Bugzilla – Bug 45975
[Gen4 + ILK] render with pointcoord will fail to render
Last modified: 2012-05-28 01:18:48 UTC
Bug detailed description:
When rendering with pointcoord on Ironlake platforms, it will fail to render correctly.
2. run cases using pointcoord
Change the title, since this issue also existed on Gen4 platforms.
Fixed by the following commit:
Author: Yuanhan Liu <email@example.com>
Date: Mon Feb 27 15:46:32 2012 +0800
i965: handle gl_PointCoord for Gen4 and Gen5 platforms
This patch add the support of gl_PointCoord gl builtin variable for
platform gen4 and gen5(ILK).
Unlike gen6+, we don't have a hardware support of gl_PointCoord, means
hardware will not calculate the interpolation coefficient for you.
Instead, you should handle it yourself in sf shader stage.
But badly, gl_PointCoord is a FS instead of VS builtin variable, thus
it's not included in c.vue_map generated in VS stage. Thus the current
code doesn't aware of this attribute. And to handle it correctly, we
need add it to c.vue_map manually to let SF shader generate the needed
interpolation coefficient for FS shader. SF stage has it's own copy of
vue_map, thus I think it's safe to do it manually.
Since handling gl_PointCoord for gen4 and gen5 platforms is somehow a
little special, I added a lot of comments and hope I didn't overdo it ;)
v2: add a /* _NEW_BUFFERS */ comment to note the state flag dependency
and also add the _NEW_BUFFERS dirty mask (Eric).
Piglit: glsl-fs-pointcoord and fbo-gl_pointcoord
NOTE: This is a candidate for stable release branches.
Signed-off-by: Yuanhan Liu <firstname.lastname@example.org>
Reviewed-by: Eric Anholt <email@example.com>