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PointInPolygon

vtk-examples/Cxx/Utilities/PointInPolygon

Question

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Code

PointInPolygon.cxx

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

int main(int, char*[])
{
  // Create the polygon
  vtkNew<vtkPolygon> polygon;
  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.