On 08/03/2011 12:47 PM, Ian Romanick wrote:
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 08/03/2011 12:11 PM, Bryan Cain wrote:
On 08/03/2011 01:58 PM, Ian Romanick wrote:
I think this solves the issue for the compressor and for the software
decompressor. I don't think this solves the problem for the
decompressor for hardware drivers, so that may still pose a problem for
Linux distros.
Pardon my ignorance, but why do hardware drivers need a decompressor?
To quote the EXT_texture_compression_s3tc spec:
WARNING: Vendors able to support S3TC texture compression in Direct3D
drivers do not necessarily have the right to use the same
functionality in
OpenGL.
This is the same issue that Linux distros have with ARB_texture_float
being enabled in hardware drivers. The hardware may implement the
functionality, and the hardware vendor may have some license for the
patent, but that license may not cover making the functionality
available in Mesa. That S3 has sued Apple is some indication that these
licenses may have very narrow scope.
Not being a lawyer (nor even playing one on television), all this is
doing is feeding data in a form the hardware can interpret. The
algorithms used in the creation of the data in this case bears no
resemblance to any algorithms that create "high quality" data that the
hardware, which was created under license from S3, might consume.
You could argue that using the next courser MIP level (2x2 subsampling
with low-pass filtering) in an RGB565 format with dithering to get a
virtual 32-bit color space accomplishes a similar effect with a
comparable decrease in the memory footprint, since S3TC uses 2 16-bit
colors and a 4x4 matrix of 2-bit fields per 4x4 collection of texels.
This shouldn't infringe on S3's S3TC compression and/or decompression
algorithms (although I cannot comment on whether it infringes on any
other patents).
YMMV. If you want a definitive answer, you might want to consult an
attorney who is willing to defend you in the event of infringement.
Otherwise, all bets are off. But if I were a gambling man (and weren't
employed by a company that may not want to place such a bet without
appropriate legal advice), ...
Ultimately, this a legal, not a technological, question.
cheers, danm
Disclaimer: I wrote the original reference implementation of S3TC as
well as the Game Developer article with John Brothers that described
S3's technology while an employee of S3. I no longer work for S3. Also,
I am not a lawyer (see my first point in the reply).
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)
Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/
iEYEARECAAYFAk45peMACgkQX1gOwKyEAw9p+ACgiCiOZLUcLM4ItXGtCKWvlRTl
+wMAnA3wUg5WcXsgwsZZQnq+iCT2Rr7h
=6myP
-----END PGP SIGNATURE-----
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
