ESRT is a project I started for fun after attending a computer graphics course. It is a very basic raytracing library that only provides basic shapes and colors.
ESRT stands for extremly slow raytracer - I chose the name because I don't have, and never had any intention of making this a viable product, so there are basically no performance optimizations. This combined with the language choice results in anything more than a few spheres taking many seconds to render.