# CommandSubclass

VTKExamples/Cxx/Utilities/CommandSubclass

### Code

CommandSubclass.cxx

    #include <vtkSmartPointer.h>
    #include <vtkObjectFactory.h>
    #include <vtkSphereSource.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkCommand.h>

    class CommandSubclass2 : public vtkCommand
    {
      public:
        vtkTypeMacro(CommandSubclass2, vtkCommand);

        static CommandSubclass2 *New()
        {
          return new CommandSubclass2;
        }

        void Execute(vtkObject *vtkNotUsed(caller), unsigned long vtkNotUsed(eventId),
                            void *vtkNotUsed(callData))
        {
          std::cout << "timer callback" << std::endl;
        }

    };

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

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

      // Create a renderer, render window, and interactor
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // Initialize must be called prior to creating timer events.
      renderWindowInteractor->Initialize();
      renderWindowInteractor->CreateRepeatingTimer(500);

      vtkSmartPointer<CommandSubclass2> timerCallback =
        vtkSmartPointer<CommandSubclass2>::New();
      renderWindowInteractor->AddObserver ( vtkCommand::TimerEvent, timerCallback );

      // Add the actor to the scene
      renderer->AddActor(actor);
      renderer->SetBackground(1,1,1); // Background color white

      // Render and interact
      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(CommandSubclass)

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

    add_executable(CommandSubclass MACOSX_BUNDLE CommandSubclass.cxx )

    target_link_libraries(CommandSubclass ${VTK_LIBRARIES})

### Download and Build CommandSubclass

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

    cd CommandSubclass/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:

    ./CommandSubclass

WINDOWS USERS

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