# WarpScalar

VTKExamples/Cxx/PolyData/WarpScalar

### Code

WarpScalar.cxx

    #include <vtkActor.h>
    #include <vtkDoubleArray.h>
    #include <vtkPointData.h>
    #include <vtkPolyData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkSmartPointer.h>
    #include <vtkSphereSource.h>
    #include <vtkWarpScalar.h>
    #include <vtkMath.h>

    int main(int, char *[])
    {
      // Create a sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->Update();

      // Create Scalars
      vtkSmartPointer<vtkDoubleArray> scalars =
        vtkSmartPointer<vtkDoubleArray>::New();
      int numberOfPoints = sphereSource->GetOutput()->GetNumberOfPoints();
      scalars->SetNumberOfTuples(numberOfPoints);

      vtkMath::RandomSeed(8775070); // for reproducibility
      for(vtkIdType i = 0; i < numberOfPoints; ++i)
      {
        scalars->SetTuple1(i, vtkMath::Random(0.0, 1.0 / 7.0));
      }

      sphereSource->GetOutput()->GetPointData()->SetScalars(scalars);

      vtkSmartPointer<vtkWarpScalar> warpScalar =
        vtkSmartPointer<vtkWarpScalar>::New();
      warpScalar->SetInputConnection(sphereSource->GetOutputPort());
      warpScalar->SetScaleFactor(1); // use the scalars themselves

      // Required for SetNormal to have an effect
      warpScalar->UseNormalOn();
      warpScalar->SetNormal(0, 0, 1);

      warpScalar->Update();

      // Create a mapper and actor
      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(warpScalar->GetOutputPort());

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

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

      renderer->AddActor(actor);
      renderer->SetBackground(1,1,1); // Background color white

      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(WarpScalar)

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

    add_executable(WarpScalar MACOSX_BUNDLE WarpScalar.cxx )

    target_link_libraries(WarpScalar ${VTK_LIBRARIES})

### Download and Build WarpScalar

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

    cd WarpScalar/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:

    ./WarpScalar

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.