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

Mesh object


A mesh is just a large collection of triangles:

For collision detection, a mesh should be treated as a linear list of triangles. Meshes can be constructed by hand, or loaded from a file. An OBJ loader sample is included with the code accompanying this chapter.

Getting ready

In this section, we are going to declare the Mesh structure that will be used to test for collisions against arbitrary 3D models.

How to do it…

Follow these steps to implement a mesh primitive:

  1. Declare the Mesh structure in Geometry3D.h:

    typedef struct Mesh {
  2. We need to know how many triangles the mesh will have:

        int numTriangles;
  3. With this anonymous union we can access the data of the triangle in one of three ways. We can access it as triangle primitives, as points of a triangle or the ray float components:

        union {
            Triangle* triangles;//size = numTriangles
            Point* vertices;    //size = numTriangles * 3
            float* values;      //size = numTriangles * 3 * 3
        };
    } Mesh;

How it works…

The preceding...