Selectively setting parts of image transperent for vtkImageActor in 3D scene

Support
5

Here is an example from the VTK Examples site:
https://examples.vtk.org/site/Cxx/Visualization/ClipArt/

The above is in C++, here is an example in Python:

import vtkmodules.vtkRenderingOpenGL2
from vtkmodules.vtkRenderingCore import (
     vtkActor,
     vtkPolyDataMapper,
     vtkRenderer,
     vtkRenderWindow,
     vtkRenderWindowInteractor,
     vtkTexture)
from vtkmodules.vtkInteractionStyle import vtkInteractorStyleTrackballCamera
from vtkmodules.vtkIOImage import vtkPNGReader
from vtkmodules.vtkFiltersSources import vtkPlaneSource
from vtkmodules.vtkFiltersTexture import vtkTextureMapToPlane

r = vtkPNGReader()
r.SetFileName("vtk_logo.png")
tx = vtkTexture()
tx.InterpolateOn()
tx.SetInputConnection(r.GetOutputPort())

ps = vtkPlaneSource()
ps.SetResolution(1, 1)
tm = vtkTextureMapToPlane()
tm.SetInputConnection(ps.GetOutputPort())

mapper = vtkPolyDataMapper()
mapper.SetInputConnection(tm.GetOutputPort())
actor = vtkActor()
actor.SetMapper(mapper)
actor.SetTexture(tx)

ren = vtkRenderer()
ren_win = vtkRenderWindow()
ren_win.SetWindowName('Sprite')
ren_win.SetSize(600, 600)
ren_win.AddRenderer(ren)
iren = vtkRenderWindowInteractor()
iren.SetRenderWindow(ren_win)
style = vtkInteractorStyleTrackballCamera()
iren.SetInteractorStyle(style)

ren.AddActor(actor)
ren.ResetCamera()

ren_win.Render()
iren.Start()