# PointInPolygon

VTKExamples/Cxx/Utilities/PointInPolygon

### Code

PointInPolygon.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPoints.h>
    #include <vtkPolygon.h>

    int main(int, char *[])
    {
      // Create the polygon
      vtkSmartPointer<vtkPolygon> polygon =
        vtkSmartPointer<vtkPolygon>::New();
      polygon->GetPoints()->InsertNextPoint(0.0, 0.0, 0.0);
      polygon->GetPoints()->InsertNextPoint(1.0, 0.0, 0.0);
      polygon->GetPoints()->InsertNextPoint(1.0, 1.0, 0.0);
      polygon->GetPoints()->InsertNextPoint(0.0, 1.0, 0.0);

      double testIn[3] = {0.5, 0.5, 0.0};
      double testOut[3] = {2.0, 0.5, 0.0};

      double n[3];
      polygon->ComputeNormal(polygon->GetPoints()->GetNumberOfPoints(),
              static_cast<double*>(polygon->GetPoints()->GetData()->GetVoidPointer(0)), n);

      double bounds[6];
      polygon->GetPoints()->GetBounds(bounds);

      std::cout << "testIn in polygon? " << polygon->PointInPolygon(testIn,
          polygon->GetPoints()->GetNumberOfPoints(), static_cast<double*>(
          polygon->GetPoints()->GetData()->GetVoidPointer(0)), bounds, n) << std::endl;

      std::cout << "testOut in polygon? " << polygon->PointInPolygon(testOut,
          polygon->GetPoints()->GetNumberOfPoints(), static_cast<double*>(
          polygon->GetPoints()->GetData()->GetVoidPointer(0)), bounds, n) << std::endl;

      /*
      std::cout << "New functions:" << std::endl;

      std::cout << "testIn in polygon? " << polygon->PointInPolygon(testIn) << std::endl;

      std::cout << "testOut in polygon? " << polygon->PointInPolygon(testOut) << std::endl;
      */
      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(PointInPolygon)

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

### Download and Build PointInPolygon

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

    cd PointInPolygon/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:

    ./PointInPolygon

WINDOWS USERS

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