[Mesa-dev] S2TC - yet another attempt to solve the "S3TC issue"

Ian Romanick idr at freedesktop.org
Tue Aug 9 15:13:01 PDT 2011

Hash: SHA1

On 08/07/2011 03:44 PM, Petr Sebor wrote:
> On 4.8.2011 12:19, Rudolf Polzer wrote:
>> On Wed, Aug 03, 2011 at 12:47:47PM -0700, Ian Romanick wrote:
>>> On 08/03/2011 12:11 PM, Bryan Cain wrote:
>>>> 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.
> Ian,
> I think it is really not the same issue. The S3TC patent is about the
> algorithm itself,
> not about copying blocks of memory. The quote from

Two words: contributory infringement.  The Mesa code would be doing
something that enables something else to infringe.  No distro will ship
it because it makes them liable.  Don't look for logic or reason or
sense in the legal system.  You won't find it.

> EXT_texture_compression_s3tc
> only underlines the fact that Direct3D stack (both runtime and driver)
> does not have to provide
> S3TC compression/decompression algorithm at all, whereas driver
> providing EXT_tc_s3tc
> typically has to be able to compress the textures in the software (and
> thus implement the
> patented stuff). Direct3D serves as a pass-through to the hardware, they
> don't have to mess
> with the patent at all while the hw vendor typically has the
> decompression part covered.

Microsoft has a license that they sublicense to DX implementations.
None of what you say here is relevant to any court in the USA.  See my
previous comments about logic and reason.
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