# TableBasedClipDataSetWithPolyData

VTKExamples/Cxx/Meshes/TableBasedClipDataSetWithPolyData

### Description

The example that shows how to use the vtkTableBasedClipDataSet to clip a vtkRectilinearGrid with an arbitrary polydata. vtkImplicitPolyDataDistance is used to turn the polydata into an implicit function. Every point of the grid is evaluated before sending to vtkTableBasedClipDataSet. This example uses a vtkConeSource to generate polydata to use, however any polydata could be used, including stl files.

The left part of the image shows the inside clip and the distance field on a center slice. The right side shows the outside clip. When the program exits using the "e: key, the example will report the cell type for both the inside and outside clips.

Note

Contrast this with the vtkClipDataSet example: ClipDataSetWithPolyData.

Here is the summary reported when the example exits:

    The clipped dataset(inside) contains a
    vtkUnstructuredGrid that has 14176 cells
        Cell type vtkTetra occurs 3084 times.
        Cell type vtkHexahedron occurs 6820 times.
        Cell type vtkWedge occurs 1196 times.
        Cell type vtkPyramid occurs 3076 times.

    The clipped dataset(outside) contains a
    vtkUnstructuredGrid that has 125600 cells
        Cell type vtkTetra occurs 3276 times.
        Cell type vtkHexahedron occurs 117732 times.
        Cell type vtkWedge occurs 1260 times.
        Cell type vtkPyramid occurs 3332 times.

### Code

TableBasedClipDataSetWithPolyData.cxx

    #include <vtkVersion.h>
    #include <vtkSmartPointer.h>

    #include <vtkConeSource.h>
    #include <vtkImplicitPolyDataDistance.h>
    #include <vtkPointData.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkFloatArray.h>
    #include <vtkRectilinearGrid.h>
    #include <vtkTableBasedClipDataSet.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkRectilinearGridGeometryFilter.h>
    #include <vtkDataSetMapper.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>

    #include <map>

    int main (int, char *[])
    {
      // Create polydata to slice the grid with. In this case, use a cone. This could
      // be any polydata including a stl file.
      vtkSmartPointer<vtkConeSource> cone =
        vtkSmartPointer<vtkConeSource>::New();
      cone->SetResolution(50);
      cone->SetDirection(0,0,-1);
      cone->SetHeight(3.0);
      cone->CappingOn();
      cone->Update();

      // Implicit function that will be used to slice the mesh
      vtkSmartPointer<vtkImplicitPolyDataDistance> implicitPolyDataDistance =
        vtkSmartPointer<vtkImplicitPolyDataDistance>::New();
      implicitPolyDataDistance->SetInput(cone->GetOutput());

      // create a grid
      unsigned int dimension = 51;
      vtkSmartPointer<vtkFloatArray> xCoords =
        vtkSmartPointer<vtkFloatArray>::New();
      for (unsigned int i = 0; i < dimension; ++i)
      {
        xCoords->InsertNextValue(-1.0 + i * 2.0 / static_cast<float>(dimension-1));
      }
      vtkSmartPointer<vtkFloatArray> yCoords =
        vtkSmartPointer<vtkFloatArray>::New();
      for (unsigned int i = 0; i < dimension; ++i)
      {
        yCoords->InsertNextValue(-1.0 + i * 2.0 / static_cast<float>(dimension-1));
      }
      vtkSmartPointer<vtkFloatArray> zCoords =
        vtkSmartPointer<vtkFloatArray>::New();
      for (unsigned int i = 0; i < dimension; ++i)
      {
        zCoords->InsertNextValue(-1.0 + i * 2.0 / static_cast<float>(dimension-1));
      }
      // The coordinates are assigned to the rectilinear grid. Make sure that
      // the number of values in each of the XCoordinates, YCoordinates,
      // and ZCoordinates is equal to what is defined in SetDimensions().
      vtkSmartPointer<vtkRectilinearGrid> rgrid =
        vtkSmartPointer<vtkRectilinearGrid>::New();
      rgrid->SetDimensions(xCoords->GetNumberOfTuples(),
                           yCoords->GetNumberOfTuples(),
                           zCoords->GetNumberOfTuples());
      rgrid->SetXCoordinates(xCoords);
      rgrid->SetYCoordinates(yCoords);
      rgrid->SetZCoordinates(zCoords);

      // Create an array to hold distance information
      vtkSmartPointer<vtkFloatArray> signedDistances =
        vtkSmartPointer<vtkFloatArray>::New();
      signedDistances->SetNumberOfComponents(1);
      signedDistances->SetName("SignedDistances");

      // Evaluate the signed distance function at all of the grid points
      for (vtkIdType pointId = 0; pointId < rgrid->GetNumberOfPoints(); ++pointId)
      {
        double p[3];
        rgrid->GetPoint(pointId, p);
        double signedDistance = implicitPolyDataDistance->EvaluateFunction(p);
        signedDistances->InsertNextValue(signedDistance);
      }

      // Add the SignedDistances to the grid
      rgrid->GetPointData()->SetScalars(signedDistances);

      // Use vtkTableBasedClipDataSet to slice the grid with the polydata
      vtkSmartPointer<vtkTableBasedClipDataSet> clipper =
        vtkSmartPointer<vtkTableBasedClipDataSet>::New();
    #if VTK_MAJOR_VERSION <= 5
      clipper->SetInput(rgrid);
    #else
      clipper->SetInputData(rgrid);
    #endif
      clipper->InsideOutOn();
      clipper->SetValue(0.0);
      clipper->GenerateClippedOutputOn();
      clipper->Update();

      // --- mappers, actors, render, etc. ---
      // mapper and actor to view the cone
      vtkSmartPointer<vtkPolyDataMapper> coneMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      coneMapper->SetInputConnection(cone->GetOutputPort());
      vtkSmartPointer<vtkActor> coneActor =
        vtkSmartPointer<vtkActor>::New();
      coneActor->SetMapper(coneMapper);

      // geometry filter to view the background grid
      vtkSmartPointer<vtkRectilinearGridGeometryFilter> geometryFilter =
        vtkSmartPointer<vtkRectilinearGridGeometryFilter>::New();
    #if VTK_MAJOR_VERSION <= 5
      geometryFilter->SetInput(rgrid);
    #else
      geometryFilter->SetInputData(rgrid);
    #endif
      geometryFilter->SetExtent(0, dimension, 0, dimension, dimension/2, dimension/2);
      geometryFilter->Update();

      vtkSmartPointer<vtkPolyDataMapper> rgridMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      rgridMapper->SetInputConnection(geometryFilter->GetOutputPort());
      rgridMapper->SetScalarRange(rgrid->GetPointData()->GetArray("SignedDistances")->GetRange());

      vtkSmartPointer<vtkActor> wireActor =
        vtkSmartPointer<vtkActor>::New();
      wireActor->SetMapper(rgridMapper);
      wireActor->GetProperty()->SetRepresentationToWireframe();

      // mapper and actor to view the clipped mesh
      vtkSmartPointer<vtkDataSetMapper> clipperMapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      clipperMapper->SetInputConnection(clipper->GetOutputPort());
      clipperMapper->ScalarVisibilityOff();

      vtkSmartPointer<vtkDataSetMapper> clipperOutsideMapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      clipperOutsideMapper->SetInputConnection(clipper->GetOutputPort(1));
      clipperOutsideMapper->ScalarVisibilityOff();

      vtkSmartPointer<vtkActor> clipperActor =
        vtkSmartPointer<vtkActor>::New();
      clipperActor->SetMapper(clipperMapper);
      clipperActor->GetProperty()->SetColor(0.89,0.81,0.34); // banana

      vtkSmartPointer<vtkActor> clipperOutsideActor =
        vtkSmartPointer<vtkActor>::New();
      clipperOutsideActor->SetMapper(clipperOutsideMapper);
      clipperOutsideActor->GetProperty()->SetColor(0.89,0.81,0.34); // banana

      // A renderer and render window
      // Create a renderer, render window, and interactor
      double leftViewport[4] = {0.0, 0.0, 0.5, 1.0};
      vtkSmartPointer<vtkRenderer> leftRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      leftRenderer->SetViewport(leftViewport);
      leftRenderer->SetBackground(.4, .5, .6);

      double rightViewport[4] = {0.5, 0.0, 1.0, 1.0};
      vtkSmartPointer<vtkRenderer> rightRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      rightRenderer->SetViewport(rightViewport);
      rightRenderer->SetBackground(.5, .6, .6);

      // add the actors
      leftRenderer->AddActor(wireActor);
      leftRenderer->AddActor(clipperActor);
      rightRenderer->AddActor(clipperOutsideActor);

      vtkSmartPointer<vtkRenderWindow> renwin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renwin->SetSize(640, 480);
      renwin->AddRenderer(leftRenderer);
      renwin->AddRenderer(rightRenderer);

      // An interactor
      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renwin);

      // Share the camera

      leftRenderer->GetActiveCamera()->SetPosition(0, -1, 0);
      leftRenderer->GetActiveCamera()->SetFocalPoint(0, 0, 0);
      leftRenderer->GetActiveCamera()->SetViewUp(0, 0, 1);
      leftRenderer->GetActiveCamera()->Azimuth(30);
      leftRenderer->GetActiveCamera()->Elevation(30);
      leftRenderer->ResetCamera();
      rightRenderer->SetActiveCamera(leftRenderer->GetActiveCamera());

      renwin->Render();
      interactor->Start();

      // Generate a report
      vtkIdType numberOfCells = clipper->GetOutput()->GetNumberOfCells();
      std::cout << "------------------------" << std::endl;
      std::cout << "The clipped dataset(inside) 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)]++;
      }

      CellContainer::const_iterator it = cellMap.begin();
      while (it != cellMap.end())
      {
        std::cout << "\tCell type "
                  << vtkCellTypes::GetClassNameFromTypeId(it->first)
                  << " occurs " << it->second << " times." << std::endl;
        ++it;
      }

      numberOfCells = clipper->GetClippedOutput()->GetNumberOfCells();
      std::cout << "------------------------" << std::endl;
      std::cout << "The clipped dataset(outside) 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)]++;
      }

      it = outsideCellMap.begin();
      while (it != outsideCellMap.end())
      {
        std::cout << "\tCell type "
                  << vtkCellTypes::GetClassNameFromTypeId(it->first)
                  << " occurs " << it->second << " times." << std::endl;
        ++it;
      }

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(TableBasedClipDataSetWithPolyData)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(TableBasedClipDataSetWithPolyData MACOSX_BUNDLE TableBasedClipDataSetWithPolyData.cxx)

    target_link_libraries(TableBasedClipDataSetWithPolyData ${VTK_LIBRARIES})

### Download and Build TableBasedClipDataSetWithPolyData

Danger

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

    cd TableBasedClipDataSetWithPolyData/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:

    ./TableBasedClipDataSetWithPolyData

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