BoxWidget

VTKEx/Cxx/Widgets/BoxWidget

Description

This example uses a vtkBoxWidget to manipulate an actor. The class includes geometry to draw a box around the object, which is bound to it via SetProp3D. The box is dimensioned using the SetPlaceFactor method, and positioned with the PlaceWidget method. After the initial setup, synchronizing the box with the object is done through a custom callback class, which is passed to the box widget through the AddObserver method.

For a widget that isn't tied to a specific vtkProp3D and has its geometric representation separate from the interaction logic, see the example BoxWidget2.

Other languages

See (Python)

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

BoxWidget.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 vtkBoxWidget:
#include <vtkBoxWidget.h>
#include <vtkCommand.h>
#include <vtkTransform.h>

class vtkMyCallback : public vtkCommand
{
public:
  static vtkMyCallback *New()
  {
    return new vtkMyCallback;
  }
  virtual void Execute( vtkObject *caller, unsigned long, void* )
  {
    // Here we use the vtkBoxWidget to transform the underlying coneActor
    // (by manipulating its transformation matrix).
    vtkSmartPointer<vtkTransform> t =
      vtkSmartPointer<vtkTransform>::New();
    vtkBoxWidget *widget = reinterpret_cast<vtkBoxWidget*>(caller);
    widget->GetTransform( t );
    widget->GetProp3D()->SetUserTransform( t );
  }
};

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

  vtkSmartPointer<vtkPolyDataMapper> coneMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  coneMapper->SetInputConnection( cone->GetOutputPort() );

  vtkSmartPointer<vtkActor> coneActor =
    vtkSmartPointer<vtkActor>::New();
  coneActor->SetMapper( coneMapper );

  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor( coneActor );
  renderer->SetBackground( 0.1, 0.2, 0.4 );

  vtkSmartPointer<vtkRenderWindow> window =
    vtkSmartPointer<vtkRenderWindow>::New();
  window->AddRenderer( renderer );
  window->SetSize( 300, 300 );

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

  vtkSmartPointer<vtkInteractorStyleTrackballCamera> style =
    vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New();
  interactor->SetInteractorStyle( style );

  vtkSmartPointer<vtkBoxWidget> boxWidget =
    vtkSmartPointer<vtkBoxWidget>::New();
  boxWidget->SetInteractor( interactor );

  boxWidget->SetProp3D( coneActor );
  boxWidget->SetPlaceFactor( 1.25 ); // Make the box 1.25x larger than the actor
  boxWidget->PlaceWidget();

  vtkSmartPointer<vtkMyCallback> callback =
    vtkSmartPointer<vtkMyCallback>::New();
  boxWidget->AddObserver( vtkCommand::InteractionEvent, callback );

  boxWidget->On();

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(BoxWidget)

find_package(VTK COMPONENTS 
  vtkvtkCommonCore
  vtkvtkCommonTransforms
  vtkvtkFiltersSources
  vtkvtkInteractionStyle
  vtkvtkInteractionWidgets
  vtkvtkRenderingContextOpenGL2
  vtkvtkRenderingCore
  vtkvtkRenderingFreeType
  vtkvtkRenderingGL2PSOpenGL2
  vtkvtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping BoxWidget: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(BoxWidget MACOSX_BUNDLE BoxWidget.cxx )
  target_link_libraries(BoxWidget PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(BoxWidget MACOSX_BUNDLE BoxWidget.cxx )
  target_link_libraries(BoxWidget PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS BoxWidget
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build BoxWidget

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

cd BoxWidget/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:

./BoxWidget

WINDOWS USERS

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