# ProgrammableFilter

VTKExamples/Cxx/Filtering/ProgrammableFilter

### Code

ProgrammableFilter.cxx

    #include <vtkSmartPointer.h>
    #include <vtkSphereSource.h>
    #include <vtkProgrammableFilter.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>

    struct params
    {
      vtkPolyData* data;
      vtkProgrammableFilter* filter;
    };

    void AdjustPoints(void* arguments)
    {
      params* input = static_cast<params*>(arguments);

      vtkPoints* inPts = input->data->GetPoints();
      vtkIdType numPts = inPts->GetNumberOfPoints();
      vtkSmartPointer<vtkPoints> newPts =
          vtkSmartPointer<vtkPoints>::New();
      newPts->SetNumberOfPoints(numPts);

      for(vtkIdType i = 0; i < numPts/2; i++)
      {
        double p[3];
        inPts->GetPoint(i, p);
        p[0] = p[0] + .5;
        p[1] = p[1] + .5;
        p[2] = p[2] + .5;
        newPts->SetPoint(i, p);
      }

      for(vtkIdType i = numPts/2; i < numPts; i++)
      {
        double p[3];
        inPts->GetPoint(i, p);
        p[0] = p[0] - .5;
        p[1] = p[1] - .5;
        p[2] = p[2] - .5;
        newPts->SetPoint(i, p);
      }

      input->filter->GetPolyDataOutput()->CopyStructure(input->data);
      input->filter->GetPolyDataOutput()->SetPoints(newPts);

    }

    int main(int, char *[])
    {
      //Create a sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
          vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->Update();

      vtkSmartPointer<vtkProgrammableFilter> programmableFilter =
          vtkSmartPointer<vtkProgrammableFilter>::New();
      programmableFilter->SetInputConnection(sphereSource->GetOutputPort());

      params myParams;
      myParams.data = sphereSource->GetOutput();
      myParams.filter = programmableFilter;

      programmableFilter->SetExecuteMethod(AdjustPoints, &myParams);
      programmableFilter->Update();

      //Create a mapper and actor
      vtkSmartPointer<vtkPolyDataMapper> mapper =
          vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(programmableFilter->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(.4, .5, .6); // Background color white

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ProgrammableFilter)

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

    add_executable(ProgrammableFilter MACOSX_BUNDLE ProgrammableFilter.cxx )

    target_link_libraries(ProgrammableFilter ${VTK_LIBRARIES})

### Download and Build ProgrammableFilter

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

    cd ProgrammableFilter/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:

    ./ProgrammableFilter

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.