i Beginning Android 4 Games Development ■ ■ ■ Mario Zechner Robert Green Beginning Android 4 Games Development Copyright © 2011 by Mario Zechner and Robert Green 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): 978-1-4302-3987-1 ISBN-13 (electronic): 978-1-4302-3988-8 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. 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Dedicated to our idols, fans, families, and loved ones iv Contents at a Glance Contents v About the Authors . xii Acknowledgments . xiii Introduction xiv ■Chapter 1: Android, the New Kid on the Block 1 ■Chapter 2: First Steps with the Android SDK . 25 ■Chapter 3: Game Development 101 . 53 ■Chapter 4: Android for Game Developers 107 ■Chapter 5: An Android Game Development Framework 195 ■Chapter 6: Mr. Nom Invades Android 239 ■Chapter 7: OpenGL ES: A Gentle Introduction 279 ■Chapter 8: 2D Game Programming Tricks . 357 ■Chapter 9: Super Jumper: A 2D OpenGL ES Game . 435 ■Chapter 10: OpenGL ES: Going 3D 495 ■Chapter 11: 3D Programming Tricks . 533 ■Chapter 12: Droid Invaders: The Grand Finale . 587 ■Chapter 13: Publishing Your Game 635 ■Chapter 14: What’s Next? 647 Index . 653 v Contents Contents at a Glance iv About the Authors . xii Acknowledgments . xiii Introduction xiv ■Chapter 1: Android, the New Kid on the Block 1 A Brief History of Android . 2  Fragmentation . 3  The Role of Google 4  The Android Open Source Project 4  The Android Market . 4  Challenges, Device Seeding, and Google I/O . 5  Android’s Features and Architecture 6  The Kernel 7  The Runtime and Dalvik . 7  System Libraries 8  The Application Framework . 9  The Software Development Kit . 10  The Developer Community 11  Devices, Devices, Devices! . 12  Hardware . 12  The Range of Devices 14  Compatibility Across All Devices . 19  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  Setting Up the Android SDK . 26  ■ CONTENTS vi Installing Eclipse 28  Installing the ADT Eclipse Plug-In 28  A Quick Tour of Eclipse 30  Helpful Eclipse Shortcuts . 32  Hello World, Android Style 33  Creating the Project . 33  Exploring the Project 34  Writing the Application Code . 36  Running and Debugging Android Applications 39  Connecting a Device 39  Creating an Android Virtual Device 39  Running an Application 41  Debugging an Application 44  LogCat and DDMS 48  Using ADB 50  Summary 51  ■Chapter 3: Game Development 101 . 53 Genres: To Each One’s Taste 54  Casual Games 54  Puzzle Games . 56  Action and Arcade Games 58  Tower-Defense Games 61  Innovation 62  Game Design: The Pen Is Mightier Than the Code 63  Core Game Mechanics . 64  A Story and an Art Style . 66  Screens and Transitions 67  Code: The Nitty-Gritty Details 73  Application and Window Management 74  Input . 75  File I/O 79  Audio 79  Graphics . 84  The Game Framework 97  Summary 105  ■Chapter 4: Android for Game Developers 107 Defining an Android Application: The Manifest File 108  The <manifest> Element . 109  The <application> Element . 110  The <activity> Element . 111  The <uses-permission> Element 113  The <uses-feature> Element . 114  The <uses-sdk> Element 116  Android Game Project Setup in Ten Easy Steps . 117  Market Filters . 119  Defining the Icon of Your Game . 119  Android API Basics 121  ■ CONTENTS vii Creating a Test Project 121  The Activity Life Cycle 125  Input Device Handling 132  File Handling 152  Audio Programming . 158  Playing Sound Effects 159  Streaming Music 163  Basic Graphics Programming 167  Best Practices . 192  Summary 193  ■Chapter 5: An Android Game Development Framework 195 Plan of Attack 195  The AndroidFileIO Class 196  AndroidAudio, AndroidSound, and AndroidMusic: Crash, Bang, Boom! . 197  AndroidInput and AccelerometerHandler 202  AccelerometerHandler: Which Side Is Up? 202  CompassHandler . 204  The Pool Class: Because Reuse Is Good for You! . 205  KeyboardHandler: Up, Up, Down, Down, Left, Right . . . 207  Touch Handlers 211  AndroidInput: The Great Coordinator . 219  AndroidGraphics and AndroidPixmap: Double Rainbow . 221  Handling Different Screen Sizes and Resolutions 221  AndroidPixmap: Pixels for the People 226  AndroidGraphics: Serving Our Drawing Needs 227  AndroidFastRenderView: Loop, Stretch, Loop, Stretch 231  AndroidGame: Tying Everything Together . 234  Summary 238  ■Chapter 6: Mr. Nom Invades Android 239 Creating the Assets . 239  Setting Up the Project . 241  MrNomGame: The Main Activity . 242  Assets: A Convenient Asset Store 242  Settings: Keeping Track of User Choices and High Scores 243  LoadingScreen: Fetching the Assets from Disk . 246  The Main Menu Screen . 247  The HelpScreen Class(es) . 251  The High-Scores Screen . 253  Rendering Numbers: An Excursion 253  Implementing the Screen . 255  Abstracting… . 257  Abstracting the World of Mr. Nom: Model, View, Controller 258  The GameScreen Class 270  Summary 277  ■Chapter 7: OpenGL ES: A Gentle Introduction 279 What is OpenGL ES and Why Should I Care? 279  The Programming Model: An Analogy 280  ■ CONTENTS viii Projections . 282  Normalized Device Space and the Viewport 284  Matrices . 284  The Rendering Pipeline 285  Before We Begin . 286  GLSurfaceView: Making Things Easy Since 2008 . 287  GLGame: Implementing the Game Interface . 290  Look Mom, I Got a Red Triangle! . 297  Defining the Viewport 298  Defining the Projection Matrix . 298  Specifying Triangles 302  Putting It Together . 306  Specifying Per Vertex Color 309  Texture Mapping: Wallpapering Made Easy 313  Texture Coordinates . 313  Uploading Bitmaps . 315  Texture Filtering . 316  Disposing of Textures 317  A Helpful Snippet . 318  Enabling Texturing . 318  Putting It Together . 318  A Texture Class 321  Indexed Vertices: Because Re-use is Good for You 323  Putting It Together . 324  A Vertices Class . 326  Alpha Blending: I Can See Through You 329  More Primitives: Points, Lines, Strips, and Fans 333  2D Transformations: Fun with the Model-View Matrix . 334  World and Model Space . 334  Matrices Again . 335  An Initial Example Using Translation . 336  More Transformations . 341  Optimizing for Performance 345  Measuring Frame Rate . 345  The Curious Case of the Hero on Android 1.5 347  What’s Making My OpenGL ES Rendering So Slow? 347  Removing Unnecessary State Changes . 349  Reducing Texture Size Means Fewer Pixels to be Fetched . 351  Reducing Calls to OpenGL ES/JNI Methods . 352  The Concept of Binding Vertices 352  In Closing . 356  Summary 356  ■Chapter 8: 2D Game Programming Tricks . 357 Before We Begin . 357  In the Beginning . . . There Was the Vector . 358  Working with Vectors . 359  A Little Trigonometry . 361  Implementing a Vector Class . 363  ■ CONTENTS ix A Simple Usage Example . 366  A Little Physics in 2D 371  Newton and Euler, Best Friends Forever . 371  Force and Mass . 372  Playing Around, Theoretically 373  Playing Around, Practically 374  Collision Detection and Object Representation in 2D 378  Bounding Shapes . 379  Constructing Bounding Shapes 381  Game Object Attributes 383  Broad-Phase and Narrow-Phase Collision Detection . 384  An Elaborate Example 391  A Camera in 2D . 404  The Camera2D Class 407  An Example 409  Texture Atlas: Because Sharing Is Caring . 410  An Example 412  Texture Regions, Sprites, and Batches: Hiding OpenGL ES 416  The TextureRegion Class . 417  The SpriteBatcher Class 418  Sprite Animation . 427  The Animation Class 428  An Example 429  Summary 433  ■Chapter 9: Super Jumper: A 2D OpenGL ES Game . 435 Core Game Mechanics 435  A Backstory and Art Style . 436  Screens and Transitions . 437  Defining the Game World 438  Creating the Assets . 441  The UI Elements . 441  Handling Text with Bitmap Fonts . 443  The Game Elements . 445  Texture Atlas to the Rescue . 447  Music and Sound . 448  Implementing Super Jumper 449  The Assets Class 450  The Settings Class . 453  The Main Activity . 454  The Font Class . 456  GLScreen 457  The Main Menu Screen 458  The Help Screens . 461  The High-Scores Screen 463  The Simulation Classes 466  The Game Screen . 481  The WorldRenderer Class 489  . the copyright owner and the publisher. ISBN- 13 (pbk): 978-1- 430 2 -39 87-1 ISBN- 13 (electronic): 978-1- 430 2 -39 88-8 Trademarked names, logos, and images may. 33 3  2D Transformations: Fun with the Model-View Matrix . 33 4