Table Of ContentGame Development Patterns
with Unity 2021
Second Edition
Explore practical game development using software design
patterns and best practices in Unity and C#
David Baron
BIRMINGHAM - MUMBAI
Game Development Patterns with Unity 2021
Second Edition
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First published: March 2019
Second edition: July 2021
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This book is dedicated to my mother, Katia Galano, for her continuous words of
encouragement and support and for always helping me through difficult times.
– David Baron
Contributors
About the author
David Baron is a game developer with over 15 years of experience in the industry. He has
worked for some well-known AAA, mobile, and indie game studios in Montreal, Canada.
His skill set includes programming, design, and 3D art. As a programmer, he has worked
on various games for various platforms, including virtual reality, mobile, and consoles.
I would like to first and foremost thank my family for their continued support, patience,
and encouragement throughout the long process of writing this book. I also want to give
special thanks to the following individuals who offered me valuable feedback while writing
this book: Nicolas Eypert, Guillaume Leroy, Dave Sirois, and Frédéric Lévesque.
About the reviewers
Lucas Bertolini has 10+ years' experience as a video game software developer. He has
worked on three major projects: for Pollux Ltd. (Hong Kong) as a game developer and
designer; for Schell Games (Pittsburgh, US) where he moved and worked as a developer
until the project was completed; and for Globant as a developer.
He has worked in technical education for 5+ years and has taught a variety of programming
courses. He is the cofounder of NGA and Bytenarchy Studios, both digital services
development companies that use Unity as their main technology.
Lucas has written Hands-On Game Development without Coding, available from Packt.
Mark Bonasoro grew up in the late 80s in a family with computers from a young age. In the
mid-90s, Mark started building his own PCs. His interest in game development started
when he used Softimage on a Silicon Graphics machine in high school. Mark's
programming skills ramped up in the 2000s when he started college, using C++ to make
business applications, and worked in a small indie game company using a 3D
multiplatform game engine, still in circulation, called Intrinsic Alchemy. In 2006, Mark
started a game studio, as an excuse to learn with his classmates to make mobile games for
Java 2 Micro Edition-featured phones for Sony Ericsson and Nokia. He graduated in
software engineering in 2010 from Concordia University and worked as a Unity developer
for Affordance Studios producing educational games.
I would like to thank David for all the opportunities he offered and am honored to be
included as a technical reviewer for his latest book.
Table of Contents
Preface 1
Sections 1: Fundamentals
Chapter 1: Before We Begin 8
Notes about the new edition 8
The philosophy of the book 9
What are design patterns? 10
Which subjects aren't covered in this book? 10
The game project 11
Summary 12
Chapter 2: The Game Design Document 13
The design document 14
Game overview 14
Unique selling points 14
Minimum requirements 15
Game synopsis 15
Game objectives 16
Game rules 17
Game loop 17
Game environment 18
Camera, control, character (3Cs) 18
Camera 18
Character 19
Character description 19
Character metrics 20
Character states 20
Controller 21
Game ingredients 21
Superbikes 22
Pickups 22
Obstacles 23
Weaponry 23
Game systems 23
Game menu 25
Game HUD 25
Summary 26
Further reading 26
Chapter 3: A Short Primer to Programming in Unity 27
What you should already know 28
Table of Contents
C# language features 28
Unity engine features 32
Summary 34
Further reading 34
Section 2: Core Patterns
Chapter 4: Implementing a Game Manager with the Singleton 36
Technical requirements 37
Understanding the Singleton pattern 37
Benefits and drawbacks 39
Designing a Game Manager 39
Implementing the Game Manager 40
Testing the Game Manager 45
Summary 47
Chapter 5: Managing Character States with the State Pattern 48
Technical requirements 49
An overview of the State pattern 49
Defining character states 51
Implementing the State pattern 52
Implementing the State pattern 53
Testing the State pattern implementation 58
Benefits and drawbacks of the State pattern 59
Reviewing alternative solutions 61
Summary 62
Chapter 6: Managing Game Events with the Event Bus 63
Technical requirements 64
Understanding the Event Bus pattern 64
Benefits and drawbacks of the Event Bus pattern 66
When to use the Event Bus 67
Managing global race events 67
Implementing a Race Event Bus 68
Testing the Race Event Bus 70
Reviewing the Event Bus implementation 75
Reviewing some alternative solutions 76
Summary 76
Chapter 7: Implement a Replay System with the Command Pattern 77
Technical requirements 78
Understanding the Command pattern 78
Benefits and drawbacks of the Command pattern 81
When to use the Command pattern 81
Designing a replay system 82
[ ii ]
Table of Contents
Implementing a replay system 84
Implementing the replay system 84
Testing the replay system 88
Reviewing the implementation 92
Reviewing alternative solutions 93
Summary 93
Chapter 8: Optimizing with the Object Pool Pattern 94
Technical requirements 95
Understanding the Object Pool pattern 95
Benefits and drawbacks of the Object Pool pattern 96
When to use the Object Pool pattern 97
Implementing the Object Pool pattern 98
Steps for implementing the Object Pool pattern 98
Testing the Object Pool implementation 103
Reviewing the Object Pool implementation 105
Reviewing alternative solutions 105
Summary 105
Chapter 9: Decoupling Components with the Observer Pattern 106
Technical requirements 107
Understanding the Observer pattern 107
Benefits and drawbacks of the Observer pattern 108
When to use the Observer pattern 109
Decoupling core components with the Observer pattern 109
Implementing the Observer pattern 111
Testing the Observer pattern implementation 117
Reviewing alternative solutions 119
Summary 119
Chapter 10: Implementing Power-Ups with the Visitor Pattern 120
Technical requirements 121
Understanding the Visitor pattern 121
Benefits and drawbacks of the Visitor pattern 123
Designing a power-up mechanic 124
Implementing a power-up mechanic 125
Implementing the power-up system 125
Testing the power-up system implementation 131
Reviewing the power-up system implementation 133
Summary 134
Chapter 11: Implementing a Drone with the Strategy Pattern 135
Technical requirements 136
Understanding the Strategy pattern 136
Benefits and drawbacks of the Strategy pattern 137
When to use the Strategy pattern 138
[ iii ]
Table of Contents
Designing an enemy drone 139
Implementing an enemy drone 141
Steps to implementing an enemy drone 141
Testing the enemy drone implementation 146
Reviewing the enemy drone implementation 148
Reviewing alternative solutions 148
Summary 149
Chapter 12: Using the Decorator to Implement a Weapon System 150
Technical requirements 150
Understanding the Decorator pattern 151
Benefits and drawbacks of the Decorator pattern 152
When to use the Decorator pattern 153
Designing a weapon system 154
Implementing a weapon system 155
Implementing the weapon system 155
Testing the weapon system 162
Reviewing the weapon system 165
Reviewing alternative solutions 166
Summary 166
Chapter 13: Implementing a Level Editor with Spatial Partition 167
Technical requirements 168
Understanding the Spatial Partition pattern 168
When to use the Spatial Partition pattern 170
Designing a level editor 170
Implementing a level editor 173
Steps for implementing a level editor 173
Using the level editor 179
Reviewing the level-editor implementation 179
Reviewing alternative solutions 179
Summary 180
Section 3: Alternative Patterns
Chapter 14: Adapting Systems with an Adapter 182
Technical requirements 183
Understanding the Adapter pattern 183
Benefits and drawbacks of the Adapter pattern 185
When to use the Adapter pattern 186
Implementing the Adapter pattern 187
Implementing the Adapter pattern 187
Testing the Adapter pattern implementation 190
Summary 191
Chapter 15: Concealing Complexity with a Facade Pattern 192
[ iv ]
