[MP2]

^ That's what I'm trying to do - I need to work out how to get the coordinates.

I think this may actually be a lot simpler than I imagined. The curved line is a quarter-circle, so sin/cos needs using, I know that much. The mid-point of the vault door object is 1 meter/unit out, so it's just a unit circle..

I'm thinking it's simply going to be

sin/cos 180
->
sin/cos 270

and that will give me the x/y offset (from the hinges).