ATI compressed texture formats & auto-compression

[Ian Romanick]

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Hamish wrote:

| In my OpenGL SUperBible, there's a section on compressed textures.
According
| to the code in there you can get the hardware to compress a texture when
| loading it... But I can't seem to get a sane response from OpenGL when
I'm
| doing it...

[snip]

| glxinfo says
|
| 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 the typical OpenGL way of doing things.  The existence of the
means that the functionality is there to ask which, *if any*, compressed
formats the hardware / driver supports.  Right now, none of the drivers
except Intel support any compressed formats out of the box.  Intel
happens to support 3dfx's texture compression (FXT1).

Perhaps someone may have some insight as to why FXT1 never caught on.

As Keith mentioned, S3TC isn't supported out-of-the-box due to S3's
patents.  Google may help you find a work-around.

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