5 - Remote Procedure Call

---

In this tutorial, we are going to use an RPC (Remote Procedure Call) to set our nickname randomly. RPC is the most primitive way to sync things in the game. It's not recommended to use RPCs most of the time, and should only be used for infrequent actions like sending the player's name to the server.

Learn More About RPCs

UI Setup

1. In PlayerCharacter prefab, on the Visual transform, add a UI > Text - TextMeshPro.
2. It might asks you to Import TMP Essentials, import it and close the window afterwards.
3. Change the Canvas Render Mode from Screen Space - Overlay to World Space.
4. Position your canvas to be Pos X: 0 Pos Y: 2
5. Change the canvas scale to 0.005 for all axis.

6. In your text component, change font size to 128, and middle & center alignment. Make sure your text now is in the center.

PlayerCharacterNametag

1. Create a new script and name it PlayerCharacterNametag.
2. Change parent class to NetworkBehaviour.
3. Create a network property named Nickname and give it the type of NetworkString32 (string works too, however you should always use NetworkString as string can't work as an RPC parameter or a struct field).

RPC Implementation

We're going to set the RPC source to InputSource and the target to Owner (Server/Host). This means only the input source peer is able to call this RPC, but only the server will execute the RPC. We also want to set isReliable to true, this will ensure that this RPC will arrive to the server, even if packet loss occurs.

using UnityEngine;
using Netick;
using Netick.Unity;

public class PlayerCharacterNametag : NetworkBehaviour
{
    [Networked] public NetworkString32 Nickname { get; set; }

    [Rpc(source: RpcPeers.InputSource, target: RpcPeers.Owner, isReliable: true)]
    public void RPC_SetNicknameRandom()
    {
        Nickname = new NetworkString32($"Player_{Random.Range(1000, 9999)}");
    }
}

Calling the RPC

RPCs can be called from any place. We're going to call them from inside NetworkUpdate (not to be confused with NetworkFixedUpdate) which is just a regular Unity Update. We only want to call the RPC if we have the input authority and if we press the Enter keycode.

public class PlayerCharacterNametag : NetworkBehaviour
{
    //....

    public override void NetworkUpdate()
    {
        if (IsInputSource && Input.GetKeyDown(KeyCode.Return) && Sandbox.InputEnabled)
        {
            RPC_SetNicknameRandom();
        }
    }

    //...
}

Nickname OnChanged

Then, we're going to use an OnChanged callback for our Nickname:

public class PlayerCharacterNametag : NetworkBehaviour
{
    //...
    public TMP_Text TextNametag;
    //...

    [OnChanged(nameof(Nickname))]
    private void OnNicknameChanged(OnChangedData onChangedData)
    {
        TextNametag.SetText(Nickname);
    }

    //...
}

Assign the TextNametag with the TextMeshPro UI we have created before.

Final Testing

Let's press the Enter key repeatedly to check if the RPC is working.