How to Show/Render a vtkMultiBlockDataset with the Paraview Python wrapper

ParaView Support
1

Hi,

I am trying to use paraview.simple to render a vtkMultiBlockDataset.
If I try to do:

paraview.simple.Show(multiblock)

I get the following error:
RuntimeError: Cannot show a sink i.e. algorithm with no output.

I understand I need to wrap the vtkMultiBlockDataset in some kind of wrapper but I can’t find any documentation on how to do this. Can anyone help me understand how to make this work and where to find this information?

Thank you very much.

2

Hi,

In case the object of vtkMultiBlockDataSet has a name ‘multiblock’, the following code works for me:

mb = paraview.simple.FindSource('multiblock')
paraview.simple.Show(mb)
paraview.simple.Render()

Best Regards,
Pavel

3

Hi Pavel, thank you or your reply.

I am using pvpython to run my script. I have a HDF5 file for which we have a library that converts it to a vtkMultiBlockDataset.

So I currently have this VTK version:

mb = read_hdf5(file) # mb is of type vtkMultiBlockDataset
mapper = vtk.vtkCompositePolyDataMapper2()
mapper.SetInputDataObject(mb)
cdda = mapper.GetCompositeDataDisplayAttributes()
mapper.SetCompositeDataDisplayAttributes(cdda)

if not mapper.GetScalarVisibility():
    mapper.SetColorModeToMapScalars()
    mapper.ScalarVisibilityOn()

mapper.SelectColorArray("PressureCoefficient")
mapper.SetScalarModeToUsePointFieldData()
mapper.InterpolateScalarsBeforeMappingOn()

renderer = vtk.vtkRenderer()
renderWindow = vtk.vtkRenderWindow()
renderWindow.AddRenderer(renderer)

renderWindowInteractor = vtk.vtkRenderWindowInteractor()
renderWindowInteractor.SetRenderWindow(renderWindow)
renderWindowInteractor
    .GetInteractorStyle()
    .SetCurrentStyleToTrackballCamera()

actor = vtk.vtkActor()
actor.SetMapper(mapper)

renderer.AddActor(actor)
renderer.ResetCamera()
renderWindow.Render()

I am looking to replace this with a Paraview version where I use paraview.simple but I don’t know how to add the mb vtkMultiBlockDataset to the Paraview pipeline.

Thank you very much.