Mesa (master): i965/msaa: Implement GL_SAMPLE_ALPHA_TO_{COVERAGE, ONE}.
Paul Berry
stereotype441 at kemper.freedesktop.org
Tue Jun 26 14:49:20 UTC 2012
Module: Mesa
Branch: master
Commit: bc53e14d98de11593788d302c0bb198e3a2097a4
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=bc53e14d98de11593788d302c0bb198e3a2097a4
Author: Paul Berry <stereotype441 at gmail.com>
Date: Fri Jun 22 20:27:18 2012 -0700
i965/msaa: Implement GL_SAMPLE_ALPHA_TO_{COVERAGE,ONE}.
This patch enables the multisampling parameters
GL_SAMPLE_ALPHA_TO_COVERAGE and GL_SAMPLE_ALPHA_TO_ONE, which allow
the fragment shader's alpha output to be converted into a sample
coverage mask and ignored for blending. i965 supports these
parameters through the BLEND_STATE structure.
The GL spec allows, but does not require, the implementation to dither
the conversion from alpha to a sample coverage mask, so that alpha
values that aren't a multiple of 1/num_samples result in the correct
proportion of samples being lit. A bit exists in the BLEND_STATE
structure to enable this functionality, but according to the hardware
docs it must be disabled on Sandy Bridge (see the Sandy Bridge PRM,
Vol2, Part1, p379: AlphaToCoverage Dither Enable). So it is enabled
for Gen7 only.
Fixes piglit tests
"EXT_framebuffer_multisample/sample-alpha-to-{coverage,one} {2,4}".
Reviewed-by: Anuj Phogat <anuj.phogat at gmail.com>
---
src/mesa/drivers/dri/i965/gen6_cc.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/gen6_cc.c b/src/mesa/drivers/dri/i965/gen6_cc.c
index b4c5329..e0523ef 100644
--- a/src/mesa/drivers/dri/i965/gen6_cc.c
+++ b/src/mesa/drivers/dri/i965/gen6_cc.c
@@ -161,6 +161,13 @@ gen6_upload_blend_state(struct brw_context *brw)
blend[b].blend1.write_disable_g = !ctx->Color.ColorMask[b][1];
blend[b].blend1.write_disable_b = !ctx->Color.ColorMask[b][2];
blend[b].blend1.write_disable_a = !ctx->Color.ColorMask[b][3];
+
+ /* _NEW_MULTISAMPLE */
+ blend[b].blend1.alpha_to_coverage =
+ ctx->Multisample._Enabled && ctx->Multisample.SampleAlphaToCoverage;
+ blend[b].blend1.alpha_to_one =
+ ctx->Multisample._Enabled && ctx->Multisample.SampleAlphaToOne;
+ blend[b].blend1.alpha_to_coverage_dither = (brw->intel.gen >= 7);
}
brw->state.dirty.cache |= CACHE_NEW_BLEND_STATE;
@@ -169,7 +176,8 @@ gen6_upload_blend_state(struct brw_context *brw)
const struct brw_tracked_state gen6_blend_state = {
.dirty = {
.mesa = (_NEW_COLOR |
- _NEW_BUFFERS),
+ _NEW_BUFFERS |
+ _NEW_MULTISAMPLE),
.brw = BRW_NEW_BATCH,
.cache = 0,
},
More information about the mesa-commit
mailing list