just put these textures onto quads for display. Philipp -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFF5ArnbtUV+xsoLpoRAoI6AJ0ftxIsljTMOR0nuXhEWJdh7vCrBQCdEeAJ KXXLUrG2BmvqthdpKCQeeog= =mtBI -----END PGP SIGNATURE----- _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
