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

Mesh optimization


Every operation on a mesh will simply loop through all of the triangles that make up the mesh and perform the requested operation on every triangle. With medium to large size meshes this becomes very expensive, very fast. Because of the expensive nature of these tests, we are going to add an optional acceleration structure to our Mesh object.

The optimization structure we are adding is a Bounding Volume Hierarchy (BVH), an Octree to be specific. First we will need to find an AABB that contains the entire mesh. Next, we will divide the box into eight sub-boxes. We assign each triangle of the mesh to one (or more) of the nine boxes it belongs to. We will recursively repeat this process:

Now that every triangle is inside an AABB, we can use this hierarchy to accelerate intersection testing. At the top level, we check if the intersection touches the AABB containing the box. Next, we check if the intersection touches any of the AABB's eight children. We recursively repeat this...