# PolygonalSurfacePointPlacer

VTKExamples/Cxx/PolyData/PolygonalSurfacePointPlacer

### Description

This example demonstrates how to draw curves on a surface.

### Code

PolygonalSurfacePointPlacer.cxx

    #include <vtkSmartPointer.h>
    #include <vtkCommand.h>
    #include <vtkProperty.h>
    #include <vtkContourWidget.h>
    #include <vtkSphereSource.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkPolyDataCollection.h>
    #include <vtkPolygonalSurfacePointPlacer.h>
    #include <vtkOrientedGlyphContourRepresentation.h>

    class MyCallback : public vtkCommand
    {
      public:
        static MyCallback *New()
        {
          return new MyCallback;
        }
        MyCallback(){}

        virtual void Execute(vtkObject *caller, unsigned long, void*)
        {
          vtkContourWidget *contourWidget = reinterpret_cast<vtkContourWidget*>(caller);
          vtkContourRepresentation* rep = static_cast<vtkContourRepresentation *>(contourWidget->GetRepresentation());
          std::cout << "There are " << rep->GetNumberOfNodes() << " nodes." << std::endl;
        }

      void SetSphereSource(vtkSmartPointer<vtkSphereSource> sphere) {this->SphereSource = sphere;}

      private:
        vtkSmartPointer<vtkSphereSource> SphereSource;
    };

    int main(int, char *[])
    {
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetRadius(5);
      sphereSource->Update();

      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(sphereSource->GetOutputPort());

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

      // Create the RenderWindow, Renderer
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renderWindow);

      renderer->AddActor(actor);

      vtkSmartPointer<vtkContourWidget> contourWidget =
        vtkSmartPointer<vtkContourWidget>::New();
      contourWidget->SetInteractor(interactor);

      vtkSmartPointer<MyCallback> callback =
        vtkSmartPointer<MyCallback>::New();
      callback->SetSphereSource(sphereSource);
      contourWidget->AddObserver(vtkCommand::InteractionEvent,callback);

      vtkOrientedGlyphContourRepresentation* rep =
        vtkOrientedGlyphContourRepresentation::SafeDownCast(
        contourWidget->GetRepresentation());

      vtkSmartPointer<vtkPolygonalSurfacePointPlacer> pointPlacer =
        vtkSmartPointer<vtkPolygonalSurfacePointPlacer>::New();
      pointPlacer->AddProp(actor);
      pointPlacer->GetPolys()->AddItem(sphereSource->GetOutput());

      rep->GetLinesProperty()->SetColor(1, 0, 0);
      rep->GetLinesProperty()->SetLineWidth(3.0);
      rep->SetPointPlacer(pointPlacer);

      contourWidget->EnabledOn();
      renderer->ResetCamera();
      renderWindow->Render();
      interactor->Initialize();

      interactor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(PolygonalSurfacePointPlacer)

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

    add_executable(PolygonalSurfacePointPlacer MACOSX_BUNDLE PolygonalSurfacePointPlacer.cxx )

    target_link_libraries(PolygonalSurfacePointPlacer ${VTK_LIBRARIES})

### Download and Build PolygonalSurfacePointPlacer

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

    cd PolygonalSurfacePointPlacer/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:

    ./PolygonalSurfacePointPlacer

WINDOWS USERS

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