def METHOD_NAME(self):
    """
    Draw the new roughness on the graph.
    """
    n = self.profile.layer_num
    z = self.profile.boundary[1:-1]
    show_left = self._left is not None
    show_right = self._right is not None
    self.markers[0].set(visible=show_left)
    self.lines[0].set(visible=show_left)
    if show_left:
        self.markers[0].set_xdata([z[n-1]+self._left.value])
        self.lines[0].set_xdata([z[n-1], z[n-1]+self._left.value])
    self.markers[1].set(visible=show_right)
    self.lines[1].set(visible=show_right)
    if show_right:
        self.markers[1].set_xdata([z[n]-self._right.value])
        self.lines[1].set_xdata([z[n],z[n]-self._right.value])