... was trying to do 3D on early computers - big BW pixels! By late 80s I saw ray tracing and had to write my own.
I wrote the 1st ver while taking vector calculus and CAD programming classes c. '92. I was intrigued not only by the beauty of the math but also ray tracing curved metals. This is actually the 2nd ver, ported from MFC to gnome (with enhancements like optional GL) c. '00 with some help from David.
Apr'17: Updated to compile on recent Ubuntu/Debian - still runs, even on a pi!