[gnome-shell] st: Adapt the mutter implementation for create_texture_material

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

commit 05f9f991d8d5796b77def6c096a36786b5307351
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Thu Aug 7 14:06:40 2014 -0400

    st: Adapt the mutter implementation for create_texture_material
    
    This is the new API that uses set_null_texture instead of a dummy texture.

 src/st/st-private.c |   48 +++++++++++++++++++++---------------------------
 1 files changed, 21 insertions(+), 27 deletions(-)
---
diff --git a/src/st/st-private.c b/src/st/st-private.c
index e3307b0..7a846dd 100644
--- a/src/st/st-private.c
+++ b/src/st/st-private.c
@@ -171,38 +171,32 @@ _st_set_text_from_style (ClutterText *text,
 CoglHandle
 _st_create_texture_material (CoglHandle src_texture)
 {
-  static CoglHandle texture_material_template = COGL_INVALID_HANDLE;
-  CoglHandle material;
-
-  g_return_val_if_fail (src_texture != COGL_INVALID_HANDLE,
-                        COGL_INVALID_HANDLE);
-
-  /* We use a material that has a dummy texture as a base for all
-     texture materials. The idea is that only the Cogl texture object
-     would be different in the children so it is likely that Cogl will
-     be able to share GL programs between all the textures. */
-  if (G_UNLIKELY (texture_material_template == COGL_INVALID_HANDLE))
+  static CoglPipeline *texture_pipeline_template = NULL;
+  CoglPipeline *pipeline;
+
+  /* The only state used in the pipeline that would affect the shader
+     generation is the texture type on the layer. Therefore we create
+     a template pipeline which sets this state and all texture
+     pipelines are created as a copy of this. That way Cogl can find
+     the shader state for the pipeline more quickly by looking at the
+     pipeline ancestry instead of resorting to the shader cache. */
+  if (G_UNLIKELY (texture_pipeline_template == NULL))
     {
-      static const guint8 white_pixel[] = { 0xff, 0xff, 0xff, 0xff };
-      CoglHandle dummy_texture;
-
-      dummy_texture =
-        cogl_texture_new_from_data (1, 1,
-                                    COGL_TEXTURE_NONE,
-                                    COGL_PIXEL_FORMAT_RGBA_8888_PRE,
-                                    COGL_PIXEL_FORMAT_ANY,
-                                    4, white_pixel);
-
-      texture_material_template = cogl_material_new ();
-      cogl_material_set_layer (texture_material_template, 0, dummy_texture);
-      cogl_handle_unref (dummy_texture);
+      CoglContext *ctx =
+        clutter_backend_get_cogl_context (clutter_get_default_backend ());
+
+      texture_pipeline_template = cogl_pipeline_new (ctx);
+      cogl_pipeline_set_layer_null_texture (texture_pipeline_template,
+                                            0, /* layer */
+                                            COGL_TEXTURE_TYPE_2D);
     }
 
-  material = cogl_material_copy (texture_material_template);
+  pipeline = cogl_pipeline_copy (texture_pipeline_template);
 
-  cogl_material_set_layer (material, 0, src_texture);
+  if (src_texture != NULL)
+    cogl_pipeline_set_layer_texture (pipeline, 0, src_texture);
 
-  return material;
+  return pipeline;
 }
 
 /*****