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

AABB-to-plane


An AABB does not intersect a plane if all four corners of the box are on the same side of the plane. A naive solution to this problem would be to get all eight corners of the plane as points, and then perform a half space test with every corner against the plane.

A better solution would be to use the GetInterval function we wrote in the AABB to OBB section of this chapter to get the interval of the box along the normal of the plane. Then, we just have to make sure that the min and max intervals of the AABB are both greater than 0, or less than 0. If the signs of the min and max are different, we have an intersection.

We are going to take a third, more optimal approach. We will project the half extents of the box onto the plane. Then, we will find the distance between the box and the plane. We find the distance between the box and the plane by measuring how far the projected box interval is from the origin along the normal. If the distance of the box from the plane is less than...