private DelaunayTriangle getOppositeTriangle(DTSweepConstraint edge, DelaunayTriangle current)
	{
		DelaunayTriangle opposite1 = current.neighborAcross(edge.p);
		DelaunayTriangle opposite2 = current.neighborAcross(edge.q);
		if(opposite1!= null && opposite1.isInterior())
			return opposite1;
		else if(opposite2!= null && opposite2.isInterior())
			return opposite2;
		return null;
	}