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# ClipUnstructuredGridWithPlane2

VTKEx/Python/UnstructuredGrid/ClipUnstructuredGridWithPlane2

### Description

The example uses vtkClipDataSet to clip a vtkUnstructuredGrid. The resulting output and clipped output are presented in yellow and red respectively. To illustrate the clipped interfaces, the example uses a vtkTransform to rotate each output about their centers.

Note that this clipping filter does not retain the original cells if they are not clipped.

After exiting, the example reports the number of each cell type for each output:

    The inside dataset contains a
      vtkUnstructuredGrid that has 110148 cells
            Cell type vtkTetra occurs 106998 times.
            Cell type vtkWedge occurs 3150 times.
    The clipped dataset contains a
      vtkUnstructuredGrid that has 111824 cells
            Cell type vtkTetra occurs 107420 times.
            Cell type vtkWedge occurs 4404 times.

Compare these results with ClipUnstructuredGridWithPlane (C++) ClipUnstructuredGridWithPlane (Python). Notice that in this example, the original vtkHexahedron in the unclipped regions are converted to vtkTetra. Also, the resulting vtkUnstructuredGrid's have more than 4 times the number of cells.

usage

ClipUnstructuredGridWithPlane2 treemesh.vtk

thanks

Thanks to Bane Sullivan for sharing the treemesh.vtk unstructured grid dataset.

Other languages

See (Cxx)

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

### Code

ClipUnstructuredGridWithPlane2.py

    #!/usr/bin/env python

    import collections

    import vtk

    def get_program_parameters():
        import argparse
        description = 'Use a vtkClipDataSet to clip a vtkUnstructuredGrid..'
        epilogue = '''
     Use a vtkClipDataSet to clip a vtkUnstructuredGrid..
     The resulting output and clipped output are presented in yellow and red respectively.
     To illustrate the clipped interfaces, the example uses a vtkTransform to rotate each
        output about their centers.
     Note: This clipping filter does not retain the original cells if they are not clipped.
       '''
        parser = argparse.ArgumentParser(description=description, epilog=epilogue,
                                         formatter_class=argparse.RawDescriptionHelpFormatter)
        parser.add_argument('filename', help='treemesh.vtk.')
        args = parser.parse_args()
        return args.filename

    def main():
        filename = get_program_parameters()

        # Create the reader for the data.
        reader = vtk.vtkUnstructuredGridReader()
        reader.SetFileName(filename)
        reader.Update()

        bounds = reader.GetOutput().GetBounds()
        center = reader.GetOutput().GetCenter()

        colors = vtk.vtkNamedColors()
        renderer = vtk.vtkRenderer()
        renderer.SetBackground(colors.GetColor3d("Wheat"))
        renderer.UseHiddenLineRemovalOn()

        renderWindow = vtk.vtkRenderWindow()
        renderWindow.AddRenderer(renderer)
        renderWindow.SetSize(640, 480)

        interactor = vtk.vtkRenderWindowInteractor()
        interactor.SetRenderWindow(renderWindow)

        xnorm = [-1.0, -1.0, 1.0]

        clipPlane = vtk.vtkPlane()
        clipPlane.SetOrigin(reader.GetOutput().GetCenter())
        clipPlane.SetNormal(xnorm)

        clipper = vtk.vtkClipDataSet()
        clipper.SetClipFunction(clipPlane)
        clipper.SetInputData(reader.GetOutput())
        clipper.SetValue(0.0)
        clipper.GenerateClippedOutputOn()
        clipper.Update()

        insideMapper = vtk.vtkDataSetMapper()
        insideMapper.SetInputData(clipper.GetOutput())
        insideMapper.ScalarVisibilityOff()

        insideActor = vtk.vtkActor()
        insideActor.SetMapper(insideMapper)
        insideActor.GetProperty().SetDiffuseColor(colors.GetColor3d("banana"))
        insideActor.GetProperty().SetAmbient(.3)
        insideActor.GetProperty().EdgeVisibilityOn()

        clippedMapper = vtk.vtkDataSetMapper()
        clippedMapper.SetInputData(clipper.GetClippedOutput())
        clippedMapper.ScalarVisibilityOff()

        clippedActor = vtk.vtkActor()
        clippedActor.SetMapper(clippedMapper)
        clippedActor.GetProperty().SetDiffuseColor(colors.GetColor3d("tomato"))
        insideActor.GetProperty().SetAmbient(.3)
        clippedActor.GetProperty().EdgeVisibilityOn()

        # Create transforms to make a better visualization
        insideTransform = vtk.vtkTransform()
        insideTransform.Translate(-(bounds[1] - bounds[0]) * 0.75, 0, 0)
        insideTransform.Translate(center[0], center[1], center[2])
        insideTransform.RotateY(-120.0)
        insideTransform.Translate(-center[0], -center[1], -center[2])
        insideActor.SetUserTransform(insideTransform)

        clippedTransform = vtk.vtkTransform()
        clippedTransform.Translate((bounds[1] - bounds[0]) * 0.75, 0, 0)
        clippedTransform.Translate(center[0], center[1], center[2])
        clippedTransform.RotateY(60.0)
        clippedTransform.Translate(-center[0], -center[1], -center[2])
        clippedActor.SetUserTransform(clippedTransform)

        renderer.AddViewProp(clippedActor)
        renderer.AddViewProp(insideActor)

        renderer.ResetCamera()
        renderer.GetActiveCamera().Dolly(1.4)
        renderer.ResetCameraClippingRange()
        renderWindow.Render()
        renderWindow.SetWindowName('ClipUnstructuredGridWithPlane2')
        renderWindow.Render()

        interactor.Start()

        # Generate a report
        numberOfCells = clipper.GetOutput().GetNumberOfCells()
        print("------------------------")
        print("The inside dataset contains a \n", clipper.GetOutput().GetClassName(), " that has ", numberOfCells, " cells")
        cellMap = dict()
        for i in range(0, numberOfCells):
            cellMap.setdefault(clipper.GetOutput().GetCellType(i), 0)
            cellMap[clipper.GetOutput().GetCellType(i)] += 1
        # Sort by key and put into an OrderedDict.
        # An OrderedDict remembers the order in which the keys have been inserted.
        for k, v in collections.OrderedDict(sorted(cellMap.items())).items():
            print("\tCell type ", vtk.vtkCellTypes.GetClassNameFromTypeId(k), " occurs ", v, " times.")

        numberOfCells = clipper.GetClippedOutput().GetNumberOfCells()
        print("------------------------")
        print("The clipped dataset contains a \n", clipper.GetClippedOutput().GetClassName(), " that has ", numberOfCells,
              " cells")
        outsideCellMap = dict()
        for i in range(0, numberOfCells):
            outsideCellMap.setdefault(clipper.GetClippedOutput().GetCellType(i), 0)
            outsideCellMap[clipper.GetClippedOutput().GetCellType(i)] += 1
        for k, v in collections.OrderedDict(sorted(outsideCellMap.items())).items():
            print("\tCell type ", vtk.vtkCellTypes.GetClassNameFromTypeId(k), " occurs ", v, " times.")

    if __name__ == "__main__":
        main()