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PkK
06-30-2008, 09:00 AM
What happened to 3Dc, ATI's texture compression system for normal maps?
AFAIK there was an extension for it in some of their drivers, there's ATI's whitepaper, but it seems there's no extension specification.
Why did ATI kill 3Dc? Did they?

Philipp

Groovounet
07-01-2008, 12:52 AM
The extension is GL_ATI_texture_compression_3dc and is still available with drivers 8.6...

Dark Photon
07-01-2008, 05:41 AM
In fact, NVidia liked it so well they implemented 3Dc too (in GeForce 8), but just renamed it LATC2:

* EXT_texture_compression_latc (http://www.opengl.org/registry/specs/EXT/texture_compression_latc.txt)
* ATI 3Dc whitepaper (http://www.ati.com/products/radeonx800/3DcWhitePaper.pdf)

AFAIK, both are verbatim copies of the alpha channel compression used in DXT5 (http://www.opengl.org/registry/specs/EXT/texture_compression_s3tc.txt). The NVidia extension also supports LATC1 as well, for when you only want to compress one component.