There are raytracing tutorials going back to the early 1990's at least (because there is one in Graham's Ansi Common Lisp). Here is one in Lisp I googled: http

There are raytracing tutorials going back to the early 1990's at least (because there is one in Graham's Ansi Common Lisp). Here is one in Lisp I googled: http://www.ulisp.com/show?2NWA http://www.ulisp.com/show?2NWA