[mutter/gbsneto/pick-culling: 3/3] clutter/actor: Cull out when picking

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

commit f56d77f7aa7ee6b634685dc58d268c7ee2df9951
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Thu Oct 22 21:12:10 2020 -0300

    clutter/actor: Cull out when picking
    
    Testing points and rays against boxes is substantially cheaper - in
    fact, almost trivial - compared to triangles. Check if the actor's
    paint volume doesn't intersect with the current pick point / ray,
    and skip recursing altogether in those cases.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1520

 clutter/clutter/clutter-actor.c                | 11 +++++++++++
 clutter/clutter/clutter-pick-context-private.h |  4 ++++
 clutter/clutter/clutter-pick-context.c         |  8 ++++++++
 3 files changed, 23 insertions(+)
---
diff --git a/clutter/clutter/clutter-actor.c b/clutter/clutter/clutter-actor.c
index ad181b70d2..42bea5f7b6 100644
--- a/clutter/clutter/clutter-actor.c
+++ b/clutter/clutter/clutter-actor.c
@@ -635,6 +635,7 @@
 #include "clutter-paint-nodes.h"
 #include "clutter-paint-node-private.h"
 #include "clutter-paint-volume-private.h"
+#include "clutter-pick-context-private.h"
 #include "clutter-private.h"
 #include "clutter-property-transition.h"
 #include "clutter-scriptable.h"
@@ -3949,6 +3950,15 @@ clutter_actor_pick (ClutterActor       *actor,
   /* mark that we are in the paint process */
   CLUTTER_SET_PRIVATE_FLAGS (actor, CLUTTER_IN_PICK);
 
+  if (priv->paint_volume_valid && priv->last_paint_volume_valid)
+    {
+      graphene_box_t box;
+
+      clutter_paint_volume_to_box (&priv->last_paint_volume, &box);
+      if (!clutter_pick_context_intersects_box (pick_context, &box))
+        goto out;
+    }
+
   if (priv->enable_model_view_transform)
     {
       graphene_matrix_t matrix;
@@ -3997,6 +4007,7 @@ clutter_actor_pick (ClutterActor       *actor,
   if (transform_pushed)
     clutter_pick_context_pop_transform (pick_context);
 
+out:
   /* paint sequence complete */
   CLUTTER_UNSET_PRIVATE_FLAGS (actor, CLUTTER_IN_PICK);
 }
diff --git a/clutter/clutter/clutter-pick-context-private.h b/clutter/clutter/clutter-pick-context-private.h
index cc8baf8814..f40de6f3df 100644
--- a/clutter/clutter/clutter-pick-context-private.h
+++ b/clutter/clutter/clutter-pick-context-private.h
@@ -30,4 +30,8 @@ clutter_pick_context_new_for_view (ClutterStageView         *view,
 ClutterPickStack *
 clutter_pick_context_steal_stack (ClutterPickContext *pick_context);
 
+gboolean
+clutter_pick_context_intersects_box (ClutterPickContext   *pick_context,
+                                     const graphene_box_t *box);
+
 #endif /* CLUTTER_PICK_CONTEXT_PRIVATE_H */
diff --git a/clutter/clutter/clutter-pick-context.c b/clutter/clutter/clutter-pick-context.c
index b9758366d4..2f054d318f 100644
--- a/clutter/clutter/clutter-pick-context.c
+++ b/clutter/clutter/clutter-pick-context.c
@@ -189,3 +189,11 @@ clutter_pick_context_pop_transform (ClutterPickContext *pick_context)
 {
   clutter_pick_stack_pop_transform (pick_context->pick_stack);
 }
+
+gboolean
+clutter_pick_context_intersects_box (ClutterPickContext   *pick_context,
+                                     const graphene_box_t *box)
+{
+  return graphene_box_contains_point (box, &pick_context->point) ||
+         graphene_ray_intersects_box (&pick_context->ray, box);
+}