To invent, you need a good imagination
and a pile of junk - Thomas Edison

Concept 3.1: Specifying Vertices
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Idea:
=====
With OpenGL, all geometric objects are ultimately 
described as an ordered set of vertices.  

void glVertex{234}{sifd}[v](TYPE coords);

Specifies a vertex for use in describing a 
geometric object.  You an supply upto four 
coordinates (x, y, z, w)for a particular vertex
or as few as two (x, y) by selecting the appropriate
version of the command.

Examples:
=========
1)  glVertex2s(2,3);
2)  glVertex3d(0.0, 0.0, 3.14159276567);
3)  glVertex4f(2.3, 1.0, -2.2, 2.0);

4)  GLdouble dvect[3] = {5.0, 9.0, 1992.0};
    glVertex3dv(dvect);

The first example represents a vertex with three
dimensional coordinates (2,3,0).  Remember that if
it is not specified the z coordinate is understood to
be 0.  In example 4) dvect is a pointer to an array
of three double-precision floating point numbers.