# ImplicitPlaneWidget2

VTKExamples/Cxx/Widgets/ImplicitPlaneWidget2

### Description

This example shows how to use the second generation ImplicitPlaneWidget2 to interactively define the clipping plane for a polydata. If no arguments are specified, a vtkSphereSource generates the polydata. By specifying a .vtp file, the example can operate on arbitrary polydata.

For example, try VTKData/Data/cow.vtp.

### Code

ImplicitPlaneWidget2.cxx

    #include <vtkSmartPointer.h>

    #include <vtkXMLPolyDataReader.h>
    #include <vtkSphereSource.h>
    #include <vtkClipPolyData.h>
    #include <vtkPlane.h>

    #include <vtkCommand.h>
    #include <vtkImplicitPlaneWidget2.h>
    #include <vtkImplicitPlaneRepresentation.h>

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

    // Callback for the interaction
    // This does the actual work: updates the vtkPlane implicit function.
    // This in turn causes the pipeline to update and clip the object.
    class vtkIPWCallback : public vtkCommand
    {
    public:
      static vtkIPWCallback *New()
        { return new vtkIPWCallback; }
      virtual void Execute(vtkObject *caller, unsigned long, void*)
      {
        vtkImplicitPlaneWidget2 *planeWidget =
          reinterpret_cast<vtkImplicitPlaneWidget2*>(caller);
        vtkImplicitPlaneRepresentation *rep =
          reinterpret_cast<vtkImplicitPlaneRepresentation*>(planeWidget->GetRepresentation());
        rep->GetPlane(this->Plane);
      }
      vtkIPWCallback():Plane(0),Actor(0) {}
      vtkPlane *Plane;
      vtkActor *Actor;

    };

    int main(int argc, char *argv[])
    {
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetRadius(10.0);

      vtkSmartPointer<vtkXMLPolyDataReader> reader =
        vtkSmartPointer<vtkXMLPolyDataReader>::New();

      // Setup a visualization pipeline
      vtkSmartPointer<vtkPlane> plane =
        vtkSmartPointer<vtkPlane>::New();
      vtkSmartPointer<vtkClipPolyData> clipper =
        vtkSmartPointer<vtkClipPolyData>::New();
      clipper->SetClipFunction(plane);
      clipper->InsideOutOn();
      if (argc < 2)
      {
        clipper->SetInputConnection(sphereSource->GetOutputPort());
      }
      else
      {
        reader->SetFileName(argv[1]);
        clipper->SetInputConnection(reader->GetOutputPort());
      }

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

      vtkSmartPointer<vtkProperty> backFaces =
        vtkSmartPointer<vtkProperty>::New();
      backFaces->SetDiffuseColor(.8, .8, .4);

      actor->SetBackfaceProperty(backFaces);

      // A renderer and render window
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      renderer->AddActor(actor);

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

      renderWindow->Render();

      // The callback will do the work
      vtkSmartPointer<vtkIPWCallback> myCallback =
        vtkSmartPointer<vtkIPWCallback>::New();
      myCallback->Plane = plane;
      myCallback->Actor = actor;

      vtkSmartPointer<vtkImplicitPlaneRepresentation> rep =
        vtkSmartPointer<vtkImplicitPlaneRepresentation>::New();
      rep->SetPlaceFactor(1.25); // This must be set prior to placing the widget
      rep->PlaceWidget(actor->GetBounds());
      rep->SetNormal(plane->GetNormal());

      vtkSmartPointer<vtkImplicitPlaneWidget2> planeWidget =
        vtkSmartPointer<vtkImplicitPlaneWidget2>::New();
      planeWidget->SetInteractor(renderWindowInteractor);
      planeWidget->SetRepresentation(rep);
      planeWidget->AddObserver(vtkCommand::InteractionEvent,myCallback);

      // Render

      renderWindowInteractor->Initialize();
      renderWindow->Render();
      planeWidget->On();

      // Begin mouse interaction
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(ImplicitPlaneWidget2)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersCore
      vtkFiltersSources
      vtkIOXML
      vtkInteractionStyle
      vtkInteractionWidgets
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping ImplicitPlaneWidget2: ${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(ImplicitPlaneWidget2 MACOSX_BUNDLE ImplicitPlaneWidget2.cxx )
      target_link_libraries(ImplicitPlaneWidget2 PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(ImplicitPlaneWidget2 MACOSX_BUNDLE ImplicitPlaneWidget2.cxx )
      target_link_libraries(ImplicitPlaneWidget2 PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS ImplicitPlaneWidget2
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build ImplicitPlaneWidget2

Click here to download ImplicitPlaneWidget2 and its CMakeLists.txt file. Once the tarball ImplicitPlaneWidget2.tar has been downloaded and extracted,

    cd ImplicitPlaneWidget2/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:

    ./ImplicitPlaneWidget2

WINDOWS USERS

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