BreadthFirstDistance

Description¶

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

Question

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

Code¶

BreadthFirstDistance.cxx

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

int main(int, char*[])
{
  vtkNew<vtkMutableUndirectedGraph> g;

  // 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);

  vtkNew<vtkBoostBreadthFirstSearch> BFS;
  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 3.12 FATAL_ERROR)

project(BreadthFirstDistance)

find_package(VTK COMPONENTS 
  CommonCore
  CommonDataModel
  InfovisBoostGraphAlgorithms
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "BreadthFirstDistance: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
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}
)

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.