tomevault-io Setup Multiplayer Networking (Godot 4.x)
Core Principle
Godot 4.x replaces the old remote func system with the High-Level Multiplayer API using MultiplayerSpawner, MultiplayerSynchronizer, and @rpc annotations. Authority determines who controls what—server authority is the default safe pattern.
What Changed from Godot 3.x
| Godot 3.x | Godot 4.x |
|---|---|
remote func |
@rpc annotation |
remotesync |
@rpc(any_peer, call_local) |
master |
@rpc(authority) with is_multiplayer_authority() |
slave |
@rpc called from non-authority |
get_tree().network_peer |
multiplayer.multiplayer_peer |
| Custom sync | MultiplayerSynchronizer |
| Custom spawn | MultiplayerSpawner |
Multiplayer API Setup
MultiplayerPeer Configuration
The foundation of networking in Godot 4.x:
extends Node
@export var port: int = 7000
@export var max_players: int = 8
func create_host() -> void:
var peer = ENetMultiplayerPeer.new()
var error = peer.create_server(port, max_players)
if error == OK:
multiplayer.multiplayer_peer = peer
print("Server started on port ", port)
_setup_multiplayer_signals()
else:
push_error("Failed to create server: ", error)
func join_host(address: String) -> void:
var peer = ENetMultiplayerPeer.new()
var error = peer.create_client(address, port)
if error == OK:
multiplayer.multiplayer_peer = peer
print("Connecting to ", address, ":", port)
_setup_multiplayer_signals()
else:
push_error("Failed to create client: ", error)
Connection Handling
func _setup_multiplayer_signals() -> void:
multiplayer.peer_connected.connect(_on_peer_connected)
multiplayer.peer_disconnected.connect(_on_peer_disconnected)
multiplayer.connected_to_server.connect(_on_connected_to_server)
multiplayer.connection_failed.connect(_on_connection_failed)
multiplayer.server_disconnected.connect(_on_server_disconnected)
func _on_peer_connected(id: int) -> void:
print("Player connected: ", id)
if multiplayer.is_server():
_spawn_player(id)
func _on_peer_disconnected(id: int) -> void:
print("Player disconnected: ", id)
if multiplayer.is_server():
_despawn_player(id)
func _on_connected_to_server() -> void:
print("Connected to server as ", multiplayer.get_unique_id())
func _on_connection_failed() -> void:
push_error("Failed to connect to server")
func _on_server_disconnected() -> void:
push_warning("Server disconnected")
multiplayer.multiplayer_peer = null
Node Synchronization
MultiplayerSpawner Setup
Automatically spawn/despawn nodes across all clients:
# In your main game scene or world node
extends Node2D
@onready var spawner: MultiplayerSpawner = $MultiplayerSpawner
func _ready() -> void:
# Set the spawn path (where spawned nodes will be added)
spawner.spawn_path = "../Players"
# Add the player scene to auto-spawn list
var player_scene = preload("res://scenes/player.tscn")
spawner.add_spawnable_scene(player_scene.resource_path)
func _spawn_player(id: int) -> void:
# Only the server spawns players
if not multiplayer.is_server():
return
var player = preload("res://scenes/player.tscn").instantiate()
player.name = str(id) # Name must match peer ID for authority
player.set_multiplayer_authority(id)
# Add to spawn path - spawner handles replication
$Players.add_child(player, true) # "true" makes it replicated
MultiplayerSynchronizer Configuration
Synchronize properties automatically:
# player.gd
extends CharacterBody2D
@export var speed: float = 200.0
@export var health: int = 100
# Properties to sync (configured in editor)
@onready var synchronizer: MultiplayerSynchronizer = $MultiplayerSynchronizer
func _ready() -> void:
# Configure what to sync (can also do this in editor)
var config = synchronizer.get_replication_config()
config.add_property(":position")
config.add_property(":velocity")
config.add_property(":health")
# Sync interval (lower = more frequent, more bandwidth)
synchronizer.replication_interval = 0.05 # 20 times per second
# Only sync if value changed
synchronizer.delta_interval = 0.0 # 0 = always sync
func _physics_process(delta: float) -> void:
# Only process input if we have authority
if not is_multiplayer_authority():
return
var input_dir = Input.get_vector("move_left", "move_right", "move_up", "move_down")
velocity = input_dir * speed
move_and_slide()
Scene Replication Setup
In the Godot editor:
- Add MultiplayerSpawner to your world/game scene
- Set Spawn Path to a Node where players will be added (e.g.,
../Players) - Add spawnable scenes in the inspector (player.tscn, enemy.tscn, etc.)
- Add MultiplayerSynchronizer as child of nodes that need sync
- Configure ReplicationConfig in the synchronizer inspector
RPC Patterns
@rpc Annotation Usage
Replace remote func with @rpc decorator:
# Godot 3.x style (OLD - don't use)
remote func take_damage(amount: int) -> void:
health -= amount
# Godot 4.x style (NEW)
@rpc
def take_damage(amount: int) -> void:
health -= amount
Call Modes
Control who can call and where it executes:
# Authority only (default) - only authority peer can call
@rpc
func server_only_function() -> void:
pass # Runs on all peers, but only authority can trigger
# Any peer can call
@rpc(any_peer)
func any_peer_can_call() -> void:
pass
# Call on local peer too (replaces 'remotesync')
@rpc(any_peer, call_local)
func synced_function() -> void:
pass # Runs on caller AND all remote peers
# Authority with local call
@rpc(authority, call_local)
func authority_synced() -> void:
pass
# Unreliable for fast updates (position, rotation)
@rpc(unreliable)
func fast_update(pos: Vector2) -> void:
pass
# Unreliable + ordered (good for continuous position updates)
@rpc(unreliable, ordered)
func ordered_update(pos: Vector2) -> void:
pass
RPC Reliability and Channels
# Reliable (default) - guaranteed delivery, ordered
@rpc
func important_event(data: Dictionary) -> void:
pass # Use for: scoring, death, state changes
# Unreliable - faster, may be lost
@rpc(unreliable)
func position_update(pos: Vector2) -> void:
pass # Use for: frequent position/rotation updates
# Unreliable ordered - drops old packets, keeps order
@rpc(unreliable, ordered)
func continuous_stream(data: PackedByteArray) -> void:
pass # Use for: voice chat, streaming data
# Channel configuration (0-9, default 0)
@rpc(channel=1)
func chat_message(msg: String) -> void:
pass # Separate channel for chat, won't block game data
# Mode + reliability combinations
@rpc(authority, unreliable)
func server_position_update(pos: Vector2) -> void:
pass
@rpc(any_peer, unreliable, ordered, channel=2)
func voice_data(data: PackedByteArray) -> void:
pass
Authority Patterns
Server Authority (Recommended)
Server validates all actions:
# player.gd
extends CharacterBody2D
@export var speed: float = 200.0
var input_vector: Vector2 = Vector2.ZERO
func _physics_process(delta: float) -> void:
if is_multiplayer_authority():
# Authority (usually server) handles actual movement
_process_authority(delta)
else:
# Non-authority (client) handles prediction/interpolation
_process_remote(delta)
func _process_authority(delta: float) -> void:
if multiplayer.is_server():
# Server: apply actual inputs received from clients
velocity = input_vector * speed
move_and_slide()
else:
# Client: send inputs to server, predict locally
input_vector = Input.get_vector("move_left", "move_right", "move_up", "move_down")
rpc_id(1, "receive_input", input_vector) # Send to server (peer 1)
# Client-side prediction (optional)
velocity = input_vector * speed
move_and_slide()
@rpc(any_peer)
func receive_input(input: Vector2) -> void:
# Only server processes inputs
if not multiplayer.is_server():
return
# Validate input (anti-cheat)
if input.length() > 1.0:
input = input.normalized()
input_vector = input
func _process_remote(delta: float) -> void:
# Interpolate to sync position
# MultiplayerSynchronizer handles this automatically
pass
Client-Side Prediction
Reduce perceived latency:
extends CharacterBody2D
var predicted_position: Vector2
var server_position: Vector2
var reconciliation_speed: float = 10.0
func _ready() -> void:
if is_multiplayer_authority() and not multiplayer.is_server():
# Client with authority over this player
set_physics_process(true)
func _physics_process(delta: float) -> void:
if is_multiplayer_authority() and not multiplayer.is_server():
# Client prediction
var input = Input.get_vector("move_left", "move_right", "move_up", "move_down")
velocity = input * speed
predicted_position = position + velocity * delta
# Reconcile with server
position = position.lerp(server_position, reconciliation_speed * delta)
move_and_slide()
# Send input to server
rpc_id(1, "update_input", input)
@rpc
func update_state(pos: Vector2, vel: Vector2) -> void:
# Received from server
server_position = pos
velocity = vel
State Reconciliation
Handle server corrections:
var input_history: Array[Dictionary] = []
var last_processed_input: int = 0
func _physics_process(delta: float) -> void:
if is_multiplayer_authority():
var input = get_input()
var input_id = Time.get_ticks_msec()
input_history.append({"id": input_id, "input": input})
# Apply input
apply_input(input, delta)
# Send to server with ID
rpc_id(1, "process_input", input_id, input)
@rpc
func correction(server_state: Dictionary) -> void:
# Server sends authoritative state + last processed input ID
position = server_state.position
velocity = server_state.velocity
last_processed_input = server_state.last_input_id
# Replay unprocessed inputs
for hist in input_history:
if hist.id > last_processed_input:
apply_input(hist.input, get_physics_process_delta_time())
# Clear old history
input_history = input_history.filter(func(h): return h.id > last_processed_input)
Scene Structure
Lobby Scene
# lobby.gd
extends Control
@onready var host_button: Button = $HostButton
@onready var join_button: Button = $JoinButton
@onready var address_input: LineEdit = $AddressInput
@onready var status_label: Label = $StatusLabel
func _ready() -> void:
host_button.pressed.connect(_on_host_pressed)
join_button.pressed.connect(_on_join_pressed)
multiplayer.connected_to_server.connect(_on_connection_success)
multiplayer.connection_failed.connect(_on_connection_failed)
func _on_host_pressed() -> void:
var peer = ENetMultiplayerPeer.new()
var err = peer.create_server(7000, 4)
if err == OK:
multiplayer.multiplayer_peer = peer
status_label.text = "Hosting on port 7000"
_start_game()
else:
status_label.text = "Failed to host: " + str(err)
func _on_join_pressed() -> void:
var address = address_input.text if address_input.text else "localhost"
var peer = ENetMultiplayerPeer.new()
var err = peer.create_client(address, 7000)
if err == OK:
multiplayer.multiplayer_peer = peer
status_label.text = "Connecting..."
else:
status_label.text = "Failed to connect: " + str(err)
func _on_connection_success() -> void:
status_label.text = "Connected!"
_start_game()
func _on_connection_failed() -> void:
status_label.text = "Connection failed"
func _start_game() -> void:
get_tree().change_scene_to_file("res://scenes/game.tscn")
Game Scene with Multiplayer
# game.gd
extends Node2D
@onready var spawner: MultiplayerSpawner = $MultiplayerSpawner
@onready var players_container: Node2D = $Players
func _ready() -> void:
spawner.spawn_function = _spawn_player_custom
if multiplayer.is_server():
multiplayer.peer_connected.connect(_on_peer_connected)
multiplayer.peer_disconnected.connect(_on_peer_disconnected)
# Spawn host player
_spawn_player(1)
func _on_peer_connected(id: int) -> void:
_spawn_player(id)
func _on_peer_disconnected(id: int) -> void:
var player = players_container.get_node_or_null(str(id))
if player:
player.queue_free()
func _spawn_player(id: int) -> void:
var player_data = {
"player_id": id,
"spawn_position": get_random_spawn_point()
}
spawner.spawn(player_data)
func _spawn_player_custom(data: Dictionary) -> Node:
var player = preload("res://scenes/player.tscn").instantiate()
player.name = str(data.player_id)
player.set_multiplayer_authority(data.player_id)
player.position = data.spawn_position
return player
Player Scene
# player.gd
extends CharacterBody2D
@export var speed: float = 200.0
@export var health: int = 100
@onready var synchronizer: MultiplayerSynchronizer = $MultiplayerSynchronizer
@onready var label: Label = $Label
func _ready() -> void:
label.text = str(get_multiplayer_authority())
# Only process if we have authority
set_physics_process(is_multiplayer_authority())
set_process_input(is_multiplayer_authority())
func _physics_process(delta: float) -> void:
var input_dir = Input.get_vector("move_left", "move_right", "move_up", "move_down")
velocity = input_dir * speed
move_and_slide()
@rpc(any_peer)
func take_damage(amount: int) -> void:
# Only server processes damage
if not multiplayer.is_server():
return
health -= amount
if health <= 0:
rpc("died")
_respawn()
@rpc(call_local)
func died() -> void:
visible = false
set_physics_process(false)
func _respawn() -> void:
health = 100
position = Vector2.ZERO
rpc("respawned")
@rpc(call_local)
func respawned() -> void:
visible = true
set_physics_process(is_multiplayer_authority())
Disconnection Handling
func _setup_disconnection_handling() -> void:
multiplayer.server_disconnected.connect(_on_server_disconnected)
multiplayer.peer_disconnected.connect(_on_peer_disconnected)
get_tree().auto_accept_quit = false
func _notification(what: int) -> void:
if what == NOTIFICATION_WM_CLOSE_REQUEST:
_cleanup_and_quit()
func _cleanup_and_quit() -> void:
if multiplayer.multiplayer_peer:
multiplayer.multiplayer_peer.close()
multiplayer.multiplayer_peer = null
get_tree().quit()
func _on_server_disconnected() -> void:
push_warning("Server disconnected")
multiplayer.multiplayer_peer = null
get_tree().change_scene_to_file("res://scenes/lobby.tscn")
func _on_peer_disconnected(id: int) -> void:
var player = get_node_or_null("Players/" + str(id))
if player:
player.queue_free()
Examples
Basic Host/Client Setup
# network_manager.gd - Autoload singleton
extends Node
signal player_connected(id: int)
signal player_disconnected(id: int)
signal server_started
signal connection_failed
@export var default_port: int = 7000
@export var max_players: int = 4
var peer: ENetMultiplayerPeer = null
func create_server(port: int = default_port) -> Error:
peer = ENetMultiplayerPeer.new()
var err = peer.create_server(port, max_players)
if err == OK:
multiplayer.multiplayer_peer = peer
_setup_signals()
server_started.emit()
return err
func join_server(address: String, port: int = default_port) -> Error:
peer = ENetMultiplayerPeer.new()
var err = peer.create_client(address, port)
if err == OK:
multiplayer.multiplayer_peer = peer
_setup_signals()
else:
connection_failed.emit()
return err
func _setup_signals() -> void:
multiplayer.peer_connected.connect(func(id): player_connected.emit(id))
multiplayer.peer_disconnected.connect(func(id): player_disconnected.emit(id))
func close_connection() -> void:
if peer:
peer.close()
multiplayer.multiplayer_peer = null
peer = null
Player Synchronization
# synced_player.gd
extends CharacterBody2D
@export var sync_position: Vector2:
set(value):
sync_position = value
if not is_multiplayer_authority():
position = sync_position
@export var sync_rotation: float:
set(value):
sync_rotation = value
if not is_multiplayer_authority():
rotation = sync_rotation
func _physics_process(delta: float) -> void:
if is_multiplayer_authority():
# Update sync variables (MultiplayerSynchronizer sends these)
sync_position = position
sync_rotation = rotation
var input = Input.get_vector("move_left", "move_right", "move_up", "move_down")
velocity = input * 200
move_and_slide()
State Replication
# game_state.gd - Server authoritative game state
extends Node
# Replicated to all clients
@export var game_time: float = 0.0
@export var scores: Dictionary = {}
@export var game_phase: String = "lobby"
func _physics_process(delta: float) -> void:
if multiplayer.is_server():
game_time += delta
_check_win_conditions()
func add_score(player_id: int, points: int) -> void:
# Only server modifies state
if not multiplayer.is_server():
return
if not scores.has(player_id):
scores[player_id] = 0
scores[player_id] += points
# State is automatically synced via MultiplayerSynchronizer
rpc("score_updated", player_id, scores[player_id])
@rpc(call_local)
func score_updated(player_id: int, new_score: int) -> void:
print("Player ", player_id, " score: ", new_score)
func _check_win_conditions() -> void:
for player_id in scores:
if scores[player_id] >= 100:
end_game(player_id)
func end_game(winner_id: int) -> void:
game_phase = "ended"
rpc("game_ended", winner_id)
@rpc(call_local)
func game_ended(winner_id: int) -> void:
print("Game over! Winner: ", winner_id)
get_tree().change_scene_to_file("res://scenes/victory.tscn")
Chat System
# chat_system.gd
extends Control
@onready var chat_display: RichTextLabel = $ChatDisplay
@onready var chat_input: LineEdit = $ChatInput
@onready var send_button: Button = $SendButton
func _ready() -> void:
send_button.pressed.connect(_send_message)
chat_input.text_submitted.connect(func(_t): _send_message())
func _send_message() -> void:
var message = chat_input.text.strip_edges()
if message.is_empty():
return
var sender_id = multiplayer.get_unique_id()
var sender_name = "Player " + str(sender_id)
# Send to all peers (including server)
rpc("receive_message", sender_name, message)
chat_input.clear()
@rpc(any_peer, call_local)
func receive_message(sender: String, message: String) -> void:
var formatted = "[b]%s:[/b] %s\n" % [sender, message]
chat_display.append_text(formatted)
# Auto-scroll to bottom
chat_display.scroll_to_line(chat_display.get_line_count())
Migration from Godot 3.x
Remote Functions
# Godot 3.x (OLD)
remote func attack(target_id: int, damage: int) -> void:
var target = get_node("../Players/" + str(target_id))
if target:
target.health -= damage
remotesync func update_position(pos: Vector2) -> void:
position = pos
master func validate_movement(pos: Vector2) -> bool:
return is_valid_position(pos)
slave func receive_correction(pos: Vector2) -> void:
position = pos
# Godot 4.x (NEW)
@rpc(any_peer)
func attack(target_id: int, damage: int) -> void:
var target = get_node("../Players/" + str(target_id))
if target:
target.health -= damage
@rpc(any_peer, call_local)
func update_position(pos: Vector2) -> void:
position = pos
@rpc(authority)
func validate_movement(pos: Vector2) -> bool:
return is_valid_position(pos)
@rpc
func receive_correction(pos: Vector2) -> void:
position = pos
RPC Calls
# Godot 3.x (OLD)
rpc("function_name", arg1, arg2)
rpc_id(peer_id, "function_name", arg1, arg2)
rpc_unreliable("function_name", arg1)
# Godot 4.x (NEW)
rpc("function_name", arg1, arg2) # Reliable, default
rpc_id(peer_id, "function_name", arg1, arg2)
# For unreliable, use annotation on function:
@rpc(unreliable)
func fast_update() -> void:
pass
Network Peer Access
# Godot 3.x (OLD)
var peer = get_tree().network_peer
var my_id = get_tree().get_network_unique_id()
var is_server = get_tree().is_network_server()
# Godot 4.x (NEW)
var peer = multiplayer.multiplayer_peer
var my_id = multiplayer.get_unique_id()
var is_server = multiplayer.is_server()
Custom Multiplayer
# Godot 3.x (OLD) - custom MultiplayerAPI
var custom_multiplayer = MultiplayerAPI.new()
custom_multiplayer.set_root_node(self)
set_custom_multiplayer(custom_multiplayer)
# Godot 4.x (NEW) - SceneMultiplayer
var scene_multiplayer = SceneMultiplayer.new()
get_tree().set_multiplayer(scene_multiplayer, get_path())
When to Use
Build New Multiplayer Games
Setting up networking from scratch in Godot 4.x.
Migrate Existing Games
Converting Godot 3.x multiplayer to 4.x syntax.
Add Multiplayer to Single-Player
Retrofitting existing game with networking.
Common Mistakes
| Mistake | Fix |
|---|---|
remote func syntax |
Use @rpc annotation |
| Calling RPC before peer setup | Set multiplayer.multiplayer_peer first |
| Not setting authority | Use set_multiplayer_authority(id) |
| Server processing client input directly | Validate all client input |
| Synchronizing everything | Only sync what's necessary |
| Using reliable RPC for position | Use @rpc(unreliable) for frequent updates |
Forgetting call_local |
Add if function should run on caller too |
| Spawning without spawner | Use MultiplayerSpawner for replicated nodes |
Integration
Works with:
- godot-modernize-gdscript - Use with modern GDScript features
- godot-profile-performance - Optimize network bandwidth
- godot-setup-navigation - Multiplayer AI pathfinding
Safety
- Always validate client input on server
- Use server authority for critical game state
- Sanitize chat messages (prevent injection)
- Limit RPC call frequency (rate limiting)
- Use unreliable channels for non-critical data
Resources
- Godot 4.x High-Level Multiplayer: https://docs.godotengine.org/en/stable/tutorials/networking/high_level_multiplayer.html
- RPC Tutorial: https://docs.godotengine.org/en/stable/tutorials/networking/rpc.html
- MultiplayerSynchronizer: https://docs.godotengine.org/en/stable/classes/class_multiplayersynchronizer.html
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