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

Point and ray

A ray is the same as a directed line. Unlike a line segment, which has a start and an end point, a ray has only a start point and a direction. The ray extends infinitely in this one direction. Because of the ray's similarity to a line, operations on a ray are similar to those on a line.

Because a ray's direction is a normal vector, we can use the dot product to check its direction against other known vectors. For example, to test whether a point is on a ray, we need to get a normalized vector from the origin of the ray to the test point. We can then use the dot product to see if this new normal vector is the same as the normal of the ray. If two vectors point in the same direction, the result of the dot product will be 1:

Getting ready

We are going to implement two functions: one to check if a test point is on a ray and one to get the closest point on a ray to a test point. Both of these functions are going to rely heavily on the dot product.

How to do it…

Perform the following...