[Mesa-dev] [PATCH 11/18] i965: Check for alpha channel just like in gen6+.

[Rafael Antognolli]

gen6+ uses _mesa_base_format_has_channel() to check for the alpha
channel, while gen4-5 use ctx->DrawBuffer->Visual.alphaBits. By using
_mesa_base_format_has_channel() here we keep the same behavior accross
all gen.

While initially both ways of checking the alpha channel seemed correct
to me, this change also seems to fix fbo-blending-formats piglit test on
gen4.

Signed-off-by: Rafael Antognolli <rafael.antognolli at intel.com>
---
 src/mesa/drivers/dri/i965/brw_cc.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_cc.c b/src/mesa/drivers/dri/i965/brw_cc.c
index 78d3bc8..cdaa696 100644
--- a/src/mesa/drivers/dri/i965/brw_cc.c
+++ b/src/mesa/drivers/dri/i965/brw_cc.c
@@ -34,6 +34,7 @@
 #include "brw_state.h"
 #include "brw_defines.h"
 #include "brw_util.h"
+#include "main/glformats.h"
 #include "main/macros.h"
 #include "main/stencil.h"
 #include "intel_batchbuffer.h"
@@ -122,25 +123,27 @@ static void upload_cc_unit(struct brw_context *brw)
       GLenum srcA = ctx->Color.Blend[0].SrcA;
       GLenum dstA = ctx->Color.Blend[0].DstA;
 
+      if (eqRGB == GL_MIN || eqRGB == GL_MAX) {
+	 srcRGB = dstRGB = GL_ONE;
+      }
+
+      if (eqA == GL_MIN || eqA == GL_MAX) {
+	 srcA = dstA = GL_ONE;
+      }
+
       /* If the renderbuffer is XRGB, we have to frob the blend function to
        * force the destination alpha to 1.0.  This means replacing GL_DST_ALPHA
        * with GL_ONE and GL_ONE_MINUS_DST_ALPHA with GL_ZERO.
        */
-      if (ctx->DrawBuffer->Visual.alphaBits == 0) {
+      const struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];
+      if (rb && !_mesa_base_format_has_channel(rb->_BaseFormat,
+                                               GL_TEXTURE_ALPHA_TYPE)) {
 	 srcRGB = brw_fix_xRGB_alpha(srcRGB);
 	 srcA   = brw_fix_xRGB_alpha(srcA);
 	 dstRGB = brw_fix_xRGB_alpha(dstRGB);
 	 dstA   = brw_fix_xRGB_alpha(dstA);
       }
 
-      if (eqRGB == GL_MIN || eqRGB == GL_MAX) {
-	 srcRGB = dstRGB = GL_ONE;
-      }
-
-      if (eqA == GL_MIN || eqA == GL_MAX) {
-	 srcA = dstA = GL_ONE;
-      }
-
       cc->cc6.dest_blend_factor = brw_translate_blend_factor(dstRGB);
       cc->cc6.src_blend_factor = brw_translate_blend_factor(srcRGB);
       cc->cc6.blend_function = brw_translate_blend_equation(eqRGB);
-- 
2.9.4