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# Shadows

VTKEx/Cxx/Rendering/Shadows

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See (Python)

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

### Code

Shadows.cxx

    // test baking shadow maps

    #include <vtkSmartPointer.h>

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkCameraPass.h>
    #include <vtkCellArray.h>
    #include <vtkCubeSource.h>
    #include <vtkLight.h>
    #include <vtkNamedColors.h>
    #include <vtkOpenGLRenderer.h>
    #include <vtkOpenGLTexture.h>
    #include <vtkPlaneSource.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkRenderPassCollection.h>
    #include <vtkRenderStepsPass.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkSequencePass.h>
    #include <vtkShadowMapBakerPass.h>
    #include <vtkShadowMapPass.h>

    #include <vtkBYUReader.h>
    #include <vtkOBJReader.h>
    #include <vtkPLYReader.h>
    #include <vtkPolyDataReader.h>
    #include <vtkSTLReader.h>
    #include <vtkSphereSource.h>
    #include <vtkXMLPolyDataReader.h>

    #include <array>
    #include <vtksys/SystemTools.hxx>

    namespace {
    vtkSmartPointer<vtkPolyData> ReadPolyData(const char* fileName);
    }

    //----------------------------------------------------------------------------
    int main(int argc, char* argv[])
    {
      // Read the polyData
      auto polyData = ReadPolyData(argc > 1 ? argv[1] : "");
      ;

      auto colors = vtkSmartPointer<vtkNamedColors>::New();
      colors->SetColor("HighNoonSun", 1.0, 1.0, .9843, 1.0); // Color temp. 5400k
      colors->SetColor("100W Tungsten", 1.0, .8392, .6667,
                       1.0); // Color temp. 2850k

      auto renderer = vtkSmartPointer<vtkRenderer>::New();
      renderer->SetBackground(colors->GetColor3d("Silver").GetData());

      auto renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(640, 480);
      renderWindow->AddRenderer(renderer);

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

      auto light1 = vtkSmartPointer<vtkLight>::New();
      light1->SetFocalPoint(0, 0, 0);
      light1->SetPosition(0, 1, 0.2);
      light1->SetColor(colors->GetColor3d("HighNoonSun").GetData());
      light1->SetIntensity(0.3);
      renderer->AddLight(light1);

      auto light2 = vtkSmartPointer<vtkLight>::New();
      light2->SetFocalPoint(0, 0, 0);
      light2->SetPosition(1.0, 1.0, 1.0);
      light2->SetColor(colors->GetColor3d("100W Tungsten").GetData());
      light2->SetIntensity(0.8);
      renderer->AddLight(light2);

      auto mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputData(polyData);

      auto actor = vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetAmbientColor(
          colors->GetColor3d("SaddleBrown").GetData());
      actor->GetProperty()->SetDiffuseColor(colors->GetColor3d("Sienna").GetData());
      actor->GetProperty()->SetSpecularColor(colors->GetColor3d("White").GetData());
      actor->GetProperty()->SetSpecular(0.51);
      actor->GetProperty()->SetDiffuse(0.7);
      actor->GetProperty()->SetAmbient(0.7);
      actor->GetProperty()->SetSpecularPower(30.0);
      actor->GetProperty()->SetOpacity(1.0);
      renderer->AddActor(actor);

      // add a plane
      std::array<double, 6> bounds;
      polyData->GetBounds(bounds.data());

      std::array<double, 3> range;
      range[0] = bounds[1] - bounds[0];
      range[1] = bounds[3] - bounds[2];
      range[2] = bounds[5] - bounds[4];
      std::cout << "range: " << range[0] << "," << range[1] << "," << range[2]
                << std::endl;
      double expand = 1.0;
      auto thickness = range[2] * 0.1;
      auto plane = vtkSmartPointer<vtkCubeSource>::New();
      plane->SetCenter((bounds[1] + bounds[0]) / 2.0, bounds[2] - thickness / 2.0,
                       (bounds[5] + bounds[4]) / 2.0);
      plane->SetXLength(bounds[1] - bounds[0] + (range[0] * expand));
      plane->SetYLength(thickness);
      plane->SetZLength(bounds[5] - bounds[4] + (range[2] * expand));

      auto planeMapper = vtkSmartPointer<vtkPolyDataMapper>::New();
      planeMapper->SetInputConnection(plane->GetOutputPort());

      auto planeActor = vtkSmartPointer<vtkActor>::New();
      planeActor->SetMapper(planeMapper);
      renderer->AddActor(planeActor);

      renderWindow->SetMultiSamples(0);

      auto shadows = vtkSmartPointer<vtkShadowMapPass>::New();

      auto seq = vtkSmartPointer<vtkSequencePass>::New();

      auto passes = vtkSmartPointer<vtkRenderPassCollection>::New();
      passes->AddItem(shadows->GetShadowMapBakerPass());
      passes->AddItem(shadows);
      seq->SetPasses(passes);

      auto cameraP = vtkSmartPointer<vtkCameraPass>::New();
      cameraP->SetDelegatePass(seq);

      // tell the renderer to use our render pass pipeline
      vtkOpenGLRenderer* glrenderer =
          dynamic_cast<vtkOpenGLRenderer*>(renderer.GetPointer());
      glrenderer->SetPass(cameraP);

      renderer->GetActiveCamera()->SetPosition(-0.2, 0.2, 1);
      renderer->GetActiveCamera()->SetFocalPoint(0, 0, 0);
      renderer->GetActiveCamera()->SetViewUp(0, 1, 0);
      renderer->ResetCamera();
      renderer->GetActiveCamera()->Dolly(2.25);
      renderer->ResetCameraClippingRange();
      renderWindow->Render();
      renderWindow->SetWindowName("Shadows");

      interactor->Start();

      return EXIT_SUCCESS;
    }

    namespace {
    vtkSmartPointer<vtkPolyData> ReadPolyData(const char* fileName)
    {
      vtkSmartPointer<vtkPolyData> polyData;
      std::string extension =
          vtksys::SystemTools::GetFilenameLastExtension(std::string(fileName));
      if (extension == ".ply")
      {
        auto reader = vtkSmartPointer<vtkPLYReader>::New();
        reader->SetFileName(fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtp")
      {
        auto reader = vtkSmartPointer<vtkXMLPolyDataReader>::New();
        reader->SetFileName(fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".obj")
      {
        auto reader = vtkSmartPointer<vtkOBJReader>::New();
        reader->SetFileName(fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".stl")
      {
        auto reader = vtkSmartPointer<vtkSTLReader>::New();
        reader->SetFileName(fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtk")
      {
        auto reader = vtkSmartPointer<vtkPolyDataReader>::New();
        reader->SetFileName(fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".g")
      {
        auto reader = vtkSmartPointer<vtkBYUReader>::New();
        reader->SetGeometryFileName(fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else
      {
        auto source = vtkSmartPointer<vtkSphereSource>::New();
        source->SetThetaResolution(100);
        source->SetPhiResolution(100);
        source->Update();
        polyData = source->GetOutput();
      }
      return polyData;
    }
    } // namespace

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(Shadows)

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

### Download and Build Shadows

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

    cd Shadows/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:

    ./Shadows

WINDOWS USERS

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