# Animation

VTKExamples/Cxx/Utilities/Animation

### Description

This example demonstrates how to create a simple animation. A timer is used to move a sphere across a scene.

Other Languages

See (Python)

### Code

Animation.cxx

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

    class vtkTimerCallback2 : public vtkCommand
    {
      public:
        static vtkTimerCallback2 *New()
        {
          vtkTimerCallback2 *cb = new vtkTimerCallback2;
          cb->TimerCount = 0;
          return cb;
        }

        virtual void Execute(vtkObject *caller, unsigned long eventId,
                             void * vtkNotUsed(callData))
        {
          if (vtkCommand::TimerEvent == eventId)
          {
            ++this->TimerCount;
          }
          std::cout << this->TimerCount << std::endl;
          actor->SetPosition(this->TimerCount, this->TimerCount,0);
          vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::SafeDownCast(caller);
          iren->GetRenderWindow()->Render();
        }

      private:
        int TimerCount;
      public:
        vtkActor* actor;
    };

    int main(int, char* [])
    {
      // Create a sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetCenter(0.0, 0.0, 0.0);
      sphereSource->SetRadius(5.0);
      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);

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

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

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

      // Sign up to receive TimerEvent
      vtkSmartPointer<vtkTimerCallback2> cb =
        vtkSmartPointer<vtkTimerCallback2>::New();
      cb->actor = actor;
      renderWindowInteractor->AddObserver(vtkCommand::TimerEvent, cb);

      int timerId = renderWindowInteractor->CreateRepeatingTimer(100);
      std::cout << "timerId: " << timerId << std::endl;

      // Start the interaction and timer
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(Animation)

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

### Download and Build Animation

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

    cd Animation/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:

    ./Animation

WINDOWS USERS

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