VTK/Examples/Cxx/Developers/GraphAlgorithmSource

This example produces a vtkGraph as output. Current it does not work - producing errors such as

You are trying to instantiate DataObjectType "vtkGraph" which does not exist.

and

Algorithm vtkTestSource(0x9fee918) did not create output for port 0 when asked by REQUEST_DATA_OBJECT and does not specify a concrete DATA_TYPE_NAME.

SourceExample.cxx

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

#include "vtkTestSource.h"

int main (int argc, char *argv[])
{
  vtkSmartPointer<vtkTestSource> source = vtkSmartPointer<vtkTestSource>::New();
  source->Update();
  
  vtkGraph* outputGraph = source->GetOutput();
  vtkstd::cout << "Output number of vertices: " << outputGraph->GetNumberOfVertices() << vtkstd::endl;
  
  return 0;
}

vtkTestSource.h

#ifndef __vtkTestSource_h
#define __vtkTestSource_h

#include "vtkGraphAlgorithm.h"

class vtkTestSource : public vtkGraphAlgorithm 
{
public:
  vtkTypeRevisionMacro(vtkTestSource,vtkGraphAlgorithm);
  void PrintSelf(ostream& os, vtkIndent indent);

  static vtkTestSource *New();
	
protected:
  vtkTestSource();
  ~vtkTestSource();
  
  //int RequestData(vtkInformation *, vtkInformationVector **, vtkInformationVector *);
  int RequestDataObject(vtkInformation *, vtkInformationVector **, vtkInformationVector *);

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

};

#endif

vtkTestSource.cxx

#include "vtkTestSource.h"

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

vtkCxxRevisionMacro(vtkTestSource, "$Revision: 1.70 $");
vtkStandardNewMacro(vtkTestSource);

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

vtkTestSource::~vtkTestSource()
{

}

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


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

CMakeLists.txt

cmake_minimum_required(VERSION 2.6)
PROJECT(vtkGraphAlgorithmSource)

FIND_PACKAGE(VTK REQUIRED)
INCLUDE(${VTK_USE_FILE})

ADD_EXECUTABLE(SourceExample SourceExample.cxx vtkTestSource.cxx)
TARGET_LINK_LIBRARIES(SourceExample vtkHybrid)