# InEdgeIterator

VTKExamples/Cxx/Graphs/InEdgeIterator

### Code

InEdgeIterator.cxx

    #include <vtkMutableUndirectedGraph.h>
    #include <vtkMutableDirectedGraph.h>
    #include <vtkSmartPointer.h>
    #include <vtkInEdgeIterator.h>

    static void Undirected();
    static void Directed();

    int main(int, char *[])
    {
      Undirected();
      Directed();

      return EXIT_SUCCESS;
    }

    void Undirected()
    {
      vtkSmartPointer<vtkMutableUndirectedGraph> g =
        vtkSmartPointer<vtkMutableUndirectedGraph>::New();

      // Create a graph
      vtkIdType v0 = g->AddVertex();
      vtkIdType v1 = g->AddVertex();
      vtkIdType v2 = g->AddVertex();

      g->AddEdge(v0, v1);
      g->AddEdge(v1, v2);
      g->AddEdge(v0, v2);

      // Find all incoming edges connected to a vertex
      vtkSmartPointer<vtkInEdgeIterator> it =
        vtkSmartPointer<vtkInEdgeIterator>::New();
      g->GetInEdges(0, it);

      while(it->HasNext())
      {
        vtkInEdgeType edge = it->Next();
        std::cout << "Edge id: " << edge.Id << " Source: " << edge.Source << std::endl;
      }
    }

    void Directed()
    {
      vtkSmartPointer<vtkMutableDirectedGraph> g =
        vtkSmartPointer<vtkMutableDirectedGraph>::New();

      // Create a graph
      vtkIdType v0 = g->AddVertex();
      vtkIdType v1 = g->AddVertex();
      vtkIdType v2 = g->AddVertex();

      g->AddEdge(v0, v1);
      g->AddEdge(v0, v2);

      {
      std::cout << "Finding edges connected to vertex 0" << std::endl;
      vtkSmartPointer<vtkInEdgeIterator> it =
        vtkSmartPointer<vtkInEdgeIterator>::New();
      g->GetInEdges(0, it);

      while(it->HasNext())
      {
        vtkInEdgeType edge = it->Next();
        std::cout << "Edge id: " << edge.Id << " " << "Source: " << edge.Source << std::endl;
      }

      std::cout << "Nothing should be output, vertex 0 has no incoming edges!" << std::endl;
      }

      {
      std::cout << "Finding edges connected to vertex 1" << std::endl;
      vtkSmartPointer<vtkInEdgeIterator> it =
        vtkSmartPointer<vtkInEdgeIterator>::New();
      g->GetInEdges(1, it);

      while(it->HasNext())
      {
        vtkInEdgeType edge = it->Next();
        std::cout << "Edge id: " << edge.Id << " " << "Source: " << edge.Source << std::endl;
      }
      }

    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(InEdgeIterator)

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

    add_executable(InEdgeIterator MACOSX_BUNDLE InEdgeIterator.cxx )

    target_link_libraries(InEdgeIterator ${VTK_LIBRARIES})

### Download and Build InEdgeIterator

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

    cd InEdgeIterator/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:

    ./InEdgeIterator

WINDOWS USERS

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