GitLab

Applying the vtkExtractCellsByType filter on an unstructured grid does not copy cell data arrays.

Python script to reproduce:

import vtk

# Create unstructured grid
cellSource = vtk.vtkCellTypeSource()
cellSource.SetCellType(vtk.VTK_TETRA)
cellSource.Update()

# Create cell data array
arrayGenerator = vtk.vtkRandomAttributeGenerator()
arrayGenerator.SetInputConnection(cellSource.GetOutputPort())
arrayGenerator.SetGenerateCellScalarsOn()
arrayGenerator.Update()

# Extract cells
extr = vtk.vtkExtractCellsByType()
extr.SetInputConnection(arrayGenerator.GetOutputPort())
extr.AddCellType(vtk.VTK_TETRA)
extr.Update()

# Cell data is missing
if extr.GetOutput().GetCellData().HasArray("RandomCellScalars") != 1:
    print("Cell data missing.")