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

Linetest Oriented Bounding Box

Rays and Line segments are similar. The slab test for raycasting and the slap test to see if a Line and OBB intersect are almost the same. The only thing a linetest does different from a Raycast is it normalizes the result of the t value to the length of the line segment.

Because the two tests are so similar, we are going to build the linetest using the existing Raycast against the OBB function. Comparing the squared value of t against the squared length of the line segment is more efficient than normalizing t to the length of the Line.

Getting ready

We are going to implement a function to check if a Line segment and an OBB intersect. This function will return a Boolean result. The linetest function is going to build a ray out of the line and use the existing Raycast against the OBB function.

How to do it…

Follow these steps to implement line testing against an OBB:

  1. Declare the Linetest function in Geometry3D.h:

    bool Linetest(const OBB& obb, const Line& line...