From 6ea4c67ba24194b4411897af07bf8a9584e26edc Mon Sep 17 00:00:00 2001
From: Neil Roberts <neil@linux.intel.com>
Date: Thu, 13 May 2010 13:17:19 +0100
Subject: [PATCH] cogl-material: Enable blending if a transparent blend constant is used

If the blend constant is used by one of the blending factors and the
constant is not fully opaque then blending will now be enabled.
---
 clutter/cogl/cogl/cogl-material.c |   55 +++++++++++++++++++++++++-----------
 1 files changed, 38 insertions(+), 17 deletions(-)

diff --git a/clutter/cogl/cogl/cogl-material.c b/clutter/cogl/cogl/cogl-material.c
index 5c6b93b..0bd071f 100644
--- a/clutter/cogl/cogl/cogl-material.c
+++ b/clutter/cogl/cogl/cogl-material.c
@@ -166,6 +166,28 @@ _cogl_material_free (CoglMaterial *material)
   g_slice_free (CoglMaterial, material);
 }

+#ifndef HAVE_COGL_GLES
+
+static gboolean
+blend_factor_uses_constant (GLenum blend_factor)
+{
+  return (blend_factor == GL_CONSTANT_COLOR ||
+          blend_factor == GL_ONE_MINUS_CONSTANT_COLOR ||
+          blend_factor == GL_CONSTANT_ALPHA ||
+          blend_factor == GL_ONE_MINUS_CONSTANT_ALPHA);
+}
+
+static gboolean
+_cogl_material_any_blend_factor_uses_constant (CoglMaterial *material)
+{
+  return (blend_factor_uses_constant (material->blend_src_factor_rgb) ||
+          blend_factor_uses_constant (material->blend_src_factor_alpha) ||
+          blend_factor_uses_constant (material->blend_dst_factor_rgb) ||
+          blend_factor_uses_constant (material->blend_dst_factor_alpha));
+}
+
+#endif /* HAVE_COGL_GLES */
+
 static gboolean
 _cogl_material_needs_blending_enabled (CoglMaterial *material,
                                        GLubyte      *override_color)
@@ -188,6 +210,12 @@ _cogl_material_needs_blending_enabled (CoglMaterial *material,
       material->emission[3] != 1.0f)
     return TRUE;

+#ifndef HAVE_COGL_GLES
+  if (_cogl_material_any_blend_factor_uses_constant (material) &&
+      material->blend_constant[3] != 1.0f)
+    return TRUE;
+#endif
+
   for (tmp = material->layers; tmp != NULL; tmp = tmp->next)
     {
       CoglMaterialLayer *layer = tmp->data;
@@ -707,6 +735,10 @@ cogl_material_set_blend (CoglHandle handle,

   material->flags &= ~COGL_MATERIAL_FLAG_DEFAULT_BLEND;

+  /* If the blend mode is changed to use a the blend constant for one
+     of the factors then it may now need blending enabled */
+  handle_automatic_blend_enable (material);
+
   return TRUE;
 }

@@ -732,6 +764,11 @@ cogl_material_set_blend_constant (CoglHandle handle,
   constant[3] = cogl_color_get_alpha_float (constant_color);

   material->flags &= ~COGL_MATERIAL_FLAG_DEFAULT_BLEND;
+
+  /* If the constant is not fully opaque then the material may now
+     need blending enabled */
+  handle_automatic_blend_enable (material);
+
 #endif
 }

@@ -1636,19 +1673,6 @@ _cogl_material_flush_layers_gl_state (CoglMaterial *material,
     }
 }

-#ifndef HAVE_COGL_GLES
-
-static gboolean
-blend_factor_uses_constant (GLenum blend_factor)
-{
-  return (blend_factor == GL_CONSTANT_COLOR ||
-          blend_factor == GL_ONE_MINUS_CONSTANT_COLOR ||
-          blend_factor == GL_CONSTANT_ALPHA ||
-          blend_factor == GL_ONE_MINUS_CONSTANT_ALPHA);
-}
-
-#endif
-
 static void
 _cogl_material_flush_base_gl_state (CoglMaterial *material,
                                     gboolean skip_gl_color)
@@ -1717,10 +1741,7 @@ _cogl_material_flush_base_gl_state (CoglMaterial *material,
       else
         GE (glBlendEquation (material->blend_equation_rgb));

-      if (blend_factor_uses_constant (material->blend_src_factor_rgb) ||
-          blend_factor_uses_constant (material->blend_src_factor_alpha) ||
-          blend_factor_uses_constant (material->blend_dst_factor_rgb) ||
-          blend_factor_uses_constant (material->blend_dst_factor_alpha))
+      if (_cogl_material_any_blend_factor_uses_constant (material))
         GE (glBlendColor (material->blend_constant[0],
                           material->blend_constant[1],
                           material->blend_constant[2],
--
1.6.5.rc1.46.g4d818