Hey all, I’m looking to create an underwater deep ocean scene for a submarine that includes both caustics and god rays. I’m using UE version 5.7, I’ve found a few youtube tutorials on the caustics and underwater environment but having a hard time with the god rays. Looking to render something like this image:
For a deep-ocean look, I’d split it into two separate pieces:
God rays
- Directional light: enable Light Shaft Bloom/Occlusion for the cheap screen-space version, or turn on Volumetric Fog (Exponential Height Fog > Volumetric Fog) and raise the light’s Volumetric Scattering Intensity for real shafts.
- Underwater, push fog density and inscattering color toward blue-green, and use a post process volume (sized to the water body) to tint and lower exposure.
- If volumetric fog looks banded or blocky, lower r.VolumetricFog.GridPixelSize (more quality, more cost) and raise r.VolumetricFog.GridSizeZ.
Caustics
- Make a Light Function material: a tiling caustic texture panned with Time, multiplied with a second layer panning in another direction (Min of the two gives the interference look). Assign it to the directional light’s Light Function Material.
For the submarine headlight, a spot light with its own volumetric scattering gives the beam.