> > OK, I don't exactly want to stir up this hornets nest *again*, but a > > couple of things aren't entirely clear to me and I'd appreciate any > > clarifications. > > > > As I understand it, the situation is as follows: > > > > The S3TC algorithm is patented and therefore no-one can distribute an > > implementation of the algorithm without a licence from the patent > > holders. > > > > S3TC decompression must be implemented in the hardware (otherwise > > what's the point), therefore hardware which uses S3TC can be assumed > > to have a valid licence to use the code, otherwise the patent owners > > would be down on the hardware manufacturers like the proverbial ton of > > bricks. > > Patent law is actually more complicated than that. I'm not in a > position to go into it, but it gets complicated when you have multiple > components (i.e., software and hardware) working together to implement > something. > > > As far as I'm aware, the main users of S3TC are modern games with > > their vast arrays of textures -- presumably such games come with the > > textures precompressed, or are able to compress them and cache the > > compressed textures themselves. Presumably again, the authors of the > > games have paid for a licence to use the S3TC algorithm from the > > patent holders. > > > > Now, if an OpenGL application has a pile of textures already > > compressed with the S3TC algorithm, then I don't understand why the > > dri drivers can't simply offer the S3TC interfaces to the hardware, > > pass the compressed textures to the hardware and let the hardware get > > on with its licensed decompression of the textures as required. > > Likewise, if the OpenGL application passes compressed textures to the > > S3TC API then how it gets hold of the compressed textures in the first > > place is it's own responsibility -- the OpenGL API just passes them > > on. > > Look at the ARB_texture_compression and EXT_texture_compression_s3tc > specs again. You can specify uncompressed textures and have the driver > compress the AND you can specify compressed textures and have the driver > decompress them (to read them back into the application). For example, > Quake3 can use the S3's vendor-specific extension (can't remember the > name of it right now), but it does NOT have ANY textures pre-compressed. > It expects the driver to do the work. > > Can we add this to the FAQ, please?
Instructions at teh bottom of: http://dri.sourceforge.net/help.phtml Alternatively if you know how it works go straight there: http://dri.sourceforge.net/faq/faq_add.phtml No one appears to be abusing it so I'm happy to let it be open. Liam ---- it depends ------------------------------------------------------- This SF.net email is sponsored by: SlickEdit Inc. Develop an edge. The most comprehensive and flexible code editor you can use. Code faster. C/C++, C#, Java, HTML, XML, many more. FREE 30-Day Trial. www.slickedit.com/sourceforge _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
