Book Image

OpenGL Game Development By Example

By : Stephen Madsen, Robert Madsen
Book Image

OpenGL Game Development By Example

By: Stephen Madsen, Robert Madsen

Overview of this book

OpenGL is one of the most popular rendering SDKs used to develop games. OpenGL has been used to create everything from 3D masterpieces running on desktop computers to 2D puzzles running on mobile devices. You will learn to apply both 2D and 3D technologies to bring your game idea to life. There is a lot more to making a game than just drawing pictures and that is where this book is unique! It provides a complete tutorial on designing and coding games from the setup of the development environment to final credits screen, through the creation of a 2D and 3D game. The book starts off by showing you how to set up a development environment using Visual Studio, and create a code framework for your game. It then walks you through creation of two games–a 2D platform game called Roboracer 2D and a 3D first-person space shooter game–using OpenGL to render both 2D and 3D graphics using a 2D coordinate system. You'll create sprite classes, render sprites and animation, and navigate and control the characters. You will also learn how to implement input, use audio, and code basic collision and physics systems. From setting up the development environment to creating the final credits screen, the book will take you through the complete journey of creating a game engine that you can extend to create your own games.
Table of Contents (19 chapters)
OpenGL Game Development By Example
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Circular collision detection


One way to detect collision is to see how far each of the objects are from each other's center. This is known as circular collision detection because it treats each object as if it is bound by a circle, and uses the radius of that circle to determine whether the objects are close enough to collide.

Take a look at the following diagram:

The circles on the left are not colliding, while the circles on the right are colliding. For the non-colliding circles, the distance (d) between the center points of the two circles is greater than the sum of the two radii (r1 + r2). For the colliding circles, the distance (d) between the two centers is less than the sum of the two radii (r1 + r2). We can use this knowledge to test any two objects for collision based on the radii of the circles and the distance between the objects center point.

So, how do we use this information?

  1. We will know r1 and r2 because we set them when we create the sprite.

  2. We will calculate two legs of a right...