Cleanup: split `BKE_scene_get_depsgraph()` into two functions

Split the depsgraph allocation into a separate function
`BKE_scene_ensure_depsgraph()`. Parameters are only passed to those
functions that actually need them. This removes the the "if that boolean
is `false` this pointer is allowed to be `NULL`" logic and more cleanly
decouples code.

No functional changes.

1 files changed, 6 insertions, 4 deletions

diff --git a/source/blender/blenkernel/BKE_scene.h b/source/blender/blenkernel/BKE_scene.h
index 2a5e4527676..05966ec3989 100644
--- a/source/blender/blenkernel/BKE_scene.h
+++ b/source/blender/blenkernel/BKE_scene.h
@@ -219,10 +219,12 @@ void BKE_scene_ensure_depsgraph_hash(struct Scene *scene);
 void BKE_scene_free_depsgraph_hash(struct Scene *scene);
 void BKE_scene_free_view_layer_depsgraph(struct Scene *scene, struct ViewLayer *view_layer);
 
-struct Depsgraph *BKE_scene_get_depsgraph(struct Main *bmain,
-                                          struct Scene *scene,
-                                          struct ViewLayer *view_layer,
-                                          bool allocate);
+/* Do not allocate new depsgraph. */
+struct Depsgraph *BKE_scene_get_depsgraph(struct Scene *scene, struct ViewLayer *view_layer);
+/* Allocate new depsgraph if necessary. */
+struct Depsgraph *BKE_scene_ensure_depsgraph(struct Main *bmain,
+                                             struct Scene *scene,
+                                             struct ViewLayer *view_layer);
 
 struct GHash *BKE_scene_undo_depsgraphs_extract(struct Main *bmain);
 void BKE_scene_undo_depsgraphs_restore(struct Main *bmain, struct GHash *depsgraph_extract);