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GraphToPolyData

vtk-examples/Cxx/Graphs/GraphToPolyData


Description

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

Other languages

See (Python)

Question

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

Code

GraphToPolyData.cxx

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

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  // Create a graph
  vtkNew<vtkMutableUndirectedGraph> g;

  // 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
  vtkNew<vtkPoints> points;
  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
  vtkNew<vtkGraphToPolyData> graphToPolyData;
  graphToPolyData->SetInputData(g);
  graphToPolyData->Update();

  // Create a mapper and actor
  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(graphToPolyData->GetOutputPort());

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);

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

  // Add the actor to the scene
  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("Green").GetData());

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(GraphToPolyData)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

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

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.