# Circle

VTKExamples/Python/GeometricObjects/Circle

### Description

A circle is simply the limiting case of a regular polygon. In this example vtkRegularPolygonSource is used with a large number of Sides to approximate a circle. A disk is in fact generated here, to generate a circle, uncomment the line: `polygonSource.GeneratePolygonOff()`

Other Languages

See (Cxx), (Java)

### Code

Circle.py

    #!/usr/bin/env python
    import vtk

    def main():
        colors = vtk.vtkNamedColors()

        # Create a circle
        polygonSource = vtk.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)

        #  Visualize
        mapper = vtk.vtkPolyDataMapper()
        mapper.SetInputConnection(polygonSource.GetOutputPort())

        actor = vtk.vtkActor()
        actor.SetMapper(mapper)
        actor.GetProperty().SetColor(colors.GetColor3d('Cornsilk'))

        renderer = vtk.vtkRenderer()
        renderWindow = vtk.vtkRenderWindow()
        renderWindow.SetWindowName("Circle")
        renderWindow.AddRenderer(renderer)
        renderWindowInteractor = vtk.vtkRenderWindowInteractor()
        renderWindowInteractor.SetRenderWindow(renderWindow)

        renderer.AddActor(actor)
        renderer.SetBackground(colors.GetColor3d('DarkGreen'))

        renderWindow.Render()
        renderWindowInteractor.Start()

    if __name__ == '__main__':
        main()