GraphAlgorithmSource

Description¶

This example produces a vtkGraph as output.

You will need the following in your CMakeLists.txt file:

find_package(VTK
 COMPONENTS
    CommonCore
    CommonDataModel
    CommonExecutionModel
    FiltersSources
    InfovisCore
)

Question

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

Code¶

GraphAlgorithmSource.cxx

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

#include "vtkTestGraphAlgorithmSource.h"

int main(int, char*[])
{
  vtkNew<vtkTestGraphAlgorithmSource> source;
  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) override;

protected:
  vtkTestGraphAlgorithmSource();
  ~vtkTestGraphAlgorithmSource();

  int RequestData(vtkInformation*, vtkInformationVector**,
                  vtkInformationVector*) override;

  int RequestDataObject(vtkInformation*, vtkInformationVector**,
                        vtkInformationVector*) override;

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

#endif

vtkTestGraphAlgorithmSource.cxx

#include "vtkTestGraphAlgorithmSource.h"

#include <vtkDataObject.h>
#include <vtkGraph.h>
#include <vtkInformation.h>
#include <vtkInformationVector.h>
#include <vtkMutableUndirectedGraph.h>
#include <vtkNew.h>
#include <vtkObjectFactory.h>
#include <vtkStreamingDemandDrivenPipeline.h>
#include <vtkUndirectedGraph.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 =
      dynamic_cast<vtkGraph*>(outInfo->Get(vtkDataObject::DATA_OBJECT()));

  vtkNew<vtkMutableUndirectedGraph> NewGraph;

  // add 3 vertices
  NewGraph->AddVertex();
  NewGraph->AddVertex();
  NewGraph->AddVertex();

  output->ShallowCopy(NewGraph);

  return 1;
}

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

  vtkNew<vtkUndirectedGraph> output;
  this->GetExecutive()->SetOutputData(0, output);

  return 1;
}

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

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(GraphAlgorithmSource)

find_package(VTK COMPONENTS 
  CommonCore
  CommonDataModel
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "GraphAlgorithmSource: 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(GraphAlgorithmSource MACOSX_BUNDLE GraphAlgorithmSource.cxx )
  target_link_libraries(GraphAlgorithmSource PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS GraphAlgorithmSource
  MODULES ${VTK_LIBRARIES}
)

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

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