http://graphics.cs.uni-sb.de/~woop/rpu/rpu.html (http://graphics.cs.uni-sb.de/~woop/rpu/rpu.html)
Also See Build a basic 3D Render Engine (https://www.underwaredesign.com/forums/index.php?topic=4644.0) Ray Tracing in PlayBASIC
Ooooh, Real-time ray tracing GOOOOD