# MutableDirectedGraphToDirectedGraph

VTKExamples/Cxx/Graphs/MutableDirectedGraphToDirectedGraph

### Code

MutableDirectedGraphToDirectedGraph.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPoints.h>
    #include <vtkMutableDirectedGraph.h>
    #include <vtkDirectedGraph.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<vtkDirectedGraph> dg =
          vtkSmartPointer<vtkDirectedGraph>::New();
      if(!dg->CheckedShallowCopy(mdg))
      {
        std::cerr << "Could not convert graph to tree!" << std::endl;
        return EXIT_FAILURE;
      }

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(MutableDirectedGraphToDirectedGraph)

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

### Download and Build MutableDirectedGraphToDirectedGraph

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

    cd MutableDirectedGraphToDirectedGraph/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:

    ./MutableDirectedGraphToDirectedGraph

WINDOWS USERS

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