[trevortheblack]

If anyone is interested in getting started on Ray Tracing _today_. I recommend Peter Shirley's _Ray Tracing In One Weekend_ Series.

https://raytracing.github.io/

(I edited the later editions)

[s800]

Another recommendation: DKBtrace, which is a predecessor to Povray, has easier to grok code. IMHO.

[grep_it]

Real Time Rendering maintains a list of high quality free resources including "Ray Tracing: In One Weekend" http://www.realtimerendering.com/#intro

[packetslave]

also Jamis Buck's "The Ray Tracer Challenge"