Unreal Deposition/Accumulation shader?

Dakkon

Hi everyone.  I'm not sure what the general term is for this, but I'm looking for a deposition shader, or an example of one, for Unreal.  Basically it's a shader that allows me to mask snow accumulation on the top of a rock, for example, based on the upward facing normal of the object.  Pretty standard stuff, I'm just coming from another engine and I'd like to see an example of how Unreal does it.

Obscura

Get vertex or pixel normal world space, get the component that you want (z is up) and use that as an alpha in a lerp to blend between the rock and snow texture.

If you want to do this on the normal channel, you may need to recreate the pixel normal, by just transforming your normalmap into world space and then do the same thing as what you would do normally - get the component that you want and lerp.

Butthair

https://www.youtube.com/watch?v=lH6SIFQ0ROE