That’s how I did it for the 2nd picture, it’s just two polygons wrapped around the edge that bulge out from the edge slightly. This is the geo / texture:
There are many problems with this method though - matching the colour/material is a pain, Z fighting at a distance would be a problem, if you look at the surface flat you can see the masked section floating out from the wall, but worst of all it gets picked up by SSAO.
****, that was the topic I remember it being discussed in - well remembered! I’ll have a proper read of the thread and see if there’s anything I can glean from it…