public void switchDoors(Gameboard gameboard)
	{
		Field[][] fields = gameboard.getFields();
		
		for(int i = 0; i < fields.length; i++)
		{
			for(int j = 0; j < fields[i].length; j++)
			{
				if(fields[i][j].getType() == 2 && Math.random() < GlobalGameboard.doorSwitchFrequency)
				{
					if(fields[i][j].isDoorOpen()) fields[i][j].setDoorOpen(false);
					else                          fields[i][j].setDoorOpen(true);
					
					if(!fields[i][j].isDoorOpen() && fields[i][j].getAnt() != null)
					{
						killAnt(gameboard, fields[i][j].getAnt());
					}
				}
			}
		}
	}