This article is the third in a series concerning the GL Utility
Toolkit (GLUT) written by Mark Kilgard. GLUT is a very useful
tool kit for OpenGL developers because it abstracts in a simple
to learn and simple to use API the architecture-dependent part
of the OpenGL application. As discused in previous articles by
design reasons OpenGL only includes the architecture independent
directives of an advanced 3D API. Opening windows, handling
keyboard input, etc.. are strongly platform dependent and
therefore it is out of the scope of OpenGL. GLUT is an answer to
this problem: GLUT offers a common interface to multiple
platforms for handling things like windows, double buffering,
text rendering, keyboard input and menus. Today we will explore
the use of menus within our OpenGL applications. A menu is one
more means of user-application communication. In our previous
article we demonstrated another technique for user input, hot
keys. GLUT captures keyboard input events as well as mouse
button events and let us regist