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

source/blender/depsgraph/DEG_depsgraph.h

@@ -127,6 +127,12 @@ void DEG_graph_id_tag_update(struct Main *bmain,
                              struct ID *id,
                              int flag);
 
+/* Tag all dependency graphs when time has changed. */
+void DEG_time_tag_update(struct Main *bmain);
+
+/* Tag a dependency graph when time has changed. */
+void DEG_graph_time_tag_update(struct Depsgraph *depsgraph);
+
 /* Mark a particular datablock type as having changing. This does
  * not cause any updates but is used by external render engines to detect if for
  * example a datablock was removed. */
@@ -155,8 +161,6 @@ void DEG_evaluate_on_framechange(Depsgraph *graph, float ctime);
 /* Data changed recalculation entry point. */
 void DEG_evaluate_on_refresh(Depsgraph *graph);
 
-bool DEG_needs_eval(Depsgraph *graph);
-
 /* Editors Integration  -------------------------- */
 
 /* Mechanism to allow editors to be informed of depsgraph updates,

source/blender/depsgraph/intern/depsgraph.cc

@@ -63,7 +63,6 @@ namespace deg {
 Depsgraph::Depsgraph(Main *bmain, Scene *scene, ViewLayer *view_layer, eEvaluationMode mode)
     : time_source(nullptr),
       need_update(true),
-      need_update_time(false),
       bmain(bmain),
       scene(scene),
       view_layer(view_layer),
@@ -103,6 +102,11 @@ TimeSourceNode *Depsgraph::find_time_source() const
   return time_source;
 }
 
+void Depsgraph::tag_time_source()
+{
+  time_source->tag_update(this, DEG_UPDATE_SOURCE_TIME);
+}
+
 IDNode *Depsgraph::find_id_node(const ID *id) const
 {
   return id_hash.lookup_default(id, nullptr);

source/blender/depsgraph/intern/depsgraph.h

@@ -68,6 +68,7 @@ struct Depsgraph {
 
   TimeSourceNode *add_time_source();
   TimeSourceNode *find_time_source() const;
+  void tag_time_source();
 
   IDNode *find_id_node(const ID *id) const;
   IDNode *add_id_node(ID *id, ID *id_cow_hint = nullptr);
@@ -121,10 +122,6 @@ struct Depsgraph {
   /* Nodes which have been tagged as "directly modified". */
   Set<OperationNode *> entry_tags;
 
-  /* Special entry tag for time source. Allows to tag invisible dependency graphs for update when
-   * scene frame changes, so then when dependency graph becomes visible it is on a proper state. */
-  bool need_update_time;
-
   /* Convenience Data ................... */
 
   /* XXX: should be collected after building (if actually needed?) */

source/blender/depsgraph/intern/depsgraph_eval.cc

@@ -47,38 +47,37 @@
 
 namespace deg = blender::deg;
 
+static void deg_flush_updates_and_refresh(deg::Depsgraph *deg_graph)
+{
+  /* Update the time on the cow scene. */
+  if (deg_graph->scene_cow) {
+    BKE_scene_frame_set(deg_graph->scene_cow, deg_graph->ctime);
+  }
+
+  deg::deg_graph_flush_updates(deg_graph);
+  deg::deg_evaluate_on_refresh(deg_graph);
+}
+
 /* Evaluate all nodes tagged for updating. */
 void DEG_evaluate_on_refresh(Depsgraph *graph)
 {
   deg::Depsgraph *deg_graph = reinterpret_cast<deg::Depsgraph *>(graph);
-  deg_graph->ctime = BKE_scene_frame_get(deg_graph->scene);
-  /* Update time in scene. */
-  if (deg_graph->scene_cow) {
-    BKE_scene_frame_set(deg_graph->scene_cow, deg_graph->ctime);
+  const Scene *scene = DEG_get_input_scene(graph);
+  const float ctime = BKE_scene_frame_get(scene);
+
+  if (ctime != deg_graph->ctime) {
+    deg_graph->tag_time_source();
+    deg_graph->ctime = ctime;
   }
-  deg::deg_graph_flush_updates(deg_graph);
-  deg::deg_evaluate_on_refresh(deg_graph);
-  deg_graph->need_update_time = false;
+
+  deg_flush_updates_and_refresh(deg_graph);
 }
 
 /* Frame-change happened for root scene that graph belongs to. */
 void DEG_evaluate_on_framechange(Depsgraph *graph, float ctime)
 {
   deg::Depsgraph *deg_graph = reinterpret_cast<deg::Depsgraph *>(graph);
+  deg_graph->tag_time_source();
   deg_graph->ctime = ctime;
-  deg_graph->need_update_time = true;
-  deg::deg_graph_flush_updates(deg_graph);
-  /* Update time in scene. */
-  if (deg_graph->scene_cow) {
-    BKE_scene_frame_set(deg_graph->scene_cow, deg_graph->ctime);
-  }
-  /* Perform recalculation updates. */
-  deg::deg_evaluate_on_refresh(deg_graph);
-  deg_graph->need_update_time = false;
-}
-
-bool DEG_needs_eval(Depsgraph *graph)
-{
-  deg::Depsgraph *deg_graph = reinterpret_cast<deg::Depsgraph *>(graph);
-  return !deg_graph->entry_tags.is_empty() || deg_graph->need_update_time;
+  deg_flush_updates_and_refresh(deg_graph);
 }

source/blender/depsgraph/intern/depsgraph_tag.cc

@@ -66,6 +66,7 @@
 #include "intern/node/deg_node_factory.h"
 #include "intern/node/deg_node_id.h"
 #include "intern/node/deg_node_operation.h"
+#include "intern/node/deg_node_time.h"
 
 namespace deg = blender::deg;
 
@@ -230,9 +231,6 @@ void depsgraph_tag_to_component_opcode(const ID *id,
     case ID_RECALC_SOURCE:
       *component_type = NodeType::PARAMETERS;
       break;
-    case ID_RECALC_TIME:
-      BLI_assert(!"Should be handled outside of this function");
-      break;
     case ID_RECALC_ALL:
     case ID_RECALC_PSYS_ALL:
       BLI_assert(!"Should not happen");
@@ -372,12 +370,6 @@ void graph_id_tag_update_single_flag(Main *bmain,
     }
     return;
   }
-  if (tag == ID_RECALC_TIME) {
-    if (graph != nullptr) {
-      graph->need_update_time = true;
-    }
-    return;
-  }
   /* Get description of what is to be tagged. */
   NodeType component_type;
   OperationCode operation_code;
@@ -462,8 +454,8 @@ const char *update_source_as_string(eUpdateSource source)
 
 int deg_recalc_flags_for_legacy_zero()
 {
-  return ID_RECALC_ALL & ~(ID_RECALC_PSYS_ALL | ID_RECALC_ANIMATION | ID_RECALC_SOURCE |
-                           ID_RECALC_TIME | ID_RECALC_EDITORS);
+  return ID_RECALC_ALL &
+         ~(ID_RECALC_PSYS_ALL | ID_RECALC_ANIMATION | ID_RECALC_SOURCE | ID_RECALC_EDITORS);
 }
 
 int deg_recalc_flags_effective(Depsgraph *graph, int flags)
@@ -734,8 +726,6 @@ const char *DEG_update_tag_as_string(IDRecalcFlag flag)
       return "AUDIO";
     case ID_RECALC_PARAMETERS:
       return "PARAMETERS";
-    case ID_RECALC_TIME:
-      return "TIME";
     case ID_RECALC_SOURCE:
       return "SOURCE";
     case ID_RECALC_ALL:
@@ -772,6 +762,19 @@ void DEG_graph_id_tag_update(struct Main *bmain,
   deg::graph_id_tag_update(bmain, graph, id, flag, deg::DEG_UPDATE_SOURCE_USER_EDIT);
 }
 
+void DEG_time_tag_update(struct Main *bmain)
+{
+  for (deg::Depsgraph *depsgraph : deg::get_all_registered_graphs(bmain)) {
+    DEG_graph_time_tag_update(reinterpret_cast<::Depsgraph *>(depsgraph));
+  }
+}
+
+void DEG_graph_time_tag_update(struct Depsgraph *depsgraph)
+{
+  deg::Depsgraph *deg_graph = reinterpret_cast<deg::Depsgraph *>(depsgraph);
+  deg_graph->tag_time_source();
+}
+
 /* Mark a particular datablock type as having changing. */
 void DEG_graph_id_type_tag(Depsgraph *depsgraph, short id_type)
 {

source/blender/depsgraph/intern/eval/deg_eval_flush.cc

@@ -357,14 +357,9 @@ void deg_graph_flush_updates(Depsgraph *graph)
   BLI_assert(graph != nullptr);
   Main *bmain = graph->bmain;
 
+  graph->time_source->flush_update_tag(graph);
+
   /* Nothing to update, early out. */
-  if (graph->need_update_time) {
-    const Scene *scene_orig = graph->scene;
-    const float ctime = BKE_scene_frame_get(scene_orig);
-    TimeSourceNode *time_source = graph->find_time_source();
-    graph->ctime = ctime;
-    time_source->tag_update(graph, DEG_UPDATE_SOURCE_TIME);
-  }
   if (graph->entry_tags.is_empty()) {
     return;
   }
@@ -412,6 +407,8 @@ void deg_graph_clear_tags(Depsgraph *graph)
   }
   /* Clear any entry tags which haven't been flushed. */
   graph->entry_tags.clear();
+
+  graph->time_source->tagged_for_update = false;
 }
 
 }  // namespace deg

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);

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;
 };
 

source/blender/editors/screen/screen_edit.c

@@ -1576,7 +1576,7 @@ void ED_update_for_newframe(Main *bmain, Depsgraph *depsgraph)
 {
   Scene *scene = DEG_get_input_scene(depsgraph);
 
-  DEG_id_tag_update_ex(bmain, &scene->id, ID_RECALC_TIME);
+  DEG_time_tag_update(bmain);
 
 #ifdef DURIAN_CAMERA_SWITCH
   void *camera = BKE_scene_camera_switch_find(scene);

source/blender/makesdna/DNA_ID.h

@@ -686,10 +686,6 @@ typedef enum IDRecalcFlag {
 
   ID_RECALC_PARAMETERS = (1 << 21),
 
-  /* Makes it so everything what depends on time.
-   * Basically, the same what changing frame in a timeline will do. */
-  ID_RECALC_TIME = (1 << 22),
-
   /* Input has changed and datablock is to be reload from disk.
    * Applies to movie clips to inform that copy-on-written version is to be refreshed for the new
    * input file or for color space changes. */