Running Linux, 5th Edition

Introduction to OpenGL Programming

Before we finish this chapter with a look at integrated development environments and in particular KDevelop, let's do some fun stuff—three-dimensional graphics programming using the OpenGL libraries!

Of course, it would be far too ambitious to give proper coverage of OpenGL programming in this book, so we just concentrate on a simple example and show how to get started and how OpenGL integrates with two popular toolkits.

GLUT

The GL Utility Toolkit was written by Mark Kilgard of SGI fame. It is not free software, but it comes with full source code and doesn't cost anything. The strength of GLUT is that it is tailored specifically for being very simple to get started with programming OpenGL. Mesa comes with a copy of GLUT included, and a free software reimplementation of GLUT is available from http://freeglut.sourceforge.net/. Basically, GLUT helps with initial housekeeping, such as setting up a window and so on, so you quickly can get to the fun part, namely, writing OpenGL code.

To use GLUT, you first need to access its definitions:

#include <GL/glut.h>

Next, call a couple of initialization functions in main():

glutInit(&argc, argv)

to initialize GLUT and allow it to parse command-line parameters, and then:

glutInitDisplayMode( unsigned int mode )

where mode is a bitwise OR of some constants from glut.h. We will use GLUT_RGBA|GLUT_SINGLE to get a true-color single-buffered window.

The window size is set using:

glutInitWindowSize(500,500)

and finally the window ...