This can be realized for example by Linux distributions setting this to "Provide:" libtxc_dxtn, and shipping this one by default. Then the user can replace it by the "full" libtxc_dxtn with S3TC support by an apt-get command (on Debian/Ubuntu). Alternatively, an alternatives mechanism can be used (update-alternatives) to even allow both packages to be installed at the same time.
Also, Mesa COULD include this code, or reimplement S2TC on their own (in a probably more optimized and faster fashion). In any case, I would prefer support for full S3TC libtxc_dxtn to remain.
so... did anyone involved in mesa ask S3 already if it's ok to have a free implementation, or do we have to speculate for the next 50 years whether there might be some legal problems or not?
Ok, so if i rename S2TC library file as libtxc_dxtn would it make auto magicly my S3TC games run properly without S3TC, or would it require some extra work from the game devs?
It would automatically work, provided your graphics card supports S3TC decoding. In case it does not, Mesa may implement it using S2TC decoding, but even if it will work, it will be slower. You basically don't want software fallbacks to happen.
Quite likely though, your card DOES support S3TC, and libtxc_dxtn will then work for you without fps loss.
While I too think it's better to have low quality over black by default, it really is an US issue. Why should people outside have low quality by default, when they can legally get the better one?
this patent is bullshit.. ignore it...
I'm not sure simply ignoring a patent somehow makes it go away...
The reason that ignoring it isn't a solution is that the US is -- for better or worse -- still one of the largest drivers and absolutely the largest consumer of software, games, and technology in the world. If some random user in some other part of the world gets access to an encumbered algorithm, good for him, but that does nothing for the larger ecosystem. Game developers will still absolutely refuse to waste time targeting Linux if we know that even 60% of the Linux userbase in our target market would be unable to use that software.
So far as S3TC, you already have the option to use a Mesa plugin for it in parts of the world that don't uphold software patents, so quit your damn whining already. :p