# MultipleActors

VTKExamples/Cxx/Visualization/MultipleActors

### Description

This example creates two spheres and renders them. The idea is to show that each object needs its own mapper and actor and then multiple actors can be added to a renderer.

### Code

MultipleActors.cxx

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

    int main (int, char *[])
    {
      // Sphere 1
      vtkSmartPointer<vtkSphereSource> sphereSource1 =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource1->SetCenter(0.0, 0.0, 0.0);
      sphereSource1->SetRadius(4.0);
      sphereSource1->Update();

      vtkSmartPointer<vtkPolyDataMapper> mapper1 =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper1->SetInputConnection(sphereSource1->GetOutputPort());

      vtkSmartPointer<vtkActor> actor1 =
        vtkSmartPointer<vtkActor>::New();
      actor1->SetMapper(mapper1);

      // Sphere 2
      vtkSmartPointer<vtkSphereSource> sphereSource2 =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource2->SetCenter(10.0, 0.0, 0.0);
      sphereSource2->SetRadius(3.0);

      // Create a mapper
      vtkSmartPointer<vtkPolyDataMapper> mapper2 =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper2->SetInputConnection(sphereSource2->GetOutputPort());

      // Create an actor
      vtkSmartPointer<vtkActor> actor2 =
        vtkSmartPointer<vtkActor>::New();
      actor2->SetMapper(mapper2);

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

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

      // Add the actors to the scene
      renderer->AddActor(actor1);
      renderer->AddActor(actor2);
      renderer->SetBackground(1,1,1); // Background color white

      // Render
      renderWindow->Render();

      vtkSmartPointer<vtkInteractorStyleTrackballCamera> style =
        vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New(); //like paraview

      renderWindowInteractor->SetInteractorStyle( style );

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(MultipleActors)

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

### Download and Build MultipleActors

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

    cd MultipleActors/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:

    ./MultipleActors

WINDOWS USERS

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