Shaders provide a way to alter, augment or completely replace a
material. TGLShader is the abstract base class for all shaders.
Some of the available shaders include:
TGLTexCombineShader
TGLMultiMaterialShader
TGLUserShader
TGLOutlineShader
TGLHiddenLineShader
TGLCelShader
TGLBumpShader
TGLPhongShader
Unit:
GLTexture∞
