[Net] New replication interface, spawner and synchronizer nodes.

Initial implementation of the MultiplayerReplicationInterface and its
default implementation (SceneReplicationInterface).

New MultiplayerSpawner node helps dealing with instantiation of scenes
on remote peers (e.g. clients).
It supports both custom spawns via a `_spawn_custom` virtual function,
and optional auto-spawn of known scenes via a TypedArray<PackedScenes>
property.

New MultiplayerSynchornizer helps synchronizing states between the local
and remote peers, supports both sync and spawn properties and is
configured via a `SceneReplicationConfig` resource.
It can also sync via path (i.e. without being spawned by a
MultiplayerSpawner if both peers has it in tree, but will not send the
spawn state in that case, only the sync one.

2 files changed, 277 insertions, 0 deletions

diff --git a/scene/resources/scene_replication_config.cpp b/scene/resources/scene_replication_config.cpp
new file mode 100644
index 0000000000..2acc0f1922
--- /dev/null
+++ b/scene/resources/scene_replication_config.cpp
@@ -0,0 +1,187 @@
+/*************************************************************************/
+/*  scene_replication_config.cpp                                         */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "scene_replication_config.h"
+
+#include "core/multiplayer/multiplayer_api.h"
+#include "scene/main/node.h"
+
+bool SceneReplicationConfig::_set(const StringName &p_name, const Variant &p_value) {
+	String name = p_name;
+
+	if (name.begins_with("properties/")) {
+		int idx = name.get_slicec('/', 1).to_int();
+		String what = name.get_slicec('/', 2);
+
+		if (properties.size() == idx && what == "path") {
+			ERR_FAIL_COND_V(p_value.get_type() != Variant::NODE_PATH, false);
+			NodePath path = p_value;
+			ERR_FAIL_COND_V(path.is_empty() || path.get_subname_count() == 0, false);
+			add_property(path);
+			return true;
+		}
+		ERR_FAIL_COND_V(p_value.get_type() != Variant::BOOL, false);
+		ERR_FAIL_INDEX_V(idx, properties.size(), false);
+		ReplicationProperty &prop = properties[idx];
+		if (what == "sync") {
+			prop.sync = p_value;
+			sync_props.push_back(prop.name);
+			return true;
+		} else if (what == "spawn") {
+			prop.spawn = p_value;
+			spawn_props.push_back(prop.name);
+			return true;
+		}
+	}
+	return false;
+}
+
+bool SceneReplicationConfig::_get(const StringName &p_name, Variant &r_ret) const {
+	String name = p_name;
+
+	if (name.begins_with("properties/")) {
+		int idx = name.get_slicec('/', 1).to_int();
+		String what = name.get_slicec('/', 2);
+		ERR_FAIL_INDEX_V(idx, properties.size(), false);
+		const ReplicationProperty &prop = properties[idx];
+		if (what == "path") {
+			r_ret = prop.name;
+			return true;
+		} else if (what == "sync") {
+			r_ret = prop.sync;
+			return true;
+		} else if (what == "spawn") {
+			r_ret = prop.spawn;
+			return true;
+		}
+	}
+	return false;
+}
+
+void SceneReplicationConfig::_get_property_list(List<PropertyInfo> *p_list) const {
+	for (int i = 0; i < properties.size(); i++) {
+		p_list->push_back(PropertyInfo(Variant::STRING, "properties/" + itos(i) + "/path", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
+		p_list->push_back(PropertyInfo(Variant::STRING, "properties/" + itos(i) + "/spawn", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
+		p_list->push_back(PropertyInfo(Variant::STRING, "properties/" + itos(i) + "/sync", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
+	}
+}
+
+TypedArray<NodePath> SceneReplicationConfig::get_properties() const {
+	TypedArray<NodePath> paths;
+	for (const ReplicationProperty &prop : properties) {
+		paths.push_back(prop.name);
+	}
+	return paths;
+}
+
+void SceneReplicationConfig::add_property(const NodePath &p_path, int p_index) {
+	ERR_FAIL_COND(properties.find(p_path));
+
+	if (p_index < 0 || p_index == properties.size()) {
+		properties.push_back(ReplicationProperty(p_path));
+		return;
+	}
+
+	ERR_FAIL_INDEX(p_index, properties.size());
+
+	List<ReplicationProperty>::Element *I = properties.front();
+	int c = 0;
+	while (c < p_index) {
+		I = I->next();
+		c++;
+	}
+	properties.insert_before(I, ReplicationProperty(p_path));
+}
+
+void SceneReplicationConfig::remove_property(const NodePath &p_path) {
+	properties.erase(p_path);
+}
+
+int SceneReplicationConfig::property_get_index(const NodePath &p_path) const {
+	for (int i = 0; i < properties.size(); i++) {
+		if (properties[i].name == p_path) {
+			return i;
+		}
+	}
+	ERR_FAIL_V(-1);
+}
+
+bool SceneReplicationConfig::property_get_spawn(const NodePath &p_path) {
+	List<ReplicationProperty>::Element *E = properties.find(p_path);
+	ERR_FAIL_COND_V(!E, false);
+	return E->get().spawn;
+}
+
+void SceneReplicationConfig::property_set_spawn(const NodePath &p_path, bool p_enabled) {
+	List<ReplicationProperty>::Element *E = properties.find(p_path);
+	ERR_FAIL_COND(!E);
+	if (E->get().spawn == p_enabled) {
+		return;
+	}
+	E->get().spawn = p_enabled;
+	spawn_props.clear();
+	for (const ReplicationProperty &prop : properties) {
+		if (prop.spawn) {
+			spawn_props.push_back(p_path);
+		}
+	}
+}
+
+bool SceneReplicationConfig::property_get_sync(const NodePath &p_path) {
+	List<ReplicationProperty>::Element *E = properties.find(p_path);
+	ERR_FAIL_COND_V(!E, false);
+	return E->get().sync;
+}
+
+void SceneReplicationConfig::property_set_sync(const NodePath &p_path, bool p_enabled) {
+	List<ReplicationProperty>::Element *E = properties.find(p_path);
+	ERR_FAIL_COND(!E);
+	if (E->get().sync == p_enabled) {
+		return;
+	}
+	E->get().sync = p_enabled;
+	sync_props.clear();
+	for (const ReplicationProperty &prop : properties) {
+		if (prop.sync) {
+			sync_props.push_back(p_path);
+		}
+	}
+}
+
+void SceneReplicationConfig::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("get_properties"), &SceneReplicationConfig::get_properties);
+	ClassDB::bind_method(D_METHOD("add_property", "path", "index"), &SceneReplicationConfig::add_property, DEFVAL(-1));
+	ClassDB::bind_method(D_METHOD("remove_property", "path"), &SceneReplicationConfig::remove_property);
+	ClassDB::bind_method(D_METHOD("property_get_index", "path"), &SceneReplicationConfig::property_get_index);
+	ClassDB::bind_method(D_METHOD("property_get_spawn", "path"), &SceneReplicationConfig::property_get_spawn);
+	ClassDB::bind_method(D_METHOD("property_set_spawn", "path", "enabled"), &SceneReplicationConfig::property_set_spawn);
+	ClassDB::bind_method(D_METHOD("property_get_sync", "path"), &SceneReplicationConfig::property_get_sync);
+	ClassDB::bind_method(D_METHOD("property_set_sync", "path", "enabled"), &SceneReplicationConfig::property_set_sync);
+}
diff --git a/scene/resources/scene_replication_config.h b/scene/resources/scene_replication_config.h
new file mode 100644
index 0000000000..b791be9414
--- /dev/null
+++ b/scene/resources/scene_replication_config.h
@@ -0,0 +1,90 @@
+/*************************************************************************/
+/*  scene_replication_config.h                                           */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef SCENE_REPLICATION_CONFIG_H
+#define SCENE_REPLICATION_CONFIG_H
+
+#include "core/io/resource.h"
+
+#include "core/variant/typed_array.h"
+
+class SceneReplicationConfig : public Resource {
+	GDCLASS(SceneReplicationConfig, Resource);
+	OBJ_SAVE_TYPE(SceneReplicationConfig);
+	RES_BASE_EXTENSION("repl");
+
+private:
+	struct ReplicationProperty {
+		NodePath name;
+		bool spawn = true;
+		bool sync = true;
+
+		bool operator==(const ReplicationProperty &p_to) {
+			return name == p_to.name;
+		}
+
+		ReplicationProperty() {}
+
+		ReplicationProperty(const NodePath &p_name) {
+			name = p_name;
+		}
+	};
+
+	List<ReplicationProperty> properties;
+	List<NodePath> spawn_props;
+	List<NodePath> sync_props;
+
+protected:
+	static void _bind_methods();
+
+	bool _set(const StringName &p_name, const Variant &p_value);
+	bool _get(const StringName &p_name, Variant &r_ret) const;
+	void _get_property_list(List<PropertyInfo> *p_list) const;
+
+public:
+	TypedArray<NodePath> get_properties() const;
+
+	void add_property(const NodePath &p_path, int p_index = -1);
+	void remove_property(const NodePath &p_path);
+
+	int property_get_index(const NodePath &p_path) const;
+	bool property_get_spawn(const NodePath &p_path);
+	void property_set_spawn(const NodePath &p_path, bool p_enabled);
+
+	bool property_get_sync(const NodePath &p_path);
+	void property_set_sync(const NodePath &p_path, bool p_enabled);
+
+	const List<NodePath> &get_spawn_properties() { return spawn_props; }
+	const List<NodePath> &get_sync_properties() { return sync_props; }
+
+	SceneReplicationConfig() {}
+};
+
+#endif // SCENE_REPLICATION_CONFIG_H