You can learn quite a lot by writing a toy raytracer with things like textures, shadows, bump mapping and the like. Of course raytracers don't work like polygo

You can learn quite a lot by writing a toy raytracer with things like textures, shadows, bump mapping and the like. Of course raytracers don't work like polygonal hardware rendering but a lot of the maths and concept do carry over I've found. If you understand how normal mapping and reflections work in a software Raytracer you shouldn't have too much trouble implementing the same algorithms in a hardware accelerated pixel shader for instance. In general I think that implementing a raytracer is just one of these projects that's just too cool and simple not to do, so I don't think you'll be wasting your time anyway.