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
About the Author
About the Reviewer
Customer Feedback

Axis angle rotation

As discussed earlier, we can combine yaw, pitch, and roll using matrix multiplication to create a complete rotation matrix. Creating a rotation matrix by performing each rotation sequentially introduces the possibility of a Gimbal Lock.

We can avoid that Gimbal Lock if we change how a rotation is represented. Instead of using three Euler angles to represent a rotation, we can use an arbitrary axis, and some angle to rotate around that axis.

Given axis , we can define a matrix that will rotate some angle around that axis:

Where and XYZ = Arbitrary Axis (unit length). We will explore how this matrix is derived in the How it works… section.

Getting ready

Like before, we are going to implement two versions of this function. One version will return a 4 X 4 matrix; the other will return a 3 X 3 matrix. To avoid having to constantly calculate sin and cos, we're going to create local variables for c, s, and t. The axis being passed in does not have to be normalized. Because of this...