Collected Wisdom of Game AI Professionals

612 Pages·2014·5.63 MB·English

by  Steven Rabin

collEctEd wisdom
Successful games merge art and technology in truly unique ways. Fused under tight
of gamE ai
production deadlines and strict performance requirements, shaped by demanding player
expectations, games are among the most complex software projects created today. Game profEssionals
AI Pro: Collected Wisdom of Game AI Professionals covers both the art and the technology
of game AI. Nothing covered is theory or guesswork. The book brings together the
accumulated wisdom, cutting-edge ideas, and clever tricks and techniques of 54 of today’s
top game AI professionals. Some chapters present techniques that have been developed
and passed down within the community for years while others discuss the most exciting
new research and ideas from today’s most innovative games.
The book includes core algorithms that you’ll need to succeed, such as behavior trees,
utility theory, spatial representation, path planning, motion control, and tactical reasoning.
It also describes tricks and techniques that will truly bring your game to life, including
perception systems, social modeling, smart camera systems, player prediction, and even
an AI sound designer. Throughout, the book discusses the optimizations and performance
enhancements that enable your game to run while maintaining 60 frames per second.
Features
• Contains 48 articles from 54 of the game industry’s top developers
• Presents many practical, cutting-edge techniques drawn from successful games
• Includes both the core algorithms that are widely used in the industry today as well as
new ideas and research that are being shared for the first time
• Provides example programs and source code at www.gameaipro.com
EditEd by
K16125 stEvE rabin
Computer Game Development

ColleCted Wisdom
of Game ai
Professionals

CollECtEd WiSdom
of GamE ai
PRofESSionalS
EditEd by
StEvEn Rabin
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Contents
Preface xi
Web Materials xiii
Acknowledgments xv
The Editors xvii
The Contributors xix
Part I General Wisdom
1 What Is Game AI? 3
Kevin Dill
2 Informing Game AI through the Study of Neurology 11
Brett Laming
3 Advanced Randomness Techniques for Game AI:
Gaussian Randomness, Filtered Randomness, and Perlin Noise 29
Steve Rabin, Jay Goldblatt, and Fernando Silva
v
Part II Architecture
4 Behavior Selection Algorithms: An Overview 47
Michael Dawe, Steve Gargolinski, Luke Dicken, Troy Humphreys,
and Dave Mark
5 Structural Architecture—Common Tricks of the Trade 61
Kevin Dill
6 The Behavior Tree Starter Kit 73
Alex J. Champandard and Philip Dunstan
7 Real-World Behavior Trees in Script 93
Michael Dawe
8 Simulating Behavior Trees: A Behavior Tree/Planner Hybrid
Approach 99
Daniel Hilburn
9 An Introduction to Utility Theory 113
David “Rez” Graham
10 Building Utility Decisions into Your Existing Behavior Tree 127
Bill Merrill
11 Reactivity and Deliberation in Decision-Making Systems 137
Carle Côté
12 Exploring HTN Planners through Example 149
Troy Humphreys
13 Hierarchical Plan-Space Planning for Multi-unit Combat Maneuvers 169
William van der Sterren
14 Phenomenal AI Level-of-Detail Control with the LOD Trader 185
Ben Sunshine-Hill
15 Runtime Compiled C++ for Rapid AI Development 201
Doug Binks, Matthew Jack, and Will Wilson
16 Plumbing the Forbidden Depths: Scripting and AI 219
Mike Lewis
vi Contents
Part III Movement and Pathfinding
17 Pathfinding Architecture Optimizations 241
Steve Rabin and Nathan R. Sturtevant
18 Choosing a Search Space Representation 253
Nathan R. Sturtevant
19 Creating High-Order Navigation Meshes through Iterative
Wavefront Edge Expansions 259
D. Hunter Hale and G. Michael Youngblood
20 Precomputed Pathfinding for Large and Detailed Worlds
on MMO Servers 269
Fabien Gravot, Takanori Yokoyama, and Youichiro Miyake
21 Techniques for Formation Movement Using Steering Circles 289
Stephen Bjore
22 Collision Avoidance for Preplanned Locomotion 297
Bobby Anguelov
23 Crowd Pathfinding and Steering Using Flow Field Tiles 307
Elijah Emerson
24 Efficient Crowd Simulation for Mobile Games 317
Graham Pentheny
25 Animation-Driven Locomotion with Locomotion Planning 325
Jarosław Ciupiński
Part IV Strategy and Tactics
26 Tactical Position Selection: An Architecture and Query Language 337
Matthew Jack
27 Tactical Pathfinding on a NavMesh 361
Daniel Brewer
Contents vii
28 Beyond the Kung-Fu Circle: A Flexible System for Managing
NPC Attacks 369
Michael Dawe
29 Hierarchical AI for Multiplayer Bots in Killzone 3 377
Remco Straatman, Tim Verweij, Alex Champandard, Robert Morcus,
and Hylke Kleve
30 Using Neural Networks to Control Agent Threat Response 391
Michael Robbins
Part V Agent Awareness and
Knowledge Representation
31 Crytek’s Target Tracks Perception System 403
Rich Welsh
32 How to Catch a Ninja: NPC Awareness in a 2D Stealth Platformer 413
Brook Miles
33 Asking the Environment Smart Questions 423
Mieszko Zielinski
34 A Simple and Robust Knowledge Representation System 433
Phil Carlisle
35 A Simple and Practical Social Dynamics System 441
Phil Carlisle
36 Breathing Life into Your Background Characters 451
David “Rez” Graham
37 Alibi Generation: Fooling All the Players All the Time 459
Ben Sunshine-Hill
Part VI Racing
38 An Architecture Overview for AI in Racing Games 471
Simon Tomlinson and Nic Melder
39 Representing and Driving a Race Track for AI Controlled Vehicles 481
Simon Tomlinson and Nic Melder
viii Contents