GraphToPolyData

VTKExamples/Cxx/Graphs/GraphToPolyData


Description

This example creates a simple graph and then converts it to a polydata for visualization using Paraview.

Code

GraphToPolyData.cxx

#include <vtkSmartPointer.h>
#include <vtkPoints.h>
#include <vtkMutableUndirectedGraph.h>
#include <vtkGraphToPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>

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

  // Add 4 vertices to the graph
  vtkIdType v1 = g->AddVertex();
  vtkIdType v2 = g->AddVertex();
  vtkIdType v3 = g->AddVertex();
  vtkIdType v4 = g->AddVertex();

  // Add 3 edges to the graph
  g->AddEdge ( v1, v2 );
  g->AddEdge ( v1, v3 );
  g->AddEdge ( v1, v4 );

  // Create 4 points - one for each vertex
  vtkSmartPointer<vtkPoints> points = 
    vtkSmartPointer<vtkPoints>::New();
  points->InsertNextPoint(0.0, 0.0, 0.0);
  points->InsertNextPoint(1.0, 0.0, 0.0);
  points->InsertNextPoint(0.0, 1.0, 0.0);
  points->InsertNextPoint(0.0, 0.0, 1.0);

  // Add the coordinates of the points to the graph
  g->SetPoints(points);

  // Convert the graph to a polydata
  vtkSmartPointer<vtkGraphToPolyData> graphToPolyData = 
      vtkSmartPointer<vtkGraphToPolyData>::New();
  graphToPolyData->SetInput(g);
  graphToPolyData->Update();

  // Create a mapper and actor
  vtkSmartPointer<vtkPolyDataMapper> mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(graphToPolyData->GetOutputPort());

  vtkSmartPointer<vtkActor> actor = 
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  // Create a renderer, render window, and interactor
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actor to the scene
  renderer->AddActor(actor);
  renderer->SetBackground(.3, .6, .3); // Background color green

  // Render and interact
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(GraphToPolyData)

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

add_executable(GraphToPolyData MACOSX_BUNDLE GraphToPolyData.cxx )

target_link_libraries(GraphToPolyData ${VTK_LIBRARIES})

Download and Build GraphToPolyData

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

cd GraphToPolyData/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:

./GraphToPolyData

WINDOWS USERS

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