Book Image

Game Physics Cookbook

By : Gabor Szauer
Book Image

Game Physics Cookbook

By: Gabor Szauer

Overview of this book

Physics is really important for game programmers who want to add realism and functionality to their games. Collision detection in particular is a problem that affects all game developers, regardless of the platform, engine, or toolkit they use. This book will teach you the concepts and formulas behind collision detection. You will also be taught how to build a simple physics engine, where Rigid Body physics is the main focus, and learn about intersection algorithms for primitive shapes. You’ll begin by building a strong foundation in mathematics that will be used throughout the book. We’ll guide you through implementing 2D and 3D primitives and show you how to perform effective collision tests for them. We then pivot to one of the harder areas of game development—collision detection and resolution. Further on, you will learn what a Physics engine is, how to set up a game window, and how to implement rendering. We’ll explore advanced physics topics such as constraint solving. You’ll also find out how to implement a rudimentary physics engine, which you can use to build an Angry Birds type of game or a more advanced game. By the end of the book, you will have implemented all primitive and some advanced collision tests, and you will be able to read on geometry and linear Algebra formulas to take forward to your own games!
Table of Contents (27 chapters)
Game Physics Cookbook
About the Author
About the Reviewer
Customer Feedback


Like the AABB to OBB test, checking if two OBBs overlap is best done using the separating axis theorem. The actual SAT function will be very similar to the AABB to OBB test. Like AABB to OBB, there are 15 axes of potential separation to test. The 15 axes that we need to test are similar to AABB to OBB, except the first three axis are the orientation of the first OBB.

If we have two OBBs, A and B, we can find the 15 axes of potential separation between them as follows:

The first three axes of separation are the basis vectors of the orientation of the first OBB:




The next three axes of separation are the basis vectors of the orientation of the second OBB:




The last nine axes of separation are the cross products of every basis axis from both OBBs:

A.XAxis x B.XAxis

A.YAxis x B.XAxis

A.ZAxis x B.XAxis

A.XAxis x B.YAxis

A.YAxis x B.YAxis

A.ZAxis x B.YAxis

A.XAxis X B.ZAxis

A.YAxis x B.ZAxis

A.ZAxis x B.ZAxis