# TreeToMutableDirectedGraph

VTKExamples/Cxx/Graphs/Conversions/TreeToMutableDirectedGraph

### Code

TreeToMutableDirectedGraph.cxx

    #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;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(TreeToMutableDirectedGraph)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(TreeToMutableDirectedGraph MACOSX_BUNDLE TreeToMutableDirectedGraph.cxx )

    target_link_libraries(TreeToMutableDirectedGraph ${VTK_LIBRARIES})

### Download and Build TreeToMutableDirectedGraph

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

    cd TreeToMutableDirectedGraph/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:

    ./TreeToMutableDirectedGraph

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