How to Master Unity Netcode in 7 Easy Steps

Step by step tutorial on Unity Netcode for multiplayer

Unity's Netcode for GameObjects (formerly UNet) provides a powerful and relatively straightforward way to add multiplayer functionality to your Unity games. While networking can seem daunting, breaking it down into manageable steps makes the process much less intimidating. This article will guide you through mastering Unity Netcode in seven easy steps, from setting up your project to testing a simple "Hello World" scenario. Check out the detailed step by step tutorial for creating multiplayer game in unity using unity netcode.

1. Create a New Project in Unity

First things first, you'll need a Unity project. If you're starting from scratch, create a new 3D project in the Unity Hub. Give it a descriptive name like "MyNetcodeProject" and choose a suitable location to save it. If you already have a project you want to add multiplayer to, you can skip this step. Remember to consider your target platforms and set up your project accordingly.

2. Install Netcode

Netcode isn't included by default. You'll need to install it via the Unity Package Manager.

1. Open the Package Manager (Window > Package Manager).
2. Select "Unity Registry" from the dropdown menu.
3. Search for "Netcode for GameObjects."
4. Click "Install" to add the package to your project.

Be sure to check for the latest recommended version of Netcode. Keeping your packages up-to-date is crucial for stability and access to the newest features.

3. Create the Basic Components

This is where the magic begins. We'll set up the essential components for Netcode to function.

Creating Network Manager and Selecting the Transport

The Network Manager is the heart of your multiplayer setup. It handles connections, spawning, and other network-related tasks.

1. Create an empty GameObject in your scene and name it "NetworkManager."
2. Add the NetworkManager component to this GameObject.
3. You'll see a section for "Transport." The default transport is typically UDP, which is suitable for most games. You can explore other transports later if needed. For this tutorial, stick with the default.

Creating an Object to Spawn for Each Connected Player

We need a GameObject that represents each player in the game. This will be spawned automatically when a new player connects.

1. Create a simple 3D object (e.g., a cube or sphere) and name it "Player." This will be your player prefab.
2. Add a NetworkObject component to the "Player" prefab. This component is crucial; it marks this object as network-synced.
3. In the Network Manager, in the "Player Prefab" field, drag and drop your "Player" prefab.

Adding Your Scene to the Build

To test multiplayer, you'll need to create a build of your game. Add your scene to the build settings:

1. Go to File > Build Settings.
2. Click "Add Open Scenes" to include your current scene in the build.

Creating a Command Line Helper

For easier testing, especially with multiple clients, we'll create a simple command-line helper. This allows you to launch multiple instances of your game with specific roles (server or client).

1. Create a new C# script named "CommandLineHelper" and attach it to a GameObject in your scene (or create a new empty GameObject).
2. Add the following code to the script:

C#

using UnityEngine;
using Unity.Netcode;

public class CommandLineHelper : MonoBehaviour
{
    void Start()
    {
        if (Application.isEditor) return; // Don't run this in the editor

        string[] args = System.Environment.GetCommandLineArgs();
        for (int i = 0; i < args.Length; i++)
        {
            if (args[i] == "-server")
            {
                NetworkManager.Singleton.StartServer();
                break;
            }
            else if (args[i] == "-client")
            {
                NetworkManager.Singleton.StartClient();
                break;
            }
        }
    }
}

Testing the Command Line Helper

Now, build your game (File > Build). Navigate to the build directory in your file explorer. You can now launch your game as a server or client using the command line:

• Server: MyNetcodeProject.exe -server
• Client: MyNetcodeProject.exe -client

4. Testing "Hello World"

Let's implement a simple "Hello World" message to verify that the network is working.

Route 1 - Editor

While you can technically test in the editor, it's not ideal for true multiplayer simulation. However, for initial testing, you can use two game windows in the editor. One window will act as the server and the other as a client. Remember, this is not a perfect representation of a real multiplayer scenario.

1. In the Network Manager, set "Start in Client Mode" to false. Run the game in the editor. This will be the server.
2. Open another game window (Game > New Game Window). In the Network Manager of this new window, set "Start in Client Mode" to true. This will be the client.

Route 2 - Command Line (Recommended)

This is the preferred method for testing multiplayer functionality.

1. Build your game.
2. Open a command prompt or terminal.
3. Navigate to your build directory.
4. Open one instance of your game as a server: MyNetcodeProject.exe -server
5. Open another instance (or multiple instances) as clients: MyNetcodeProject.exe -client

Implementing the "Hello World" Logic

1. Open your "Player" prefab.
2. Add a new C# script called "PlayerController."
3. Add the following code to the script:

C#

using UnityEngine;
using Unity.Netcode;

public class PlayerController : NetworkBehaviour
{
    public override void OnNetworkSpawn()
    {
        if (IsOwner) // Only the player who owns this object can control it
        {
            Debug.Log("Hello, world! I am the player.");
        }
    }
}

Now, when you run your game in multiplayer mode, each client will see the "Hello, world!" message in their console, but only for the player object they control. This confirms that the network is working and that each client has its own player instance.

5. Next Steps

Congratulations! You've successfully implemented basic multiplayer functionality with Unity Netcode. From here, you can explore more advanced topics like:

• Player Movement: Implement synchronized player movement across the network.
• Game Logic: Add game mechanics, like shooting, scoring, or interacting with the environment.
• RPCs (Remote Procedure Calls): Use RPCs to send commands from the client to the server (e.g., for shooting or interacting with objects).
• Network Variables: Use Network Variables to synchronize data between clients and the server (e.g., player health, score, or position).
• Handling Disconnections: Implement logic to handle player disconnections gracefully.
• Optimization: Optimize your network code for performance, especially when dealing with many players or complex game mechanics.
• Security: Implement security measures to prevent cheating and protect your game.

By following these seven steps and exploring the next steps, you'll be well on your way to mastering Unity Netcode and creating engaging multiplayer experiences. Remember to consult the official Unity Netcode documentation and community forums for further learning and support. Networking can be complex, but with practice and patience, you can achieve your multiplayer game development goals.