Book Image

Unreal Development Kit Game Programming with UnrealScript: Beginner's Guide

By : Rachel Cordone
Book Image

Unreal Development Kit Game Programming with UnrealScript: Beginner's Guide

By: Rachel Cordone

Overview of this book

Unreal Development Kit is the free edition of Unreal Engine—the largest game engine in existence with hundreds of shipped commercial titles. The Unreal Engine is a very powerful tool for game development but with something so complex it's hard to know where to start.This book will teach you how to use the UnrealScript language to create your own games with the Unreal Development Kit by using an example game that you can create and play for yourself. It breaks down the UnrealScript language into easy to follow chapters that will quickly bring you up to speed with UnrealScript game programming.Unreal Development Kit Game Programming with UnrealScript takes you through the UnrealScript language for the Unreal Development Kit. It starts by walking through a project setup and setting up programs to write and browse code. It then takes you through using variables, functions, and custom classes to alter the game's behavior and create our own functionality. The use and creation of Kismet is also covered. Later, using replication to create and test multiplayer games is discussed. The book closes with code optimization and error handling as well as a few of the less common but useful features of UnrealScript.
Table of Contents (18 chapters)
Unreal Development Kit Game Programming with UnrealScript
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Time for action – Dealing with Accessed None


To test this we need to purposely create an Accessed None, so let's do that now. We'll add a PostBeginPlay function to our BrokenActor.

  1. Let's say we wanted to know the speed of a Projectile. We could add a variable and write a function like this in our PostBeginPlay:

    var Projectile MyProjectile;
    
    simulated function PostBeginPlay()
    {
        local float ProjectileSpeed;
    
        ProjectileSpeed = MyProjectile.Speed;
        `log("ProjectileSpeed:" @ ProjectileSpeed);
    }
  2. Compile the code and run the game.

  3. Exit the game and check the log:

    [0004.99] ScriptWarning: Accessed None 'P'
    	BrokenActor BrokenMap.TheWorld:PersistentLevel.BrokenActor_0
    	Function BrokenGame.BrokenActor:PostBeginPlay:004F
    [0004.99] ScriptLog: ProjectileSpeed: 0.0000
  4. We're getting an Accessed None warning and the speed is logging as 0. That doesn't seem right, especially when the default for the Projectile class is 2000. Let's add another log to see what's going on:

    var Projectile MyProjectile;
    ...