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
Credits
About the Author
Acknowledgements
About the Reviewer
Acknowledgements
www.PacktPub.com
Customer Feedback
Preface
Index

Manifold for boxes


Finding the collision manifold between two OBBs is difficult. The collision normal and penetration distance come right from the Separating Axis Theorem. Recall that there are potentially 15 axes of potential separation between two OBBs. While performing the SAT tests, we keep track of which axis had the least penetration; that is the axis of intersection. The collision normal is the same as the axis of intersection. The penetration depth is the difference between the centers of both the OBBs projected onto this axis.

What makes finding the manifold for OBBs difficult is determining the contact points between the boxes. There are several ways in which two boxes could intersect, each producing different types of contact points:

We will implement a less than optimal and simple solution. Given two OBBs, A and B, we will find the intersection points of the edges of A and the planes of B as well as the edges of B and planes of A. This essentially clips each box against the other...