[mutter] tower: make sure not to blend when updating tower

[Jasper St. Pierre <jstpierre src gnome org>]

commit 2b940f6ababcfa7c02616574bc8a5203e582e86d
Author: Robert Bragg <robert linux intel com>
Date:   Wed Aug 21 01:52:16 2013 +0100

    tower: make sure not to blend when updating tower
    
    Each level in the tower is initialized by binding the texture for that
    level to an offscreen framebuffer and rendering the previous level as a
    textured rectangle. The problem was that we were blending the previous
    level with undefined data so argb32 windows with transparencies would
    result in artefacts. This makes sure to disable blending when drawing
    the textured rectangle.

 src/compositor/meta-texture-tower.c |   49 +++++++++++++++++++++++-----------
 1 files changed, 33 insertions(+), 16 deletions(-)
---
diff --git a/src/compositor/meta-texture-tower.c b/src/compositor/meta-texture-tower.c
index 6c2b900..fd28983 100644
--- a/src/compositor/meta-texture-tower.c
+++ b/src/compositor/meta-texture-tower.c
@@ -62,6 +62,7 @@ struct _MetaTextureTower
   CoglTexture *textures[MAX_TEXTURE_LEVELS];
   CoglOffscreen *fbos[MAX_TEXTURE_LEVELS];
   Box invalid[MAX_TEXTURE_LEVELS];
+  CoglPipeline *pipeline_template;
 };
 
 /**
@@ -93,6 +94,9 @@ meta_texture_tower_free (MetaTextureTower *tower)
 {
   g_return_if_fail (tower != NULL);
 
+  if (tower->pipeline_template != NULL)
+    cogl_object_unref (tower->pipeline_template);
+
   meta_texture_tower_set_base_texture (tower, NULL);
 
   g_slice_free (MetaTextureTower, tower);
@@ -394,30 +398,43 @@ texture_tower_revalidate_fbo (MetaTextureTower *tower,
   int dest_texture_width = cogl_texture_get_width (dest_texture);
   int dest_texture_height = cogl_texture_get_height (dest_texture);
   Box *invalid = &tower->invalid[level];
-  CoglMatrix modelview;
+  CoglFramebuffer *fb;
+  CoglError *catch_error = NULL;
+  CoglPipeline *pipeline;
 
   if (tower->fbos[level] == NULL)
-    tower->fbos[level] = cogl_offscreen_new_to_texture (dest_texture);
+    tower->fbos[level] = cogl_offscreen_new_with_texture (dest_texture);
 
-  if (tower->fbos[level] == NULL)
-    return FALSE;
+  fb = COGL_FRAMEBUFFER (tower->fbos[level]);
 
-  cogl_push_framebuffer (COGL_FRAMEBUFFER (tower->fbos[level]));
+  if (!cogl_framebuffer_allocate (fb, &catch_error))
+    {
+      cogl_error_free (catch_error);
+      return FALSE;
+    }
 
-  cogl_ortho (0, dest_texture_width, dest_texture_height, 0, -1., 1.);
+  cogl_framebuffer_orthographic (fb, 0, 0, dest_texture_width, dest_texture_height, -1., 1.);
+
+  if (!tower->pipeline_template)
+    {
+      CoglContext *ctx =
+        clutter_backend_get_cogl_context (clutter_get_default_backend ());
+      tower->pipeline_template = cogl_pipeline_new (ctx);
+      cogl_pipeline_set_blend (tower->pipeline_template, "RGBA = ADD (SRC_COLOR, 0)", NULL);
+    }
 
-  cogl_matrix_init_identity (&modelview);
-  cogl_set_modelview_matrix (&modelview);
+  pipeline = cogl_pipeline_copy (tower->pipeline_template);
+  cogl_pipeline_set_layer_texture (pipeline, 0, tower->textures[level - 1]);
 
-  cogl_set_source_texture (tower->textures[level - 1]);
-  cogl_rectangle_with_texture_coords (invalid->x1, invalid->y1,
-                                      invalid->x2, invalid->y2,
-                                      (2. * invalid->x1) / source_texture_width,
-                                      (2. * invalid->y1) / source_texture_height,
-                                      (2. * invalid->x2) / source_texture_width,
-                                      (2. * invalid->y2) / source_texture_height);
+  cogl_framebuffer_draw_textured_rectangle (fb, pipeline,
+                                            invalid->x1, invalid->y1,
+                                            invalid->x2, invalid->y2,
+                                            (2. * invalid->x1) / source_texture_width,
+                                            (2. * invalid->y1) / source_texture_height,
+                                            (2. * invalid->x2) / source_texture_width,
+                                            (2. * invalid->y2) / source_texture_height);
 
-  cogl_pop_framebuffer ();
+  cogl_object_unref (pipeline);
 }
 
 static void