iPhone
‡
3D Game
Programming
All in One
Jeremy Alessi
Course Technology PTR
A part of Cengage Learning
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iPhone
‡
3D
Game Programming
All in One
Jeremy Alessi
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Library of Congress Control Number: 2009942391
ISBN-13: 978-1-4354-5478-1
ISBN-10: 1-4354-5478-2
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This book is dedicated to my mother, my father, and my wife. Mom, thanks for
always believing in me. Life’s not the same without you. Dad, thanks for teaching me
the value of hard work by making me lift those five-gallon buckets when I was three
years old. Finally, thank you, Hilary, for putting up with all the late nights and long
hours that go into game development. Your love and support are mind-boggling!
Acknowledgments
I would like to thank all of my friends and family who helped me along the

this book would not be possible. Thank you Ori Cohen for helping me produce
Skyline Blade. When that game hit the App Store, I finally saw the light at the end
of the tunnel. Thank you Fraser McInnes at Pocket Gamer for making me realize
just how much more of the tunnel I have left to traverse before I reach the light.
Thank you Rich Smith, you worked alongside me during the hardest time of my
life, and that office was depressing without you. Finally, thank you to all the
players for downloading the heck out of Crash For Cash. You answered a prayer
of mine by taking the game all the way to a #1-ranked position. It’s hard to feel
down about anything when your game has been played nearly two million times.
In addition, I’d like to thank my new family-in-laws. The past year has been
tough, and there’s no rest for the weary. Luckily, there was a lot of laughter, good
company, and good food (always good food). I’m a family person and without
you all I would have been awfully lonely this year. I cannot possibly thank you
enough for all that you’ve done!
Lastly, thanks Apple for developing a revolutionary gaming platform to write
about. I can’t wait to see what’s next!
Acknowledgments
v
About the Author
Jeremy Alessi has been developing video games for over a decade. Scholastic,
Garage Games, and Reflexive Entertainment have published his work. His first
independent title, Aerial Antics (2004), was nominated for Sim Game of the Year
by Game Tunnel, was listed as a top-five physics download by Computer Gam-
ing World, and was featured on the G4 Network TV show Cinematech. Jeremy
has produced numerous titles for the iPhone through independent studio Mid-
night Status. Several of his iPhone titles have held top 100 positions in the App
Store, including Crash For Cash, a #1-ranked title that has been played nearly two
million times. Jeremy is also a freelance tech writer, having created the popular
Games Demystified series of articles that appear on Gamasutra. Last, but not
least, Jeremy works part-time programming serious games for L3 Communica-

And Now a Demonstration of This Fully Armed and Operational
Game Development Tool . . . .................................... 27
Main Menu . . . ............................................... 42
File . . . ....................................................42
Edit . . . ....................................................43
Assets . ....................................................57
GameObject................................................59
Component ................................................61
Inspector .................................................... 61
Transform Component Inspector Menu.........................63
Mesh Component Inspector Menu .............................63
Collider Component Inspector Menu...........................65
Box Collider Inspector Menu ..................................66
Sphere Collider Inspector Menu . ..............................69
Capsule Collider Inspector Menu ..............................69
Mesh Collider Inspector Menu . . ..............................72
Wheel Collider Inspector Menu . ..............................74
Raycast Collider Inspector Menu. ..............................80
Additional Menu Options . . .................................... 82
Scene View Submenu .......................................... 82
Game View Submenu .......................................... 87
Hierarchy View Submenu. . . .................................... 89
Project View Submenu ......................................... 90
Conclusion ................................................... 98
Chapter 4 Creating the Perfect Concept ...........................99
Out with the Old, in with the New.............................. 104
Creating Complex iPhone Experiences. . . ........................ 106
What Will We Create? ........................................ 108
The Devil’s in the Details . . . ................................... 110
iPhone Tailored.............................................. 111

Code Analysis. . . ............................................. 247
Conclusion .................................................. 251
Chapter 8 Play Testing and Iterating.............................253
Testing Criteria . ............................................. 254
Prepping the Prototype ....................................... 255
Conclusion .................................................. 280
Contents
ix
Chapter 9 Production Art ......................................281
Conclusion .................................................. 352
Chapter 10 Tying Up Loose Ends .................................353
Conclusion .................................................. 388
Chapter 11 Shipping and Handling Extra ..........................391
Conclusion .................................................. 400
Index...........................................................403
Contents
x
Introduction
The iPhone platform is the newest and most revolutionary game platform in
existence today. Developers, both large and small, are finding critical and
financial success while game players are now able to have fun with more experi-
ences for less money than ever before. This book focuses on 3D game development
for the iPhone and iPod Touch utilizing Unity (unity3d.com). Unity is an ex-
cellent tool capable of PC, Mac, Xbox 360, and Wii development, as well as iPhone
and iPod Touch deployment. Unity can be acquired free via the ‘‘indie’’ version,
although more experienced users may want to opt for the advanced version of
Unity to unlock professional-level features.
Aside from covering Unity, this book will cover certain aspects of Xcode, concept
art, basic 3D modeling, math, physics, game prototyping, and the business
aspects to help you become successful on the App Store. Creating games isn’t just

development for iPhone games. The second part of the book covers the actual
creative and engineering process necessary to create and ship a game.
Part I: Some Assembly Required
■
Ready, Fire, Aim! covers the basics from the iPhone hardware to general
programming. In this chapter, you’ll learn about the hardware needed to
test applications and the subtle differences between each revision released by
Apple. Beyond the hardware, the first chapter highlights the software
packages and general programming skills necessary to create a game.
■
Apple’s Ring, Apple’s Ropes explores the boundaries Apple has created for
developers to operate within and explains the registration, certificate, and
Introduction
xii
provisioning processes involved in creating an iPhone game. By the
completion of this chapter, you’ll be a registered iPhone developer ready to
dive into Unity and begin developing that dream game.
■
Unity Fundamentals dissects the Unity iPhone interface. You’ll learn about
the Unity Editor’s general functionality. You’ll create a Unity 3D scene that
could be deployed to the iPhone.
■
Creating the Perfect Concept sets the stage for the creative endeavor that is
involved in game development. In this chapter, you’ll determine through
logical analysis exactly what game you’re going to develop. We’ll lay out the
groundwork for Tropical Tailspin, a game that will be released on the App
Store.
Part II: Game Makin’
■
The Strengths and Weaknesses of the iPhone’s Unique Input Interface

texture an island chain, acquire, rig, and animate a seaplane, and set up our
final scene in Unity including lights, skybox, and detail scenery.
■
Tying Up Loose Ends is a rough and wild ride. This chapter covers the
crunch period in which many rapid solutions are developed in order to
deliver Tropical Tailspin. By the end of this chapter, we’ll have created a fully
functional game and covered many new technical solutions to the problems
encountered along the way.
■
Shipping and Handling Extra takes us beyond the development of Tropical
Tailspin and onto the process of packaging the game for delivery to Apple.
This chapter describes Xcode and the iTunes Connect Web site. By the
completion of this chapter, Tropical Tailspin will be waiting in line for
approval by Apple and be just one step away from players’ hands.
About the CD-ROM
The iPhone 3D Game Programming All in One CD comes packed with the simple
code samples that appear in Chapters 1-5, the full Tropical Tailspin game package,
the seaplane model donated for educational use by Toma
´
s
ˇ
Dr
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novsky
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, a variety of
media resources, and the Unity3D trial software. To use the Tropical Tailspin
and sample code (also referred to in the text as the iPhone3DGamePro-

with Unity. One thing to note is that Unity is based on the Mono Project
(www.mono-project.com). This means that Unity’s specialized functionality is
covered within Unity documentation, but its base functionality (such as string
handling) is documented on the Mono Project Web site. For this reason, some-
times JavaScript calls can be excessively long if they reference a method deep
within the Mono Project’s code base. If the same code were written with C#, then
a simple ‘‘using’’ call would be made at the top of the script so that long nested
class calls could be avoided.
Part 1
■
Some Assembly Required
2
chapter 1
Ready, Fire, Aim!
Before we delve into the depths of iPhone development, there are a few things
you’ll need. First and foremost, it’s important to have an iPhone or iPod Touch
to develop and test your games on. There are various revisions of each device on
the market, and it’s important to know the differences before developing
your game.
The iPhone has three incarnations. The original iPhone that was released in
2007, the iPhone 3G, released during the summer of 2008, and the iPhone 3GS,
released in June 2009. The original and 3G versions are pretty similar in terms of
performance. The iPhone 3G is slightly but not noticeably quicker. The biggest
difference between the two phones is the inclusion of GPS (global positioning
system) in the iPhone 3G. If your game idea revolves around GPS, then you may
have to exclude original iPhone owners.
The iPhone 3GS is a whole new ball game in terms of performance. The 3GS
model is four times faster than the iPhone 3G and includes a new graphics chip,
called the PowerVR SGX. This chip replaces the PowerVR MBX Lite included
with the older iPhones. This new chip supports OpenGL ES 2.0, so not only will

Ready, Fire, Aim!
4
being downloaded only to a supported device via iTunes Connect, which we’ll
cover in depth later.
The final hardware variances are the inclusion of a camera on both of the
iPhones, the exclusion of any sort of microphone on both iPods, and
the exclusion of a speaker from the first-generation iPod Touch. These hardware
variances are fairly subtle and do not affect most games. However, it is important
that you pick the right device if you’re developing a specialized game. Beyond
that, it’s also very helpful to test your game on multiple devices to consider the
performance and tactile feedback differences caused by the subtle hardware up-
grades Apple has executed over the lifetime of the platform. Here is a descending
list of iPhone/iTouch hardware from most to least powerful.
■
iPhone 3GS
■
iPod Touch third generation
■
iPod Touch second generation
■
iPhone 3G
■
iPhone
■
iPod Touch first generation
With the various hardware configurations out of the way and with an i-Device in
hand, it’s time to pick up a development machine. The cheapest way to jump
into iPhone development is with an Intel-based Mac Mini equipped with OS X
Leopard ($599). It’s important to note that older versions of OS X– and Power
PC– (PPC) based Macs cannot be used for iPhone development. Whichever Mac

serves its own book, so we will cover the basic principles for importing assets into
Unity iPhone, but we won’t be covering any one specific 3D application in depth.
See the following lists for a few 2D/3D solutions.
Figure 1.3
Zombieville USA.
Chapter 1
■
Ready, Fire, Aim!
6
2D Graphics Applications
■
Adobe Photoshop
■
Corel PaintShop Pro
■
GIMP (free)
3D Graphics Applications
■
Autodesk 3DS Max
■
Autodesk Maya
■
Milkshape3D
■
Wings3D (free)
■
Blender (free)
The Apple Developer and iTunes Connect Web interfaces are both fairly self-
explanatory, but we’ll cover them in depth as clearly and concisely as possible
because many developers have struggled with them.

It’s Not the Size of the Game, It’s the Motion of the
Air-to-Surface Missiles
Three-dimensional games involve gameplay occurring in three spatial dimen-
sions. You may have heard whispers of these mysterious three dimensions in
math class, but I’ll bet you never applied them to a planet-devouring cluster
bomb, right? If you want to shoot someone in a game, you have to know where
to aim within the confines of good old X, Y, and Z. Those letters represent the
three axes of motion within space, and they lay the guidelines for blowing stuff
up. You’re not a violent person? Still, if you want to run around a planet, travel
through Einstein-Rosen portals, or race someone, you’ll be doing that along
these three axes of motion as well. See Figure 1.4 for the obligatory triple axis
visual. These are the three axes of motion.
In Unity iPhone, things moving left and right are moving along the X-axis,
things moving up and down are on the Y-axis, and things moving in and out are
traveling along the Z-axis. Just for fun, let’s skip ahead a bit to see how we’d
actually move something in Unity. This is just a sample of what you’ll actually be
working with later on, so there’s no need to whip out the old text editor yet.
This is how we’d create and move a ball up in Unity:
var ball : GameObject;
ball ¼ GameObject.CreatePrimitive( PrimitiveType.Sphere );
ball.transform.position ¼ Vector3( 0, 0, 0 );
ball.transform.position.y þ¼ 1;
Chapter 1
■
Ready, Fire, Aim!
8
That wasn’t so bad, was it? This code tells your iPhone to create a
GameObject
called
ball

second.
Figure 1.4
Obligatory triple-axis gizmo.
A Long Time Ago (Like a Millisecond), Far, Far Away
9
Time not only affects the speed of objects moving within your game world and
the reaction of your game to player input, but the performance of your game as
well. It’s important to understand the implications of each line of code to your
game’s bottom line, which in many cases is time itself. The more you try to do
with your code, the less time the CPU/GPU has to execute each event. Of course,
as any good magician knows, the tricks of the trade can make a huge difference.
Still, the laws of physics cannot be broken. There’s only so much kinetic energy
your iPhone can generate, and that has to be distributed between the bulk of
your game code and the speed at which the player experiences the game.
Time is easily accessible in Unity. The ball won’t move until two seconds have
passed.
var ball : GameObject;
ball ¼ GameObject.CreatePrimitive( PrimitiveType.Sphere );
ball.transform.position ¼ Vector3( 0, 0, 0 );
var moveTheBallIn2Seconds ¼ Time.time; //Time.time gives us the cur-
rent time
if ( moveTheBallIn2Seconds þ 2 < Time.time );
{
ball.transform.position.y þ¼ 1;
}
Both time and motion have been intertwined here in a rudimentary way. Creat-
ing actual game code will be more complex, but not by much. If these principles
are making sense, then you are well on your way to becoming an expert game
programmer.
What’s a Vector, Victor?