# PolyDataIsoLines

VTKExamples/Cxx/PolyData/PolyDataIsoLines

### Code

PolyDataIsoLines.cxx

    #include <vtkSmartPointer.h>
    #include <vtkBandedPolyDataContourFilter.h>

    #include <vtkCellArray.h>
    #include <vtkFloatArray.h>
    #include <vtkPointData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkProperty.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkXMLPolyDataReader.h>
    #include <vtkXMLPolyDataWriter.h>
    #include <vtkCamera.h>

    #include <vtkNamedColors.h>

    int main(int argc, char *argv[])
    {
      // Parse command line arguments
      if(argc != 2)
      {
        std::cout << "Required arguments: Filename" << std::endl;
        return EXIT_FAILURE;
      }

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

      vtkSmartPointer<vtkXMLPolyDataReader> reader =
          vtkSmartPointer<vtkXMLPolyDataReader>::New();
      reader->SetFileName(argv[1]);
      reader->Update();

      //float range[2];
      double range[2];
      reader->GetOutput()->GetPointData()->GetScalars()->GetRange(range);
      //std::cout << "Range: " << range[0] << " , " << range[1] << std::endl;

      vtkSmartPointer<vtkBandedPolyDataContourFilter> bf =
        vtkSmartPointer<vtkBandedPolyDataContourFilter>::New();
      bf->SetInputConnection(reader->GetOutputPort());
      int numContours = 30;
      bf->GenerateValues(numContours, range);
      bf->GenerateContourEdgesOn();
      bf->Update();

      // Color the contours
      bf->GetOutput(1)->GetPointData()->SetScalars(bf->GetOutput()->GetPointData()->GetScalars());

      // Make sure the mapper uses the new colors
      bf->GetOutput(0)->GetPointData()->SetActiveScalars("Scalars");

      {
      vtkSmartPointer<vtkXMLPolyDataWriter> writer =
        vtkSmartPointer<vtkXMLPolyDataWriter>::New();
      writer->SetInputConnection(bf->GetOutputPort());
      writer->SetFileName("output.vtp");
      writer->Update();
      }

      {
      vtkSmartPointer<vtkXMLPolyDataWriter> writer =
        vtkSmartPointer<vtkXMLPolyDataWriter>::New();
      writer->SetInputConnection(bf->GetOutputPort(1));
      writer->SetFileName("ContourEdges.vtp");
      writer->Update();
      }

      /*
      // See which isocontours are being generated
      double values[10];
      bf->GetValues(values);
      for(unsigned int i = 0; i < 10; i++)
        {
        cout << values[i] << " ";
        }
      cout << endl;
      */

      // Color actor
      vtkSmartPointer<vtkPolyDataMapper> colorMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      colorMapper->SetInputConnection(bf->GetOutputPort(0));
      colorMapper->SetScalarRange(range);

      vtkSmartPointer<vtkActor> colorActor =
        vtkSmartPointer<vtkActor>::New();
      colorActor->SetMapper(colorMapper);

      // Edge actor
      vtkSmartPointer<vtkPolyDataMapper> edgeMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      edgeMapper->SetInputConnection(bf->GetOutputPort(1));
      edgeMapper->SetScalarRange(range);

      vtkSmartPointer<vtkActor> edgeActor =
          vtkSmartPointer<vtkActor>::New();
      edgeActor->SetMapper(edgeMapper);
      edgeActor->GetProperty()->SetLineWidth(5);

      // Create the RenderWindow, Renderer and both Actors

      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renderWindow);

      // Add the actors to the renderer
      renderer->AddActor(colorActor);
      renderer->AddActor(edgeActor);

      renderer->SetBackground(colors->GetColor3d("Silver").GetData());
      renderWindow->Render();

      interactor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(PolyDataIsoLines)

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

### Download and Build PolyDataIsoLines

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

    cd PolyDataIsoLines/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:

    ./PolyDataIsoLines

WINDOWS USERS

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