Skip to content

OutEdgeIterator

vtk-examples/Cxx/Graphs/OutEdgeIterator

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

OutEdgeIterator.cxx

#include <vtkMutableUndirectedGraph.h>
#include <vtkMutableDirectedGraph.h>
#include <vtkNew.h>
#include <vtkOutEdgeIterator.h>

namespace {

void Undirected();

void Directed();

}

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

  return EXIT_SUCCESS;
}

namespace {
void Undirected()
{
  vtkNew<vtkMutableUndirectedGraph> g;

  // 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 outgoing edges connected to a vertex
  vtkNew<vtkOutEdgeIterator> it;
  g->GetOutEdges(0, it); // Get the edges connected to vertex 0

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

void Directed()
{
  vtkNew<vtkMutableDirectedGraph> g;

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

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

  {
    std::cout << "Finding edges connected to vertex 0" << std::endl;
    vtkNew<vtkOutEdgeIterator> it;
    g->GetOutEdges(0, it);

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

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

  {
    std::cout << "Finding edges connected to vertex 1" << std::endl;
    vtkNew<vtkOutEdgeIterator> it;
    g->GetOutEdges(1, it);

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

}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(OutEdgeIterator)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping OutEdgeIterator: ${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(OutEdgeIterator MACOSX_BUNDLE OutEdgeIterator.cxx )
  target_link_libraries(OutEdgeIterator PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(OutEdgeIterator MACOSX_BUNDLE OutEdgeIterator.cxx )
  target_link_libraries(OutEdgeIterator PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS OutEdgeIterator
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build OutEdgeIterator

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

cd OutEdgeIterator/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:

./OutEdgeIterator

WINDOWS USERS

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