# SphereWidget

VTKExamples/Python/Widgets/SphereWidget

### Description

[Examples Python Widgets SphereWidget.png]]([File:VTK)

This example shows how to use the SphereWidget.

### Code

SphereWidget.py

    import vtk

    # Call back function
    def sphereCallback(obj, event):
        print('Center: {}, {}, {}'.format(*obj.GetCenter()))

    # A renderer and render window
    renderer = vtk.vtkRenderer()
    renderer.SetBackground(1, 1, 1)

    renwin = vtk.vtkRenderWindow()
    renwin.AddRenderer(renderer)

    # An interactor
    interactor = vtk.vtkRenderWindowInteractor()
    interactor.SetRenderWindow(renwin)

    # A Sphere widget
    sphereWidget = vtk.vtkSphereWidget()
    sphereWidget.SetInteractor(interactor)
    sphereWidget.SetRepresentationToSurface()
    sphereWidget.On()

    # Connect the event to a function
    sphereWidget.AddObserver("InteractionEvent", sphereCallback)

    # Start
    interactor.Initialize()
    interactor.Start()