def set_mlimits(self, min=None, max=None):
        """Set limits for the point meta (colormap).

        Point meta values outside this range will be clipped.

        :param min: value corresponding to the start of the colormap.
            If None, it will be calculated.
        :param max: value corresponding to the end of the colormap.
            If None, it will be calculated.

        """
        self.limits['mmin'] = min
        self.limits['mmax'] = max