Depsgraph: Ignore action time dependency if it's not needed

It is possible to have action which is not nullptr but which have no
f-curves in it (for example, animate cube's location, then delete all
f-curves).

Such situation should not add time dependency as it could slow down
scene evaluation on frame change.

1 files changed, 5 insertions, 3 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index db7c1e5ceae..3e0ab9684da 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -1403,9 +1403,11 @@ void DepsgraphRelationBuilder::build_action(bAction *action)
   if (built_map_.checkIsBuiltAndTag(action)) {
     return;
   }
-  TimeSourceKey time_src_key;
-  ComponentKey animation_key(&action->id, NodeType::ANIMATION);
-  add_relation(time_src_key, animation_key, "TimeSrc -> Animation");
+  if (!BLI_listbase_is_empty(&action->curves)) {
+    TimeSourceKey time_src_key;
+    ComponentKey animation_key(&action->id, NodeType::ANIMATION);
+    add_relation(time_src_key, animation_key, "TimeSrc -> Animation");
+  }
 }
 
 void DepsgraphRelationBuilder::build_driver(ID *id, FCurve *fcu)