# AdjacentVertexIterator

VTKExamples/Cxx/Graphs/AdjacentVertexIterator

### Description

The visualization in is example is currently broken. vtkGraphLayoutView does not currently allow coloring with a vtkUnsignedCharArray.

### Code

AdjacentVertexIterator.cxx

    #include <vtkMutableUndirectedGraph.h>
    #include <vtkSmartPointer.h>
    #include <vtkAdjacentVertexIterator.h>
    #include <vtkUnsignedCharArray.h>
    #include <vtkLookupTable.h>
    #include <vtkMutableDirectedGraph.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkViewTheme.h>
    #include <vtkDataSetAttributes.h>
    #include <vtkGraphLayoutView.h>

    // For compatibility with new VTK generic data arrays
    #ifdef vtkGenericDataArray_h
    #define InsertNextTupleValue InsertNextTypedTuple
    #endif

    int main(int, char *[])
    {
      vtkSmartPointer<vtkMutableUndirectedGraph> g =
        vtkSmartPointer<vtkMutableUndirectedGraph>::New();

      //create 3 vertices
      vtkIdType v0 = g->AddVertex();
      vtkIdType v1 = g->AddVertex();
      vtkIdType v2 = g->AddVertex();
      vtkIdType v3 = g->AddVertex();

      //add edges
      g->AddEdge(v0, v1);
      g->AddEdge(v0, v2);
      g->AddEdge(v2, v3);

      // Create the color array
      vtkSmartPointer<vtkUnsignedCharArray> vertexColors =
        vtkSmartPointer<vtkUnsignedCharArray>::New();
      vertexColors->SetNumberOfComponents(3);
      vertexColors->SetName("color");

      //setup colors
      unsigned char red[3] = {255, 0, 0};
      unsigned char green[3] = {0, 255, 0};
      unsigned char blue[3] = {0, 0, 255};

      for(unsigned int i = 0; i < 4; i++)
      {
        vertexColors->InsertNextTupleValue(blue);//not connected vertices
      }

      vtkSmartPointer<vtkAdjacentVertexIterator> iterator =
        vtkSmartPointer<vtkAdjacentVertexIterator>::New();
      g->GetAdjacentVertices(0, iterator);

      vertexColors->SetTupleValue(0, red);//origin

      while(iterator->HasNext())
      {
        vtkIdType nextVertex = iterator->Next();
        std::cout << "Next vertex: " << nextVertex << std::endl;
        vertexColors->SetTupleValue(nextVertex, green);//connected vertices
      }

      // Add the color array to the graph
      g->GetVertexData()->AddArray(vertexColors);

      vtkSmartPointer<vtkGraphLayoutView> graphLayoutView =
        vtkSmartPointer<vtkGraphLayoutView>::New();
      graphLayoutView->AddRepresentationFromInput(g);
      graphLayoutView->SetLayoutStrategyToTree();

      graphLayoutView->SetVertexColorArrayName("color");
      graphLayoutView->ColorVerticesOn();

      vtkSmartPointer<vtkViewTheme> theme =
        vtkSmartPointer<vtkViewTheme>::New();
      //theme->SetPointLookupTable(lookupTable);
      theme->ScalePointLookupTableOff();
      graphLayoutView->ApplyViewTheme(theme);

      graphLayoutView->ResetCamera();
      graphLayoutView->GetInteractor()->Initialize();
      graphLayoutView->GetInteractor()->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(AdjacentVertexIterator)

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

    add_executable(AdjacentVertexIterator MACOSX_BUNDLE AdjacentVertexIterator.cxx )

    target_link_libraries(AdjacentVertexIterator ${VTK_LIBRARIES})

### Download and Build AdjacentVertexIterator

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

    cd AdjacentVertexIterator/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:

    ./AdjacentVertexIterator

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.