public Point tryMove(int quad)
	/*
	 * The quadrant is translated into a tile coordinate, and tested for
	 * validity. The translation varies depending on if the row position of the
	 * curent tile (yTile) is even or odd. null is returned if the new position
	 * is invalid.
	 */
	{
		Point nextPt;
		if (quad == NE)
			nextPt = (yTile % 2 == 0) ? new Point(xTile, yTile - 1)
					: new Point(xTile + 1, yTile - 1);
		else if (quad == SE)
			nextPt = (yTile % 2 == 0) ? new Point(xTile, yTile + 1)
					: new Point(xTile + 1, yTile + 1);
		else if (quad == SW)
			nextPt = (yTile % 2 == 0) ? new Point(xTile - 1, yTile + 1)
					: new Point(xTile, yTile + 1);
		else if (quad == NW)
			nextPt = (yTile % 2 == 0) ? new Point(xTile - 1, yTile - 1)
					: new Point(xTile, yTile - 1);
		else
			return null;

		if (world.validTileLoc(nextPt.x, nextPt.y))
			// ask WorldDisplay if the proposed tile is in a valid location
			return nextPt;
		else
			return null;
	} // end of tryMove()