VTK/Examples/Cxx/Graphs/BreadthFirstDistance

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

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 = vtkIntArray::SafeDownCast(
    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;
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(BreadthFirstDistance)

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

add_executable(BreadthFirstDistance MACOSX_BUNDLE BreadthFirstDistance.cxx)

if(VTK_LIBRARIES)
  target_link_libraries(BreadthFirstDistance ${VTK_LIBRARIES})
else()
  target_link_libraries(BreadthFirstDistance vtkHybrid vtkWidgets)
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 PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.