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authorEric Anholt <[email protected]>2011-05-11 14:07:44 -0700
committerEric Anholt <[email protected]>2011-05-18 13:57:16 -0700
commit367020d87ce8c27aeb58b3887fbd29d216fdc151 (patch)
treeccbdecf64088e2294c67e156e78ae8d43ac21754 /src/mesa/drivers
parent51761a1aefd31b7df12edd9467ac630b9cbbbbc9 (diff)
i965/gen6: Fix blending state when no color buffer is bound.
This is part of fixing fbo-alphatest-nocolor -- a regression in 35e8fe5c99b285f348cb8a1bba2931f120f7c0a1 after the initial regression, that had us using a garbage BLEND_STATE[0] (in particular, the alpha test enable) if no color buffer was bound.
Diffstat (limited to 'src/mesa/drivers')
-rw-r--r--src/mesa/drivers/dri/i965/gen6_cc.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/src/mesa/drivers/dri/i965/gen6_cc.c b/src/mesa/drivers/dri/i965/gen6_cc.c
index 66357f00fa6..2b16d6cdc01 100644
--- a/src/mesa/drivers/dri/i965/gen6_cc.c
+++ b/src/mesa/drivers/dri/i965/gen6_cc.c
@@ -39,8 +39,18 @@ prepare_blend_state(struct brw_context *brw)
struct gen6_blend_state *blend;
int b;
int nr_draw_buffers = ctx->DrawBuffer->_NumColorDrawBuffers;
- int size = sizeof(*blend) * nr_draw_buffers;
-
+ int size;
+
+ /* We need at least one BLEND_STATE written, because we might do
+ * thread dispatch even if _NumColorDrawBuffers is 0 (for example
+ * for computed depth or alpha test), which will do an FB write
+ * with render target 0, which will reference BLEND_STATE[0] for
+ * alpha test enable.
+ */
+ if (nr_draw_buffers == 0 && ctx->Color.AlphaEnabled)
+ nr_draw_buffers = 1;
+
+ size = sizeof(*blend) * nr_draw_buffers;
blend = brw_state_batch(brw, size, 64, &brw->cc.blend_state_offset);
memset(blend, 0, size);