[Mesa-dev] llvmpipe and transform feedback of position

Dave Airlie airlied at gmail.com
Wed Dec 12 20:29:08 PST 2012


So I've been playing around a bit more with transform feedback with
llvmpipe, and it seems the position output from the vertex shader is
different from what softpipe produces.

using from piglit ./bin/ext_transform_feedback-builtin-varyings gl_Position

the position with softpipe for the first call is
0	0.00390625	0.0078125	0.01171875
for llvmpipe it is
16	10.666666	0.833333373	85.3333359

so is there some intermediate storage or transform that isn't
happening in the llvm vertex shader, that should?

I start to realise how little I know about the vertex shading side of
things, when I hit stuff like this!


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