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

Cloth


We can use springs to model interesting soft body objects. Unlike a rigidbody, a soft body can change its shape. In this section, we will use springs to simulate cloth. Cloth is implemented as a point mass system. In a point mass system, every vertex of a mesh is represented by a particle. Every particle is attached to other particles by springs to force the object to maintain its shape.

If we arrange all the particles representing the vertices of a cloth in a grid, we can connect every row and column using springs. These springs are the structural springs of the cloth:

This, however, is not enough for an accurate simulation. If we set any one of the particles to have infinite mass so that it does not move, the cloth will collapse into a rope. We can improve the structural integrity of the cloth by adding shear springs. Shear springs connect every particle to its neighbors diagonally:

Having both structural and shear springs makes the cloth behave as expected in the scenario where one...