Re: [AD] WIP compressed texture support patch

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On 12/09/2014 08:35 PM, SiegeLordEx wrote:
On 12/09/2014 02:33 PM, Trent Gamblin wrote:
Does the OpenGL flipping thing in any way potentially cause patent
issues? I
notice it's almost decoding and re-encoding rows, but I'm no expert.

Yeah, I am a little worried about that. The code is not doing any
compression/decompression, but merely taking advantage of the memory
layout of the blocks. Some of these layouts are the same as those used
by formats which are not patent encumbered (e.g. consider RGTC which
uses the same format as the alpha block of DXT5). Mesa implements RGTC,
so it must be fine by them.

I looked a little more into this, and I think we're almost certainly in the clear. To infringe on a patent, you need to implement all of its claims. Since a few of the claims of the S3TC patent are explicitly about compression/decompression (which we don't do), I don't think we are anywhere close to infringing.

-SL




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