/** defines the updating at 60Hz for the sea bottom */
  @Override
  public void onTick() {
    xPos -= 6;
    xPos2 -= 6;
    if (xPos <= -5 * Util.getDISTANCE_TO_EDGE()) {
      xPos = xPos2 + (Util.getDISTANCE_TO_EDGE() * 4 - 30);

    } else if (xPos2 <= -Util.getDISTANCE_TO_EDGE() * 5) {
      xPos2 = xPos + Util.getDISTANCE_TO_EDGE() * 4 - 30;
    }

    line1.setX(xPos);
    line2.setX(xPos2);
  }
  /**
   * reutrns true if the sea bottom and the Charcter c have collided
   *
   * @param c the character
   * @return boolean true or false
   */
  public boolean isIn(characters.Character c) {

    return line1.isBelowLine(c.getX(), c.getY()) || line2.isBelowLine(c.getX(), c.getY());
  }