# InteractorStyleUser

VTKExamples/Cxx/Interaction/InteractorStyleUser

### Description

This style is designed to NOT provide any default functionality. You must specify how to handle every event that you want handled.

### Code

InteractorStyleUser.cxx

    #include <vtkSmartPointer.h>
    #include <vtkCallbackCommand.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkPolyData.h>
    #include <vtkSphereSource.h>
    #include <vtkInteractorStyleUser.h>

    static void ClickCallbackFunction ( vtkObject* caller,
                                        long unsigned int eventId,
                                        void* clientData,
                                        void* callData );

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

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

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

      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<vtkCallbackCommand> clickCallback =
        vtkSmartPointer<vtkCallbackCommand>::New();
      clickCallback->SetCallback(ClickCallbackFunction);

      renderWindowInteractor->AddObserver ( vtkCommand::LeftButtonPressEvent, clickCallback );

      vtkSmartPointer<vtkInteractorStyleUser> style =
        vtkSmartPointer<vtkInteractorStyleUser>::New();
      renderWindowInteractor->SetInteractorStyle(style);

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

    void ClickCallbackFunction (vtkObject *,
                                long unsigned int,
                                void *,
                                void *)
    {
      std::cout << "Click callback" << std::endl;

      // We can get the calling object like this:
      // vtkRenderWindowInteractor *iren =
      //  static_cast<vtkRenderWindowInteractor*>(caller);
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(InteractorStyleUser)

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

### Download and Build InteractorStyleUser

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

    cd InteractorStyleUser/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:

    ./InteractorStyleUser

WINDOWS USERS

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