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, 141 insertions, 1 deletions

diff --git a/scene/multiplayer/multiplayer_synchronizer.cpp b/scene/multiplayer/multiplayer_synchronizer.cpp
index 68f6e54fa8..e1b7433968 100644
--- a/scene/multiplayer/multiplayer_synchronizer.cpp
+++ b/scene/multiplayer/multiplayer_synchronizer.cpp
@@ -43,6 +43,11 @@ Object *MultiplayerSynchronizer::_get_prop_target(Object *p_obj, const NodePath
 }
 
 void MultiplayerSynchronizer::_stop() {
+#ifdef TOOLS_ENABLED
+	if (Engine::get_singleton()->is_editor_hint()) {
+		return;
+	}
+#endif
 	Node *node = is_inside_tree() ? get_node_or_null(root_path) : nullptr;
 	if (node) {
 		get_multiplayer()->replication_stop(node, this);
@@ -50,9 +55,42 @@ void MultiplayerSynchronizer::_stop() {
 }
 
 void MultiplayerSynchronizer::_start() {
+#ifdef TOOLS_ENABLED
+	if (Engine::get_singleton()->is_editor_hint()) {
+		return;
+	}
+#endif
 	Node *node = is_inside_tree() ? get_node_or_null(root_path) : nullptr;
 	if (node) {
 		get_multiplayer()->replication_start(node, this);
+		_update_process();
+	}
+}
+
+void MultiplayerSynchronizer::_update_process() {
+#ifdef TOOLS_ENABLED
+	if (Engine::get_singleton()->is_editor_hint()) {
+		return;
+	}
+#endif
+	Node *node = is_inside_tree() ? get_node_or_null(root_path) : nullptr;
+	if (!node) {
+		return;
+	}
+	set_process_internal(false);
+	set_physics_process_internal(false);
+	if (!visibility_filters.size()) {
+		return;
+	}
+	switch (visibility_update_mode) {
+		case VISIBILITY_PROCESS_IDLE:
+			set_process_internal(true);
+			break;
+		case VISIBILITY_PROCESS_PHYSICS:
+			set_physics_process_internal(true);
+			break;
+		case VISIBILITY_PROCESS_NONE:
+			break;
 	}
 }
 
@@ -85,6 +123,66 @@ Error MultiplayerSynchronizer::set_state(const List<NodePath> &p_properties, Obj
 	return OK;
 }
 
+bool MultiplayerSynchronizer::is_visibility_public() const {
+	return peer_visibility.has(0);
+}
+
+void MultiplayerSynchronizer::set_visibility_public(bool p_visible) {
+	set_visibility_for(0, p_visible);
+}
+
+bool MultiplayerSynchronizer::is_visible_to(int p_peer) {
+	if (visibility_filters.size()) {
+		Variant arg = p_peer;
+		const Variant *argv[1] = { &arg };
+		for (Callable filter : visibility_filters) {
+			Variant ret;
+			Callable::CallError err;
+			filter.call(argv, 1, ret, err);
+			ERR_FAIL_COND_V(err.error != Callable::CallError::CALL_OK || ret.get_type() != Variant::BOOL, false);
+			if (!ret.operator bool()) {
+				return false;
+			}
+		}
+	}
+	return peer_visibility.has(0) || peer_visibility.has(p_peer);
+}
+
+void MultiplayerSynchronizer::add_visibility_filter(Callable p_callback) {
+	visibility_filters.insert(p_callback);
+	_update_process();
+}
+
+void MultiplayerSynchronizer::remove_visibility_filter(Callable p_callback) {
+	visibility_filters.erase(p_callback);
+	_update_process();
+}
+
+void MultiplayerSynchronizer::set_visibility_for(int p_peer, bool p_visible) {
+	if (peer_visibility.has(p_peer) == p_visible) {
+		return;
+	}
+	if (p_visible) {
+		peer_visibility.insert(p_peer);
+	} else {
+		peer_visibility.erase(p_peer);
+	}
+	update_visibility(p_peer);
+}
+
+bool MultiplayerSynchronizer::get_visibility_for(int p_peer) const {
+	return peer_visibility.has(p_peer);
+}
+
+void MultiplayerSynchronizer::set_visibility_update_mode(VisibilityUpdateMode p_mode) {
+	visibility_update_mode = p_mode;
+	_update_process();
+}
+
+MultiplayerSynchronizer::VisibilityUpdateMode MultiplayerSynchronizer::get_visibility_update_mode() const {
+	return visibility_update_mode;
+}
+
 void MultiplayerSynchronizer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_root_path", "path"), &MultiplayerSynchronizer::set_root_path);
 	ClassDB::bind_method(D_METHOD("get_root_path"), &MultiplayerSynchronizer::get_root_path);
@@ -95,9 +193,29 @@ void MultiplayerSynchronizer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_replication_config", "config"), &MultiplayerSynchronizer::set_replication_config);
 	ClassDB::bind_method(D_METHOD("get_replication_config"), &MultiplayerSynchronizer::get_replication_config);
 
+	ClassDB::bind_method(D_METHOD("set_visibility_update_mode", "mode"), &MultiplayerSynchronizer::set_visibility_update_mode);
+	ClassDB::bind_method(D_METHOD("get_visibility_update_mode"), &MultiplayerSynchronizer::get_visibility_update_mode);
+	ClassDB::bind_method(D_METHOD("update_visibility", "for_peer"), &MultiplayerSynchronizer::update_visibility, DEFVAL(0));
+
+	ClassDB::bind_method(D_METHOD("set_visibility_public", "visible"), &MultiplayerSynchronizer::set_visibility_public);
+	ClassDB::bind_method(D_METHOD("is_visibility_public"), &MultiplayerSynchronizer::is_visibility_public);
+
+	ClassDB::bind_method(D_METHOD("add_visibility_filter", "filter"), &MultiplayerSynchronizer::add_visibility_filter);
+	ClassDB::bind_method(D_METHOD("remove_visibility_filter", "filter"), &MultiplayerSynchronizer::remove_visibility_filter);
+	ClassDB::bind_method(D_METHOD("set_visibility_for", "peer", "visible"), &MultiplayerSynchronizer::set_visibility_for);
+	ClassDB::bind_method(D_METHOD("get_visibility_for", "peer"), &MultiplayerSynchronizer::get_visibility_for);
+
 	ADD_PROPERTY(PropertyInfo(Variant::NODE_PATH, "root_path"), "set_root_path", "get_root_path");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "replication_interval", PROPERTY_HINT_RANGE, "0,5,0.001,suffix:s"), "set_replication_interval", "get_replication_interval");
-	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "replication_config", PROPERTY_HINT_RESOURCE_TYPE, "SceneReplicationConfig"), "set_replication_config", "get_replication_config");
+	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "replication_config", PROPERTY_HINT_RESOURCE_TYPE, "SceneReplicationConfig", PROPERTY_USAGE_NO_EDITOR), "set_replication_config", "get_replication_config");
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "visibility_update_mode", PROPERTY_HINT_ENUM, "Idle,Physics,None"), "set_visibility_update_mode", "get_visibility_update_mode");
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "public_visibility"), "set_visibility_public", "is_visibility_public");
+
+	BIND_ENUM_CONSTANT(VISIBILITY_PROCESS_IDLE);
+	BIND_ENUM_CONSTANT(VISIBILITY_PROCESS_PHYSICS);
+	BIND_ENUM_CONSTANT(VISIBILITY_PROCESS_NONE);
+
+	ADD_SIGNAL(MethodInfo("visibility_changed", PropertyInfo(Variant::INT, "for_peer")));
 }
 
 void MultiplayerSynchronizer::_notification(int p_what) {
@@ -118,6 +236,11 @@ void MultiplayerSynchronizer::_notification(int p_what) {
 		case NOTIFICATION_EXIT_TREE: {
 			_stop();
 		} break;
+
+		case NOTIFICATION_INTERNAL_PROCESS:
+		case NOTIFICATION_INTERNAL_PHYSICS_PROCESS: {
+			update_visibility(0);
+		} break;
 	}
 }
 
@@ -142,6 +265,18 @@ Ref<SceneReplicationConfig> MultiplayerSynchronizer::get_replication_config() {
 	return replication_config;
 }
 
+void MultiplayerSynchronizer::update_visibility(int p_for_peer) {
+#ifdef TOOLS_ENABLED
+	if (Engine::get_singleton()->is_editor_hint()) {
+		return;
+	}
+#endif
+	Node *node = is_inside_tree() ? get_node_or_null(root_path) : nullptr;
+	if (node && get_multiplayer()->has_multiplayer_peer() && is_multiplayer_authority()) {
+		emit_signal(SNAME("visibility_changed"), p_for_peer);
+	}
+}
+
 void MultiplayerSynchronizer::set_root_path(const NodePath &p_path) {
 	_stop();
 	root_path = p_path;
@@ -162,3 +297,8 @@ void MultiplayerSynchronizer::set_multiplayer_authority(int p_peer_id, bool p_re
 	Node::set_multiplayer_authority(p_peer_id, p_recursive);
 	get_multiplayer()->replication_start(node, this);
 }
+
+MultiplayerSynchronizer::MultiplayerSynchronizer() {
+	// Publicly visible by default.
+	peer_visibility.insert(0);
+}