def flip_around_x(pc_data):
    """ flip a structured array around x, in place"""
    pc_data['y'] = -pc_data['y']
    pc_data['z'] = -pc_data['z']
    if 'x_origin' in pc_data:
        pc_data['y_origin'] = -pc_data['y_origin']
        pc_data['z_origin'] = -pc_data['z_origin']
