ABU 7-aug-2007 v 1.0 (obsolete)
ABU 9-aug-2007 v 1.1
ABU 19-feb-2012 v 1.2
Now a pure "Phong model is used" Previously the half-vector was used (as approximation of Reflection-Vector); Now a real Reflection Vector is used.
Based on work of G.Sookahet Simple raytracing, here is a more interactive program.
Shading now uses the "Blinn-Phong Shading Model" for handling specular reflection, too.
Note that the geometrical model has been simplified (this implies faster processing-time).