Caustic Monkey Project File for Blender 3.1

This Blender project file uses 100% Geometry Nodes to create a fake caustic effect.

Inspired by Evan Wallace, it works best in Eevee as Cycles tries to merge the geometry and screws things up.

You can swap the monkey for any other geometry in Edit Mode.

The amount of subdivisions control the caustic quality, but also the brightness. The light shader has a Divide node which controls the caustic brightness.

Geometry Nodes control the IOR values of the inside and outside materials, plus chromatic dispersion and colour is adjustable.

Please note this isn't physically accurate for many reasons, mainly because the light doesn't bend back to normal as it exits the monkey.

Requires at least Blender 3.1 due to the Face Area node.