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

Point and line


To test if a point is on a line, or to get the point on a line closest to a test point, we first have to project the point onto the line. This projection will result in a floating point value, t. We use this new t value to find the distance of the point along the line segment using the distance(t) = start + t * (end - start)function. The start point of the line is at t = 0, the end point is at t = 1. We have to take two edge cases into account, when t is less than 0 or greater than 1:

Getting ready

We are going to implement two functions, one to get the point on a line closest to a test point and one to determine if a test point is on a line. The ClosestPoint function is going to project the test point onto the line and evaluate the parametric function, distance(t) = start + t * (end - start).

To determine if a test point is on a line segment, we still need the point on the segment closest to the test point. We are then able to measure the distance between the test point and...