Jim E. Brooks  http://www.palomino3d.org
$LastChangedDate: 2010-11-12 11:27:22 -0500 (Fri, 12 Nov 2010) $

ComputeDiffuseSpecular() function is based on the brick shader of the Orange book.

Shader code is partly based on OpenSceneGraph's osgShadow/MinimalShadowMap (OpenSceneGraph Public License).
Unnecessary code such as computing spotlight was kept but isn't used.
This program's shaders override osgShadow since they're attached directly to nodes under ShadowedScene.

Avoid using "const" in GLSL.
"const" can cause compile errors (which wouldn't occur in C/C++).
