clutter-offscreen-effect: Don't recreate the material when FBO changes

Previously whenever the size of the FBO changes it would create a new
material and attach the texture to it. This is not good for Cogl
because it throws away any cached state for the material. In
test-rotate the size of the FBO changes constantly so it effectively
uses a new material every paint. For shader effects this also ends up
relinking the shader every paint because the linked programs are part
of the material state.

diff --git a/clutter/clutter-offscreen-effect.c b/clutter/clutter-offscreen-effect.c
index 21b3035..f034cfd 100644 (file)
--- a/clutter/clutter-offscreen-effect.c
+++ b/clutter/clutter-offscreen-effect.c
@@ -152,13 +152,8 @@ update_fbo (ClutterEffect *effect, int fbo_width, int fbo_height)
       priv->target_height == fbo_height)
     return TRUE;
 
-  if (priv->target != COGL_INVALID_HANDLE)
-    {
-      cogl_handle_unref (priv->target);
-      cogl_handle_unref (priv->offscreen);
-    }
-
-  priv->target = cogl_material_new ();
+  if (priv->target == COGL_INVALID_HANDLE)
+    priv->target = cogl_material_new ();
 
   texture =
     clutter_offscreen_effect_create_texture (self, fbo_width, fbo_height);
@@ -175,6 +170,9 @@ update_fbo (ClutterEffect *effect, int fbo_width, int fbo_height)
   priv->target_width = cogl_texture_get_width (texture);
   priv->target_height = cogl_texture_get_height (texture);
 
+  if (priv->offscreen != COGL_INVALID_HANDLE)
+    cogl_handle_unref (priv->offscreen);
+
   priv->offscreen = cogl_offscreen_new_to_texture (texture);
   if (priv->offscreen == COGL_INVALID_HANDLE)
     {