# LoopBooleanPolyDataFilter

VTKExamples/Cxx/PolyData/LoopBooleanPolyDataFilter

### Description

The vtkLoopBooleanPolyDataFilter works best with "clean" data, so this examples first runs vtkTriangleFilter and then vtkCleanPolyData.

This example can be run in three ways:

1. LoopBooleanPolyDataFilter - Computes the intersection of two spheres

2. LoopBooleanPolyDataFilter intersection|difference|union - Computes the intersection(difference or union) of two spheres

3. LoopBooleanPolyDataFilter input1.vtk intersection|difference|union input2.vtk - Computes the intersection(difference or union) of two vtkPolyData's

Seealso

BooleanOperationPolyDataFilter uses an alternative algorithm to do the boolean operations.

### Code

LoopBooleanPolyDataFilter.cxx

    #include <vtkSmartPointer.h>
    #include <vtkLoopBooleanPolyDataFilter.h>

    #include <vtkCleanPolyData.h>
    #include <vtkTriangleFilter.h>
    #include <vtkActor.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkNamedColors.h>

    #include <vtkBYUReader.h>
    #include <vtkOBJReader.h>
    #include <vtkPLYReader.h>
    #include <vtkPolyDataReader.h>
    #include <vtkSTLReader.h>
    #include <vtkXMLPolyDataReader.h>
    #include <vtkSphereSource.h>
    #include <vtksys/SystemTools.hxx>

    #include <vtkCamera.h>
    namespace
    {
    vtkSmartPointer<vtkPolyData> ReadPolyData(const char *fileName);
    void PositionCamera(vtkSmartPointer<vtkRenderer> &renderer,
                        double *viewUp,
                        double *position);
    }

    int main(int argc, char *argv[])
    {
      vtkSmartPointer<vtkPolyData> input1;
      vtkSmartPointer<vtkPolyData> input2;

      std::string operation("intersection");

      if (argc == 4)
      {
        vtkSmartPointer<vtkPolyData> poly1;
        poly1 = ReadPolyData(argv[1]);
        vtkSmartPointer<vtkTriangleFilter> tri1 =
          vtkSmartPointer<vtkTriangleFilter>::New();
        tri1->SetInputData(poly1);
        vtkSmartPointer<vtkCleanPolyData> clean1 =
          vtkSmartPointer<vtkCleanPolyData>::New();
        clean1->SetInputConnection(tri1->GetOutputPort());
        clean1->Update();
        input1 = clean1->GetOutput();

        vtkSmartPointer<vtkPolyData> poly2;
        poly2 = ReadPolyData(argv[3]);
        vtkSmartPointer<vtkTriangleFilter> tri2 =
          vtkSmartPointer<vtkTriangleFilter>::New();
        tri2->SetInputData(poly2);
        tri2->Update();
        vtkSmartPointer<vtkCleanPolyData> clean2 =
          vtkSmartPointer<vtkCleanPolyData>::New();
        clean2->SetInputConnection(tri2->GetOutputPort());
        clean2->Update();
        input2 = clean2->GetOutput();
        operation = argv[2];
      }
      else
      {
        vtkSmartPointer<vtkSphereSource> sphereSource1 =
          vtkSmartPointer<vtkSphereSource>::New();
        sphereSource1->SetCenter(.25, 0, 0);
        sphereSource1->SetPhiResolution(21);
        sphereSource1->SetThetaResolution(21);
        sphereSource1->Update();
        input1 = sphereSource1->GetOutput();

        vtkSmartPointer<vtkSphereSource> sphereSource2 =
          vtkSmartPointer<vtkSphereSource>::New();
        sphereSource2->Update();
        input2 = sphereSource2->GetOutput();

        if (argc == 2)
        {
          operation = argv[1];
        }
      }

      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      vtkSmartPointer<vtkPolyDataMapper> input1Mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      input1Mapper->SetInputData( input1 );
      input1Mapper->ScalarVisibilityOff();
      vtkSmartPointer<vtkActor> input1Actor =
        vtkSmartPointer<vtkActor>::New();
      input1Actor->SetMapper( input1Mapper );
      input1Actor->GetProperty()->SetDiffuseColor(colors->GetColor3d("Tomato").GetData());
      input1Actor->GetProperty()->SetSpecular(.6);
      input1Actor->GetProperty()->SetSpecularPower(20);
      input1Actor->SetPosition(
        input1->GetBounds()[1]-input1->GetBounds()[0],
        0, 0);
      vtkSmartPointer<vtkPolyDataMapper> input2Mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      input2Mapper->SetInputData( input2 );
      input2Mapper->ScalarVisibilityOff();
      vtkSmartPointer<vtkActor> input2Actor =
        vtkSmartPointer<vtkActor>::New();
      input2Actor->SetMapper( input2Mapper );
      input2Actor->GetProperty()->SetDiffuseColor(colors->GetColor3d("Mint").GetData());
      input2Actor->GetProperty()->SetSpecular(.6);
      input2Actor->GetProperty()->SetSpecularPower(20);
      input2Actor->SetPosition(
        -(input1->GetBounds()[1]-input1->GetBounds()[0]),
        0, 0);
      vtkSmartPointer<vtkLoopBooleanPolyDataFilter> booleanOperation =
        vtkSmartPointer<vtkLoopBooleanPolyDataFilter>::New();
      if (operation == "union")
      {
          booleanOperation->SetOperationToUnion();
      }
      else if (operation == "intersection")
      {
          booleanOperation->SetOperationToIntersection();
      }
      else if (operation == "difference")
      {
          booleanOperation->SetOperationToDifference();
      }
      else
      {
        std::cout << "Unknown operation: " << operation << std::endl;
        return EXIT_FAILURE;
      }
      booleanOperation->SetInputData( 0, input1 );
      booleanOperation->SetInputData( 1, input2 );

      vtkSmartPointer<vtkPolyDataMapper> booleanOperationMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      booleanOperationMapper->SetInputConnection( booleanOperation->GetOutputPort() );
      booleanOperationMapper->ScalarVisibilityOff();

      vtkSmartPointer<vtkActor> booleanOperationActor =
        vtkSmartPointer<vtkActor>::New();
      booleanOperationActor->SetMapper( booleanOperationMapper );
      booleanOperationActor->GetProperty()->SetDiffuseColor(colors->GetColor3d("Banana").GetData());
      booleanOperationActor->GetProperty()->SetSpecular(.6);
      booleanOperationActor->GetProperty()->SetSpecularPower(20);

      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      renderer->AddViewProp(input1Actor);
      renderer->AddViewProp(input2Actor);
      renderer->AddViewProp(booleanOperationActor);
      renderer->SetBackground(colors->GetColor3d("Silver").GetData());
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer( renderer );
      renderWindow->SetSize(640, 480);
      double viewUp[3] = {0.0, 0.0, 1.0};
      double position[3] = {0.0, -1.0, 0.0};
      PositionCamera(renderer, viewUp, position);
      renderer->GetActiveCamera()->Dolly(1.5);
      renderer->ResetCameraClippingRange();

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

      renderWindow->Render();
      renWinInteractor->Start();

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

    void PositionCamera(vtkSmartPointer<vtkRenderer> &renderer,
                        double *viewUp,
                        double *position)
    {
      renderer->GetActiveCamera()->SetFocalPoint(0.0, 0.0, 0.0);
      renderer->GetActiveCamera()->SetViewUp(viewUp);
      renderer->GetActiveCamera()->SetPosition(position);
      renderer->ResetCamera();
      return;
    }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(LoopBooleanPolyDataFilter)

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

### Download and Build LoopBooleanPolyDataFilter

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

    cd LoopBooleanPolyDataFilter/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:

    ./LoopBooleanPolyDataFilter

WINDOWS USERS

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