VTK/Examples/Cxx/Developers/GraphAlgorithmSource

This example produces a vtkGraph as output.

GraphAlgorithmSource.cxx

#include <vtkSmartPointer.h>
#include <vtkGraph.h>
#include <vtkMutableUndirectedGraph.h>

#include "vtkTestGraphAlgorithmSource.h"

int main (int, char *[])
{
  vtkSmartPointer<vtkTestGraphAlgorithmSource> source =
    vtkSmartPointer<vtkTestGraphAlgorithmSource>::New();
  source->Update();
  
  vtkGraph* outputGraph = source->GetOutput();
  
  std::cout << "Output number of vertices: "
            << outputGraph->GetNumberOfVertices() << std::endl;
  
  return EXIT_SUCCESS;
}

vtkTestGraphAlgorithmSource.h

#ifndef __vtkTestGraphAlgorithmSource_h
#define __vtkTestGraphAlgorithmSource_h

#include "vtkGraphAlgorithm.h"

class vtkTestGraphAlgorithmSource : public vtkGraphAlgorithm 
{
public:
  static vtkTestGraphAlgorithmSource *New();
  vtkTypeMacro(vtkTestGraphAlgorithmSource,vtkGraphAlgorithm);
  void PrintSelf(ostream& os, vtkIndent indent);
	
protected:
  vtkTestGraphAlgorithmSource();
  ~vtkTestGraphAlgorithmSource();
  
  int RequestData(vtkInformation *, vtkInformationVector **, vtkInformationVector *);
  
  int RequestDataObject(vtkInformation *, vtkInformationVector **, vtkInformationVector *);

private:
  vtkTestGraphAlgorithmSource(const vtkTestGraphAlgorithmSource&);  // Not implemented.
  void operator=(const vtkTestGraphAlgorithmSource&);  // Not implemented.

};

#endif

vtkTestGraphAlgorithmSource.cxx

#include "vtkTestGraphAlgorithmSource.h"

#include "vtkObjectFactory.h"
#include "vtkStreamingDemandDrivenPipeline.h"
#include "vtkInformationVector.h"
#include "vtkInformation.h"
#include "vtkDataObject.h"
#include "vtkSmartPointer.h"
#include "vtkMutableUndirectedGraph.h"
#include "vtkUndirectedGraph.h"
#include "vtkGraph.h"

vtkStandardNewMacro(vtkTestGraphAlgorithmSource);

vtkTestGraphAlgorithmSource::vtkTestGraphAlgorithmSource()
{
  this->SetNumberOfInputPorts(0);
  this->SetNumberOfOutputPorts(1);
}

vtkTestGraphAlgorithmSource::~vtkTestGraphAlgorithmSource()
{

}

int vtkTestGraphAlgorithmSource::RequestData(
  vtkInformation *vtkNotUsed(request),
  vtkInformationVector **vtkNotUsed(inputVector),
  vtkInformationVector *outputVector)
{
  
  vtkInformation *outInfo = outputVector->GetInformationObject(0);
  
  vtkGraph *output = vtkGraph::SafeDownCast(
    outInfo->Get(vtkDataObject::DATA_OBJECT()));
  
  vtkSmartPointer<vtkMutableUndirectedGraph> NewGraph =
    vtkSmartPointer<vtkMutableUndirectedGraph>::New();
    
  //add 3 vertices
  NewGraph->AddVertex();
  NewGraph->AddVertex();
  NewGraph->AddVertex();
  
  output->ShallowCopy(NewGraph);
  
  return 1;
}

int vtkTestGraphAlgorithmSource::RequestDataObject(
  vtkInformation*, 
  vtkInformationVector**, 
  vtkInformationVector* )
{

  vtkUndirectedGraph *output = 0;
  output = vtkUndirectedGraph::New();
  
  
  this->GetExecutive()->SetOutputData(0, output);
  output->Delete();

  return 1;
}

//----------------------------------------------------------------------------
void vtkTestGraphAlgorithmSource::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os,indent);
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(GraphAlgorithmSource)

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

add_executable(GraphAlgorithmSource MACOSX_BUNDLE GraphAlgorithmSource vtkTestGraphAlgorithmSource)

if(VTK_LIBRARIES)
  target_link_libraries(GraphAlgorithmSource ${VTK_LIBRARIES})
else()
  target_link_libraries(GraphAlgorithmSource vtkHybrid vtkWidgets)
endif()

Download and Build GraphAlgorithmSource

Click here to download GraphAlgorithmSource. and its CMakeLists.txt file.

Once the tarball GraphAlgorithmSource.tar has been downloaded and extracted,

cd GraphAlgorithmSource/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:

./GraphAlgorithmSource

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.