Depsgraph: refactor tagging after time changes

This reverts {rB1693a5efe91999b60b3dc0bdff727473b3bd00bb}
and implements an alternative solution.

The old patch had the problem that the depsgraph would always
evaluate at the current frame of the original scene (even when
`DEG_evaluate_on_framechange` was used). Now it is possible
to evaluate the depsgraph at a specific frame without having to
change the original scene.

Reviewers: sergey, sybren

Differential Revision: https://developer.blender.org/D8616

2 files changed, 13 insertions, 1 deletions

diff --git a/source/blender/depsgraph/intern/node/deg_node_time.cc b/source/blender/depsgraph/intern/node/deg_node_time.cc
index af931fbae34..4f7f70fef33 100644
--- a/source/blender/depsgraph/intern/node/deg_node_time.cc
+++ b/source/blender/depsgraph/intern/node/deg_node_time.cc
@@ -31,8 +31,16 @@
 namespace blender {
 namespace deg {
 
-void TimeSourceNode::tag_update(Depsgraph *graph, eUpdateSource /*source*/)
+void TimeSourceNode::tag_update(Depsgraph * /*graph*/, eUpdateSource /*source*/)
 {
+  tagged_for_update = true;
+}
+
+void TimeSourceNode::flush_update_tag(Depsgraph *graph)
+{
+  if (!tagged_for_update) {
+    return;
+  }
   for (Relation *rel : outlinks) {
     Node *node = rel->to;
     node->tag_update(graph, DEG_UPDATE_SOURCE_TIME);
diff --git a/source/blender/depsgraph/intern/node/deg_node_time.h b/source/blender/depsgraph/intern/node/deg_node_time.h
index fe17684abb0..79ad92f336f 100644
--- a/source/blender/depsgraph/intern/node/deg_node_time.h
+++ b/source/blender/depsgraph/intern/node/deg_node_time.h
@@ -30,10 +30,14 @@ namespace deg {
 
 /* Time Source Node. */
 struct TimeSourceNode : public Node {
+  bool tagged_for_update = false;
+
   // TODO: evaluate() operation needed
 
   virtual void tag_update(Depsgraph *graph, eUpdateSource source) override;
 
+  void flush_update_tag(Depsgraph *graph);
+
   DEG_DEPSNODE_DECLARE;
 };