Fix T75686: Animating scene audio volume doesn't work

Scene audio volume changes require the scene to be tagged with
`ID_RECALC_AUDIO_VOLUME` (see `BKE_scene_update_sound()`). Tagging
happens in the RNA update function `rna_Scene_volume_update()`, but that
function is not called by the animation system. As a result, animated
volume changes are not sent to the audio system.

This commit adds a new depsgraph operation node that sets this tag when
necessary, so that the animated values are used in the rest of the
depsgraph evaluation.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D7429

1 files changed, 9 insertions, 1 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index 89def9e0bdc..e968ad1ea5d 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -2544,8 +2544,16 @@ void DepsgraphRelationBuilder::build_scene_sequencer(Scene *scene)
   }
 }
 
-void DepsgraphRelationBuilder::build_scene_audio(Scene * /*scene*/)
+void DepsgraphRelationBuilder::build_scene_audio(Scene *scene)
 {
+  OperationKey scene_audio_volume_key(&scene->id, NodeType::AUDIO, OperationCode::AUDIO_VOLUME);
+  OperationKey scene_sound_eval_key(&scene->id, NodeType::AUDIO, OperationCode::SOUND_EVAL);
+  add_relation(scene_audio_volume_key, scene_sound_eval_key, "Audio Volume -> Sound");
+
+  if (scene->audio.flag & AUDIO_VOLUME_ANIMATED) {
+    ComponentKey scene_anim_key(&scene->id, NodeType::ANIMATION);
+    add_relation(scene_anim_key, scene_audio_volume_key, "Animation -> Audio Volume");
+  }
 }
 
 void DepsgraphRelationBuilder::build_scene_speakers(Scene * /*scene*/, ViewLayer *view_layer)