Programming Linux Games discusses the most important Linux multimedia toolkits and teaches the basics of game programming, all in the context of real-world examples. The author starts with an overview of Linux gaming and then introduces the use of essential tools in the Linux development environment. Detailed discussions cover such topics as graphics, sound, and input programming; audio programming to get the most out of the major audio APIs; how to develop a powerful game engine and write a game in Tcl; the X Window System and its performance; networked gaming; and Linux game licensing issues.

Foreword ..... I

Preface ..... III

Who This Book Is For ..... IV

Online Resources ..... IV

Acknowledgments ..... V

1: The Anatomy of a Game ..... 1

A Quick Survey of Game Genres ..... 2

Simulation Games ..... 2

First-Person Shooters ..... 4

Real-time Strategy Games ..... 6

Turn-Based Strategy Games ..... 7

Role-Playing Games ..... 7

Puzzle Games ..... 9

Multiuser Dungeons ..... 10

A Quick Look Under the Hood ..... 11

The Input Subsystem ..... 12

The Display Subsystem ..... 12

The Audio Subsystem ..... 13

The Network Subsystem ..... 14

The Update Subsystem ..... 14

The Game Loop ..... 15

2: Linux Development Tools ..... 17

Programming Editors ..... 17

vi ..... 18

Emacs ..... 19

NEdit ..... 20

Compiling Programs Under Linux ..... 20

Using the Make Utility ..... 24

Creating Makefiles ..... 24

Error Handling ..... 28

Working with Libraries ..... 29

Static Libraries ..... 29

Shared Libraries ..... 29

Linux Linker Quirks ..... 32

Debugging Linux Applications ..... 33

Compiling for Debugging ..... 33

gdb ..... 34

ddd ..... 41

Bug Tracking ..... 42

Project Management with CVS ..... 42

A Brief Tutorial on CVS ..... 43

Other Useful Tools ..... 49

Rapid Text Searching with grep ..... 49

Updating Source with diff and patch ..... 50

3: Linux Gaming APIs ..... 53

Graphics APIs ..... 55

SVGALib ..... 55

GGI ..... 56

SDL ..... 56

C1anLib ..... 57

OpenGL ..... 57

Plib ..... 57

Glide ..... 58

Xlib ..... 58

Graphical User Interface Toolkits ..... 59

GTK+ ..... 59

Tk ..... 59

Fltk ..... 60

Qt ..... 60

SDL GUI Support ..... 60

Audio APIs ..... 61

OSS ..... 61

ALSA ..... 62

ESD ..... 62

OpenAL ..... 63

Scripting Libraries ..... 63

Tcl ..... 63

Guile and MzScheme ..... 63

Python and Perl ..... 64

Networking APIs ..... 64

BSD Sockets ..... 65

OpenPlay ..... 65

IPX and SPX ..... 65

File Handling ..... 66

libpng and libjpeg ..... 66

libaudiofile and libsndfile ..... 67

Ogg Vorbis ..... 67

The SDL MPEG Library, SMPEG ..... 68

zlib ..... 68

4: Mastering SDL ..... 69

Computer Graphics Hardware ..... 70

The Framebuffer ..... 71

The SDL Video API ..... 72

Setting Up the Display ..... 74

Direct Surface Drawing ..... 77

Drawing with Blits ..... 83

Colorkeys and Transparency ..... 87

Loading Other Image Formats ..... 92

Alpha Blending ..... 92

Achieving Smooth Animation with SDL ..... 97

Input and Event Processing ..... 107

Processing Mouse Events ..... 108

Processing Keyboard Events ..... 112

Processing Joystick Events ..... 116

Multithreading with SDL ..... 120

SDL Audio Programming ..... 125

Representing Sound with PCM ..... 125

Feeding a Sound Card ..... 128

An Example of SDL Audio Playback ..... 129

Integrating OpenGL with SDL ..... 140

Penguin Warrior ..... 144

Creating Graphics ..... 146

Implementing a Parallaxing Scroller in SDL ..... 147

A Simple Particle System ..... 153

Game Timing ..... 158

5: Linux Audio Programming ..... 161

Competing APIs ..... 162

Introducing Multi-Play ..... 163

Loading Sound Files ..... 164

Using libsndfile ..... 164

Other Options ..... 170

Using OSS ..... 170

Reality Check ..... 175

Achieving Higher Performance with Direct DMA Buffer Access ..... 178

Playing Sound with ALSA ..... 187

Sharing the Sound Card with ESD ..... 195

Building Multi-Play ..... 200

Environmental Audio with OpenAL ..... 206

OpenAL Basics ..... 207

Adding Environmental Audio to Penguin Warrior ..... 213

Implementing Game Music with Ogg Vorbis ..... 222

Working with Vorbis Files ..... 223

Adding Music to Penguin Warrior ..... 227

6: Game Scripting Under Linux ..... 237

A Crash Course in Tel ..... 238

Built-in Tel Commands ..... 241

Interfacing Tel with C ..... 245

Linking Against Tel ..... 246

Executing Scripts ..... 246

Understanding Commands and Objects ..... 250

A Simple Scripting Engine ..... 252

Designing a Game Script ..... 258

Applying Scripting to the Real World ..... 265

Single Versus Multiple Contexts ..... 266

Can We Trust the Script? ..... 267

Script Performance ..... 267

Who's Writing the Script? ..... 268

7: Networked Gaming with Linux ..... 271

'Tis a Big Net, Quoth the Raven ..... 272

Internet Protocols ..... 272

Addresses and Ports ..... 273

Name Resolution ..... 274

Socket Programming 101 ..... 275

Sockets ..... 275

Connecting TCP Sockets ..... 276

Receiving TCP Connections ..... 285

Working with UDP Sockets ..... 292

Multiplayer Penguin Warrior ..... 300

Network Gaming Models ..... 301

Penguin Warrior's Networking System ..... 302

Network Game Performance ..... 311

Security Issues ..... 312

8: Gaming with the Linux Console ..... 315

Pros and Cons of the Linux Framebuffer ..... 316

Setting Up a Framebuffer Device ..... 318

A First Foray into Framebuffer Programming ..... 318

Setting Framebuffer Video Modes ..... 326

How Video Scanning Works ..... 327

The Mode Database ..... 330

An Example ..... 330

Use the Source, Luke! ..... 337

Console Input Handling ..... 337

Keyboard Input from a Terminal ..... 338

Mouse Input with GPM ..... 348

9: Finishing Penguin Warrior ..... 355

Adding Weapons ..... 355

Drawing Phasers ..... 356

Detecting Phaser Hits ..... 362

Imposing a Sane Rate of Fire ..... 364

Creating Status Displays ..... 364

In Retrospect ..... 375

10: To Every Man a Linux Distribution ..... 379

Source or Binary? ..... 380

Local Configuration ..... 381

Linux Isn't Alone: Supporting FreeBSD ..... 383

Packaging Systems ..... 384

Graphical Installation Goodness: Loki's Setup Program ..... 387

Understanding the Linux Filesystem Standard ..... 393

Glossary of Terms ..... 399

Bibliography ..... 405