This is something I wanted to try for some time - 4d raytracer program. Lighting works the same way, except computations are performed in 4d space.
This project is based off shadertoy shader I also wrote:
I"ve ported it to unity in order to see if 4d parallax woudl look interested in VR Cardboard headset. Unfortunately, the effect was not as strong as I expected.
The code is currently available on github, under zlib license.