playing with idea to use the dot product of incoming ray and surface normal to generate superfast fake caustic’s
here are some tests:
Arnold Caustics shader
Art and VFX Blog
playing with idea to use the dot product of incoming ray and surface normal to generate superfast fake caustic’s
here are some tests:
Heri.Blog 
Which rays are you dot’ing? The incident ray from camera to the crystal surface? Maybe you could give a bit more explanation please? I’d like to test creating this in houdini.
sorry for the delay, the the cross product from incoming ray and surface normal, –> pipeline into a ramp and then into shadow plug of ray switch shader.
I was inspired by this tutorial, https://www.youtube.com/watch?v=1p7l9MNpLdo&t=1612s
when I computer is running again I can post a hip file.