# BoxWidget2

VTKExamples/Cxx/Widgets/BoxWidget2

### Description

This example uses a {{class|vtkBoxWidget2}} to manipulate an actor. The widget only contains the interaction logic; the actual box is drawn by the accompanying {{class|vtkBoxRepresentation}}. Contrary to the older {{class|vtkBoxWidget|older implementation}}, this widget doesn't provide functionality to assign it to one or more actors, so that has to be implemented manually. The box is dimensioned and positioned by passing a bounding box to `PlaceWidget` method, with the `SetPlaceFactor` method providing a scaling factor in relation to that bounding box. The transformations applied to the box can be used to manipulate any number of object(s), via a custom callback class, which is passed to the box widget through the `AddObserver` method.

The older implementation {{class|vtkBoxWidget}} provides functionality to receive a {{class|vtkProp3D}} for the initial positioning and sizing, but the transformation synchronization still needs to be done manually. See for a simple example of how to use it.

### Code

BoxWidget2.cxx

    #include <vtkSmartPointer.h>
    // For the rendering pipeline setup:
    #include <vtkConeSource.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkInteractorStyleTrackballCamera.h>
    // For vtkBoxWidget2:
    #include <vtkBoxWidget2.h>
    #include <vtkBoxRepresentation.h>
    #include <vtkCommand.h>
    #include <vtkTransform.h>

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

      vtkSmartPointer<vtkActor> m_actor;

      void SetActor( vtkSmartPointer<vtkActor> actor )
      {
        m_actor = actor;
      }

      virtual void Execute( vtkObject *caller, unsigned long, void* )
      {
        vtkSmartPointer<vtkBoxWidget2> boxWidget =
          vtkBoxWidget2::SafeDownCast(caller);

        vtkSmartPointer<vtkTransform> t =
          vtkSmartPointer<vtkTransform>::New();

        vtkBoxRepresentation::SafeDownCast( boxWidget->GetRepresentation() )->GetTransform( t );
        this->m_actor->SetUserTransform( t );
      }

      vtkBoxCallback(){}
    };

    int main( int vtkNotUsed( argc ), char* vtkNotUsed( argv )[] )
    {
      vtkSmartPointer<vtkConeSource> coneSource =
        vtkSmartPointer<vtkConeSource>::New();
      coneSource->SetHeight( 1.5 );

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

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

      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      renderer->AddActor(actor);
      renderer->ResetCamera(); // Reposition camera so the whole scene is visible

      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer( renderer );

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

      // Use the "trackball camera" interactor style, rather than the default "joystick camera"
      vtkSmartPointer<vtkInteractorStyleTrackballCamera> style =
        vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New();
      renderWindowInteractor->SetInteractorStyle( style );

      vtkSmartPointer<vtkBoxWidget2> boxWidget =
        vtkSmartPointer<vtkBoxWidget2>::New();
      boxWidget->SetInteractor( renderWindowInteractor );
      boxWidget->GetRepresentation()->SetPlaceFactor( 1 ); // Default is 0.5
      boxWidget->GetRepresentation()->PlaceWidget(actor->GetBounds());

      // Set up a callback for the interactor to call so we can manipulate the actor
      vtkSmartPointer<vtkBoxCallback> boxCallback =
        vtkSmartPointer<vtkBoxCallback>::New();
      boxCallback->SetActor(actor);
      boxWidget->AddObserver( vtkCommand::InteractionEvent, boxCallback );

      boxWidget->On();

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(BoxWidget2)

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

    add_executable(BoxWidget2 MACOSX_BUNDLE BoxWidget2.cxx)

    target_link_libraries(BoxWidget2 ${VTK_LIBRARIES})

### Download and Build BoxWidget2

Click here to download BoxWidget2 and its CMakeLists.txt file. Once the tarball BoxWidget2.tar has been downloaded and extracted,

    cd BoxWidget2/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:

    ./BoxWidget2

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.