public void expandBranch() {
		int x, y, x1, y1;
		x = subTrees[0].x;
		y = subTrees[0].y;
		x1 = subTrees[0].x1;
		y1 = subTrees[0].y1;
		for (Rtree tree : subTrees) {
			if (tree.x < x)
				x = tree.x;
			if (tree.y < y)
				y = tree.y;
			if (tree.x1 > x1)
				x1 = tree.x1;
			if (tree.y1 > y1)
				y1 = tree.y1;
		}
		this.x = x;
		this.y = y;
		this.x1 = x1;
		this.y1 = y1;
	}