Programming Game AI by Example
provides a comprehensive and practical introduction to the “bread and
butter” AI techniques
used by the game development industry, leading the reader through the
process of designing, programming and implementing intelligent agents for
action games using the C++ programming language.

Each technique or
algorithm is described patiently, often accompanied by a step-by-step
illustrated walkthrough, to ensure the reader thoroughly understands the
principle before moving on to show how they can be combined to
create intelligent agents capable of providing the modern video game
player with an entertaining and rewarding experience. To this end the book
includes detailed descriptions of the creation of game agents capable of
playing team sports and deathmatch type games. Source code and
pre-compiled executables for all the demos and projects found in the book
can be downloaded from the Wordware website.

Here’s what some industry professionals have to say
about the book:

 

“Programming Game AI
by Example stands out from the pack by providing industrial-strength solutions
to difficult problems, like steering and goal-oriented behavior.  Mat guides the reader toward building a
foundation robust enough for real games. 
This book is a must have for anyone new to the field, and has tips for
the seasoned professional as well.  I
wish I read it eight years ago!”

 

Jeff Orkin, AI Architect, Monolith Productions, No One Lives
Forever 2 and F.E.A.R.

 

 

“…a nice combination
of a lot of really useful information, put together in a way that doesn’t make
my brain leak.”

 

Gareth Lewis, Project Leader, Lionhead Studios, Black &
White 2

 

 

“Programming Game AI
by Example is an excellent book for both the game programming neophyte, the
intermediate programmer and even the expert – it doesn’t hurt to go over
familiar ground does it? The book concisely covers all of the important areas,
including basic mathematics and physics through to graph theory and scripting
with LUA, to arm any programmer with the tools needed to create some very
sophisticated agent behaviours. Unusually for books of the type Programming
Game AI by Example is solid in it’s software engineering too, with the example
code demonstrating game uses of familiar design patterns. I’d have no qualms
about recommending Programming Game AI by Example to any programmer, it’s an
excellent read and an excellent springboard for ideas.”

 

Chris Keegan, Technical Director, Climax Studios (Solent).

 

 

“Using easy to
follow and well described examples, this book shows you how to use most of the
techniques professional AI programmers use.  A great introduction for the
beginner and an excellent reference for the more experienced!”

 

Eric Martel, AI Programmer, Ubisoft, Far Cry (XBox)

 

 

“Each chapter of Mat’s
book gently introduces the reader to a fundamental game AI technology, before
expanding the new idea into a fully formed solution replete with extensive code
and clearly worded examples. The tone of the book is uncomplicated and accessible
to the reader, allowing a novice programmer the opportunity to get to grips
with the basics of game AI programming by implementing their own systems direct
from theory or expanding upon code examples offered to gain understanding in a
sandbox environment. Once individual technologies are fully understood the book
goes on to combine these ideas into several complete game environments allowing
the reader to understand the relationships between the interacting systems of
an overarching game architecture.”

 

Mike Ducker, AI Programmer, Lionhead Studios, Fable

 

 

 

Order

 

Programming Game AI by Example
is on the shelves at last! Here are links to the Amazon listings:

 

Amazon.com

Amazon.co.uk

 

 

 

 

 

Table Of Contents

 

 

 

Foreword by Steve Woodcock

 

Click to read

 

 

Introduction

 

 

Chapter 1: Math & Physics

 

Some knowledge of
mathematics and physics is necessary to understand game AI. This chapter
assumes the reader has very little experience with either and provides
explanations of all the math and physics used in the techniques described in
this book.

 

           

Chapter 2: State Driven Agents

 

State based agent
architectures have been the bread and butter of game AI for the last 25 years.
This chapter describes how you can implement them in your own games.

 

Discussion, code and demos
of: switch based, transition table based, embedded transitions, state design
pattern, state class, templated state class, global states, blip states,
templated state machine class, message handling.

 


Part of this chapter is
now available to read online.

 

 

Chapter 3: Steering Behaviors  

 

Most computer game
characters move around and this chapter shows you how to program them to do it.

 

Code and demos for:
individual and group movement including the behaviors seek, flee, arrive,
pursuit, wander, evade, obstacle avoidance, wall avoidance, interpose, hide,
path following, offset pursuit, separation, alignment, cohesion, flocking,
combining steering behaviors, weighted truncated sum, weighted prioritized
truncated sum, prioritized dithering, non penetration constraints, space
partitioning, smoothing.

 

 

Chapter 4: Simple Soccer

 

This chapter walks through
the development of a five a side soccer game from start to finish explicitly
demonstrating how the techniques the reader has learned in previous chapters
(plus a couple of new ones) can be made to work together to implement a simple
but entertaining AI for a team based sports game.

 

Discussion, code and demo
of:  sports game framework, layered AI architecture, soccer ball physics,
field player states and movement, goal keeper states and movement, team states,
spot sampling, making estimates and assumptions work for you

 

 

Chapter 5: Graph Theory

 

Whenever a game agent needs
to find a path from A to B or the best way to traverse a technology tree it
will more often than not be using search algorithms to traverse some kind of
graph-like data structure. This chapter provides an overview of graphs and very
detailed (no more headaches trying to understand this stuff!) walkthroughs of
the most commonly used search algorithms and their  implementation in C++.

 

Discussions of: trees,
graphs, digraphs, graph density, state graphs, dependency graphs, navigation
graphs, iterative deepening search, bi-directional search, heuristic policies

 

Discussion, code and demos
of:  graph node class, graph edge class, graph class, depth first search,
breadth first search, edge relaxation, shortest path trees, Dijkstra’s search,
A*.

 

 

Chapter 6: Scripting

 

Over the last few years
scripting  has grown enormously in popularity with game developers. This
chapter will tell you why, what scripting is, what you can use it for and how
to implement it in your own games.

 

Discussion, code and demos
of:  what scripting is, what scripts are, how they are used by AI
developers, introduction to Lua, interfacing with C++, exposing C++ functions
to Lua, using Lua scripts with C++, introduction to Luabind, exposing C++
classes to Lua, creating a scripted state machine.

 

 

Chapter 7: Raven – An Overview

 

This chapter provides a
detailed overview of  the Raven game architecture and the design of the AI
of the agents that fight within its maps. Raven is a game framework that
combines elements of FPS, RPG and RTS type AI, which I use to demonstrate
several newly introduced techniques. In particular Raven is used to demonstrate
explicitly how just about all the methods described in the book can combined
to create sophisticated game playing agents. (Some of the techniques mentioned 
are too complex a topic to cover properly in a single chapter and are discussed
in detail in later chapters).

 

Discussion, code and demos
of:  game architecture, map objects, weapon objects, projectile objects,
triggers, trigger regions, respawning triggers, limited lifetime triggers,
giver triggers, sound notification triggers, trigger system class, AI design
considerations, decision making, path planning, movement, perception, sensory
and memory modeling, target selection, weapon selection, weapon handling, AI
update frequencies.

 

 

Chapter 8: Practical Path Planning

 

There’s probably more
written about path planning than any other technique currently used in the game
industry. This chapter provides an overview of the problems faced by today’s
game developers and shows you — using the Raven framework — how to solve
them.

 

Discussions of: tile based
navgraphs, points of visibility navgraphs, expanded geometry navgraphs,
navmeshes, hierarchical pathfinding

 

Discussion, code and demos
of:  coarse versus fine grained navgraphs, using spatial partitioning to
speed up proximity queries, creating a path planner class, planning a path to a
specific location, planning a path to an item type, creating custom termination
condition policies for graph searches, node paths versus edge paths, annotating
navgraphs, smoothing paths, reducing CPU overhead, pre-calculating path lookup
tables, pre-calculating cost lookup tables, time-sliced path planning,
preventing the twiddling of thumbs, getting out of sticky situations

 

 

 

Chapter 9: Hierarchical Goal Based Agents

 

This chapter introduces
agents that are motivated by hierarchical goals. This type of architecture is
far more flexible than the one described in Chapter 2 allowing AI programmers
to easily imbue game characters with the brains necessary to do all sorts of
funky stuff.

 

Discussion, code and demos
of: atomic goals, composite goals, goal arbitration, creating goal evaluation
functions,  implementation in Raven, using goal evaluations to create personalities,
goals and agent memory, automatic resuming of interrupted activities,
negotiating special path obstacles such as elevators, doors or moving
platforms, command queuing, scripting behavior.

 

 

 

Chapter 10: Fuzzy Logic

 

Fuzzy logic, enables a computer
to reason about linguistic terms and rules in a way similar to humans thereby
making it easy to extract domain specific knowledge from an expert and to
present it in a form a game playing agent can utilize. This chapter provides a
solid grounding in the theory and practice of fuzzy logic and demonstrates how
it is used by the Raven agents to help select the correct weapon for the
correct situation.

 

Discussion, code and demos
of: crisp set theory, fuzzy set theory, membership functions, fuzzy operators,
hedges, fuzzy linguistic variables (FLVs), fuzzy rules, designing FLVs for
weapon selection, duzzification, fuzzy inference, defuzzification methods (mean
of maxima, average of maxima, centroid), FuzzyModule class, FuzzySet class
hierarchy, FLV class, how to build a fuzzy rule base using the C++ classes, the
Combs method for reducing combinatorial explosion.

 

 

Final Words

 

Bibliography

 

Appendix A: C++ Templates

 

Appendix B: UML Notation (available online)

 

Appendix C: Setting up the Development Environment

 

 

 


Source Code
and Binaries

 

You can download the source code
and binaries that accompany the book from
here.

 

(1/8/12:
Petr Bilek is writing Java versions of the examples in Programming Game AI by
Example. You can find them here.)

 

 

 


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