Merge pull request #107178 from lawnjelly/scenetreefti_fix_hidden_forced

[3.x] `SceneTreeFTI` - Fix `force_update` flag for invisible nodes

scene/main/scene_tree_fti.cpp

@@ -288,7 +288,12 @@ void SceneTreeFTI::_create_depth_lists() {
 			}
 #endif
 
+			// Prevent being added to the dest_list twice when on
+			// the frame_xform_list AND the frame_xform_list_forced.
 			if ((l == 0) && s->data.fti_frame_xform_force_update) {
+#ifdef GODOT_SCENE_TREE_FTI_EXTRA_CHECKS
+				DEV_ASSERT(data.frame_xform_list_forced.find(s) != -1);
+#endif
 				continue;
 			}
 
@@ -563,11 +568,6 @@ void SceneTreeFTI::_update_dirty_spatials(Node *p_node, uint32_t p_current_half_
 		// Upload to VisualServer the interpolated global xform.
 		s->fti_update_servers_xform();
 
-		// Only do this at most for one frame,
-		// it is used to catch objects being removed from the tick lists
-		// that have a deferred frame update.
-		s->data.fti_frame_xform_force_update = false;
-
 		// Ensure branches are only processed once on each traversal.
 		s->data.fti_processed = true;
 
@@ -706,6 +706,17 @@ void SceneTreeFTI::frame_update(Node *p_root, bool p_frame_start) {
 
 #endif //  not GODOT_SCENE_TREE_FTI_VERIFY
 
+	// In theory we could clear the `force_update` flags from the nodes in the traversal.
+	// The problem is that hidden nodes are not recursed into, therefore the flags would
+	// never get cleared and could get out of sync with the forced list.
+	// So instead we are clearing them here manually.
+	// This is not ideal in terms of cache coherence so perhaps another method can be
+	// explored in future.
+	uint32_t forced_list_size = data.frame_xform_list_forced.size();
+	for (uint32_t n = 0; n < forced_list_size; n++) {
+		Spatial *s = data.frame_xform_list_forced[n];
+		s->data.fti_frame_xform_force_update = false;
+	}
 	data.frame_xform_list_forced.clear();
 
 	if (!p_frame_start && data.periodic_debug_log) {