Skip to content


# ClipUnstructuredGridWithPlane2

VTKEx/Cxx/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 (Python)

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.cxx

    #include <vtkSmartPointer.h>
    #include <vtkClipDataSet.h>
    #include <vtkUnstructuredGridReader.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkPlane.h>
    #include <vtkTransform.h>

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkCellTypes.h>
    #include <vtkDataSetMapper.h>
    #include <vtkLookupTable.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>

    #include <vtkNamedColors.h>

    int main(int argc, char *argv[])
    {
      if (argc < 2)
      {
        std::cout << "Usage: " << argv[0] << " filename.vtk" << std::endl;
        return EXIT_FAILURE;
      }
      // Create the reader for the data.
      std::string filename = argv[1];
      std::cout << "Loading " << filename.c_str() << std::endl;
      auto reader =
        vtkSmartPointer<vtkUnstructuredGridReader>::New();
      reader->SetFileName(filename.c_str());
      reader->Update();

      double bounds[6];
      reader->GetOutput()->GetBounds(bounds);
      double center[3];
      reader->GetOutput()->GetCenter(center);

      auto colors =
        vtkSmartPointer<vtkNamedColors>::New();
      auto renderer = vtkSmartPointer<vtkRenderer>::New();
      renderer->SetBackground(colors->GetColor3d("Wheat").GetData());
      renderer->UseHiddenLineRemovalOn();

      auto renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      renderWindow->SetSize(640, 480);

      auto interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renderWindow);

      double xnorm[3] = {-1.0, -1.0, 1.0};

      auto clipPlane = vtkSmartPointer<vtkPlane>::New();
      clipPlane->SetOrigin(reader->GetOutput()->GetCenter());
      clipPlane->SetNormal(xnorm);

      auto clipper =
        vtkSmartPointer<vtkClipDataSet>::New();
      clipper->SetClipFunction(clipPlane);
      clipper->SetInputData(reader->GetOutput());
      clipper->SetValue(0.0);
      clipper->GenerateClippedOutputOn();
      clipper->Update();

      auto insideMapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      insideMapper->SetInputData(clipper->GetOutput());
      insideMapper->ScalarVisibilityOff();

      auto insideActor =
        vtkSmartPointer<vtkActor>::New();
      insideActor->SetMapper(insideMapper);
      insideActor->GetProperty()->SetDiffuseColor(colors->GetColor3d("banana").GetData());
      insideActor->GetProperty()->SetAmbient(.3);
      insideActor->GetProperty()->EdgeVisibilityOn();

      auto clippedMapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      clippedMapper->SetInputData(clipper->GetClippedOutput());
      clippedMapper->ScalarVisibilityOff();

      auto clippedActor =
        vtkSmartPointer<vtkActor>::New();
      clippedActor->SetMapper(clippedMapper);
      clippedActor->GetProperty()->SetDiffuseColor(colors->GetColor3d("tomato").GetData());
      insideActor->GetProperty()->SetAmbient(.3);
      clippedActor->GetProperty()->EdgeVisibilityOn();

      // Create transforms to make a better visualization
      auto insideTransform = vtkSmartPointer<vtkTransform>::New();
      insideTransform->Translate(-(bounds[1] - bounds[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);

      auto clippedTransform = vtkSmartPointer<vtkTransform>::New();
      clippedTransform->Translate((bounds[1] - bounds[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
      vtkIdType numberOfCells = clipper->GetOutput()->GetNumberOfCells();
      std::cout << "------------------------" << std::endl;
      std::cout << "The inside dataset contains a " << std::endl
                << clipper->GetOutput()->GetClassName()
                <<  " that has " << numberOfCells << " cells" << std::endl;
      typedef std::map<int,int> CellContainer;
      CellContainer cellMap;
      for (vtkIdType i = 0; i < numberOfCells; i++)
      {
        cellMap[clipper->GetOutput()->GetCellType(i)]++;
      }

      for (auto c : cellMap)
      {
        std::cout << "\tCell type "
                  << vtkCellTypes::GetClassNameFromTypeId(c.first)
                  << " occurs " << c.second << " times." << std::endl;
      }

      numberOfCells = clipper->GetClippedOutput()->GetNumberOfCells();
      std::cout << "------------------------" << std::endl;
      std::cout << "The clipped dataset contains a " << std::endl
                << clipper->GetClippedOutput()->GetClassName()
                <<  " that has " << numberOfCells << " cells" << std::endl;
      typedef std::map<int,int> OutsideCellContainer;
      CellContainer outsideCellMap;
      for (vtkIdType i = 0; i < numberOfCells; i++)
      {
        outsideCellMap[clipper->GetClippedOutput()->GetCellType(i)]++;
      }

      for (auto c : outsideCellMap)
      {
        std::cout << "\tCell type "
                  << vtkCellTypes::GetClassNameFromTypeId(c.first)
                  << " occurs " << c.second << " times." << std::endl;
      }
      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(ClipUnstructuredGridWithPlane2)

    find_package(VTK COMPONENTS
      vtkCommonColor
      vtkCommonCore
      vtkCommonDataModel
      vtkCommonTransforms
      vtkFiltersGeneral
      vtkIOLegacy
      vtkInteractionStyle
      vtkRenderingContextOpenGL2
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingGL2PSOpenGL2
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping ClipUnstructuredGridWithPlane2: ${VTK_NOT_FOUND_MESSAGE}")
      return ()
    endif()
    message (STATUS "VTK_VERSION: ${VTK_VERSION}")
    if (VTK_VERSION VERSION_LESS "8.90.0")
      # old system
      include(${VTK_USE_FILE})
      add_executable(ClipUnstructuredGridWithPlane2 MACOSX_BUNDLE ClipUnstructuredGridWithPlane2.cxx )
      target_link_libraries(ClipUnstructuredGridWithPlane2 PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(ClipUnstructuredGridWithPlane2 MACOSX_BUNDLE ClipUnstructuredGridWithPlane2.cxx )
      target_link_libraries(ClipUnstructuredGridWithPlane2 PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS ClipUnstructuredGridWithPlane2
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build ClipUnstructuredGridWithPlane2

Click here to download ClipUnstructuredGridWithPlane2 and its CMakeLists.txt file. Once the tarball ClipUnstructuredGridWithPlane2.tar has been downloaded and extracted,

    cd ClipUnstructuredGridWithPlane2/build

If VTK is installed:

    cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

    cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

    make

and run it:

    ./ClipUnstructuredGridWithPlane2

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.