# AppendFilter

VTKExamples/Cxx/Filtering/AppendFilter

### Description

This example loads points into a polydata and an unstructured grid then combines them.

The example should be extended to show cells being combined as well.

Other Languages

See (Python)

### Code

AppendFilter.cxx

    #include <vtkSmartPointer.h>
    #include <vtkAppendFilter.h>

    #include <vtkActor.h>
    #include <vtkDataSetMapper.h>
    #include <vtkPointSource.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkNamedColors.h>

    int main(int, char *[])
    {
      // Create 5 points (vtkPolyData)
      vtkSmartPointer<vtkPointSource> pointSource =
        vtkSmartPointer<vtkPointSource>::New();
      pointSource->SetNumberOfPoints(5);
      pointSource->Update();

      vtkSmartPointer<vtkPolyData> polydata = pointSource->GetOutput();

      std::cout << "There are " << polydata->GetNumberOfPoints()
                << " points in the polydata." << std::endl;

      // Create 2 points in a vtkUnstructuredGrid

      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(0,0,0);
      points->InsertNextPoint(0,0,1);

      vtkSmartPointer<vtkUnstructuredGrid> ug =
        vtkSmartPointer<vtkUnstructuredGrid>::New();
      ug->SetPoints(points);

      std::cout << "There are " << ug->GetNumberOfPoints()
                << " points in the unstructured grid." << std::endl;

      // Combine the two data sets
      vtkSmartPointer<vtkAppendFilter> appendFilter =
        vtkSmartPointer<vtkAppendFilter>::New();
      appendFilter->AddInputData(polydata);
      appendFilter->AddInputData(ug);
      appendFilter->Update();

      vtkSmartPointer<vtkUnstructuredGrid> combined =
        appendFilter->GetOutput();
      std::cout << "There are " << combined->GetNumberOfPoints()
                << " points combined." << std::endl;

      // Create a mapper and actor
      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      vtkSmartPointer<vtkDataSetMapper> mapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      mapper->SetInputConnection(appendFilter->GetOutputPort());

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetPointSize(5);

      // 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(colors->GetColor3d("SlateGray").GetData());

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(AppendFilter)

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

### Download and Build AppendFilter

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

    cd AppendFilter/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:

    ./AppendFilter

WINDOWS USERS

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