# SelectAVertex

VTKExamples/Cxx/Interaction/SelectAVertex

### Description

Click and drag a vertex by "ghosting" a glyph over the selected vertex and using it for the interaction.

### Code

SelectAVertex.cxx

    #include <vtkVersion.h>
    #include <vtkSmartPointer.h>
    #include <vtkPointPicker.h>
    #include <vtkSphereSource.h>
    #include <vtkGlyph3D.h>
    #include <vtkPointData.h>
    #include <vtkIdTypeArray.h>
    #include <vtkDataSetSurfaceFilter.h>
    #include <vtkRendererCollection.h>
    #include <vtkProperty.h>
    #include <vtkPlanes.h>
    #include <vtkObjectFactory.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkPolyData.h>
    #include <vtkPointSource.h>
    #include <vtkInteractorStyleTrackballActor.h>
    #include <vtkAreaPicker.h>
    #include <vtkExtractGeometry.h>
    #include <vtkDataSetMapper.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkVertexGlyphFilter.h>
    #include <vtkIdFilter.h>

    // Define interaction style
    class InteractorStyle2 : public vtkInteractorStyleTrackballActor
    {
      public:
        static InteractorStyle2* New();
        vtkTypeMacro(InteractorStyle2,vtkInteractorStyleTrackballActor);

        InteractorStyle2()
        {
          this->Move = false;
          this->PointPicker = vtkSmartPointer<vtkPointPicker>::New();

          // Setup ghost glyph
          vtkSmartPointer<vtkPoints> points =
            vtkSmartPointer<vtkPoints>::New();
          points->InsertNextPoint(0,0,0);
          this->MovePolyData = vtkSmartPointer<vtkPolyData>::New();
          this->MovePolyData->SetPoints(points);
          this->MoveGlyphFilter = vtkSmartPointer<vtkVertexGlyphFilter>::New();
    #if VTK_MAJOR_VERSION <= 5
          this->MoveGlyphFilter->SetInputConnection(
            this->MovePolyData->GetProducerPort());
    #else
          this->MoveGlyphFilter->SetInputData(this->MovePolyData);
    #endif
          this->MoveGlyphFilter->Update();

          this->MoveMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
          this->MoveMapper->SetInputConnection(this->MoveGlyphFilter->GetOutputPort());

          this->MoveActor = vtkSmartPointer<vtkActor>::New();
          this->MoveActor->SetMapper(this->MoveMapper);
          this->MoveActor->VisibilityOff();
          this->MoveActor->GetProperty()->SetPointSize(10);
          this->MoveActor->GetProperty()->SetColor(1,0,0);
        }

        void OnMouseMove()
        {
          if(!this->Move)
          {
            return;
          }

          vtkInteractorStyleTrackballActor::OnMouseMove();

        }

        void OnMiddleButtonUp()
        {
          this->EndPan();

          this->Move = false;
          this->MoveActor->VisibilityOff();

          this->Data->GetPoints()->SetPoint(this->SelectedPoint, this->MoveActor->GetPosition());
          this->Data->Modified();
          this->GetCurrentRenderer()->Render();
          this->GetCurrentRenderer()->GetRenderWindow()->Render();

        }
        void OnMiddleButtonDown()
        {
          // Get the selected point
          int x = this->Interactor->GetEventPosition()[0];
          int y = this->Interactor->GetEventPosition()[1];
          this->FindPokedRenderer(x, y);

          this->PointPicker->Pick(this->Interactor->GetEventPosition()[0],
                     this->Interactor->GetEventPosition()[1],
                     0,  // always zero.
                     this->Interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer());

          if(this->PointPicker->GetPointId() >= 0)
          {
            this->StartPan();
            this->MoveActor->VisibilityOn();
            this->Move = true;
            this->SelectedPoint = this->PointPicker->GetPointId();

            std::cout << "Dragging point " << this->SelectedPoint << std::endl;

            double p[3];
            this->Data->GetPoint(this->SelectedPoint, p);
            std::cout << "p: " << p[0] << " " << p[1] << " " << p[2] << std::endl;
            this->MoveActor->SetPosition(p);

            this->GetCurrentRenderer()->AddActor(this->MoveActor);
            this->InteractionProp = this->MoveActor;
          }
        }

      vtkPolyData* Data;
      vtkPolyData* GlyphData;

      vtkSmartPointer<vtkPolyDataMapper> MoveMapper;
      vtkSmartPointer<vtkActor> MoveActor;
      vtkSmartPointer<vtkPolyData> MovePolyData;
      vtkSmartPointer<vtkVertexGlyphFilter> MoveGlyphFilter;

      vtkSmartPointer<vtkPointPicker> PointPicker;

      bool Move;
      vtkIdType SelectedPoint;
    };
    vtkStandardNewMacro(InteractorStyle2);

    int main (int, char *[])
    {
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(0,0,0);
      points->InsertNextPoint(1,0,0);
      points->InsertNextPoint(2,0,0);

      vtkSmartPointer<vtkPolyData> input =
        vtkSmartPointer<vtkPolyData>::New();
      input->SetPoints(points);

      vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter =
        vtkSmartPointer<vtkVertexGlyphFilter>::New();
    #if VTK_MAJOR_VERSION <= 5
      glyphFilter->SetInputConnection(input->GetProducerPort());
    #else
      glyphFilter->SetInputData(input);
    #endif
      glyphFilter->Update();

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

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetPointSize(10);

      // 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();

      vtkSmartPointer<InteractorStyle2> style =
        vtkSmartPointer<InteractorStyle2>::New();
      renderWindowInteractor->SetInteractorStyle( style );
      style->Data = input;

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(SelectAVertex)

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

    add_executable(SelectAVertex MACOSX_BUNDLE SelectAVertex.cxx )

    target_link_libraries(SelectAVertex ${VTK_LIBRARIES})

### Download and Build SelectAVertex

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

    cd SelectAVertex/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:

    ./SelectAVertex

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.