CellEdges

#include <vtkIdList.h>
#include <vtkNew.h>
#include <vtkPoints.h>
#include <vtkTriangle.h>

int main(int, char*[])
{
  vtkNew<vtkTriangle> triangle;
  triangle->GetPoints()->SetPoint(0, 1.0, 0.0, 0.0);
  triangle->GetPoints()->SetPoint(1, 0.0, 0.0, 0.0);
  triangle->GetPoints()->SetPoint(2, 0.0, 1.0, 0.0);
  triangle->GetPointIds()->SetId(0, 0);
  triangle->GetPointIds()->SetId(1, 1);
  triangle->GetPointIds()->SetId(2, 2);

  std::cout << "The cell has " << triangle->GetNumberOfEdges() << " edges."
            << std::endl;

  for (vtkIdType i = 0; i < triangle->GetNumberOfEdges(); i++)
  {
    vtkCell* edge = triangle->GetEdge(i);

    vtkIdList* pointIdList = edge->GetPointIds();
    std::cout << "Edge " << i << " has " << pointIdList->GetNumberOfIds()
              << " points." << std::endl;

    for (vtkIdType p = 0; p < pointIdList->GetNumberOfIds(); p++)
    {
      std::cout << "Edge " << i << " uses point " << pointIdList->GetId(p)
                << std::endl;
    }
  }

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(CellEdges)

find_package(VTK COMPONENTS 
  CommonCore
  CommonDataModel
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "CellEdges: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(CellEdges MACOSX_BUNDLE CellEdges.cxx )
  target_link_libraries(CellEdges PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS CellEdges
  MODULES ${VTK_LIBRARIES}
)

cd CellEdges/build

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./CellEdges