# Curvatures

VTKExamples/Cxx/PolyData/Curvatures

### Code

Curvatures.cxx

    #include <vtkSmartPointer.h>

    #include <vtkCurvatures.h>

    #include <vtkXMLPolyDataReader.h>

    #include <vtkLookupTable.h>
    #include <vtkColorTransferFunction.h>
    #include <vtkColorSeries.h>

    #include <vtkPointData.h>

    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkScalarBarActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>

    int main(int argc, char *argv[])
    {
      // Parse command line arguments
      if(argc < 2)
      {
        std::cerr << "Usage: " << argv[0] << " Filename(.vtp)" << std::endl;
        return EXIT_FAILURE;
      }

      // Create a polydata
      vtkSmartPointer<vtkXMLPolyDataReader> reader =
        vtkSmartPointer<vtkXMLPolyDataReader>::New();
      reader->SetFileName(argv[1]);

      vtkSmartPointer<vtkCurvatures> curvaturesFilter =
        vtkSmartPointer<vtkCurvatures>::New();
      curvaturesFilter->SetInputConnection(reader->GetOutputPort());
      curvaturesFilter->SetCurvatureTypeToMinimum();
      curvaturesFilter->SetCurvatureTypeToMaximum();
      curvaturesFilter->SetCurvatureTypeToGaussian();
      curvaturesFilter->SetCurvatureTypeToMean();
      curvaturesFilter->Update();

      // Get scalar range from command line if present, otherwise use
      // range of computed curvature
      double scalarRange[2];
      if (argc >= 4)
      {
        scalarRange[0] = atof(argv[2]);
        scalarRange[1] = atof(argv[3]);
      }
      else
      {
        curvaturesFilter->GetOutput()->GetScalarRange(scalarRange);
      }

      int scheme = 16;
      if (argc >= 5)
      {
        scheme = atoi(argv[4]);
      }

      // Build a lookup table
      vtkSmartPointer<vtkColorSeries> colorSeries =
        vtkSmartPointer<vtkColorSeries>::New();
      colorSeries->SetColorScheme(scheme);
      std::cout << "Using color scheme #: "
                << colorSeries->GetColorScheme() << " is "
                << colorSeries->GetColorSchemeName() << std::endl;

      vtkSmartPointer<vtkColorTransferFunction> lut =
        vtkSmartPointer<vtkColorTransferFunction>::New();
      lut->SetColorSpaceToHSV();

      // Use a color series to create a transfer function
      int numColors = colorSeries->GetNumberOfColors();
      for (int i = 0; i < numColors; i++)
      {
          vtkColor3ub color = colorSeries->GetColor(i);
        double dColor[3];
        dColor[0] = static_cast<double> (color[0]) / 255.0;
        dColor[1] = static_cast<double> (color[1]) / 255.0;
        dColor[2] = static_cast<double> (color[2]) / 255.0;
        double t = scalarRange[0] + (scalarRange[1] - scalarRange[0])
          / (numColors - 1) * i;
        lut->AddRGBPoint(t, dColor[0], dColor[1], dColor[2]);
      }

      // Create a mapper and actor
      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(curvaturesFilter->GetOutputPort());
      mapper->SetLookupTable(lut);
      mapper->SetScalarRange(scalarRange);

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);

      // Create a scalar bar
      vtkSmartPointer<vtkScalarBarActor> scalarBar =
        vtkSmartPointer<vtkScalarBarActor>::New();
      scalarBar->SetLookupTable(mapper->GetLookupTable());
      scalarBar->SetTitle(
        curvaturesFilter->GetOutput()->GetPointData()->GetScalars()->GetName());
      scalarBar->SetNumberOfLabels(5);

      // Create a renderer, render window, and interactor
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // Add the actors to the scene
      renderer->AddActor(actor);
      renderer->AddActor2D(scalarBar);

      renderer->SetBackground(.1, .2, .3); // Background color blue

      // Render and interact
      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(Curvatures)

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

    add_executable(Curvatures MACOSX_BUNDLE Curvatures.cxx )

    target_link_libraries(Curvatures ${VTK_LIBRARIES})

### Download and Build Curvatures

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

    cd Curvatures/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:

    ./Curvatures

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.