shaped-texture: Pass along the snippet to the texture tower

The snippet is used make sure the right source is sampled in the shader.
This wasn't done in the texture tower, meaning the textures from the
tower were not correct.

Related: https://gitlab.gnome.org/GNOME/mutter/-/issues/528
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2278>

src/compositor/meta-shaped-texture.c

@@ -1144,6 +1144,8 @@ meta_shaped_texture_set_snippet (MetaShapedTexture *stex,
   g_clear_pointer (&stex->snippet, cogl_object_unref);
   if (snippet)
     stex->snippet = cogl_object_ref (snippet);
+
+  meta_texture_tower_set_snippet (stex->paint_tower, snippet);
 }
 
 /**

src/compositor/meta-texture-tower.c

@@ -62,6 +62,7 @@ struct _MetaTextureTower
   CoglOffscreen *fbos[MAX_TEXTURE_LEVELS];
   Box invalid[MAX_TEXTURE_LEVELS];
   CoglPipeline *pipeline_template;
+  CoglSnippet *snippet;
 };
 
 /**
@@ -97,6 +98,7 @@ meta_texture_tower_free (MetaTextureTower *tower)
     cogl_object_unref (tower->pipeline_template);
 
   meta_texture_tower_set_base_texture (tower, NULL);
+  cogl_clear_object (&tower->snippet);
 
   g_free (tower);
 }
@@ -216,6 +218,28 @@ meta_texture_tower_update_area (MetaTextureTower *tower,
     }
 }
 
+void
+meta_texture_tower_set_snippet (MetaTextureTower *tower,
+                                CoglSnippet      *snippet)
+{
+  int i;
+
+  if (tower->snippet == snippet)
+    return;
+
+  g_clear_pointer (&tower->snippet, cogl_object_unref);
+
+  if (snippet)
+    tower->snippet = cogl_object_ref (snippet);
+
+  for (i = 1; i < tower->n_levels; i++)
+    {
+      cogl_clear_object (&tower->textures[i]);
+      g_clear_object (&tower->fbos[i]);
+    }
+  cogl_clear_object (&tower->pipeline_template);
+}
+
 /* It generally looks worse if we scale up a window texture by even a
  * small amount than if we scale it down using bilinear filtering, so
  * we always pick the *larger* adjacent level. */
@@ -410,6 +434,9 @@ texture_tower_revalidate (MetaTextureTower *tower,
   pipeline = cogl_pipeline_copy (tower->pipeline_template);
   cogl_pipeline_set_layer_texture (pipeline, 0, tower->textures[level - 1]);
 
+  if (tower->snippet && level == 1)
+    cogl_pipeline_add_layer_snippet (pipeline, 0, tower->snippet);
+
   cogl_framebuffer_draw_textured_rectangle (fb, pipeline,
                                             invalid->x1, invalid->y1,
                                             invalid->x2, invalid->y2,

src/compositor/meta-texture-tower.h

@@ -63,6 +63,9 @@ void              meta_texture_tower_update_area       (MetaTextureTower *tower,
 CoglTexture      *meta_texture_tower_get_paint_texture (MetaTextureTower    *tower,
                                                         ClutterPaintContext *paint_context);
 
+void meta_texture_tower_set_snippet (MetaTextureTower *tower,
+                                     CoglSnippet      *snippet);
+
 G_END_DECLS
 
 #endif /* __META_TEXTURE_TOWER_H__ */