Path-tracing is basically a different rendering strategy that's built on ray-tracing, so if you write a ray tracer it's not too hard to turn it into a path trac

Path-tracing is basically a different rendering strategy that's built on ray-tracing, so if you write a ray tracer it's not too hard to turn it into a path tracer later. Ray tracers are generally simpler and easier to write; it was probably also easier for the author to fit a ray tracer on a business card.