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Version: 1.5.2

Golden Path Module One

Golden Path One continues on the work from Hello World to add a few more features.

This guide covers:

  • Adding scripts to your objects
  • Adding editor modes inside your game (Host, Server, and Client)
  • Basic Player Movement
  • Permissions
  • Basic RPC use
note

The videos on this page were removed because they were out-of-date and caused more confusion than help. All videos in the Hello World and Golden Path series will be recreated and added back at a later time.

Prerequisites​

You should have completed the Hello World project before starting this tutorial. We use Hello World as the base for this and other Golden Path modules.

Open your Hello World project​

  1. Open Unity Hub.
  2. Select Hello World from the list of projects displayed.

Adding Editor Modes to Hello World​

In the HelloWorld project, you created a NetworkManager by adding the pre-created NetworkManager component. In Play Mode, the NetworkManager shows Editor buttons labeled Start Host, Start Client, and Start Server in its inspector. These call the StartHost, StartClient and StartServer methods of the NetworkManager respectively, to initiate a networking session. Inside the HelloWorldManager.cs script, we define two methods which mimic this functionality via UI buttons and status labels.

  1. Create an empty GameObject rename it HelloWorldManager.
  2. Open the Scripts Folder.
  3. Create a script called HelloWorldManager.
  4. Open the HelloWorldManager.cs script.
  5. Edit the HelloWorldManager.cs script to match the following.
tip

You can copy the script from here and paste it into your file.

  1. Select the code sample.
  2. Click Copy in the top right corner.
  3. Paste it into your code editor.
Click to show/hide the Code.

using Unity.Netcode;
using UnityEngine;

namespace HelloWorld
{
    public class HelloWorldManager : MonoBehaviour
    {
        void OnGUI()
        {
            GUILayout.BeginArea(new Rect(10, 10, 300, 300));
            if (!NetworkManager.Singleton.IsClient && !NetworkManager.Singleton.IsServer)
            {
                StartButtons();
            }
            else
            {
                StatusLabels();

                SubmitNewPosition();
            }

            GUILayout.EndArea();
        }

        static void StartButtons()
        {
            if (GUILayout.Button("Host")) NetworkManager.Singleton.StartHost();
            if (GUILayout.Button("Client")) NetworkManager.Singleton.StartClient();
            if (GUILayout.Button("Server")) NetworkManager.Singleton.StartServer();
        }

        static void StatusLabels()
        {
            var mode = NetworkManager.Singleton.IsHost ?
                "Host" : NetworkManager.Singleton.IsServer ? "Server" : "Client";

            GUILayout.Label("Transport: " +
                NetworkManager.Singleton.NetworkConfig.NetworkTransport.GetType().Name);
            GUILayout.Label("Mode: " + mode);
        }

        static void SubmitNewPosition()
        {
            if (GUILayout.Button(NetworkManager.Singleton.IsServer ? "Move" : "Request Position Change"))
            {
                if (NetworkManager.Singleton.IsServer && !NetworkManager.Singleton.IsClient )
                {
                    foreach (ulong uid in NetworkManager.Singleton.ConnectedClientsIds)
                        NetworkManager.Singleton.SpawnManager.GetPlayerNetworkObject(uid).GetComponent<HelloWorldPlayer>().Move();
                }
                else
                {
                    var playerObject = NetworkManager.Singleton.SpawnManager.GetLocalPlayerObject();
                    var player = playerObject.GetComponent<HelloWorldPlayer>();
                    player.Move();
                }
            }
        }
    }
}
  1. Add the HelloWorldManager script component to the HelloWorldManager GameObject.
Click to show/hide the Code.
        static void StartButtons()
        {
            if (GUILayout.Button("Host")) NetworkManager.Singleton.StartHost();
            if (GUILayout.Button("Client")) NetworkManager.Singleton.StartClient();
            if (GUILayout.Button("Server")) NetworkManager.Singleton.StartServer();
        }

        static void StatusLabels()
        {
            var mode = NetworkManager.Singleton.IsHost ?
                "Host" : NetworkManager.Singleton.IsServer ? "Server" : "Client";

            GUILayout.Label("Transport: " +
                NetworkManager.Singleton.NetworkConfig.NetworkTransport.GetType().Name);
            GUILayout.Label("Mode: " + mode);
        }

You can statically access the NetworkManager instance from any other scripts via its singleton named Singleton. This is defined when the MonoBehaviour is enabled. This component also has useful properties, such as IsClient, IsServer, and IsLocalClient. The IsClient and IsServer properties dictate the connection state we have currently established that you will use shortly.

We call these methods inside of OnGUI().

Click to show/hide the Code.

        void OnGUI()
        {
            GUILayout.BeginArea(new Rect(10, 10, 300, 300));
            if (!NetworkManager.Singleton.IsClient && !NetworkManager.Singleton.IsServer)
            {
                StartButtons();
            }
            else
            {
                StatusLabels();

                SubmitNewPosition();
            }

            GUILayout.EndArea();
        }

note

You won'tice the introduction of a new method, SubmitNewPosition(). This is used later.

Adding basic movement to the Player object​

Here we will create a HelloWorldPlayer.cs script that adds some basic movement to the Hello World player.

  1. Open the Scripts Folder.
  2. Create a new script called HelloWorldPlayer.
  3. Open the HelloWorldPlayer.cs script.
  4. Edit the HelloWorldPlayer.cs script to match the following.
Click to show/hide the Code.
using Unity.Netcode;
using UnityEngine;

namespace HelloWorld
{
    public class HelloWorldPlayer : NetworkBehaviour
    {
        public NetworkVariable<Vector3> Position = new NetworkVariable<Vector3>();

        public override void OnNetworkSpawn()
        {
            if (IsOwner)
            {
                Move();
            }
        }

        public void Move()
        {
            if (NetworkManager.Singleton.IsServer)
            {
                var randomPosition = GetRandomPositionOnPlane();
                transform.position = randomPosition;
                Position.Value = randomPosition;
            }
            else
            {
                SubmitPositionRequestServerRpc();
            }
        }

        [ServerRpc]
        void SubmitPositionRequestServerRpc(ServerRpcParams rpcParams = default)
        {
            Position.Value = GetRandomPositionOnPlane();
        }

        static Vector3 GetRandomPositionOnPlane()
        {
            return new Vector3(Random.Range(-3f, 3f), 1f, Random.Range(-3f, 3f));
        }

        void Update()
        {
            transform.position = Position.Value;
        }
    }
}
  1. Select the Player prefab.
  2. Add the script HelloWorldPlayer script as a component. This class will inherit from NetworkBehaviour instead of MonoBehaviour.
Click to show/hide the Code.
     public class HelloWorldPlayer : NetworkBehaviour

Inside this class we now define a NetworkVariable to represent this player's networked position.

Click to show/hide the Code.
        public NetworkVariable<Vector3> Position = new NetworkVariable<Vector3>();

HelloWorldPlayer overrides OnNetworkSpawn.

Click to show/hide the Code.
        public override void OnNetworkSpawn()
        {
            if (IsOwner)
            {
                Move();
            }
        }

In a networked game, the dedicated server (or host) might need to run different functions than the networked player (the client). For example, in a server-authoritative game, the client would handle the player inputs, but the server would handle the movement. All instances of this script in the game, whether running on a server/host or a client, call the OnNetworkSpawn method when the NetworkObject to which this script is attached has spawned, but only its owner will call the Move method. In the case of a Player Object, Netcode spawns an instance of the player object for every client and host (for which they're the owner). Each of these player objects contain this script. Calling the Move method in OnNetworkSpawn instead of, for example, in Awake ensures that the NetworkObject has finished spawning, so the check to see whether the player is a server/host or client is valid. The Move method can then implement different logic depending on the answer (so that servers do one thing, and clients do another).

Click to show/hide the Code.
        public void Move()
        {
            if (NetworkManager.Singleton.IsServer)
            {
                var randomPosition = GetRandomPositionOnPlane();
                transform.position = randomPosition;
                Position.Value = randomPosition;
            }
            else
            {
                SubmitPositionRequestServerRpc();
            }
        }

Some simple RPC use​

If this player is a server-owned player, at OnNetworkSpawn() we can immediately move this player, as suggested in the following code.

Click to show/hide the Code.
            if (NetworkManager.Singleton.IsServer)
            {
                var randomPosition = GetRandomPositionOnPlane();
                transform.position = randomPosition;
                Position.Value = randomPosition;
            }

If we are a client, we call a ServerRpc. A ServerRpc can be invoked by a client to be executed on the server.

Click to show/hide the Code.
            else
            {
                SubmitPositionRequestServerRpc();
            }

This ServerRpc simply sets the position NetworkVariable on the server's instance of this player by just picking a random point on the plane.

Click to show/hide the Code.
        [ServerRpc]
        void SubmitPositionRequestServerRpc(ServerRpcParams rpcParams = default)
        {
            Position.Value = GetRandomPositionOnPlane();
        }

The server instance of this player has just modified the Position NetworkVariable, meaning that if we are a client, we need to apply this position locally inside of our Update loop.

Click to show/hide the Code.
        void Update()
        {
            transform.position = Position.Value;
        }

We can now go back to HelloWorldManager.cs and define the contents of SubmitNewPosition().

Click to show/hide the Code.
        static void SubmitNewPosition()
        {
            if (GUILayout.Button(NetworkManager.Singleton.IsServer ? "Move" : "Request Position Change"))
            {
                var playerObject = NetworkManager.Singleton.SpawnManager.GetLocalPlayerObject();
                var player = playerObject.GetComponent<HelloWorldPlayer>();
                player.Move();
            }
        }

Whenever you press the GUI button (which is contextual depending on if you are server or a client), you find your local player and simply call Move().

You can now create a build which will show the concepts outlined above.

tip

Make sure SampleScene is included in BuildSettings > Scenes in Build list.

One build instance can create a host. Another client can join the host's game. Both are able to press a GUI button to move. Server will move immediately and be replicated on client. Client can request a new position, which will instruct the server to modify that server instance's position NetworkVariable. That client will apply that NetworkVariable position inside of it's Update() method.

Next Steps​

See the following content to continue your journey using Netcode: