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# Polyhedron

VTKEx/Cxx/GeometricObjects/Polyhedron

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See (Python)

Question

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### Code

Polyhedron.cxx

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkCellArray.h>
    #include <vtkCellData.h>
    #include <vtkDataArray.h>
    #include <vtkDataSetMapper.h>
    #include <vtkIdList.h>
    #include <vtkNamedColors.h>
    #include <vtkPointData.h>
    #include <vtkPoints.h>
    #include <vtkPolyhedron.h>
    #include <vtkProperty.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkSmartPointer.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkXMLUnstructuredGridWriter.h>

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

      // create polyhedron (cube)
      vtkIdType pointIds[8] = {0, 1, 2, 3, 4, 5, 6, 7};

      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(-1.0,-1.0,-1.0);
      points->InsertNextPoint( 1.0,-1.0,-1.0);
      points->InsertNextPoint( 1.0, 1.0,-1.0);
      points->InsertNextPoint(-1.0, 1.0,-1.0);
      points->InsertNextPoint(-1.0,-1.0, 1.0);
      points->InsertNextPoint( 1.0,-1.0, 1.0);
      points->InsertNextPoint( 1.0, 1.0, 1.0);
      points->InsertNextPoint(-1.0, 1.0, 1.0);

      vtkNew<vtkIdList> faces;
      vtkIdType face0[4] = {0, 3, 2, 1};
      vtkIdType face1[4] = {0, 4, 7, 3};
      vtkIdType face2[4] = {4, 5, 6, 7};
      vtkIdType face3[4] = {5, 1, 2, 6};
      vtkIdType face4[4] = {0, 1, 5, 4};
      vtkIdType face5[4] = {2, 3, 7, 6};

      auto addFace = [&](const vtkIdType face[4])
      {
        faces->InsertNextId(4);
        for (int i = 0; i < 4; ++i)
        {
          faces->InsertNextId(face[i]);
        }
      };

      addFace(face0);
      addFace(face1);
      addFace(face2);
      addFace(face3);
      addFace(face4);
      addFace(face5);

      vtkSmartPointer<vtkUnstructuredGrid> ugrid =
        vtkSmartPointer<vtkUnstructuredGrid>::New();
      ugrid->SetPoints(points);
      ugrid->InsertNextCell(
        VTK_POLYHEDRON, 8, pointIds,
        6, faces->GetPointer(0));

      // Here we write out the cube.
      vtkSmartPointer<vtkXMLUnstructuredGridWriter> writer =
        vtkSmartPointer<vtkXMLUnstructuredGridWriter>::New();
      writer->SetInputData(ugrid);
      writer->SetFileName("polyhedron.vtu");
      writer->SetDataModeToAscii();
      writer->Update();

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

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetColor(
        colors->GetColor3d("Silver").GetData());

      // Visualize
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetWindowName("Polyhedron");
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      renderer->AddActor(actor);
      renderer->SetBackground(colors->GetColor3d("Salmon").GetData());
      renderer->ResetCamera();
      renderer->GetActiveCamera()->Azimuth(30);
      renderer->GetActiveCamera()->Elevation(30);
      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(Polyhedron)

    find_package(VTK COMPONENTS
      vtkCommonColor
      vtkCommonCore
      vtkCommonDataModel
      vtkIOXML
      vtkInteractionStyle
      vtkRenderingContextOpenGL2
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingGL2PSOpenGL2
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping Polyhedron: ${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(Polyhedron MACOSX_BUNDLE Polyhedron.cxx )
      target_link_libraries(Polyhedron PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(Polyhedron MACOSX_BUNDLE Polyhedron.cxx )
      target_link_libraries(Polyhedron PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS Polyhedron
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build Polyhedron

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

    cd Polyhedron/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:

    ./Polyhedron

WINDOWS USERS

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