I've been puzzled for a few days trying to solve this problem, so far with no results.
On a map, currently a Terrain, I'd need to have some "areas" which can be controlled by a specific players. The shape of those areas can arbitrarily change during the course of the game, such as you add a marker in any point, and the area evolves (like a spline, say) to pass through that point too.
The problem isn't drawing the boundary itself, of course, but having the GameObjects detecting the area they are in.
Currently I have absolutely zero idea on how to make this exactly.
I've thought about a nice approximation, which is splitting the terrain in fixed chunks, and having the player control them "chunk by chunk": every chunk can have its own collider, and that should be easy if not trivial. So the question is how to do it "properly", since I already have this workaround.