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

Raycast Axis Aligned Bounding Box


Any ray that intersects an AABB will do so twice. The first intersection is where the ray enters the AABB; the second is where the ray exists. If we know both intersection points, the point closest to the origin of the ray is the intersection point.

We can simplify finding the intersections points by visualizing the problem top down. Looking only at the X and Y axis. In this example, the AABB is represented by two slabs. The intersections of the slabs form four planes. These planes represent the faces of the AABB. We cast a ray and check if it's intersecting the X slab:

We found two points as a result of testing the ray intersection against the X slab. We call the near point and the far point . We repeat the same intersection against the Y slab:

We now have two more points, and . The ray enters the Y slab, and then leaves the Y slab. Next, the ray enters the X slab, and then leaves the X slab. There is no intersection. We can prove this, the greatest minimum...