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

Simple and complex shapes

Sometimes a containing circle or a containing rectangle alone is not accurate enough for collision detection. When this happens we can use several simple shapes to approximate a complex shape:

Getting ready

We are going to create a new structure called BoundingShape. This new structure will hold an array of circles and an array of rectangles. It's assumed that the structure does not own the memory it is referencing. We can implement several primitive tests by looping through all the primitives that BoundingShape contains.

How to do it…

Follow these steps to create a class which represents a complex shape. A complex shape is made out of many simple shapes:

  1. Declare the BoundingShape primitive in Geometry2D.h:

    typedef struct BoundingShape {
       int numCircles;
       Circle* circles;
       int numRectangles;
       Rectangle2D* rectangles;
       inline BoundingShape() :
          numCircles(0), circles(0),
          numRectangles(0), rectangles(0) { }
  2. Define a new PointInShape function in Geometry2D...