[Mesa-dev] Another Take on the S3TC issue

[Ian Romanick]

On 08/13/2013 01:27 PM, Roland Mainz wrote:
> On Tue, Aug 13, 2013 at 10:20 PM, Ian Romanick <idr at freedesktop.org> wrote:
>> On 08/13/2013 11:53 AM, Uwe Schmidt wrote:
> [snip]
>>> SO MY PROPOSAL:
>>>
>>> If 'format' is one of the S3TC types, and format!=internalFormat is true,
>>> then set internalFormat:=format.
>>
>> 'format' cannot be a compressed type.  Compressed data can only be supplied
>> using glCompressedTexImage2D, and that function only has an internalFormat
>> parameter.
>>
>>
>>> Else, if 'internalFormat' is one of the S3TC types, but the 'format'
>>> isn't,
>>> set internalFormat:=format (or any other format, Mesa3D can encode).
>>
>>
>> The only format that Mesa can encode is FXT1.  Only Intel hardware supports
>> FXT1, and the quality (of Mesa's compressor) is not very good.  Picking that
>> format would result in bug reports of "game XYZ looks horrible on Intel
>> graphix you suck."  So that leaves us with the only option of leaving the
>> data uncompressed.
>>
>> Until S3 grants it's IP to OIN or the patents expire, this is going to be
>> the situation.  We've been through this mental exercise of the last 5 years
>> more times than I can count, and we always come back to the same place.
>
> Please don't hit me with a stick if this has been asked
> |powl(INT64_MAX, INT64_MAX)| times... but... erm... adding the code
> (sample implementation, "... do not use without a license from S3 and
> the ritual scarification of at least one software engineer...") but
> having it off in the default build won't work... right ?

That is more difficult for end-users than the current situation.  In the 
current situation, your distro can build Mesa (no S3TC), and, if you 
live in a country without software patents, you can just "drop in" the 
libtxc_dxtn library to get compression.  Putting it in Mesa, along with 
making the distros really uncomfortable, would mean you'd have to 
rebuild Mesa.

Did I mention that we've been through this mental exercise a few times?

> ----
>
> Bye,
> Roland
>