[Mesa-dev] [PATCH 2/9] i915: Fix GL_DOT3_RGBA a bit

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

The spec says using DOT4 for alpha is undefined unless DOT4 is also used
for color. It seems to do the right thing anyway, but better safe than sorry.

Also override numAlphaArgs to 2 for DOT4 since that's what it wants.
This migth fix something in case the specified alpha mode has only one
argument. Also avoids emitting a needless 3DSTATE_MAP_BLEND_ARG if
the specified alpha mode has three arguments.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 src/mesa/drivers/dri/i915/i830_texblend.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i915/i830_texblend.c b/src/mesa/drivers/dri/i915/i830_texblend.c
index 236be59..feea383 100644
--- a/src/mesa/drivers/dri/i915/i830_texblend.c
+++ b/src/mesa/drivers/dri/i915/i830_texblend.c
@@ -136,7 +136,7 @@ i830SetTexEnvCombine(struct i830_context * i830,
                      GLuint texel_op, GLuint * state, const GLfloat * factor)
 {
    const GLuint numColorArgs = combine->_NumArgsRGB;
-   const GLuint numAlphaArgs = combine->_NumArgsA;
+   GLuint numAlphaArgs = combine->_NumArgsA;
 
    GLuint blendop;
    GLuint ablendop;
@@ -209,7 +209,7 @@ i830SetTexEnvCombine(struct i830_context * i830,
       break;
    case GL_DOT3_RGBA_EXT:
    case GL_DOT3_RGBA:
-      blendop = TEXBLENDOP_DOT3;
+      blendop = TEXBLENDOP_DOT4;
       break;
    default:
       return pass_through(state, blendUnit);
@@ -273,6 +273,7 @@ i830SetTexEnvCombine(struct i830_context * i830,
    if (combine->ModeRGB == GL_DOT3_RGBA_EXT ||
        combine->ModeRGB == GL_DOT3_RGBA) {
       ablendop = TEXBLENDOP_DOT4;
+      numAlphaArgs = 2;
       args_A[0] = TEXBLENDARG_FACTOR;   /* the global factor */
       args_A[1] = TEXBLENDARG_FACTOR;
       args_A[2] = TEXBLENDARG_FACTOR;
-- 
1.8.5.5