Book Image

Unity Multiplayer Games

By : Alan R. Stagner
Book Image

Unity Multiplayer Games

By: Alan R. Stagner

Overview of this book

Unity is a game development engine that is fully integrated with a complete set of intuitive tools and rapid workflows used to create interactive 3D content. Multiplayer games have long been a staple of video games, and online multiplayer games have seen an explosion in popularity in recent years. Unity provides a unique platform for independent developers to create the most in-demand multiplayer experiences, from relaxing social MMOs to adrenaline-pumping competitive shooters. A practical guide to writing a variety of online multiplayer games with the Unity game engine, using a multitude of networking middleware from player-hosted games to standalone dedicated servers to cloud multiplayer technology. You can create a wide variety of online games with the Unity 4 as well as Unity 3 Engine. You will learn all the skills needed to make any multiplayer game you can think of using this practical guide. We break down complex multiplayer games into basic components, for different kinds of games, whether they be large multi-user environments or small 8-player action games. You will get started by learning networking technologies for a variety of situations with a Pong game, and also host a game server and learn to connect to it.Then, we will show you how to structure your game logic to work in a multiplayer environment. We will cover how to implement client-side game logic for player-hosted games and server-side game logic for MMO-style games, as well as how to deal with network latency, unreliability, and security. You will then gain an understanding of the Photon Server while creating a star collector game; and later, the Player.IO by creating a multiplayer RTS prototype game. You will also learn using PubNub with Unity by creating a chatbox application. Unity Multiplayer Games will help you learn how to use the most popular networking middleware available for Unity, from peer-oriented setups to dedicated server technology.
Table of Contents (14 chapters)
Unity Multiplayer Games
About the Author
About the Reviewers

Using RPCs

RPCs are useful for single, self-contained messages that need to be sent, such as a character firing a gun, or a player saying something in chat.

In Unity, RPCs are methods marked with the [RPC] attribute. This can be called by name via networkView.RPC( "methodName", … ). For example, the following script prints to the console on all machines when the space key is pressed.

using UnityEngine;
using System.Collections;

public class ExampleUnityNetworkCallRPC : MonoBehavior
  void Update()
    // important – make sure not to run if this networkView is notours
    if( !networkView.isMine )

    // if space key is pressed, call RPC for everybody
    if( Input.GetKeyDown( KeyCode.Space ) )
      networkView.RPC( "testRPC", RPCMode.All );

  void testRPC( NetworkMessageInfo info )
    // log the IP address of the machine that called this RPC
    Debug.Log( "Test RPC called from " + info.sender.ipAddress );

Also note the use of NetworkView.isMine to determine ownership of an object. All scripts will run 100 percent of the time regardless of whether your machine owns the object or not, so you have to be careful to avoid letting some logic run on remote machines; for example, player input code should only run on the machine that owns the object.

RPCs can either be sent to a number of players at once, or to a specific player. You can either pass an RPCMode to specify which group of players to receive the message, or a specific NetworkPlayer to send the message to. You can also specify any number of parameters to be passed to the RPC method.

RPCMode includes the following entries:

  • All (the RPC is called for everyone)

  • AllBuffered (the RPC is called for everyone, and then buffered for when new players connect, until the object is destroyed)

  • Others (the RPC is called for everyone except the sender)

  • OthersBuffered (the RPC is called for everyone except the sender, and then buffered for when new players connect, until the object is destroyed)

  • Server (the RPC is sent to the host machine)


Note that, with the exception of RPCMode.All and RPCMode.AllBuffered, a client cannot send an RPC to itself.