Multiplayer Networking with Godot: A Practical Guide

Godot is a popular open-source game engine that allows game developers to create 2D and 3D games for multiple platforms. Godot has a built-in networking system that enables developers to create multiplayer games that can be played online or on a local network. In this article, we will cover the basics of multiplayer networking with Godot and provide practical examples to help you get started.

Getting Started

Before we dive into the details of multiplayer networking with Godot, let's start with some basic concepts. Networking in games refers to the process of transmitting and receiving data between multiple devices or players. In the context of multiplayer games, networking is essential to create a seamless gaming experience where players can interact with each other in real-time.

Godot uses a client-server architecture for multiplayer networking. In this architecture, one player acts as the server, and the other players act as clients. The server is responsible for managing the game's logic and transmitting data to clients, while clients are responsible for receiving data from the server and rendering the game on their devices.

Types of Multiplayer Networking

Godot supports two types of multiplayer networking: authoritative and non-authoritative.

Authoritative Multiplayer Networking

In authoritative multiplayer networking, the server is the authority on the game state, and clients send input to the server. The server then processes the input and sends updates to all clients. This approach ensures that all clients are in sync with the server and prevents cheating. However, authoritative multiplayer networking can lead to lag and delay, as every input from the client must be sent to the server and processed before sending back updates.

Non-Authoritative Multiplayer Networking

In non-authoritative multiplayer networking, clients send input to the server and simulate the game state locally. The server then sends updates to all clients to synchronize the game state. This approach reduces lag and delay but can lead to cheating, as clients can modify their game state before sending input to the server.

Setting Up Multiplayer Networking in Godot

To enable multiplayer networking in your Godot project, follow these steps:

1. Open your project in Godot.
2. Navigate to the Project Settings menu.
3. Select the Network tab.
4. Set the Multiplayer option to Enabled.
5. Choose the appropriate Server/Client configuration for your game.

Creating a Multiplayer Game

Let's create a simple multiplayer game to demonstrate how to use multiplayer networking in Godot. In this game, two players control a spaceship and try to shoot each other down.

Creating the Spaceship Scene

1. Open Godot and create a new scene by selecting Scene > New Scene from the top menu.
2. Add a Spatial node to the scene.
3. Add a MeshInstance node to the Spatial node and select a spaceship mesh.
4. Add a Camera node to the Spatial node and position it behind the spaceship.
5. Add a CollisionShape node to the Spatial node and adjust it to fit the spaceship's shape.

Adding Multiplayer Functionality

1. Add a Multiplayer node to the scene by selecting Node > Network > Multiplayer from the top menu.
2. Connect the Multiplayer node's connected_to_server signal to a script that handles the game logic.
3. In the script, add the following code to initialize the game:

extends Node

var player_id = null

func _ready():
    if has_network_peer():
        player_id = get_tree().get_network_unique_id()
        multiplayer.rpc("spawn_player", player_id)

4. Add the following code to the script to handle player input:

func _process(delta):
    if has_network_peer():
        if Input.is_action_pressed("ui_left"):
            multiplayer.rpc_unreliable("move_left", player_id)
        elif Input.is_action_pressed("ui_right"):
            multiplayer.rpc_unreliable("move_right", player_id)
        elif Input.is_action_pressed("ui_select"):
            multiplayer.rpc("shoot", player_id)

5. Add the following code to handle incoming RPC calls:

func spawn_player(id):
    var spaceship = load("res://spaceship.tscn").instance()
    add_child(spaceship)
    spaceship.set_network_master(id)

func move_left(id):
    if has_network_peer():
        if id == player_id:
            position.x -= 10 * get_process_delta_time()

func move_right(id):
    if has_network_peer():
        if id == player_id:
            position.x += 10 * get_process_delta_time()

func shoot(id):
    if has_network_peer():
        if id == player_id:
            var bullet = load("res://bullet.tscn").instance()
            add_child(bullet)
            bullet.set_translation(translation + Vector3(0, 1, 0))
            bullet.set_network_master(id)

6. Finally, create a new scene and add two instances of the spaceship scene to it. Set one spaceship's Network mode to Master and the other's to Slave.

Conclusion

In this article, we covered the basics of multiplayer networking with Godot and provided a practical example of how to create a simple multiplayer game. We also discussed the two types of multiplayer networking in Godot: authoritative and non-authoritative. With this knowledge, you should be able to create your own multiplayer games with Godot and provide a seamless gaming experience to your players. Happy game developing!