[Net] Add state sync to replicator.

Like the spawn/despawn feature, it can be completely overridden with 2
custom callables.
The callables will be called with the list of tracked objects.
In SERVER mode, objects are automatically tracked, while in CUSTOM mode
you can manually track them via `track`/`untrack` (but that's optional).
The default sync only happens from server to client, with batch updates,
over unreliable channel (but with custom ordering).
The default sync will warn you, if your state representation gets too
big.

1 files changed, 53 insertions, 1 deletions

diff --git a/doc/classes/MultiplayerReplicator.xml b/doc/classes/MultiplayerReplicator.xml
index 15029e181f..0778a7335f 100644
--- a/doc/classes/MultiplayerReplicator.xml
+++ b/doc/classes/MultiplayerReplicator.xml
@@ -12,6 +12,7 @@
 			<argument index="0" name="scene_id" type="int" />
 			<argument index="1" name="object" type="Object" />
 			<argument index="2" name="data" type="PackedByteArray" />
+			<argument index="3" name="initial" type="bool" default="true" />
 			<description>
 				Decode the given [code]data[/code] representing a spawnable state into [code]object[/code] using the configuration associated with the provided [code]scene_id[/code]. This function is called automatically when a client receives a server spawn for a scene with [constant REPLICATION_MODE_SERVER]. See [method spawn_config].
 				Tip: You may find this function useful in servers when parsing spawn requests from clients, or when implementing your own logic with [constant REPLICATION_MODE_CUSTOM].
@@ -23,12 +24,14 @@
 			<argument index="1" name="object" type="Object" />
 			<argument index="2" name="peer_id" type="int" default="0" />
 			<description>
+				Request a despawn for the scene identified by [code]scene_id[/code] to the given [code]peer_id[/code]. This will either trigger the default behaviour, or invoke the custom spawn/despawn callables specified in [method spawn_config]. See [method send_despawn] for the default behavior.
 			</description>
 		</method>
 		<method name="encode_state">
 			<return type="PackedByteArray" />
 			<argument index="0" name="scene_id" type="int" />
 			<argument index="1" name="object" type="Object" />
+			<argument index="2" name="initial" type="bool" default="true" />
 			<description>
 				Encode the given [code]object[/code] using the configuration associated with the provided [code]scene_id[/code]. This function is called automatically when the server spawns scenes with [constant REPLICATION_MODE_SERVER]. See [method spawn_config].
 				Tip: You may find this function useful when requesting spawns from clients to server, or when implementing your own logic with [constant REPLICATION_MODE_CUSTOM].
@@ -54,12 +57,24 @@
 				Sends a spawn request for the scene identified by [code]scene_id[/code] to the given [code]peer_id[/code] (see [method MultiplayerPeer.set_target_peer]). If the scene is configured as [constant REPLICATION_MODE_SERVER] (see [method spawn_config]) and the request is sent by the server (see [method MultiplayerAPI.is_network_server]), the receiving peer(s) will automatically instantiate that scene, add it to the [SceneTree] at the given [code]path[/code] and emit the signal [signal spawned]. In all other cases no instantiation happens, and the signal [signal spawn_requested] is emitted instead.
 			</description>
 		</method>
+		<method name="send_sync">
+			<return type="int" enum="Error" />
+			<argument index="0" name="peer_id" type="int" />
+			<argument index="1" name="scene_id" type="int" />
+			<argument index="2" name="data" type="PackedByteArray" />
+			<argument index="3" name="transfer_mode" type="int" enum="MultiplayerPeer.TransferMode" default="2" />
+			<argument index="4" name="channel" type="int" default="0" />
+			<description>
+				Sends a sync request for the instances of the scene identified by [code]scene_id[/code] to the given [code]peer_id[/code] (see [method MultiplayerPeer.set_target_peer]). This function can only be called manually when overriding the send and receive sync functions (see [method sync_config]).
+			</description>
+		</method>
 		<method name="spawn">
 			<return type="int" enum="Error" />
 			<argument index="0" name="scene_id" type="int" />
 			<argument index="1" name="object" type="Object" />
 			<argument index="2" name="peer_id" type="int" default="0" />
 			<description>
+				Request a spawn for the scene identified by [code]scene_id[/code] to the given [code]peer_id[/code]. This will either trigger the default behaviour, or invoke the custom spawn/despawn callables specified in [method spawn_config]. See [method send_spawn] for the default behavior.
 			</description>
 		</method>
 		<method name="spawn_config">
@@ -70,10 +85,47 @@
 			<argument index="3" name="custom_send" type="Callable" />
 			<argument index="4" name="custom_receive" type="Callable" />
 			<description>
-				Configures the MultiplayerAPI to track instances of the [PackedScene] identified by [code]scene_id[/code] (see [method ResourceLoader.get_resource_uid]) for the purpose of network replication. When [code]mode[/code] is [constant REPLICATION_MODE_SERVER], the specified [code]properties[/code] will also be replicated to clients during the initial spawn.
+				Configures the MultiplayerReplicator to track instances of the [PackedScene] identified by [code]scene_id[/code] (see [method ResourceLoader.get_resource_uid]) for the purpose of network replication. When [code]mode[/code] is [constant REPLICATION_MODE_SERVER], the specified [code]properties[/code] will also be replicated to clients during the initial spawn. You can optionally specify a [code]custom_send[/code] and a [code]custom_receive[/code] to override the default behaviour and customize the spawn/despawn proecess.
 				Tip: You can use a custom property in the scene main script to return a customly optimized state representation.
 			</description>
 		</method>
+		<method name="sync_all">
+			<return type="int" enum="Error" />
+			<argument index="0" name="scene_id" type="int" />
+			<argument index="1" name="peer_id" type="int" default="0" />
+			<description>
+				Manually request a sync for all the instances of the scene identified by [code]scene_id[/code]. This function will trigger the default sync behaviour, or call your send custom send callable if specified in [method sync_config].
+				Note: The default implementation only allow syncing from server to clients.
+			</description>
+		</method>
+		<method name="sync_config">
+			<return type="int" enum="Error" />
+			<argument index="0" name="scene_id" type="int" />
+			<argument index="1" name="interval" type="int" />
+			<argument index="2" name="properties" type="StringName[]" default="[]" />
+			<argument index="3" name="custom_send" type="Callable" />
+			<argument index="4" name="custom_receive" type="Callable" />
+			<description>
+				Configures the MultiplayerReplicator to sync instances of the [PackedScene] identified by [code]scene_id[/code] (see [method ResourceLoader.get_resource_uid]) for the purpose of network replication at the desired [code]interval[/code] (in milliseconds). The specified [code]properties[/code] will be part of the state sync. You can optionally specify a [code]custom_send[/code] and a [code]custom_receive[/code] to override the default behaviour and customize the syncronization proecess.
+				Tip: You can use a custom property in the scene main script to return a customly optimized state representation (having a single property that returns a PackedByteArray is higly recommended when dealing with many instances).
+			</description>
+		</method>
+		<method name="track">
+			<return type="void" />
+			<argument index="0" name="scene_id" type="int" />
+			<argument index="1" name="object" type="Object" />
+			<description>
+				Track the given [code]object[/code] as an instance of the scene identified by [code]scene_id[/code]. This object will be passed to your custom sync callables (see [method sync_config]). Tracking and untracking is automatic in [constant REPLICATION_MODE_SERVER].
+			</description>
+		</method>
+		<method name="untrack">
+			<return type="void" />
+			<argument index="0" name="scene_id" type="int" />
+			<argument index="1" name="object" type="Object" />
+			<description>
+				Untrack the given [code]object[/code]. This object will no longer be passed to your custom sync callables (see [method sync_config]). Tracking and untracking is automatic in [constant REPLICATION_MODE_SERVER].
+			</description>
+		</method>
 	</methods>
 	<signals>
 		<signal name="despawn_requested">