Converting a Single Player Game to Multiplayer

This document describes steps to convert a single player game to a multiplayer game using the new networking system. The process described here is a simplified, higher level version of the actual process for a real game, and wont work exactly like this for every game, but it provides a basic recipe for the process.

NetworkManager Setup

• Add a new game object to the scene and rename it to “NetworkManager”.
• Add the NetworkManager component to the new game object.
• Add the NetworkManagerHUD component to the game object. This will provide the default UI for managing network game state.

See Using the NetworkManager.

Player Prefab Setup

• Find the prefab for the player object in the game, or create a prefab from the player object.
• Add NetworkIdentity component to player prefab.
• Check the LocalPlayerAuthority box on the NetworkIdentity.
• Set the playerPrefab in the “Spawn Info” section on the NetworkManager to the player prefab
• Remove the player object instance from the scene if it exists in the scene

See Player Objects.

Player Movement

• Add a NetworkTransform component to the player prefab
• Update input and control scripts to respect isLocalPlayer
• Fix camera to use spawned player and isLocalPlayer

For example, this script only processes input for the local player:

using UnityEngine;
using UnityEngine.Networking;

public class Controls : NetworkBehaviour
{
    void Update()
    {
        if (!isLocalPlayer)
        {
            // exit from update if this is not the local player
            return;
        }

        // handle player input for movement
    }
}

Basic Player Game State

• Make scripts that contain important data into NetworkBehaviours instead of MonoBehaviours
• Make important member variables into SyncVars

See State Synchronization.

Networked Actions

• Make scripts that perform important actions into NetworkBehaviours instead of MonoBehaviours
• Update functions that perform important player actions to be Commands

See Networked Actions.

Non-Player Objects

Fix non-player prefabs such as enemies:

• Add NetworkIdentify component
• Add NetworkTransform component
• Register spawnable prefabs with NetworkManager
• Update scripts with game state and actions

Spawners

• Potentially change spawner scripts to be NetworkBehaviours
• Modify spawners to only run on the server, use isServer property or OnStartServer() function
• Call NetworkServer.Spawn() for created objects

Spawn Positions for players

• Add new game object and place at player start location
• Add NetworkStartPosition component to new game object

Lobby

• Create Lobby Scene
• Add a new game object to the scene and rename it to “NetworkLobbyManager”.
• Add the NetworkLobbyManager component to the new game object.
• Configure the manager
  • Scenes
  • Prefabs
  • spawners