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

Picking


Picking objects in 3D space is a common problem. If you want your 3D simulation to interact with a mouse, we need to solve this problem. To implement picking, we need to find the pixel that the user has clicked relative to both the near and far planes of the camera. We can construct a ray from the point on the near plane to the point on the far plane. Finally, we can query the world using this ray.

The job of a graphics pipeline is to take a 3D point in world space and project it onto the screen. This transformation from world space to screen space is called Projection. To find the 3D world space position of a point based on the 2D pixel position of that same point we need to do the opposite of what the graphics pipeline does. Putting a pixel through the inverse of the graphics pipeline is called Unprojection.

When we unproject a pixel, it has no Z coordinate. We will provide a Z component that is a linear depth value. That is, a Z value of 0 will result in the pixel on the near plane...