# ContoursFromPolyData

VTKExamples/Cxx/Filtering/ContoursFromPolyData

### Description

This example uses vtkCutter to generate contours from a PolyData. A vtkPlane is set at the center of the PolyData and several contours are generated by specifying contour values that are distances to the center plane. The example works with a filename if provided. Otherwise is uses a vtkSphereSource.

Other Languages

See (CSharp)

### Code

ContoursFromPolyData.cxx

    #include <vtkSmartPointer.h>
    #include <vtkCutter.h>

    #include <vtkXMLPolyDataReader.h>
    #include <vtkSphereSource.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkPlane.h>
    #include <vtkProperty.h>
    #include <vtkActor.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkMath.h>
    #include <vtkNamedColors.h>

    int main(int argc, char *argv[])
    {
      vtkSmartPointer<vtkPolyData> inputPolyData;
      if(argc > 1)
      {
        vtkSmartPointer<vtkXMLPolyDataReader> reader =
          vtkSmartPointer<vtkXMLPolyDataReader>::New();
        reader->SetFileName(argv[1]);
        reader->Update();
        inputPolyData = reader->GetOutput();
      }
      else
      {
        vtkSmartPointer<vtkSphereSource> sphereSource =
          vtkSmartPointer<vtkSphereSource>::New();
        sphereSource->SetThetaResolution(30);
        sphereSource->SetPhiResolution(15);
        sphereSource->Update();
        inputPolyData = sphereSource->GetOutput();
      }

      vtkSmartPointer<vtkPolyDataMapper> inputMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      inputMapper->SetInputData(inputPolyData);

      // Create a plane to cut
      vtkSmartPointer<vtkPlane> plane =
        vtkSmartPointer<vtkPlane>::New();
      plane->SetOrigin(inputPolyData->GetCenter());
      plane->SetNormal(1,1,1);

      double minBound[3];
      minBound[0] = inputPolyData->GetBounds()[0];
      minBound[1] = inputPolyData->GetBounds()[2];
      minBound[2] = inputPolyData->GetBounds()[4];

      double maxBound[3];
      maxBound[0] = inputPolyData->GetBounds()[1];
      maxBound[1] = inputPolyData->GetBounds()[3];
      maxBound[2] = inputPolyData->GetBounds()[5];

      double center[3];
      center[0] = inputPolyData->GetCenter()[0];
      center[1] = inputPolyData->GetCenter()[1];
      center[2] = inputPolyData->GetCenter()[2];

      double distanceMin = sqrt(vtkMath::Distance2BetweenPoints(minBound, center));
      double distanceMax = sqrt(vtkMath::Distance2BetweenPoints(maxBound, center));

      // Create cutter
      vtkSmartPointer<vtkCutter> cutter =
        vtkSmartPointer<vtkCutter>::New();
      cutter->SetCutFunction(plane);
      cutter->SetInputData(inputPolyData);

      cutter->GenerateValues(20, -distanceMin, distanceMax);
      vtkSmartPointer<vtkPolyDataMapper> cutterMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      cutterMapper->SetInputConnection( cutter->GetOutputPort());
      cutterMapper->ScalarVisibilityOff();

      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      // Create plane actor
      vtkSmartPointer<vtkActor> planeActor =
        vtkSmartPointer<vtkActor>::New();
      planeActor->GetProperty()->SetColor(colors->GetColor3d("Deep_pink").GetData());
      planeActor->GetProperty()->SetLineWidth(5);
      planeActor->SetMapper(cutterMapper);

      // Create input actor
      vtkSmartPointer<vtkActor> inputActor =
        vtkSmartPointer<vtkActor>::New();
      inputActor->GetProperty()->SetColor(colors->GetColor3d("Bisque").GetData());
      inputActor->SetMapper(inputMapper);

      // Create renderers and add actors of plane and cube
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      renderer->AddActor(planeActor); //display the rectangle resulting from the cut
      renderer->AddActor(inputActor); //display the cube

      //Add renderer to renderwindow and render
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      renderWindow->SetSize(600, 600);

      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renderWindow);
      renderer->SetBackground(colors->GetColor3d("Slate_grey").GetData());
      renderWindow->Render();

      interactor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(ContoursFromPolyData)

    find_package(VTK COMPONENTS
      vtkCommonColor
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersCore
      vtkFiltersSources
      vtkIOXML
      vtkInteractionStyle
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping ContoursFromPolyData: ${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(ContoursFromPolyData MACOSX_BUNDLE ContoursFromPolyData.cxx )
      target_link_libraries(ContoursFromPolyData PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(ContoursFromPolyData MACOSX_BUNDLE ContoursFromPolyData.cxx )
      target_link_libraries(ContoursFromPolyData PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS ContoursFromPolyData
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build ContoursFromPolyData

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

    cd ContoursFromPolyData/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:

    ./ContoursFromPolyData

WINDOWS USERS

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