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


Just like with the AABB, we know that an OBB does not intersect a plane if all of the OBB vertices are on the same side of the plane. The actual test to check if an OBB and plane intersect will be very similar to the AABB-to-Plane test:

Getting ready

We are going to implement a function to test if an OBB and a Plane intersect. This function will be similar to how we checked if an AABB and Plane intersected. We will project the OBB onto the normal of the plane and find the interval of this projection. If the interval contains the origin of the plane, we know we have an intersection.

How to do it…

Follow the given steps to find intersections between an OBB and a plane:

  1. Declare OBBPlane in Geometry3D.h:

    bool OBBPlane(const OBB&obb, const Plane& plane);
  2. Dclare the PlaneOBB macro in Geometry3D.h:

    #define PlaneOBB(plane, obb) \
       OBBPlane(obb, plane)
  3. Implement OBBPlane in Geometry3D.cpp:

    bool OBBPlane(const OBB& obb, const Plane& plane) {
        // Local variables for readability...