BreadthFirstDistance

VTKExamples/Cxx/Graphs/BreadthFirstDistance

Description

This example shows how to get the distance from a vertex to the root vertex.

Question

If you have a simple question about this example contact us at VTKExamplesProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

BreadthFirstDistance.cxx

#include <vtkSmartPointer.h>

#include <vtkBoostBreadthFirstSearch.h>
#include <vtkDataSetAttributes.h>
#include <vtkDoubleArray.h>
#include <vtkIntArray.h>
#include <vtkMutableUndirectedGraph.h>
#include <vtkTree.h>

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

  // Create 3 vertices
  vtkIdType v1 = g->AddVertex();
  vtkIdType v2 = g->AddVertex();
  vtkIdType v3 = g->AddVertex();
  vtkIdType v4 = g->AddVertex();

  // Create a graph
  g->AddEdge(v1, v2);
  g->AddEdge(v1, v3);
  g->AddEdge(v2, v4);

  vtkSmartPointer<vtkBoostBreadthFirstSearch> BFS =
    vtkSmartPointer<vtkBoostBreadthFirstSearch>::New();
  BFS->SetOriginVertex(v1);
  BFS->SetInput(g);
  BFS->Update();

  vtkIntArray* level = dynamic_cast<vtkIntArray*>(
    BFS->GetOutput()->GetVertexData()->GetArray("BFS"));
  for(vtkIdType i = 0; i < level->GetNumberOfTuples(); i++)
  {
    std::cout << "id " << i << " : " << level->GetValue(i) << std::endl;
  }
  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(BreadthFirstDistance)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkInfovisBoostGraphAlgorithms QUIET)
if (NOT VTK_FOUND)
  message("Skipping BreadthFirstDistance: ${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(BreadthFirstDistance MACOSX_BUNDLE BreadthFirstDistance.cxx )
  target_link_libraries(BreadthFirstDistance PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(BreadthFirstDistance MACOSX_BUNDLE BreadthFirstDistance.cxx )
  target_link_libraries(BreadthFirstDistance PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS BreadthFirstDistance
    MODULES ${VTK_LIBRARIES}
    )
endif () 

Download and Build BreadthFirstDistance

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

cd BreadthFirstDistance/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:

./BreadthFirstDistance

WINDOWS USERS

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