# WarpSurface

VTKExamples/Cxx/PolyData/WarpSurface

### Description

The image was produced using this data and a scale of .1.

### Code

WarpSurface.cxx

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

    #include <vtkWarpVector.h>
    #include <vtkXMLPolyDataReader.h>
    #include <vtkSphereSource.h>
    #include <vtkPolyData.h>
    #include <vtkCleanPolyData.h>
    #include <vtkPolyDataNormals.h>
    #include <vtkDataSetAttributes.h>

    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>

    int main(int argc, char *argv[])
    {
      double scale = 1.0;
      vtkSmartPointer<vtkPolyData> inputPolyData;
      // If a file is provided, use it, otherwise generate a sphere
      if(argc > 1)
      {
        vtkSmartPointer<vtkXMLPolyDataReader> reader =
          vtkSmartPointer<vtkXMLPolyDataReader>::New();
        reader->SetFileName(argv[1]);
        reader->Update();
        inputPolyData = reader->GetOutput();
        if (argc > 2)
        {
          scale = atof(argv[2]);
        }
      }
      else
      {
        vtkSmartPointer<vtkSphereSource> sphereSource =
          vtkSmartPointer<vtkSphereSource>::New();
        sphereSource->SetPhiResolution(15);
        sphereSource->SetThetaResolution(15);
        sphereSource->Update();
        inputPolyData = sphereSource->GetOutput();
      }

      vtkSmartPointer<vtkCleanPolyData> clean =
        vtkSmartPointer<vtkCleanPolyData>::New();
    #if VTK_MAJOR_VERSION <= 5
      clean->SetInput(inputPolyData);
    #else
      clean->SetInputData(inputPolyData);
    #endif

      // Generate normals
      vtkSmartPointer<vtkPolyDataNormals> normals =
        vtkSmartPointer<vtkPolyDataNormals>::New();
      normals->SetInputConnection(clean->GetOutputPort());
      normals->SplittingOff();

      // Warp using the normals
      vtkSmartPointer<vtkWarpVector> warp =
        vtkSmartPointer<vtkWarpVector>::New();
      warp->SetInputConnection (normals->GetOutputPort());
      warp->SetInputArrayToProcess(0, 0, 0,
                                   vtkDataObject::FIELD_ASSOCIATION_POINTS,
                                   vtkDataSetAttributes::NORMALS);
      warp->SetScaleFactor(scale);

      // Visualize the original and warped models
      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(warp->GetOutputPort());
      mapper->ScalarVisibilityOff();

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

      vtkSmartPointer<vtkPolyDataMapper> originalMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      originalMapper->SetInputConnection(normals->GetOutputPort());
      originalMapper->ScalarVisibilityOff();

      vtkSmartPointer<vtkActor> originalActor =
        vtkSmartPointer<vtkActor>::New();
      originalActor->SetMapper(originalMapper);
      originalActor->GetProperty()->SetInterpolationToFlat();

      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(640, 480);

      // Create a camera for all renderers
      vtkSmartPointer<vtkCamera> camera =
        vtkSmartPointer<vtkCamera>::New();

      // Define viewport ranges
      // (xmin, ymin, xmax, ymax)
      double leftViewport[4] = {0.0, 0.0, 0.5, 1.0};
      double rightViewport[4] = {0.5, 0.0, 1.0, 1.0};

      // Setup both renderers
      vtkSmartPointer<vtkRenderer> leftRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      leftRenderer->SetViewport(leftViewport);
      leftRenderer->SetBackground(.6, .5, .4);
      leftRenderer->SetActiveCamera(camera);

      vtkSmartPointer<vtkRenderer> rightRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      rightRenderer->SetViewport(rightViewport);
      rightRenderer->SetBackground(.4, .5, .6);
      rightRenderer->SetActiveCamera(camera);

      leftRenderer->AddActor(originalActor);
      rightRenderer->AddActor(warpedActor);

      rightRenderer->ResetCamera();

      renderWindow->AddRenderer(rightRenderer);
      renderWindow->AddRenderer(leftRenderer);

      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renderWindow);

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(WarpSurface)

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

    add_executable(WarpSurface MACOSX_BUNDLE WarpSurface.cxx)

    target_link_libraries(WarpSurface ${VTK_LIBRARIES})

### Download and Build WarpSurface

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

    cd WarpSurface/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:

    ./WarpSurface

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.