Can you paint in realtime on a moving object?

I am trying to figure out a way of how to paint realtime on a skinned mesh. I need to be able to paint a mask when say a character’s body touches or falls into paint. i would like to use this as mask in material editor.

Last GDC Unreal’s graphics guy showcased this; I don’t know if could be helpful for what you need and I have no clue what is actually going on under the hood as I’m not a GPU person xD

I’ve seen this, but i was left confused as some stated that you have to tinker with source code, and there are no tutorials or docs pointing to how to accomplish something similar. Left me at a dead end.