# How to get a Python version of the User Guide vtkAnimationScene example running?
**URL:** https://discourse.vtk.org/t/how-to-get-a-python-version-of-the-user-guide-vtkanimationscene-example-running/11440
**Category:** Support
**Created:** [May 12, 2023, 4:59am UTC](https://discourse.vtk.org/t/how-to-get-a-python-version-of-the-user-guide-vtkanimationscene-example-running/11440 "2023-05-12T04:59:18Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@scotsman60](https://discourse.vtk.org/u/scotsman60)
#### Post date: [May 12, 2023, 4:59am UTC](https://discourse.vtk.org/t/how-to-get-a-python-version-of-the-user-guide-vtkanimationscene-example-running/11440/1 "2023-05-12T04:59:18Z")
I’ve converted the C++ animation example from the User guide to Python but I can’t quite get it to run correctly. When the code hits scene.Play(), the render window displays the test model (I can’t interact with it), the CPU pegs to 100% on one core, and the TickInternal method on the AnimationCue never gets called.
Can anyone advise what’s going on here? (Python 3.10.4, VTK 9.2)
```auto
# noinspection PyUnresolvedReferences
import vtkmodules.vtkInteractionStyle
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingOpenGL2
from vtkmodules.vtkRenderingCore import vtkRenderer, vtkRenderWindow
from vtkmodules.vtkCommonDataModel import vtkAnimationScene
from vtkmodules.vtkFiltersSources import vtkSphereSource
from vtkmodules.vtkRenderingCore import vtkPolyDataMapper, vtkActor, vtkRenderWindowInteractor
from vtkmodules.vtkCommonCore import vtkAnimationCue
find_module=False
if find_module is True:
from vtkmodules.all import *
for c in [vtkRenderer,vtkRenderWindow, vtkSphereSource, vtkPolyDataMapper,vtkAnimationCue]:
print(f"from {c. __module__ } import {c. __name__ }")
exit()
class vtkCustomAnimationCue(vtkAnimationCue):
def __init__ (self, renwin, sphere):
super(). __init__ ()
self.renwin = renwin
self.sphere = sphere
def TickInternal(self, currenttime, deltatime, clocktime):
print('TickInternal')
new_st = currenttime * 180
self.sphere.SetStartTheta(new_st)
self.renwin.Render()
ren1=vtkRenderer()
renWin=vtkRenderWindow()
renWin.SetMultiSamples(0)
renWin.AddRenderer(ren1)
#iren = vtkRenderWindowInteractor()
#iren.SetRenderWindow(renWin)
sphere = vtkSphereSource()
mapper = vtkPolyDataMapper()
mapper.SetInputConnection(sphere.GetOutputPort())
actor = vtkActor()
actor.SetMapper(mapper)
ren1.AddActor(actor)
ren1.ResetCamera()
renWin.Render()
scene = vtkAnimationScene()
scene.SetModeToSequence()
scene.SetFrameRate(1)
scene.SetStartTime(0)
scene.SetEndTime(5)
scene.SetLoop(1)
cue1 = vtkCustomAnimationCue(renWin, sphere)
cue1.SetTimeModeToNormalized()
cue1.SetStartTime(0)
cue1.SetEndTime(1.0)
scene.AddCue(cue1)
scene.Play()
scene.Stop()
#iren.Start()
```
---
### Author:  [@scotsman60](https://discourse.vtk.org/u/scotsman60)
#### Post date: [May 20, 2023, 6:58pm UTC](https://discourse.vtk.org/t/how-to-get-a-python-version-of-the-user-guide-vtkanimationscene-example-running/11440/2 "2023-05-20T18:58:44Z")
OK - I figured this out. The answer was in the Python wrapper docs"
“It is possible to subclass a VTK class from within Python, but this is of limited use because the C++ virtual methods are not hooked to the Python methods”
And sure enough, when I look at the code for vtkAnimationCue I find that TickInternal is a virtual method…
So the approach I’m using above is just never going to work. So instead of having my animator in a custom vtkAnimationCue class I need to put it into a class/method that I can then use as an Observer on vtkAnimationCue to trigger the update… Which is a little more indirect, but not really a problem.
---
### Author:  [@scotsman60](https://discourse.vtk.org/u/scotsman60)
#### Post date: [May 20, 2023, 7:02pm UTC](https://discourse.vtk.org/t/how-to-get-a-python-version-of-the-user-guide-vtkanimationscene-example-running/11440/3 "2023-05-20T19:02:29Z")
Just for completeness, here’s the running vtkAnimationScene example in Python using vtkCallbackCommand.
Next step - figure out how to support interaction with the window while the animation is running…
```auto
# noinspection PyUnresolvedReferences
import vtkmodules.vtkInteractionStyle
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingOpenGL2
from vtkmodules.vtkRenderingCore import vtkRenderer, vtkRenderWindow
from vtkmodules.vtkCommonDataModel import vtkAnimationScene
from vtkmodules.vtkFiltersSources import vtkSphereSource
from vtkmodules.vtkRenderingCore import vtkPolyDataMapper, vtkActor, vtkRenderWindowInteractor
from vtkmodules.vtkCommonCore import vtkAnimationCue, vtkCommand, vtkCallbackCommand, VTK_INT, VTK_OBJECT
find_module=False
if find_module is True:
from vtkmodules.all import *
for c in [vtkCallbackCommand]:
print(f"from {c. __module__ } import {c. __name__ }")
exit()
class SphereAnimator(vtkCallbackCommand):
def __init__ (self, renwin, sphere):
self.renwin = renwin
self.sphere = sphere
vtkCallbackCommand. __init__ (self)
def __call__ (self, obj, event):
new_st = obj.GetAnimationTime() * 180
self.sphere.SetStartTheta(new_st)
self.renwin.Render()
ren=vtkRenderer()
renWin=vtkRenderWindow()
renWin.SetMultiSamples(0)
renWin.AddRenderer(ren)
iren = vtkRenderWindowInteractor()
iren.SetRenderWindow(renWin)
sphere = vtkSphereSource()
mapper = vtkPolyDataMapper()
mapper.SetInputConnection(sphere.GetOutputPort())
actor = vtkActor()
actor.SetMapper(mapper)
ren.AddActor(actor)
ren.ResetCamera()
renWin.Render()
scene = vtkAnimationScene()
scene.SetModeToSequence()
scene.SetFrameRate(30)
scene.SetStartTime(0)
scene.SetEndTime(10)
cue = vtkAnimationCue()
cue.SetTimeModeToNormalized()
cue.SetStartTime(0)
cue.SetEndTime(1.0)
sphere_animator=SphereAnimator(renWin, sphere)
cue.AddObserver('AnimationCueTickEvent', sphere_animator)
scene.AddCue(cue)
scene.Play()
scene.Stop()
iren.Start()
```
---
### Author:  [@gxy](https://discourse.vtk.org/u/gxy)
#### Post date: [September 24, 2024, 9:20am UTC](https://discourse.vtk.org/t/how-to-get-a-python-version-of-the-user-guide-vtkanimationscene-example-running/11440/4 "2024-09-24T09:20:04Z")
Thanks for the ideas.
```
from vtkmodules.vtkCommonCore import vtkAnimationCue
from vtkmodules.vtkCommonDataModel import vtkAnimationScene
from vtkmodules.vtkFiltersSources import vtkSphereSource
from vtkmodules.vtkInteractionStyle import vtkInteractorStyleTrackballCamera
from vtkmodules.vtkRenderingCore import vtkPolyDataMapper, \
vtkActor, vtkRenderer, vtkRenderWindow, vtkRenderWindowInteractor
from vtkmodules.vtkRenderingVolumeOpenGL2 import vtkSmartVolumeMapper
class FixedAnimationCue(vtkAnimationCue):
def __init__ (self):
self.AddObserver('AnimationCueTickEvent', self._TickHandler)
def _TickHandler(self, obj, event) -> None:
currenttime = obj.GetAnimationTime()
deltatime = obj.GetDeltaTime()
clocktime = obj.GetClockTime()
self.TickInternal(currenttime, deltatime, clocktime)
def TickInternal(self, currenttime: float, deltatime: float, clocktime: float) -> None:
pass
class TestAni(FixedAnimationCue):
def __init__ (self):
super(TestAni, self). __init__ ()
self.renderWindow: vtkRenderWindow = None
self.render: vtkRenderer = None
self.sphere = None
def TickInternal(self, currenttime: float, deltatime: float, clocktime: float) -> None:
# print(currenttime, deltatime, clocktime)
camera = self.render.GetActiveCamera()
self.sphere.SetStartTheta(currenttime * 180)
# camera.Azimuth(currenttime * 180)
self.renderWindow.Render()
def showVtk():
# create actor
sphere = vtkSphereSource()
mapper = vtkPolyDataMapper()
mapper.SetInputConnection(sphere.GetOutputPort())
actor = vtkActor()
actor.SetMapper(mapper)
# vtk init
render = vtkRenderer()
renderWin = vtkRenderWindow()
renderWin.SetWindowName('vtk')
renderWin.SetSize(1024, 768)
renderWin.AddRenderer(render)
render.AddActor(actor)
render.ResetCamera()
render.SetBackground(0.0, 0.0, 0.0)
renderWin.Render()
# init ani
scene = vtkAnimationScene()
scene.SetModeToSequence()
scene.SetFrameRate(30)
scene.SetStartTime(0)
scene.SetEndTime(60)
testCue = TestAni()
testCue.render = render
testCue.renderWindow = renderWin
testCue.sphere = sphere
testCue.SetTimeModeToNormalized()
testCue.SetStartTime(0)
testCue.SetEndTime(60)
scene.AddCue(testCue)
scene.Play()
scene.Stop()
iren = vtkRenderWindowInteractor()
iren.SetRenderWindow(renderWin)
style = vtkInteractorStyleTrackballCamera()
iren.SetInteractorStyle(style)
iren.Initialize()
renderWin.Render()
iren.Start()
if __name__ == ' __main__':
showVtk()
```