ATI compressed texture formats & auto-compression

Hamish hamish at
Fri Apr 4 01:27:34 PDT 2008

On Thursday 03 April 2008 22:47:38 you wrote:
> > GL_ARB_texture_compression is supported... So why don't I get a value
> > besides 0 when getting GL_NUM_COMPRESSED_TEXTURE_FORMATS_ARB? Or am I
> > looking in the wrong place and the open driver doesn't actually support
> > any compressed textures?
> This is all about the unclear state of S3's texture compression patents as
> they apply to open-source GL implementations.
> In particular it's not clear if an opensource driver for ATI (or
> other)hardware can legally compress/decompress the S3TC textures - I tend
> tobelieve that this is somehow already covered by agreements the
> hardwarevendor would have with the patent holder, but like I said it's
> anunclear situation & people tend to be conservative in those cases.

OK. Thanks. I did see and understand about the software doing compression. 
(Although IIUC it's perfectly legal here since you can't patent software over 
here AFAIK). For some reason though, I was under the impression that it was 
possible in HARDWARE. Which the user already owns a license to use, since if 
it's in the chip, we'd assume that the manufacturer has already paid the 
patent holder...

> To get this working locally, there's some sort of library you can download
> & plug in yourself though...

Ah... I'll have a look. Thanks. It's really only of academic interest. I was 
wondering whether compressed textures might render faster... (Not that I have 
a problem at the moment).


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