def butterfly(script, iterations=<NUM_LIT:1>, edge_threshold=<NUM_LIT:0>, selected=False):
filter_xml = '<STR_LIT>'.join([<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>'.format(iterations),<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>'.format(edge_threshold),<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>'.format(str(selected).lower()),<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>',<EOL>'<STR_LIT>'])<EOL>util.write_filter(script, filter_xml)<EOL>return None<EOL>
Apply Butterfly Subdivision Surface algorithm.

    It is an interpolated method, defined on arbitrary triangular meshes.
    The scheme is known to be C1 but not C2 on regular meshes.

    Args:
        script: the FilterScript object or script filename to write
            the filter to.
        iterations (int): Number of times the model is subdivided.
        edge_threshold (float): All the edges longer than this threshold will
            be refined. Setting this value to zero will force a uniform
            refinement.
        selected (bool): If selected the filter is performed only on the
            selected faces.

    Layer stack:
        No impacts

    MeshLab versions:
        2016.12
        1.3.4BETA