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# HighlightBadCells

VTKEx/Cxx/PolyData/HighlightBadCells

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See (CSharp)

Question

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### Code

HighlightBadCells.cxx

    #include <vtkSmartPointer.h>
    #include <vtkProperty.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkPolyData.h>
    #include <vtkThreshold.h>
    #include <vtkCellData.h>
    #include <vtkDoubleArray.h>
    #include <vtkDataSet.h>
    #include <vtkDataSetMapper.h>
    #include <vtkMeshQuality.h>
    #include <vtkSphereSource.h>
    #include <vtkTriangleFilter.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->Update();

      vtkSmartPointer<vtkTriangleFilter> triangleFilter =
          vtkSmartPointer<vtkTriangleFilter>::New();
      triangleFilter->SetInputConnection(sphereSource->GetOutputPort());
      triangleFilter->Update();

        //Create a mapper and actor
      vtkSmartPointer<vtkDataSetMapper> sphereMapper =
          vtkSmartPointer<vtkDataSetMapper>::New();
      sphereMapper->SetInputConnection(triangleFilter->GetOutputPort());
      vtkSmartPointer<vtkActor> sphereActor =
          vtkSmartPointer<vtkActor>::New();
      sphereActor->SetMapper(sphereMapper);

      vtkPolyData* mesh = triangleFilter->GetOutput();
      cout << "There are " << mesh->GetNumberOfCells() << " cells." << endl;

      vtkSmartPointer<vtkMeshQuality> qualityFilter =
          vtkSmartPointer<vtkMeshQuality>::New();
      qualityFilter->SetInputData(mesh);
      qualityFilter->SetTriangleQualityMeasureToArea();
      qualityFilter->Update();

      vtkDataSet* qualityMesh = qualityFilter->GetOutput();
      vtkSmartPointer<vtkDoubleArray> qualityArray =
        dynamic_cast<vtkDoubleArray*>(qualityMesh->GetCellData()->GetArray("Quality"));

      cout << "There are " << qualityArray->GetNumberOfTuples() << " values." << endl;

      for(vtkIdType i = 0; i < qualityArray->GetNumberOfTuples(); i++)
      {
        double val = qualityArray->GetValue(i);
        cout << "value " << i << " : " << val << endl;
      }

      vtkSmartPointer<vtkThreshold> selectCells =
        vtkSmartPointer<vtkThreshold>::New();
      selectCells->ThresholdByLower(.02);
      selectCells->SetInputArrayToProcess( 0, 0, 0, vtkDataObject::FIELD_ASSOCIATION_CELLS,
                  vtkDataSetAttributes::SCALARS );
      selectCells->SetInputData(qualityMesh);
      selectCells->Update();

      vtkUnstructuredGrid* ug = selectCells->GetOutput();

      // Create a mapper and actor
      vtkSmartPointer<vtkDataSetMapper> mapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      mapper->SetInputData(ug);

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetColor(1.0, 0.0, 0.0);
      actor->GetProperty()->SetRepresentationToWireframe();
      actor->GetProperty()->SetLineWidth(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 actors to the scene
      renderer->AddActor(actor);
      renderer->AddActor(sphereActor);
      renderer->SetBackground(1,1,1); // Background color white

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(HighlightBadCells)

    find_package(VTK COMPONENTS
      vtkvtkCommonCore
      vtkvtkCommonDataModel
      vtkvtkFiltersCore
      vtkvtkFiltersSources
      vtkvtkFiltersVerdict
      vtkvtkInteractionStyle
      vtkvtkRenderingContextOpenGL2
      vtkvtkRenderingCore
      vtkvtkRenderingFreeType
      vtkvtkRenderingGL2PSOpenGL2
      vtkvtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping HighlightBadCells: ${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(HighlightBadCells MACOSX_BUNDLE HighlightBadCells.cxx )
      target_link_libraries(HighlightBadCells PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(HighlightBadCells MACOSX_BUNDLE HighlightBadCells.cxx )
      target_link_libraries(HighlightBadCells PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS HighlightBadCells
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build HighlightBadCells

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

    cd HighlightBadCells/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:

    ./HighlightBadCells

WINDOWS USERS

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