[mutter/gbsneto/actor-node-improvements: 3/3] clutter/actor: Cull actor out before painting

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 614a47979a431222a78fd4ad3a415465b54edd1f
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Sun Oct 27 08:40:45 2019 -0300

    clutter/actor: Cull actor out before painting
    
    Right now, we create the actor paint nodes before
    checking with the paint volume if the actor is
    out of bounds. When the actor is indeed out of
    bounds, we'll discard the paint nodes and bail
    out.
    
    This is a slight waste of CPU, since we can
    check the paint volumes before creating the
    paint nodes, and thus avoid creating them
    unecessarily.
    
    Move the cull checks to before paint node
    creating in clutter_actor_paint().

 clutter/clutter/clutter-actor.c | 112 ++++++++++++++++++++--------------------
 1 file changed, 56 insertions(+), 56 deletions(-)
---
diff --git a/clutter/clutter/clutter-actor.c b/clutter/clutter/clutter-actor.c
index cf543e821..cbf201e87 100644
--- a/clutter/clutter/clutter-actor.c
+++ b/clutter/clutter/clutter-actor.c
@@ -3944,6 +3944,62 @@ clutter_actor_paint (ClutterActor *self)
 
   clutter_actor_ensure_resource_scale (self);
 
+  /* We check whether we need to add the flatten effect before
+   * each paint so that we can avoid having a mechanism for
+   * applications to notify when the value of the
+   * has_overlaps virtual changes.
+   */
+  add_or_remove_flatten_effect (self);
+
+  /* We save the current paint volume so that the next time the
+   * actor queues a redraw we can constrain the redraw to just
+   * cover the union of the new bounding box and the old.
+   *
+   * We also fetch the current paint volume to perform culling so
+   * we can avoid painting actors outside the current clip region.
+   *
+   * If we are painting inside a clone, we should neither update
+   * the paint volume or use it to cull painting, since the paint
+   * box represents the location of the source actor on the
+   * screen.
+   *
+   * XXX: We are starting to do a lot of vertex transforms on
+   * the CPU in a typical paint, so at some point we should
+   * audit these and consider caching some things.
+   *
+   * NB: We don't perform culling while picking at this point because
+   * clutter-stage.c doesn't setup the clipping planes appropriately.
+   *
+   * NB: We don't want to update the last-paint-volume during picking
+   * because the last-paint-volume is used to determine the old screen
+   * space location of an actor that has moved so we can know the
+   * minimal region to redraw to clear an old view of the actor. If we
+   * update this during picking then by the time we come around to
+   * paint then the last-paint-volume would likely represent the new
+   * actor position not the old.
+   */
+  if (!in_clone_paint ())
+    {
+      gboolean success;
+      /* annoyingly gcc warns if uninitialized even though
+       * the initialization is redundant :-( */
+      ClutterCullResult result = CLUTTER_CULL_RESULT_IN;
+
+      if (G_LIKELY ((clutter_paint_debug_flags &
+                     (CLUTTER_DEBUG_DISABLE_CULLING |
+                      CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS)) !=
+                    (CLUTTER_DEBUG_DISABLE_CULLING |
+                     CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS)))
+        _clutter_actor_update_last_paint_volume (self);
+
+      success = cull_actor (self, &result);
+
+      if (G_UNLIKELY (clutter_paint_debug_flags & CLUTTER_DEBUG_REDRAWS))
+        _clutter_actor_paint_cull_result (self, success, result, actor_node);
+      else if (result == CLUTTER_CULL_RESULT_OUT && success)
+        return;
+    }
+
   actor_node = clutter_actor_node_new (self);
   root_node = clutter_paint_node_ref (actor_node);
 
@@ -4026,62 +4082,6 @@ clutter_actor_paint (ClutterActor *self)
 #endif /* CLUTTER_ENABLE_DEBUG */
     }
 
-  /* We check whether we need to add the flatten effect before
-   * each paint so that we can avoid having a mechanism for
-   * applications to notify when the value of the
-   * has_overlaps virtual changes.
-   */
-  add_or_remove_flatten_effect (self);
-
-  /* We save the current paint volume so that the next time the
-   * actor queues a redraw we can constrain the redraw to just
-   * cover the union of the new bounding box and the old.
-   *
-   * We also fetch the current paint volume to perform culling so
-   * we can avoid painting actors outside the current clip region.
-   *
-   * If we are painting inside a clone, we should neither update
-   * the paint volume or use it to cull painting, since the paint
-   * box represents the location of the source actor on the
-   * screen.
-   *
-   * XXX: We are starting to do a lot of vertex transforms on
-   * the CPU in a typical paint, so at some point we should
-   * audit these and consider caching some things.
-   *
-   * NB: We don't perform culling while picking at this point because
-   * clutter-stage.c doesn't setup the clipping planes appropriately.
-   *
-   * NB: We don't want to update the last-paint-volume during picking
-   * because the last-paint-volume is used to determine the old screen
-   * space location of an actor that has moved so we can know the
-   * minimal region to redraw to clear an old view of the actor. If we
-   * update this during picking then by the time we come around to
-   * paint then the last-paint-volume would likely represent the new
-   * actor position not the old.
-   */
-  if (!in_clone_paint ())
-    {
-      gboolean success;
-      /* annoyingly gcc warns if uninitialized even though
-       * the initialization is redundant :-( */
-      ClutterCullResult result = CLUTTER_CULL_RESULT_IN;
-
-      if (G_LIKELY ((clutter_paint_debug_flags &
-                     (CLUTTER_DEBUG_DISABLE_CULLING |
-                      CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS)) !=
-                    (CLUTTER_DEBUG_DISABLE_CULLING |
-                     CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS)))
-        _clutter_actor_update_last_paint_volume (self);
-
-      success = cull_actor (self, &result);
-
-      if (G_UNLIKELY (clutter_paint_debug_flags & CLUTTER_DEBUG_REDRAWS))
-        _clutter_actor_paint_cull_result (self, success, result, actor_node);
-      else if (result == CLUTTER_CULL_RESULT_OUT && success)
-        return;
-    }
-
   if (priv->effects == NULL)
     priv->next_effect_to_paint = NULL;
   else