    polygonSource = vtkRegularPolygonSource()  # default is 6 sides

    glyph2D = vtkGlyph2D()
    glyph2D.SetSourceConnection(polygonSource.GetOutputPort())
    glyph2D.SetInputData(polydata)
    glyph2D.Update()
--
    polygonSource = vtkRegularPolygonSource()
    # Comment this line to generate a disk instead of a circle.
    polygonSource.GeneratePolygonOff()
    polygonSource.SetNumberOfSides(50)
    polygonSource.SetRadius(5.0)
    polygonSource.SetCenter(0.0, 0.0, 0.0)
--
    polygonSource = vtkRegularPolygonSource()
    polygonSource.SetNumberOfSides(5)
    polygonSource.SetRadius(5)
    polygonSource.SetCenter(0, 0, 0)

    shrink = vtkShrinkPolyData()
--
    regular_polygon_source = vtkRegularPolygonSource()
    regular_polygon_source.SetCenter(4.0, 0.0, 0.0)
    regular_polygon_source.SetRadius(4.0)

    regular_polygon_mapper = vtkPolyDataMapper()
    regular_polygon_mapper.SetInputConnection(regular_polygon_source.GetOutputPort())
