[Vince]

Don't think it can be done. You need at least three points to form a triangle, so you can calculate an angle. For point A, you take the closest node or the location of the weapon (red dot). Once you know point B, you can calculate point C because that one is a right angle. But the question is: how to determine point B? The second closest point may not be on the slope and/or in a totally different direction.