# ColorEdges

VTKExamples/Cxx/Graphs/ColorEdges

### Code

ColorEdges.cxx

    #include <vtkSmartPointer.h>
    #include <vtkDataSetAttributes.h>
    #include <vtkGraphLayoutView.h>
    #include <vtkIntArray.h>
    #include <vtkLookupTable.h>
    #include <vtkMutableDirectedGraph.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkViewTheme.h>

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

      // Create a graph
      vtkIdType v1 = graph->AddVertex();
      vtkIdType v2 = graph->AddVertex();
      vtkIdType v3 = graph->AddVertex();
      graph->AddEdge(v1,v2);
      graph->AddEdge(v2,v3);

      // Create the color array
      vtkSmartPointer<vtkIntArray> edgeColors =
        vtkSmartPointer<vtkIntArray>::New();
      edgeColors->SetNumberOfComponents(1);
      edgeColors->SetName("Color");

      vtkSmartPointer<vtkLookupTable> lookupTable =
        vtkSmartPointer<vtkLookupTable>::New();
      lookupTable->SetNumberOfTableValues(2);
      lookupTable->SetTableValue(0, 1.0, 0.0, 0.0); // red
      lookupTable->SetTableValue(1, 0.0, 1.0, 0.0); // green
      lookupTable->Build();

      edgeColors->InsertNextValue(0);
      edgeColors->InsertNextValue(1);

      // Add the color array to the graph
      graph->GetEdgeData()->AddArray(edgeColors);

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

      graphLayoutView->SetEdgeColorArrayName("Color");
      graphLayoutView->ColorEdgesOn();

      vtkSmartPointer<vtkViewTheme> theme =
        vtkSmartPointer<vtkViewTheme>::New();
      theme->SetCellLookupTable(lookupTable);

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ColorEdges)

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

    add_executable(ColorEdges MACOSX_BUNDLE ColorEdges.cxx)

    target_link_libraries(ColorEdges ${VTK_LIBRARIES})

### Download and Build ColorEdges

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

    cd ColorEdges/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:

    ./ColorEdges

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.