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

Using an atlas


As I have mentioned already, texture memory is one of your core resources. In fact, it is common to run out of memory because of all the textures required to animate a typical 2D game. It is also time-consuming to load individual textures rather than loading on a larger texture. So, we have to come up with methods to use texture memory more efficiently.

One common technique designed to pack more textures into less space is known as atlasing. A texture atlas works much like a sprite sheet described earlier in this chapter. Instead of storing each texture as its own image, we pack all of the textures for the entire game into one or more textures known as atlases.

As the word suggests, an atlas works much like a map. We simply need to know the location of any particular image, and we can find and extract it out of the atlas. Every atlas consists of two parts:

  • The texture that contains all of the images

  • A text file that contains the positions of each image in the atlas

As you can imagine...