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.
---
src/mesa/drivers/dri/i965/gen6_cc.c | 12 +++++++++++-
1 files changed, 11 insertions(+), 1 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/gen6_cc.c
b/src/mesa/drivers/dri/i965/gen6_cc.c
index 66357f0..2b16d6c 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);
--
1.7.5.1
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