Current implementation of arb_sample_shading doesn't set 'Barycentric
Interpolation Mode' correctly. We use pixel barycentric coordinates
for per sample shading. Instead we should select perspective sample
or non-perspective sample barycentric coordinates.
It also enables using sample barycentric coordinates in case of a
fragment shader variable declared with 'sample' qualifier.
e.g. sample in vec4 pos;
A piglit test to verify the implementation has been posted on piglit
mailing list for review.
V2: Do not interpolate all the 'in' variables at sample position
if fragment shader uses 'sample' qualifier with one of them.
For example we have a fragment shader:
#version 330
#extension ARB_gpu_shader5: require
sample in vec4 a;
in vec4 b;
main()
{
...
}
Only 'a' should be sampled at sample location, not 'b'.
Cc: mesa-stable@lists.freedesktop.org
Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>
Anuj Phogat
a92e5f7cf6