[Mesa-dev] [PATCH 0/8] i965: Adding TXD/textureGrad support.

[Kenneth Graunke]

I'd really like to land this for 7.11---apparently Wine applications
really want GL_ARB_shader_texture_lod in place for SM3 shaders.

The extension adds two parts: textureLod in the fragment shader, and
textureGrad in both targets.  Lod works fine.  Grad...is tricky.

Much more testing is required.  So far, I've run Marek's piglit test
(arb_shader_texture_lod-texgrad) on Sandybridge and Ivybridge.  One
pixel fails the probe (Eric thinks it's due to a pre-existing bug in
our dFdy implementation), but visually it looks correct.

So I think color buffers work fine.  Unfortunately, shadow2DGrad and
depth textures are where all the madness comes into play.  It's very
likely broken, especially on pre-Ivybridge.  But that's sooo niche. :)

Anyway, I figured some initial review wouldn't hurt.  Better than
letting this code languish any longer.

--Kenneth