A psychiatrist is a person who will give you expensive
answers that your girlfriend will give you for free

Concept 4 : Material Colors
===========================

A material's color depends on the percentage of 
incoming red, green and blue light it reflects.
For example a perfectly red ball reflects all
the incoming red light and absorbs all the green
and blue light that strikes it.  If now we view 
this ball in white light (composed of equal amounts
of red, green and blue light) all the red is
reflected, and we see the ball as red.  If
the ball is viewed in pure red light, it still appears
to be red.  If however we now view the ball in pure 
green light, it appears black (because all the green
is absorbed, and there is no incoming red, so no light
is reflected).

Like lights, materials have different ambient, diffuse,
and specular colors which determine the ambient, diffuse
and specular reflectances of the material.
In addition materials have an emissive color, which 
simulates light originating from an object, and a shininess
factor.