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

Raycast Bounding Box

Any box in 3D space, OBB, or AABB has six sides. This means the normal of a Raycast against a box will be the normal of one of the six sides. When doing a Raycast against a Bounding Box, we find the point of impact the same way we did for a Raycast against a Sphere. The normal, however, will be the same as the normal of the side which the ray hit.

Getting ready

Several of our existing functions use Raycast against AABB or OBB internally. When we change the API, we must be careful to update every spot where these functions are used. We must update the Linetest functions and the MeshRay function. In this section we are going to rewrite the Raycast function for AABB and OBB.

How to do it…

Follow these steps to update the Raycast functions of boxes in a way that they provide additional useful data:

  1. Update the declarations of Raycast against both OBB and AABB in Geometry3D.h:

    bool Raycast(const AABB& aabb, const Ray& ray, 
       RaycastResult* outResult);
    bool Raycast(const...