mesa: Keep a computed value for dual source blend func with each buffer.

The i965 driver needed this as well for hardware setup, so instead of
duplicating the logic, just save it off.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Dave Airlie <airlied@redhat.com>

src/mesa/main/blend.c

@@ -166,6 +166,24 @@ _mesa_BlendFunc( GLenum sfactor, GLenum dfactor )
    _mesa_BlendFuncSeparateEXT(sfactor, dfactor, sfactor, dfactor);
 }
 
+static GLboolean
+blend_factor_is_dual_src(GLenum factor)
+{
+   return (factor == GL_SRC1_COLOR ||
+	   factor == GL_SRC1_ALPHA ||
+	   factor == GL_ONE_MINUS_SRC1_COLOR ||
+	   factor == GL_ONE_MINUS_SRC1_ALPHA);
+}
+
+static void
+update_uses_dual_src(struct gl_context *ctx, int buf)
+{
+   ctx->Color.Blend[buf]._UsesDualSrc =
+      (blend_factor_is_dual_src(ctx->Color.Blend[buf].SrcRGB) ||
+       blend_factor_is_dual_src(ctx->Color.Blend[buf].DstRGB) ||
+       blend_factor_is_dual_src(ctx->Color.Blend[buf].SrcA) ||
+       blend_factor_is_dual_src(ctx->Color.Blend[buf].DstA));
+}
 
 /**
  * Set the separate blend source/dest factors for all draw buffers.
@@ -220,6 +238,7 @@ _mesa_BlendFuncSeparateEXT( GLenum sfactorRGB, GLenum dfactorRGB,
       ctx->Color.Blend[buf].DstRGB = dfactorRGB;
       ctx->Color.Blend[buf].SrcA = sfactorA;
       ctx->Color.Blend[buf].DstA = dfactorA;
+      update_uses_dual_src(ctx, buf);
    }
    ctx->Color._BlendFuncPerBuffer = GL_FALSE;
 
@@ -282,6 +301,7 @@ _mesa_BlendFuncSeparatei(GLuint buf, GLenum sfactorRGB, GLenum dfactorRGB,
    ctx->Color.Blend[buf].DstRGB = dfactorRGB;
    ctx->Color.Blend[buf].SrcA = sfactorA;
    ctx->Color.Blend[buf].DstA = dfactorA;
+   update_uses_dual_src(ctx, buf);
    ctx->Color._BlendFuncPerBuffer = GL_TRUE;
 
    if (ctx->Driver.BlendFuncSeparatei) {

src/mesa/main/context.c

@@ -1703,13 +1703,6 @@ _mesa_set_mvp_with_dp4( struct gl_context *ctx,
    ctx->mvp_with_dp4 = flag;
 }
 
-static GLboolean
-blend_factor_is_dual_src(GLenum factor)
-{
-   return factor == GL_SRC1_COLOR || factor == GL_SRC1_ALPHA ||
-      factor == GL_ONE_MINUS_SRC1_COLOR || factor == GL_ONE_MINUS_SRC1_ALPHA;
-}
-
 /*
  * ARB_blend_func_extended - ERRORS section
  * "The error INVALID_OPERATION is generated by Begin or any procedure that
@@ -1722,18 +1715,15 @@ static GLboolean
 _mesa_check_blend_func_error(struct gl_context *ctx)
 {
    GLuint i;
-   for (i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) {
+   for (i = ctx->Const.MaxDualSourceDrawBuffers;
-      if (blend_factor_is_dual_src(ctx->Color.Blend[i].SrcRGB) ||
+	i < ctx->DrawBuffer->_NumColorDrawBuffers;
-          blend_factor_is_dual_src(ctx->Color.Blend[i].DstRGB) ||
+	i++) {
-          blend_factor_is_dual_src(ctx->Color.Blend[i].SrcA) ||
+      if (ctx->Color.Blend[i]._UsesDualSrc) {
-          blend_factor_is_dual_src(ctx->Color.Blend[i].DstA)) {
-         if (i >= ctx->Const.MaxDualSourceDrawBuffers) {
 	 _mesa_error(ctx, GL_INVALID_OPERATION,
 		     "dual source blend on illegal attachment");
 	 return GL_FALSE;
       }
    }
-   }
    return GL_TRUE;
 }
 

src/mesa/main/mtypes.h

@@ -755,6 +755,11 @@ struct gl_colorbuffer_attrib
       GLenum DstA;               /**< Alpha blend dest term */
       GLenum EquationRGB;        /**< GL_ADD, GL_SUBTRACT, etc. */
       GLenum EquationA;          /**< GL_ADD, GL_SUBTRACT, etc. */
+      /**
+       * Set if any blend factor uses SRC1.  Computed at the time blend factors
+       * get set.
+       */
+      GLboolean _UsesDualSrc;
    } Blend[MAX_DRAW_BUFFERS];
    /** Are the blend func terms currently different for each buffer/target? */
    GLboolean _BlendFuncPerBuffer;