Beginning Android Games (Zechner, Mario) (z-library.sk, 1lib.sk, z-lib.sk)

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i Beginning Android Games ■ ■ ■ Mario Zechner

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Beginning Android Games Copyright © 2011 by Mario Zechner 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-13 (pbk): 978-1-4302-3042-7 ISBN-13 (electronic): 978-1-4302-3043-4 Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. President and Publisher: Paul Manning Lead Editor: Steve Anglin Development Editor: Matthew Moodie Technical Reviewer: Robert Green Editorial Board: Steve Anglin, Mark Beckner, Ewan Buckingham, Gary Cornell, Jonathan Gennick, Jonathan Hassell, Michelle Lowman, Matthew Moodie, Jeff Olson, Jeffrey Pepper, Frank Pohlmann, Douglas Pundick, Ben Renow-Clarke, Dominic Shakeshaft, Matt Wade, Tom Welsh Coordinating Editor: Adam Heath Copy Editors: Damon Larson, Jim Compton Compositor: MacPS, LLC Indexer: BIM Indexing & Proofreading Services Artist: April Milne Cover Designer: Anna Ishchenko Distributed to the book trade worldwide by Springer Science+Business Media, LLC., 233 Spring Street, 6th Floor, New York, NY 10013. Phone 1-800-SPRINGER, fax (201) 348-4505, e-mail orders-ny@springer-sbm.com, or visit www.springeronline.com. For information on translations, please e-mail rights@apress.com, or visit www.apress.com. Apress and friends of ED books may be purchased in bulk for academic, corporate, or promotional use. eBook versions and licenses are also available for most titles. For more information, reference our Special Bulk Sales–eBook Licensing web page at www.apress.com/info/bulksales. 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. The source code for this book is available to readers at www.apress.com.

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Dedicated to my idols, Mom and Dad, and to my love, Stefanie

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iv Contents at a Glance Contents .............................................................................................................. v About the Author ............................................................................................... xii About the Technical Reviewer ......................................................................... xiii Acknowledgments ............................................................................................ xiv Introduction ....................................................................................................... xv ■Chapter 1: Android, the New Kid on the Block ................................................ 1 ■Chapter 2: First Steps with the Android SDK ................................................. 25 ■Chapter 3: Game Development 101 ............................................................... 51 ■Chapter 4: Android for Game Developers .................................................... 103 ■Chapter 5: An Android Game Development Framework .............................. 185 ■Chapter 6: Mr. Nom Invades Android .......................................................... 229 ■Chapter 7: OpenGL ES: A Gentle Introduction .............................................. 269 ■Chapter 8: 2D Game Programming Tricks ................................................... 351 ■Chapter 9: Super Jumper: A 2D OpenGL ES Game ....................................... 429 ■Chapter 10: OpenGL ES: Going 3D ................................................................ 489 ■Chapter 11: 3D Programming Tricks ........................................................... 525 ■Chapter 12: Droid Invaders: the Grand Finale ............................................. 577 ■Chapter 13: Publishing Your Game .............................................................. 625 ■Chapter 14: What’s Next? ............................................................................ 637 Index ............................................................................................................... 641

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v Contents Contents at a Glance .......................................................................................... iv About the Author ............................................................................................... xii About the Technical Reviewer ......................................................................... xiii Acknowledgments ............................................................................................ xiv Introduction ....................................................................................................... xv ■Chapter 1: Android, the New Kid on the Block ................................................ 1 A Brief History of Android ....................................................................................................................................... 2 Fragmentation ......................................................................................................................................................... 3 The Role of Google .................................................................................................................................................. 3 The Android Open Source Project ...................................................................................................................... 3 The Android Market ........................................................................................................................................... 4 Challenges, Device Seeding, and Google I/O ..................................................................................................... 6 Android’s Features and Architecture ...................................................................................................................... 7 The Kernel .......................................................................................................................................................... 8 The Runtime and Dalvik ..................................................................................................................................... 8 System Libraries ................................................................................................................................................ 9 The Application Framework ............................................................................................................................. 10 The Software Development Kit ............................................................................................................................. 11 The Developer Community .................................................................................................................................... 12 Devices, Devices, Devices! ................................................................................................................................... 12 Hardware ......................................................................................................................................................... 13 First Gen, Second Gen, Next Gen ..................................................................................................................... 14 Mobile Gaming Is Different ................................................................................................................................... 20 A Gaming Machine in Every Pocket ................................................................................................................. 20 Always Connected ........................................................................................................................................... 21 Casual and Hardcore ........................................................................................................................................ 22 Big Market, Small Developers .......................................................................................................................... 22 Summary .............................................................................................................................................................. 23 ■Chapter 2: First Steps with the Android SDK ................................................. 25 Setting Up the Development Environment ............................................................................................................ 25 Setting Up the JDK ........................................................................................................................................... 26

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■ CONTENTS vi Setting Up the Android SDK ............................................................................................................................. 26 Installing Eclipse .............................................................................................................................................. 28 Installing the ADT Eclipse Plug-In .................................................................................................................... 28 A Quick Tour of Eclipse .................................................................................................................................... 30 Hello World, Android Style .................................................................................................................................... 32 Creating the Project ......................................................................................................................................... 32 Exploring the Project ........................................................................................................................................ 33 Writing the Application Code ........................................................................................................................... 35 Running and Debugging Android Applications ...................................................................................................... 38 Connecting a Device ........................................................................................................................................ 38 Creating an Android Virtual Device .................................................................................................................. 38 Running an Application .................................................................................................................................... 39 Debugging an Application ................................................................................................................................ 42 LogCat and DDMS ............................................................................................................................................ 46 Using ADB ........................................................................................................................................................ 48 Summary .............................................................................................................................................................. 49 ■Chapter 3: Game Development 101 ............................................................... 51 Genres: To Each One’s Taste ................................................................................................................................ 51 Causal Games .................................................................................................................................................. 52 Puzzle Games ................................................................................................................................................... 54 Action and Arcade Games ................................................................................................................................ 56 Tower-Defense Games .................................................................................................................................... 59 Innovation ........................................................................................................................................................ 60 Game Design: The Pen Is Mightier Than the Code ................................................................................................ 60 Core Game Mechanics ..................................................................................................................................... 61 A Story and an Art Style ................................................................................................................................... 63 Screens and Transitions .................................................................................................................................. 64 Code: The Nitty-Gritty Details ................................................................................................................................ 70 Application and Window Management ............................................................................................................ 71 Input ................................................................................................................................................................. 72 File I/O .............................................................................................................................................................. 75 Audio ................................................................................................................................................................ 76 Graphics ........................................................................................................................................................... 80 The Game Framework ...................................................................................................................................... 94 Summary ............................................................................................................................................................ 101 ■Chapter 4: Android for Game Developers .................................................... 103 Defining an Android Application: The Manifest File ............................................................................................ 104 The <manifest> Element ............................................................................................................................... 105 The <application> Element ........................................................................................................................... 105 The <activity> Element ................................................................................................................................. 107 The <uses-permission> Element .................................................................................................................. 109 The <uses-feature> Element ......................................................................................................................... 110 The <uses-sdk> Element .............................................................................................................................. 112 Android Game Project Setup in Ten Easy Steps ............................................................................................. 112 Defining the Icon of Your Game ..................................................................................................................... 114 Android API Basics .............................................................................................................................................. 116 Creating a Test Project .................................................................................................................................. 116

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■ CONTENTS vii The Activity Life Cycle .................................................................................................................................... 120 Input Device Handling .................................................................................................................................... 127 File Handling .................................................................................................................................................. 144 Audio Programming ....................................................................................................................................... 150 Playing Sound Effects .................................................................................................................................... 150 Streaming Music ............................................................................................................................................ 154 Basic Graphics Programming ........................................................................................................................ 158 Best Practices ..................................................................................................................................................... 182 Summary ............................................................................................................................................................ 183 ■Chapter 5: An Android Game Development Framework .............................. 185 Plan of Attack ...................................................................................................................................................... 185 The AndroidFileIO Class ...................................................................................................................................... 186 AndroidAudio, AndroidSound, and AndroidMusic: Crash, Bang, Boom! ............................................................. 187 AndroidInput and AccelerometerHandler ............................................................................................................ 192 AccelerometerHandler: Which Side Is Up? .................................................................................................... 193 The Pool Class: Because Reuse is Good for You! ........................................................................................... 194 KeyboardHandler: Up, Up, Down, Down, Left, Right . . . ................................................................................ 196 Touch Handlers .............................................................................................................................................. 200 AndroidInput: The Great Coordinator ............................................................................................................. 207 AndroidGraphics and AndroidPixmap: Double Rainbow ..................................................................................... 209 Handling Different Screen Sizes and Resolutions .......................................................................................... 209 AndroidPixmap: Pixels for the People ............................................................................................................ 215 AndroidGraphics: Serving Our Drawing Needs .............................................................................................. 216 AndroidFastRenderView: Loop, Strech, Loop, Stretch ................................................................................... 220 AndroidGame: Tying Everything Together ........................................................................................................... 223 Summary ............................................................................................................................................................ 227 ■Chapter 6: Mr. Nom Invades Android .......................................................... 229 Creating the Assets ............................................................................................................................................. 229 Setting Up the Project ......................................................................................................................................... 232 MrNomGame: The Main Activity ......................................................................................................................... 232 Assets: A Convenient Asset Store .................................................................................................................. 233 Settings: Keeping Track of User Choices and High Scores ............................................................................ 234 LoadingScreen: Fetching the Assets from Disk ............................................................................................. 236 The Main Menu Screen ....................................................................................................................................... 237 The HelpScreen Class(es) ................................................................................................................................... 241 The High-Scores Screen ..................................................................................................................................... 243 Rendering Numbers: An Excursion ................................................................................................................ 243 Implementing the Screen ............................................................................................................................... 245 Abstracting… ..................................................................................................................................................... 247 Abstracting the World of Mr. Nom: Model, View, Controller .......................................................................... 248 The GameScreen Class .................................................................................................................................. 259 Summary ............................................................................................................................................................ 267 ■Chapter 7: OpenGL ES: A Gentle Introduction .............................................. 269 What Is OpenGL ES and Why Should I Care? ...................................................................................................... 269 The Programming Model: An Analogy ............................................................................................................ 270 Projections ..................................................................................................................................................... 272 Normalized Device Space and the Viewport .................................................................................................. 275

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■ CONTENTS viii Matrices ......................................................................................................................................................... 275 The Rendering Pipeline .................................................................................................................................. 276 Before We Begin ................................................................................................................................................. 277 GLSurfaceView: Making Things Easy Since 2008 ............................................................................................... 278 GLGame: Implementing the Game Interface ....................................................................................................... 281 Look Mom, I Got a Red Triangle! ......................................................................................................................... 288 Defining the Viewport .................................................................................................................................... 288 Defining the Projection Matrix ....................................................................................................................... 289 Specifying Triangles ...................................................................................................................................... 292 Putting It Together ......................................................................................................................................... 296 Specifying Per Vertex Color ................................................................................................................................ 300 Texture Mapping: Wallpapering Made Easy ........................................................................................................ 304 Texture Coordinates ....................................................................................................................................... 304 Uploading Bitmaps ......................................................................................................................................... 306 Texture Filtering ............................................................................................................................................. 308 Disposing of Textures .................................................................................................................................... 309 A Helpful Snippet ........................................................................................................................................... 310 Enabling Texturing ......................................................................................................................................... 310 Putting It Together ......................................................................................................................................... 310 A Texture Class .............................................................................................................................................. 313 Indexed Vertices: Because Reuse Is Good for You .............................................................................................. 315 Putting It Together ......................................................................................................................................... 316 A Vertices Class ............................................................................................................................................. 318 Alpha Blending: I Can See Through You .............................................................................................................. 321 More Primitives: Points, Lines, Strips, and Fans ................................................................................................ 325 2D Transformations: Fun with the Model-View Matrix ....................................................................................... 326 World and Model Space ................................................................................................................................. 326 Matrices Again ............................................................................................................................................... 328 An First Example Using Translation ............................................................................................................... 329 More Transformations ................................................................................................................................... 333 Optimizing for Performance ................................................................................................................................ 338 Measuring Frame Rate ................................................................................................................................... 338 The Curious Case of the Hero on Android 1.5 ................................................................................................ 339 What’s Making My OpenGL ES Rendering So Slow? ...................................................................................... 340 Removing Unnecessary State Changes ......................................................................................................... 341 Reducing Texture Size Means Fewer Pixels to Be Fetched ........................................................................... 343 Reducing Calls to OpenGL ES/JNI Methods ................................................................................................... 344 The Concept of Binding Vertices .................................................................................................................... 345 In Closing ....................................................................................................................................................... 348 Summary ............................................................................................................................................................ 349 ■Chapter 8: 2D Game Programming Tricks ................................................... 351 Before We Begin ................................................................................................................................................. 351 In the Beginning There Was the Vector ............................................................................................................... 352 Working with Vectors ..................................................................................................................................... 353 A Little Trigonometry ..................................................................................................................................... 355 Implementing a Vector Class ......................................................................................................................... 357 A Simple Usage Example ............................................................................................................................... 360 A Little Physics in 2D .......................................................................................................................................... 365

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■ CONTENTS ix Newton and Euler, Best Friends Forever ....................................................................................................... 365 Force and Mass ............................................................................................................................................. 366 Playing Around, Theoretically ........................................................................................................................ 367 Playing Around, Practically ............................................................................................................................ 368 Collision Detection and Object Representation in 2D .......................................................................................... 372 Bounding Shapes ........................................................................................................................................... 373 Constructing Bounding Shapes ...................................................................................................................... 375 Game Object Attributes .................................................................................................................................. 377 Broad-Phase and Narrow-Phase Collision Detection ..................................................................................... 378 An Elaborate Example .................................................................................................................................... 386 A Camera in 2D ................................................................................................................................................... 399 The Camera2D Class ...................................................................................................................................... 402 An Example .................................................................................................................................................... 403 Texture Atlas: Because Sharing Is Caring ........................................................................................................... 405 An Example .................................................................................................................................................... 407 Texture Regions, Sprites, and Batches: Hiding OpenGL ES ................................................................................ 411 The TextureRegion Class ............................................................................................................................... 411 The SpriteBatcher Class ................................................................................................................................ 412 Sprite Animation ................................................................................................................................................. 422 The Animation Class ...................................................................................................................................... 423 An Example .................................................................................................................................................... 424 Summary ............................................................................................................................................................ 428 ■Chapter 9: Super Jumper: A 2D OpenGL ES Game ....................................... 429 Core Game Mechanics ........................................................................................................................................ 429 A Backstory and Art Style ................................................................................................................................... 430 Screens and Transitions ..................................................................................................................................... 431 Defining the Game World .................................................................................................................................... 432 Creating the Assets ............................................................................................................................................. 435 The UI Elements ............................................................................................................................................. 435 Handling Text with Bitmap Fonts ................................................................................................................... 437 The Game Elements ....................................................................................................................................... 439 Texture Atlas to the Rescue ........................................................................................................................... 441 Music and Sound ........................................................................................................................................... 442 Implementing Super Jumper .............................................................................................................................. 444 The Assets Class ............................................................................................................................................ 444 The Settings Class ......................................................................................................................................... 447 The Main Activity ........................................................................................................................................... 448 The Font Class ............................................................................................................................................... 449 GLScreen ........................................................................................................................................................ 451 The Main Menu Screen .................................................................................................................................. 451 The Help Screens ........................................................................................................................................... 454 The High-Scores Screen ................................................................................................................................ 457 The Simulation Classes .................................................................................................................................. 459 The Game Screen ........................................................................................................................................... 475 The WorldRenderer Class .............................................................................................................................. 482 To Optimize or Not to Optimize ........................................................................................................................... 486 Summary ............................................................................................................................................................ 487

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■ CONTENTS x ■Chapter 10: OpenGL ES: Going 3D ................................................................ 489 Before We Begin ................................................................................................................................................. 489 Vertices in 3D ...................................................................................................................................................... 490 Vertices3: Storing 3D Positions ...................................................................................................................... 490 An Example .................................................................................................................................................... 492 Perspective Projection: The Closer, the Bigger ................................................................................................... 495 Z-buffer: Bringing Order into Chaos .................................................................................................................... 498 Fixing the Last Example ................................................................................................................................. 499 Blending: There’s Nothing Behind You .......................................................................................................... 500 Z-buffer Precision and Z-fighting ................................................................................................................... 503 Defining 3D Meshes ............................................................................................................................................ 504 A Cube: Hello World in 3D .............................................................................................................................. 505 An Example .................................................................................................................................................... 508 Matrices and Transformations Again .................................................................................................................. 511 The Matrix Stack ............................................................................................................................................ 512 Hierarchical Systems with the Matrix Stack .................................................................................................. 514 A Simple Camera System .............................................................................................................................. 520 Summary ............................................................................................................................................................ 524 ■Chapter 11: 3D Programming Tricks ........................................................... 525 Before We Begin ................................................................................................................................................. 525 Vectors in 3D ....................................................................................................................................................... 526 Lighting in OpenGL ES ......................................................................................................................................... 530 How Lighting Works ....................................................................................................................................... 530 Light Sources ................................................................................................................................................. 532 Materials ........................................................................................................................................................ 533 How OpenGL ES Calculates Lighting: Vertex Normals ................................................................................... 533 In Practice ...................................................................................................................................................... 534 Some Notes on Lighting in OpenGL ES .......................................................................................................... 548 Mipmapping ........................................................................................................................................................ 548 Simple Cameras .................................................................................................................................................. 553 The First-Person or Euler Camera .................................................................................................................. 553 An Euler Camera Example ............................................................................................................................. 556 A Look-At Camera .......................................................................................................................................... 562 Loading Models ................................................................................................................................................... 564 The Wavefront OBJ Format ............................................................................................................................ 565 Implementing an OBJ Loader ......................................................................................................................... 566 Using the OBJ Loader .................................................................................................................................... 570 Some Notes on Loading Models .................................................................................................................... 571 A Little Physics in 3D .......................................................................................................................................... 571 Collision Detection and Object Representation in 3D .......................................................................................... 572 Bounding Shapes in 3D .................................................................................................................................. 572 Bounding Sphere Overlap Testing ................................................................................................................. 573 GameObject3D and DynamicGameObject3D .................................................................................................. 574 Summary ............................................................................................................................................................ 576 ■Chapter 12: Droid Invaders: the Grand Finale ............................................. 577 Core Game Mechanics ........................................................................................................................................ 577 A Backstory and Art Style ................................................................................................................................... 579

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■ CONTENTS xi Screens and Transitions ..................................................................................................................................... 580 Defining the Game World .................................................................................................................................... 581 Creating the Assets ............................................................................................................................................. 582 The UI Assets ................................................................................................................................................. 582 The Game Assets ........................................................................................................................................... 584 Sound and Music ........................................................................................................................................... 586 Plan of Attack ...................................................................................................................................................... 587 The Assets Class ................................................................................................................................................. 587 The Settings Class .............................................................................................................................................. 590 The Main Activity ................................................................................................................................................ 591 The Main Menu Screen ....................................................................................................................................... 592 The Settings Screen ............................................................................................................................................ 595 The Simulation Classes ....................................................................................................................................... 598 The Shield Class ............................................................................................................................................ 598 The Shot Class ............................................................................................................................................... 598 The Ship Class ............................................................................................................................................... 599 The Invader Class ........................................................................................................................................... 601 The World Class ............................................................................................................................................. 604 The GameScreen Class ....................................................................................................................................... 610 The WorldRender Class ....................................................................................................................................... 617 Optimizations ...................................................................................................................................................... 622 Summary ............................................................................................................................................................ 623 ■Chapter 13: Publishing Your Game .............................................................. 625 A Word on Testing ............................................................................................................................................... 625 Becoming a Registered Developer ...................................................................................................................... 626 Sign Your Game’s APK ........................................................................................................................................ 627 Putting Your Game on the Market ....................................................................................................................... 631 Uploading Assets ........................................................................................................................................... 632 Listing Details ................................................................................................................................................ 633 Publishing Options ......................................................................................................................................... 633 Publish! .......................................................................................................................................................... 634 Marketing ....................................................................................................................................................... 634 The Developer Console ....................................................................................................................................... 634 Summary ............................................................................................................................................................ 636 ■Chapter 14: What’s Next? ............................................................................ 637 Getting Social ...................................................................................................................................................... 637 Location Awareness ............................................................................................................................................ 637 Multiplayer Functionality .................................................................................................................................... 638 OpenGL ES 2.0 and More .................................................................................................................................... 638 Frameworks and Engines ................................................................................................................................... 638 Resources on the Web ........................................................................................................................................ 640 Closing Words ..................................................................................................................................................... 640 Index ............................................................................................................... 641

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xii About the Author Mario Zechner is a software engineer in R&D by day, and an enthusiastic game developer by night, publishing under the name of Badlogic Games. He developed the game Newton for Android, and Quantum for Windows, Linux, and Mac OSX, besides a ton of prototypes and small-scale games. He’s currently working on an open source cross-platform solution for game development called libgdx. In addition to his coding activities, he actively writes tutorials and articles on game development, which are freely available on the Web and specifically his blog (http://www.badlogicgames.com).

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xiii About the Technical Reviewer Robert Green is an independent video game developer from Portland, Oregon, who publishes under the brand Battery Powered Games. He has developed six Android games, including Deadly Chambers, Antigen, Wixel, Light Racer, and Light Racer 3D. Before diving full-time into mobile video game development and publishing, Robert worked for software companies in Minneapolis and Chicago, including IBM Interactive. Robert’s current focus is on cross-platform game development and high-performance mobile gaming.

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xiv Acknowledgments I’d like to thank the Apress team that made this book possible in the first place. Specifically I’d like to thank Candace English and Adam Heath, my awesome coordinating editors, who never got tired answering all my silly questions; Matthew Moodie for helping me structure the sections and giving invaluable hints and suggestions to make this book a whole lot better; and Damon Larson and James Compton, for being the brave souls that had to correct all my grammar errors. Thanks guys, it’s been a pleasure working with you. Thanks to my dear friend Robert Green, who played the technical reviewer for this book. He made sure that my ramblings were technically correct. He’ll also be my scapegoat in case people discover bugs and errors. Special thanks to all my friends around the globe who gave me ideas, feedback, and comfort when I realized I was working at 3 a.m. again. This goes specifically to Nathan Sweet, Dave Clayton, Dave Fraska, Moritz Post, Christoph Widulle, and Tony Wang, the coding ninjas working with me on libgdx; John Phil and Ali Mosavian, my long-time coding buddies from Sweden; and Roman Kern and Markus Muhr, whom I have had the pleasure to work with at my day job. Last but certainly not least I’d like to thank my love, Stefanie, who put up with all the long nights alone in bed, as well as my grumpiness. Luipo!

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xv Introduction Hi there, and welcome to the world of Android game development. My name is Mario; I’ll be your guide for the next fourteen chapters. You came here to learn about game development on Android, and I hope to be the person who enables you to realize your ideas. Together we’ll cover quite a range of materials and topics: Android basics, audio and graphics programming, a little math and physics, and a scary thing called OpenGL ES. Based on all this knowledge we’ll develop three different games, one even being 3D. Game programming can be easy if you know what you’re doing. Therefore I’ve tried to present the material in a way that not only gives you helpful code snippets to reuse, but actually shows you the big picture of game development. Understanding the underlying principles is the key to tackling ever more complex game ideas. You’ll not only be able to write games similar to the ones developed over the course of this book, but you’ll also be equipped with enough knowledge to go to the Web or the bookstore and take on new areas of game development on your own. A Word About the Target Audience This book is aimed first and foremost at complete beginners in game programming. You don’t need any prior knowledge on the subject matter; I’ll walk you through all the basics. However, I need to assume a little knowledge on your end about Java. If you feel rusty on the matter, I’d suggest refreshing your memory by reading the online edition of Thinking in Java, by Bruce Eckel (Prentice Hall, 2006), an excellent introductory text on the programming language. Other than that, there are no other requirements. No prior exposure to Android or Eclipse is necessary! This book is also aimed at the intermediate-level game programmer that wants to get her hands dirty with Android. While some of the material may be old news for you, there are still a lot of tips and hints contained that should make reading this book worthwhile. Android is a strange beast at times, and this book should be considered your battle guide. How This Book Is Organized This book takes an iterative approach in that we’ll slowly but surely work our way from the absolute basics to the esoteric heights of hardware-accelerated game programming goodness. Over the course of the chapters, we’ll build up a reusable code base, so I’d suggest going through the chapters in sequence. More experienced readers can of course skip certain sections they feel confident with. Just make sure to read through the code listings of sections you skim over a little, so you will understand how the classes and interfaces are used in subsequent, more advanced sections.

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■ INTRODUCTION xvi Getting the Source Code This book is fully self-contained; all the code necessary to run the examples and games is included. However, copying the listings from the book to Eclipse is error prone, and games do not consist of code alone, but also have assets that you can’t easily copy out of the book. Also, the process of copying code from the book's text to Eclipse can introduce errors. Robert (the book’s technical reviewer) and I took great care to ensure that all the listings in this book are error free, but the gremlins are always hard at work. To make this a smooth ride, I created a Google Code project that offers you the following: • The complete source code and assets, licensed under the GPL version 3, available from the project’s Subversion repository. • A quickstart guide showing you how to import the projects into Eclipse in textual form, and a video demonstration for the same. • An issue tracker that allows you to report any errors you find, either in the book itself or in the code accompanying the book. Once you file an issue in the issue tracker, I can incorporate any fixes in the Subversion repository. This way you’ll always have an up-to-date, (hopefully) error-free version of this book’s code from which other readers can benefit as well. • A discussion group that is free for everybody to join and discuss the contents of the book. I’ll be on there as well of course. For each chapter that contains code, there’s an equivalent Eclipse project in the Subversion repository. The projects do not depend on each other, as we’ll iteratively improve some of the framework classes over the course of the book. Each project therefore stands on its own. The code for both Chapters 5 and 6 is contained in the ch06-mrnom project. The Google Code project can be found at http://code.google.com/p/beginning-android- games.

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1 1 Chapter Android, the New Kid on the Block As a kid of the early nineties, I naturally grew up with my trusty Nintendo Game Boy. I spent countless hours helping Mario rescue the princess, getting the highest score in Tetris, and racing my friends in RC Pro-Am via link cable. I took this awesome piece of hardware with me everywhere and every time I could. My passion for games made me want to create my own worlds and share them with my friends. I started programming on the PC but soon found out that I couldn’t transfer my little masterpieces to the Game Boy. I continued being an enthusiastic programmer, but over time my interest in actually playing video games faded. Also, my Game Boy broke . . . Fast forward to 2010. Smartphones are becoming the new mobile gaming platforms of the era, competing with classic dedicated handheld systems such as the Nintendo DS or the Playstation Portable. That caught my interest again, and I started investigating which mobile platforms would be suitable for my development needs. Apple’s iOS seemed like a good candidate to start coding games for. However, I quickly realized that the system was not open, that I’d be able to share my work with others only if Apple allowed it, and that I’d need a Mac to develop for the iOS. And then I found Android. I immediately fell in love with Android. Its development environment works on all the major platforms, no strings attached. It has a vibrant developer community happy to help you with any problem you encounter as well as comprehensive documentation. I can share my games with anyone without having to pay a fee to do so, and if I want to monetize my work, I can easily publish my latest and greatest innovation to a global market with millions of users in a matter of minutes. The only thing I was left with was actually figuring out how to write games for Android and how to transfer my PC game development knowledge to this new system. In the following chapters, I want to share my experience with you and get you started with Android game development. This is of course a rather selfish plan: I want to have more games to play on the go! Let’s start by getting to know our new friend: Android. 1

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CHAPTER 1: Android, the New Kid on the Block 2 A Brief History of Android Android was first publicly noticed in 2005 when Google acquired a small startup called Android, Inc. This fueled speculation that Google wanted to enter the mobile space. In 2008, the release of version 1.0 of Android put an end to all speculation, and Android became the new challenger on the mobile market. Since then, it’s been battling it out with already established platforms such as iOS (then called iPhone OS) and BlackBerry, and its chances of winning look rather good. Because Android is open source, handset manufacturers have a low barrier of entry when using the new platform. They can produce devices for all price segments, modifying Android itself to accommodate the processing power of a specific device. Android is therefore not limited to high-end devices but can also be deployed to low- budget devices, thus reaching a wider audience. A crucial ingredient for Android’s success was the formation of the Open Handset Alliance (OHA) in late 2007. The OHA includes companies such as HTC, Qualcomm, Motorola, and NVIDIA, which collaborate to develop open standards for mobile devices. Although Android’s core is developed mainly by Google, all the OHA members contribute to its source in one form or another. Android itself is a mobile operating system and platform based on the Linux kernel version 2.6 and is freely available for commercial and noncommercial use. Many members of the OHA build custom versions of Android for their devices with modified user interfaces (UIs)—for example, HTC’s HTC Sense and Motorola’s MOTOBLUR. The open source nature of Android also enables hobbyists to create and distribute their own versions of Android. These are usually called mods, firmwares, or ROMs. The most prominent ROM at the time of this writing was developed by a fellow known as Cyanogen and is aimed at bringing the latest and greatest improvements to all sorts of Android devices. Since its release in 2008, Android has received seven version updates, all code-named after desserts (with the exception of Android 1.1, which is irrelevant nowadays). Each version has added new functionality to the Android platform that has relevance in one way or another for game developers. Version 1.5 (Cupcake) added support for including native libraries in Android applications, which were previously restricted to being written in pure Java. Native code can be very beneficial in situations where performance is of upmost concern. Version 1.6 (Donut) introduced support for different screen resolutions. We will revisit this fact a couple of times in this book because it has some impact on how we approach writing games for Android. With version 2.0 (Éclair) came support for multi-touch screens, and version 2.2 (Froyo) added just-in-time (JIT) compilation to the Dalvik virtual machine (VM), which powers all the Java applications on Android. The JIT speeds up the execution of Android applications considerably—depending on the scenario, up to a factor of five. At the time of this writing, the latest version is 2.3, called Gingerbread. It adds a new concurrent garbage collector to the Dalvik VM. If you haven’t noticed yet: Android applications are written in Java. A special version of Android, targeted at tablets, is also being released in 2011. It is called Honeycomb and represents version 3.0 of Android. Honeycomb is not meant to

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CHAPTER 1: Android, the New Kid on the Block 3 run on phones at this point. However, some features of Honeycomb will be ported to the main line of Android. At the time of this writing, Android 3.0 is not available to the public, and no devices on the market are running it. Android 2.3 can be installed on many devices using custom ROMs. The only handset using Gingerbread is the Nexus S, a developer phone sold by Google directly. Fragmentation The great flexibility of Android comes at a price: companies that opt to develop their own user interfaces have to play catch-up with the fast pace at which new versions of Android are released. This can lead to handsets not older than a few months becoming outdated really fast as carriers and handset manufacturers refuse to create updates that incorporate the improvements of new Android versions. The big bogeyman called fragmentation is a result of this process. Fragmentation has many faces. For the end user, it means being unable to install and use certain applications and features because of being stuck on an old Android version. For developers, it means that some care has to be taken when creating applications that should work on all versions of Android. While applications written for earlier versions of Android will usually run fine on newer versions, the reverse is not true. Some features added in newer Android versions are of course not available on older versions, such as multi-touch support. Developers are thus forced to create separate code paths for different versions of Android. But fear not. Although this sounds terrifying, it turns out that the measures that have to be taken are minimal. Most often, you can even completely forget about the whole issue and pretend there’s only a single version of Android. As game developers, we’re less concerned with differences in APIs and more concerned about hardware capabilities. This is a different form of fragmentation, which is also a problem for platforms such as iOS, albeit not as pronounced. Throughout this book, I will cover the relevant fragmentation issues that might get in your way while you develop your next game for Android. The Role of Google Although Android is officially the brainchild of the Open Handset Alliance, Google is the clear leader when it comes to implementing Android itself as well as providing the necessary ecosystem for Android to grow. The Android Open Source Project Google’s efforts are summarized under the name Android Open Source Project. Most of the code is licensed under Apache License 2, a very open and nonrestrictive license compared to other open source licenses such as the GNU General Public License (GPL). Everyone is free to use this source code to build their own systems. However, systems that are claimed to be Android compatible first have to pass the Android Compatibility