3D Game Engine Design Using DirectX 9 and C#

Transcription

1 Introduction to 3D Game Engine Design Using DirectX 9 and C# LYNN T. HARRISON APress Media, LLC

2 Introduction to 3D Game Engine Design Using DirectX 9 and C# Copyright 2003 by Lynn T. Harrison Originally published by Apress in 2003 All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher. ISBN ISBN (ebook) DOI / Trademarked names may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, we use the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. Technical Reviewer: Patrick DeNardo Editorial Board: Dan Appleman, Craig Berry, Gary Cornell, Tony Davis, Steven Rycroft, Julian Skinner, Martin Streicher, Jim Sumser, Karen Watterson, Gavin Wray, John Zukowski Assistant Publisher: Grace Wong Project Manager: Tracy Brown Collins Copy Editor: Ami Knox Production Manager: Kari Brooks Compositor and Proofreader: Kinetic Publishing Services, ILC Indexer: Michael Brinkman Cover Designer: Kurt Krames Manufacturing Manager: Tom Debolski The information in this book is distributed on an "as is" basis, without warranty. Although every precaution has been taken in the preparation of this work, neither the author(s) nor Apress shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in this work.

3 To my wife, Gerri, for her support and patience during the process of writing this book. I couldn't have done it without you. And also to my son, Mike, who inherited my love of games of all types.

4 Contents at a Glance About the Author... xi About the Technical Reviewer... xii Acknowledgments... xiii Introduction... xv Chapter 1 Overview Chapter 2 User Interface Chapter 3 Hanging Ten: A Ride Through the Rendering Pipeline Chapter 4 Basic 3D Objects Chapter 5 Complex 3D Objects Chapter 6 Camera: The Player's View of the World Chapter 7 Adding Some Atmosphere: Lighting and Fog Chapter 8 Artificial Intelligence: Adding the Competition Chapter 9 Game Audio: Let's Make Some Noise Chapter 10 Game Physics: Keeping It Real Chapter 11 Tools of the Trade Index v

5 Contents About the Author... xi About the Technical Reviewer... xii Acknowledgments... xiii Introduction... xv Chapter 1 Overview What Is a Game Engine?... 1 How This Book's Game Engine Project Differs... 3 Starting at the Beginning-Defining a Few Primitives... 5 Interfaces: The Integration Contract... 7 Process Flow Overview Developer Splash Screen Game Splash Screen Presenting the Options Playing the Game After Action Review: Player Scoring Looking at the C# Code Summary Chapter 2 User Interface Getting Keyboard Input Getting Mouse Input Getting Joystick Input A Unified Input Interface Drawing Splash Screens Drawing Option Screens Developing the Console Pulling It All Together Summary Chapter 3 Hanging Ten: A Ride Through the Rendering Pipeline Moving Cameras and Objects Animating Objects Checking Visibility and Performing Rough Culling vii

6 Contents Selecting Level of Detail (LOD) Converting Model Coordinates to the View Frame Back Face Culling Clipping Setting Up the Vertex Buffer Shading, Texturing, and Fog Rendering Summary Chapter 4 Basic 3D Objects Seeing to the Horizon: The Skybox Traveling the Rolling Landscape Populating the Landscape: Billboards Adding Environmental Effects: Particle Systems Summary Chapter 5 Complex 3D Objects Looking at Mesh Basics Developing the Model Class Summary Chapter 6 Camera: The Player's View of the World Looking Through the Lens Summary Chapter 7 Adding Some Atmosphere: Lighting and Fog Shedding Some Light on the Subject Piercing the Fog Summary Chapter 8 Artificial Intelligence: Adding the Competition Looking at Our AI Options Implementing the Artificial Intelligence System Summary viii

7 Contents Chapter 9 Game Audio: Let's Make Some Noise Making Beautiful Music Together Hearing in Three Dimensions Summary Chapter 10 Game Physics: Keeping It Real Looking at Vehicle Dynamics Summary Chapter 11 Tools of the Trade Setting Up Your Development Environment Three-Dimensional Modeling Tools Level Editors Editing Images Audio Tools Summary Index ix

8 About the Author LYNN THOMAS IIARiusoN is both a Microsoft Certified Systems Engineer (MCSE) and Microsoft Certified Solutions Developer (MCSD) and is currently employed as a senior systems engineer for Diamond Visionics Company (a visualization engineering company). He lives in Binghamton, New York, with his wife, Gerri, and son, Michael. Lynn has been active in the simulation and graphics industries for over 22 years. xi

9 About the Technical Reviewer PATRICK DENARDO is a project director and software technical lead at Universal Instruments, Inc., where he architects and develops client-server internationalized software for the Wmdows platform. He is a Microsoft Certified Professional and has a Bachelor of Science degree in computer science from Binghamton University. Patrick enjoys reading computer books, playing golf, and spending time with his wife, Jennifer, and their dog, Abby. xii

10 Acknowledgments I would LIKE ro THANK ALL of the great people at Apress for their guidance along the way. I really had no idea when I started this book about everything that went into the process. First, thanks to Gary Cornell and Dan Appleman for their enthusiasm in this project and for getting me started. Also thanks to Sofia Marchant and Tracy Brown Collins for keeping everything organized and on track. Big thanks to my wife, Gerri, and to my copy editor, Ami Knox, who helped translate my techie ramblings into English. I would also like to thank my technical reviewer, Pat DeNardo. Pat not only made sure that the information presented in this book was technically correct, but also that the information was understandable to those new to C# and Managed DirectX. Lastly, I would like to thank my family for their support over the last 14 months. Too many weekends were spent with my computer rather than with them. Gerri and Mike, thanks for understanding my need to do this. I would also like to thank my parents for always believing me and raising me to believe in myself. xiii

11 Introduction I HAVE BEEN EDUCATING MYSELF about game design and 3D visualization for many years. My bookshelves are full of books on programming, game development, and the various graphical application programming interfaces (APis). Many books have been written that explain every part of DirectX or OpenGL. Quite a few books are also dedicated to creating portions of a game using one or both of these technologies. The book that I could never find was one on game engine design. I wanted an object -oriented, reusable package of software that was not tightly integrated to one particular game. I knew that I wasn't the only person interested in game engine design. I decided that, as I learned C# and managed DirectX 9 and ported my game engine to this new technology, I would document the process. The fact that you are reading this indicates you share my interest in 3D game engines. I have kept this book at an introductory level. When I initially began planning the book, I considered including more advanced topics such as animation, networking for multiplayer capability, and the programmable pipeline (shaders). I quickly came to the conclusion that to cover that much material in any depth at all was too much for a single book. I am hoping that at some point in the future I will have the time to do a follow-up volume that includes these and other more advanced areas. No one book can answer all questions. I encourage you to extend your research to other books and the Internet as you hone your development capabilities. The best resources for getting your questions answered are the Microsoft DirectX news groups. There are a number of newsgroups of interest that are prefixed with microsoft.public.win32.programmer.directx. The newsgroup dedicated to Managed DirectX is microsoft.public.win32.programmer.directx.managed. I often monitor this newsgroup, and I will answer any questions that I can. Chapter 1: Overview This chapter looks at several types of game engines as well as the distinction between a game and a game engine. Game engine design requires more thought than do hard-coding rendering and game logic within the game itself. The benefit is greater reuse of the underlying technology and a cleaner overall design. XV

12 Introduction Chapter 2: User Interface A game's user interface provides the means of giving the player information and obtaining the player's commands. This chapter investigates the presentation of splash screens, option screens, and a console screen. It also looks at the use of Directlnput to obtain player inputs from the keyboard, mouse, and joysticks. Chapter 3: Hanging Ten: A Ride Through the Rendering Pipeline Before diving into the actual rendering of three-dimensional objects, it is good to have a basic understanding of the rendering pipeline. This chapter walks you through the typical steps involved in the fixed-function rendering pipeline. This includes the manipulation of cameras to provide the viewpoint in the game. It also describes a base class that will be used for all rendered objects. The process of culling objects and other techniques for improving performance is also investigated. The actual illustration of these steps appears in Chapters 4 through 8. Chapter 4: Basic 30 Objects This chapter is the first of two chapters dealing with rendering the various types of objects that are used within a game. These objects include a skybox for providing a view into the distance, terrain rendering to provide a surface to move upon, billboards for simple symmetrical objects, and particle systems. Particle systems are an extremely powerful tool that may be used for dynamic systems of small objects. These include flowing water, fire, fireworks, and blowing sand. Chapter 5: Complex 30 Objects Chapter 5 is the second chapter dedicated to the rendering of objects for games. The objects described in this chapter are much more complex, with many polygons per object. These are referred to as mesh objects and are used as the primary moving models within a game. The class used to encapsulate meshes includes the capability to adjust the complexity of the mesh as a function of range from the camera to improve performance. xvi

13 Introduction Chapter 6: Camera: The Player's View of the World To control the view of the action, we need something akin to the cameras used to film a movie. This chapter illustrates the design and use of a camera class that may be employed in a variety of ways. Cameras may be positioned at static locations within the scene and follow objects as they move past or they may be attached to the moving objects themselves. Employing multiple cameras and including logic within a game can provide a cinematic flair to the game. Chapter 7: Adding Some Atmosphere: Lighting and Fog All of the rendering performed by the game engine up until this point has been under fully lit and crystal-clear conditions-conditions that are often hard to find in the real world. This chapter explores the four types of lights that may be used to illuminate a scene as well as how to configure fog to improve the realism of a game. Fog may also be used to disguise shortcomings in the ability to render objects at a large distance from the camera. Chapter 8: Artificial Intelligence: Adding the Competition Few games are much fun without opponents. Although it is possible to write games that are strictly multiplayer, in which all of the opponents are human, networking is out of the scope of this book. Instead, we will look at the different types of artificial intelligence techniques that can be used within a game. One of these methods will be developed as part of the sample game engine for the book. Chapter 9: Game Audio: Let's Make Some Noise Another method to add character to a game is through the use of audio. Background music, if chosen properly, adds mood to the play. This chapter shows you how to develop classes for the game engine that facilitate playing songs. It also includes support for sound effects within a game. Players expect certain sounds to coincide with events within a game. If a car hits another car or a tree, they expect to hear the crash as well as see a reaction between the objects involved in the collision. xvii

14 Introduction Chapter 10: Game Physics: Keeping It Real As I mentioned when talking about audio, players not only expect to hear noise in a collision, but also to see a more physical reaction. Chapter 10 concentrates on the physics involved primarily with cars. The basic mathematics applied to cars may also be applied to many types of moving objects. This chapter also covers the physics used for cloth dynamics. This type of physics is used for not only cloth, but also for many types of flexible objects such as hair or rope. Chapter 11: Tools of the Trade The final chapter of the book looks at a cross-section of tools that are used during game development. If you are just starting out in game development (or just starting out with C#), you may find it useful to check out this chapter before diving into the rest of the book. The first portion of this chapter concentrates on the development environment used to compile and test your software. Other topics covered in the chapter include the manipulation of the artistic content for the game. The artistic content includes the audio files, two-dimensional images, and three-dimensional models. xvili