private static String getPortImageFile(PortType portType)
	{
		
		switch (portType)
		{
			case WOOD:
				return "images/ports/port_wood.png";
			case BRICK:
				return "images/ports/port_brick.png";
			case SHEEP:
				return "images/ports/port_sheep.png";
			case WHEAT:
				return "images/ports/port_wheat.png";
			case ORE:
				return "images/ports/port_ore.png";
			case THREE:
				return "images/ports/port_three.png";
			default:
				assert false;
				return null;
		}
	}