Ray-tracing on postcards

The article Deciphering The Postcard Sized Raytracer by Fabien Sanglard is a wonderfully presented breakdown of how the path tracer found on a postcard does its magic. It’s not super-fast (it takes 3 minutes to produce a much rougher version on the author’s machine). He includes his final cleaned-up source code.

It comes from the same person who made the business card ray-tracer discussed in the article Decyphering The Business Card Raytracer by Fabien Sanglard.