# MergeSelections

VTKExamples/Cxx/PolyData/MergeSelections

### Description

- Fixed by Mirko Heuegger

### Code

MergeSelections.cxx

    #include <vtkActor.h>
    #include <vtkDataSetMapper.h>
    #include <vtkExtractSelection.h>
    #include <vtkIdTypeArray.h>
    #include <vtkInformation.h>
    #include <vtkPointSource.h>
    #include <vtkPolyData.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkSelection.h>
    #include <vtkSelectionNode.h>
    #include <vtkSmartPointer.h>
    #include <vtkUnstructuredGrid.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkPointSource> pointSource =
        vtkSmartPointer<vtkPointSource>::New();
      pointSource->SetNumberOfPoints(50);
      pointSource->Update();

      std::cout << "There are " << pointSource->GetOutput()->GetNumberOfPoints()
                << " input points." << std::endl;

      vtkSmartPointer<vtkIdTypeArray> ids1 =
        vtkSmartPointer<vtkIdTypeArray>::New();
      ids1->SetNumberOfComponents(1);

      // Set values
      for(unsigned int i = 10; i < 20; i++)
      {
        ids1->InsertNextValue(i);
      }

      vtkSmartPointer<vtkIdTypeArray> ids2 =
        vtkSmartPointer<vtkIdTypeArray>::New();
      ids2->SetNumberOfComponents(1);

      for(unsigned int i = 15; i < 30; i++)
      {
        ids2->InsertNextValue(i);
      }

      vtkSmartPointer<vtkSelectionNode> selectionNode1 =
        vtkSmartPointer<vtkSelectionNode>::New();
      selectionNode1->SetFieldType(vtkSelectionNode::POINT);
      selectionNode1->SetContentType(vtkSelectionNode::INDICES);
      selectionNode1->SetSelectionList(ids1);

      vtkSmartPointer<vtkSelectionNode> selectionNode2 =
        vtkSmartPointer<vtkSelectionNode>::New();
      selectionNode2->SetFieldType(vtkSelectionNode::POINT);
      selectionNode2->SetContentType(vtkSelectionNode::INDICES);
      selectionNode2->SetSelectionList(ids2);

      vtkSmartPointer<vtkSelection> selection1 =
        vtkSmartPointer<vtkSelection>::New();
      selection1->AddNode(selectionNode1);

      vtkSmartPointer<vtkSelection> selection2 =
        vtkSmartPointer<vtkSelection>::New();
      selection2->AddNode(selectionNode2);

      vtkSmartPointer<vtkSelection> selectionCombined =
        vtkSmartPointer<vtkSelection>::New();
      selectionCombined->AddNode(selectionNode1);
      selectionCombined->Union(selectionNode2);

      std::cout << "There are " << selectionCombined->GetNumberOfNodes() << " nodes." << std::endl;

      vtkSmartPointer<vtkExtractSelection> extractSelection1 =
        vtkSmartPointer<vtkExtractSelection>::New();
      extractSelection1->SetInputConnection(0, pointSource->GetOutputPort());
      extractSelection1->SetInputData(1, selection1);
      extractSelection1->Update();

      vtkSmartPointer<vtkExtractSelection> extractSelection2 =
        vtkSmartPointer<vtkExtractSelection>::New();
      extractSelection2->SetInputConnection(0, pointSource->GetOutputPort());
      extractSelection2->SetInputData(1, selection2);
      extractSelection2->Update();

      vtkSmartPointer<vtkExtractSelection> extractSelectionCombined =
        vtkSmartPointer<vtkExtractSelection>::New();
      extractSelectionCombined->SetInputConnection(0, pointSource->GetOutputPort());
      extractSelectionCombined->SetInputData(1, selectionCombined);
      extractSelectionCombined->Update();

      // In selection
      vtkDataSet* ds = vtkDataSet::SafeDownCast(extractSelectionCombined->GetOutput());
      std::cout << "There are " << ds->GetNumberOfPoints() << " points in the selection." << std::endl;
      std::cout << "There are " << ds->GetNumberOfCells() << " cells in the selection." << std::endl;

      /*
      // Not in selection
      selectionNode1->GetProperties()->Set(vtkSelectionNode::INVERSE(), 1); //invert the selection
      selectionNode2->GetProperties()->Set(vtkSelectionNode::INVERSE(), 1); //invert the selection
      extractSelection->Update();
      std::cout << "There are " << vtkDataSet::SafeDownCast (extractSelection->GetOutput())->GetNumberOfPoints()
                << " points not in the selection." << std::endl;
      */

      // Visualize
      vtkSmartPointer<vtkDataSetMapper> mapperOriginal =
        vtkSmartPointer<vtkDataSetMapper>::New();
      mapperOriginal->SetInputConnection(pointSource->GetOutputPort());
      mapperOriginal->ScalarVisibilityOff();

      vtkSmartPointer<vtkDataSetMapper> mapper1 =
        vtkSmartPointer<vtkDataSetMapper>::New();
      mapper1->SetInputConnection(extractSelection1->GetOutputPort());
      mapper1->ScalarVisibilityOff();

      vtkSmartPointer<vtkDataSetMapper> mapper2 =
        vtkSmartPointer<vtkDataSetMapper>::New();
      mapper2->SetInputConnection(extractSelection2->GetOutputPort());
      mapper2->ScalarVisibilityOff();

      vtkSmartPointer<vtkDataSetMapper> mapperCombined =
        vtkSmartPointer<vtkDataSetMapper>::New();
      mapperCombined->SetInputConnection(extractSelectionCombined->GetOutputPort());
      mapperCombined->ScalarVisibilityOff();

      vtkSmartPointer<vtkActor> originalActor =
        vtkSmartPointer<vtkActor>::New();
      originalActor->SetMapper(mapperOriginal);

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

      vtkSmartPointer<vtkActor> actor2 =
        vtkSmartPointer<vtkActor>::New();
      actor2->SetMapper(mapper2);

      vtkSmartPointer<vtkActor> actorCombined =
        vtkSmartPointer<vtkActor>::New();
      actorCombined->SetMapper(mapperCombined);

      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(1000,250);

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

      double originalViewport[4] = {0.0, 0.0, 0.25, 1.0};
      double selection1Viewport[4] = {0.25, 0.0, 0.5, 1.0};
      double selection2Viewport[4] = {0.5, 0.0, 0.75, 1.0};
      double selectionCombinedViewport[4] = {0.75, 0.0, 1.0, 1.0};

      vtkSmartPointer<vtkRenderer> originalRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      originalRenderer->SetViewport(originalViewport);

      vtkSmartPointer<vtkRenderer> selection1Renderer =
        vtkSmartPointer<vtkRenderer>::New();
      selection1Renderer->SetViewport(selection1Viewport);

      vtkSmartPointer<vtkRenderer> selection2Renderer =
        vtkSmartPointer<vtkRenderer>::New();
      selection2Renderer->SetViewport(selection2Viewport);

      vtkSmartPointer<vtkRenderer> selectionCombinedRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      selectionCombinedRenderer->SetViewport(selectionCombinedViewport);

      renderWindow->AddRenderer(originalRenderer);
      renderWindow->AddRenderer(selection1Renderer);
      renderWindow->AddRenderer(selection2Renderer);
      renderWindow->AddRenderer(selectionCombinedRenderer);

      originalRenderer->AddActor(originalActor);
      selection1Renderer->AddActor(actor1);
      selection2Renderer->AddActor(actor2);
      selectionCombinedRenderer->AddActor(actorCombined);
      //renderer->SetBackground(1,1,1); // Background color white

      renderWindow->Render();

      renderWindowInteractor->Start();
      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(MergeSelections)

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

### Download and Build MergeSelections

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

    cd MergeSelections/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:

    ./MergeSelections

WINDOWS USERS

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