Add peer visibility to MultiplayerSynchronizer.

MultiplayerSynchronizers can now be configured to limit their visibility
to a subset of the connected peers, if the synchronized node was spawned
by a MultiplayerSpawner (either automatically or via custom spawn) the
given node will also be despawned remotely.

The replication system doesn't have the logic to handle subspawn
directly, but it is possible to handle them appropriately by manually
updating the visibility of the parent before changing the one of the
nested spawns via the "update_visibility" function.

The visibility of each MultiplayerSynchronizer can be controlled by
adding or remove filters via "[add|remove]_visibility_filter(callable)".

To further optimize the network code, visibility filters can be configured
to be automatically updated during idle or physics frame, or set to always
require manual update (via the "update_visibility" function).

1 files changed, 18 insertions, 7 deletions

diff --git a/scene/multiplayer/scene_cache_interface.cpp b/scene/multiplayer/scene_cache_interface.cpp
index 7c271341db..79a7dc2d5a 100644
--- a/scene/multiplayer/scene_cache_interface.cpp
+++ b/scene/multiplayer/scene_cache_interface.cpp
@@ -187,18 +187,29 @@ bool SceneCacheInterface::is_cache_confirmed(NodePath p_path, int p_peer) {
 	return F->value;
 }
 
-bool SceneCacheInterface::send_object_cache(Object *p_obj, NodePath p_path, int p_peer_id, int &r_id) {
+int SceneCacheInterface::make_object_cache(Object *p_obj) {
 	Node *node = Object::cast_to<Node>(p_obj);
-	ERR_FAIL_COND_V(!node, false);
+	ERR_FAIL_COND_V(!node, -1);
+	NodePath for_path = multiplayer->get_root_path().rel_path_to(node->get_path());
 	// See if the path is cached.
-	PathSentCache *psc = path_send_cache.getptr(p_path);
+	PathSentCache *psc = path_send_cache.getptr(for_path);
 	if (!psc) {
 		// Path is not cached, create.
-		path_send_cache[p_path] = PathSentCache();
-		psc = path_send_cache.getptr(p_path);
+		path_send_cache[for_path] = PathSentCache();
+		psc = path_send_cache.getptr(for_path);
 		psc->id = last_send_cache_id++;
 	}
-	r_id = psc->id;
+	return psc->id;
+}
+
+bool SceneCacheInterface::send_object_cache(Object *p_obj, int p_peer_id, int &r_id) {
+	Node *node = Object::cast_to<Node>(p_obj);
+	ERR_FAIL_COND_V(!node, false);
+
+	r_id = make_object_cache(p_obj);
+	ERR_FAIL_COND_V(r_id < 0, false);
+	NodePath for_path = multiplayer->get_root_path().rel_path_to(node->get_path());
+	PathSentCache *psc = path_send_cache.getptr(for_path);
 
 	bool has_all_peers = true;
 	List<int> peers_to_add; // If one is missing, take note to add it.
@@ -233,7 +244,7 @@ bool SceneCacheInterface::send_object_cache(Object *p_obj, NodePath p_path, int
 	}
 
 	if (peers_to_add.size()) {
-		_send_confirm_path(node, p_path, psc, peers_to_add);
+		_send_confirm_path(node, for_path, psc, peers_to_add);
 	}
 
 	return has_all_peers;