[Mesa-dev] i965 Gen4/5: Garbage rendering when gl_BackColor is written but gl_FrontColor is not

Chris Forbes chrisf at ijw.co.nz
Sun Jun 9 03:30:05 PDT 2013

I noticed that if you write gl_BackColor but not gl_FrontColor, the
value that lands in gl_Color in the fragment shader is junk; same for
the corresponding secondary color builtins. This causes us to fail 12
of the interpolation piglits.

There's a series from July of last year which was supposed to fix this:


... but it looks like it went nowhere.

What's the current thinking on this? I'm happy to do the work if
there's some consensus.

-- Chris

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