help needed with vehicle movement algorithm/code

[demon at desire.wright.edu]

	Hi, I need an algorithm (or code) for the following:

given n vehicles (tanks) moving towards m vehicles (tanks)
given x obsticles (buildings, hills, etc.)

a way of moving the tanks towards each other without running into obsticles or
ending up in a dead end.

	Although this is similiar to a maze moving algorithm, the solution is
not the same, as the goals are also moving, and new obsticles are being added.

	The problem I get stuck at is encountering a hill (vehicles can not go
over them, only around).  I could simply pick a direction and go around, but
run the risk of simply circling the hill forever.

	I start with each vehicle at a specific x,y coordinate and move towards
an opposing vehicle (the closest observable).  However, if a hill or building
gets in the way, I need to move around it.  But, which direction is best?  How
about getting trapped in a "canyon" of projecting hills?
	This is for a real time system so speed is critical.  I can't spend all
day doing travelling salesmen routines.

	If anyone has done this type of thing before, let me know!

	I'll take algorithms, code, or suggestions!

	Thanx in advance.

Brett