# Assembly

VTKExamples/Cxx/Interaction/Assembly

### Code

Assembly.cxx

    #include <vtkSmartPointer.h>
    #include <vtkAssembly.h>

    #include <vtkTransform.h>
    #include <vtkCubeSource.h>
    #include <vtkProperty.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkPolyData.h>
    #include <vtkSphereSource.h>
    #include <vtkOrientationMarkerWidget.h>
    #include <vtkAxesActor.h>
    #include <vtkPropAssembly.h>

    #include <vtkNamedColors.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkNamedColors> namedColors =
        vtkSmartPointer<vtkNamedColors>::New();

      // Create a sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->Update();

      vtkSmartPointer<vtkPolyDataMapper> sphereMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      sphereMapper->SetInputConnection(sphereSource->GetOutputPort());
      vtkSmartPointer<vtkActor> sphereActor =
        vtkSmartPointer<vtkActor>::New();
      sphereActor->SetMapper(sphereMapper);
      sphereActor->GetProperty()->SetColor(
        namedColors->GetColor3d("Banana").GetData());

      // Create a cube
      vtkSmartPointer<vtkCubeSource> cubeSource =
        vtkSmartPointer<vtkCubeSource>::New();
      cubeSource->SetCenter(5.0, 0.0, 0.0);
      cubeSource->Update();

      vtkSmartPointer<vtkPolyDataMapper> cubeMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      cubeMapper->SetInputConnection(cubeSource->GetOutputPort());
      vtkSmartPointer<vtkActor> cubeActor =
        vtkSmartPointer<vtkActor>::New();
      cubeActor->SetMapper(cubeMapper);
      cubeActor->GetProperty()->SetColor(
        namedColors->GetColor3d("Tomato").GetData());
      // Combine the sphere and cube into an assembly
      vtkSmartPointer<vtkAssembly> assembly =
        vtkSmartPointer<vtkAssembly>::New();
      assembly->AddPart(sphereActor);
      assembly->AddPart(cubeActor);

      // Apply a transform to the whole assembly
      vtkSmartPointer<vtkTransform> transform =
        vtkSmartPointer<vtkTransform>::New();
      transform->PostMultiply(); //this is the key line
      transform->Translate(5.0, 0, 0);

      assembly->SetUserTransform(transform);

      // Extract each actor from the assembly and change its opacity
      vtkSmartPointer<vtkPropCollection> collection =
        vtkSmartPointer<vtkPropCollection>::New();

      assembly->GetActors(collection);
      collection->InitTraversal();
      for(vtkIdType i = 0; i < collection->GetNumberOfItems(); i++)
      {
        vtkActor::SafeDownCast(collection->GetNextProp())->GetProperty()->SetOpacity(0.5);
      }

      // Visualization
      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(assembly);
      renderer->SetBackground(namedColors->GetColor3d("SlateGray").GetData());

      renderer->ResetCamera();
      renderWindow->Render();

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(Assembly)

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

### Download and Build Assembly

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

    cd Assembly/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:

    ./Assembly

WINDOWS USERS

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