TreeToMutableDirectedGraph

#include <vtkSmartPointer.h>
#include <vtkPoints.h>
#include <vtkMutableDirectedGraph.h>
#include <vtkDirectedGraph.h>
#include <vtkTree.h>

int main (int, char *[])
{

  //create a graph
  vtkSmartPointer<vtkMutableDirectedGraph> mdg =
    vtkSmartPointer<vtkMutableDirectedGraph>::New();

  //add 4 vertices to the graph
  vtkIdType v1 = mdg->AddVertex();
  vtkIdType v2 = mdg->AddVertex();
  vtkIdType v3 = mdg->AddVertex();
  vtkIdType v4 = mdg->AddVertex();

  //add 3 edges to the graph
  mdg->AddEdge ( v1, v2 );
  mdg->AddEdge ( v1, v3 );
  mdg->AddEdge ( v1, v4 );

  //create 4 points - one for each vertex
  vtkSmartPointer<vtkPoints> points =
      vtkSmartPointer<vtkPoints>::New();
  points->InsertNextPoint(0.0, 0.0, 0.0);
  points->InsertNextPoint(1.0, 0.0, 0.0);
  points->InsertNextPoint(0.0, 1.0, 0.0);
  points->InsertNextPoint(0.0, 0.0, 2.0);

  //add the coordinates of the points to the graph
  mdg->SetPoints(points);

  std::cout << "MDG: " << std::endl;
  std::cout << "Type: " << mdg->GetClassName() << std::endl;
  std::cout << "Vertices: " << mdg->GetNumberOfVertices() << std::endl;
  std::cout << "Edges: " << mdg->GetNumberOfEdges() << std::endl;

  vtkSmartPointer<vtkTree> tree =
    vtkSmartPointer<vtkTree>::New();
  tree->CheckedShallowCopy(mdg);

  std::cout << "Tree: " << std::endl;
  std::cout << "Type: " << tree->GetClassName() << std::endl;
  std::cout << "Vertices: " << tree->GetNumberOfVertices() << std::endl;
  std::cout << "Edges: " << tree->GetNumberOfEdges() << std::endl;

  vtkSmartPointer<vtkMutableDirectedGraph> mdg2 =
      vtkSmartPointer<vtkMutableDirectedGraph>::New();
  if(!mdg2->CheckedShallowCopy(tree))
  {
    std::cerr << "Could not convert!" << std::endl;
    return EXIT_FAILURE;
  }

  std::cout << "MDG2: " << std::endl;
  std::cout << "Type: " << mdg2->GetClassName() << std::endl;
  std::cout << "Vertices: " << mdg2->GetNumberOfVertices() << std::endl;
  std::cout << "Edges: " << mdg2->GetNumberOfEdges() << std::endl;

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(TreeToMutableDirectedGraph)

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

cd TreeToMutableDirectedGraph/build

cmake ..

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

make

./TreeToMutableDirectedGraph