[vtkusers] Animation problem

[Gib Bogle]

Hi,
I'm trying to implement an animation program, basing it closely (I think) on this example:
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Utilities/Animation
Apparently I'm missing something because my program renders my actor correctly in the main program, but the code in the timer callback does not change what is being rendered.  The main program and the callback function are shown below.  The relevant part of the callback code that does not lead to a modified actor being rendered is this:

      strips->Initialize();
      MakeTube(nd, nstrips, dtheta, points, strips);
      polydata->Reset();
      polydata->SetPoints(points);
      polydata->SetStrips(strips);
      mapper->RemoveAllInputs();
      mapper->SetInput(polydata);
      actor->SetMapper(mapper);
      mapper->Update();
      vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::SafeDownCast(caller);
      iren->GetRenderWindow()->Render();

As you can see, I have been flailing around, trying various likely possibilities, revealing my obvious lack of understanding.  Initially I thought it would be sufficient to just change 'points' and 'strips', then I thought I should repopulate polydata, then...

class vtkTimerCallback2 : public vtkCommand
{
  public:
    static vtkTimerCallback2 *New()
    {
      vtkTimerCallback2 *cb = new vtkTimerCallback2;
      cb->TimerCount = 0;
      return cb;
    }

    virtual void Execute(vtkObject *caller, unsigned long eventId, void * vtkNotUsed(callData))
    {
      if (vtkCommand::TimerEvent == eventId)
        {
        ++this->TimerCount;
        }
      std::cout << this->TimerCount << std::endl;
//      actor->SetPosition(this->TimerCount/10., this->TimerCount/10.,0.);

      dtheta = new double[nstrips];
      for (int i=0; i<nstrips; i++) {
          dtheta[i] = 0.0;
      }
      strips->Initialize();
      MakeTube(nd, nstrips, dtheta, points, strips);
      polydata->Reset();
      polydata->SetPoints(points);
      polydata->SetStrips(strips);
      mapper->RemoveAllInputs();
      mapper->SetInput(polydata);
      actor->SetMapper(mapper);
      mapper->Update();

      vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::SafeDownCast(caller);
      iren->GetRenderWindow()->Render();
    }

  private:
    int TimerCount;
    double *dtheta;
  public:
    int nd;
    int nstrips;
    vtkPolyData *polydata;
    vtkCellArray *strips;
    vtkPoints *points;
    vtkDataSetMapper *mapper;
    vtkActor* actor;
};


int main(int argc, char *argv[])
{
    int nd = 20;
    int nstrips = 4;
    double *dtheta;

    PI = 4*atan(1.0);
    vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();
    vtkSmartPointer<vtkCellArray> strips = vtkSmartPointer<vtkCellArray>::New();
    vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();    // we want just one big array of points
    points->SetNumberOfPoints(nd*(nstrips+1));
    strips->SetNumberOfCells(nstrips);

    dtheta = new double[nstrips];
    dthetafinal = new double[nstrips];
    for (int i=0; i<nstrips; i++) {
        dtheta[i] = 0.1;
        dthetafinal[i] = 0.1;
    }

    MakeTube(nd, nstrips, dtheta, points, strips);
    polydata->SetPoints(points);
    polydata->SetStrips(strips);

  // Create an actor and mapper
  vtkSmartPointer<vtkDataSetMapper> mapper = vtkSmartPointer<vtkDataSetMapper>::New();
#if VTK_MAJOR_VERSION <= 5
  mapper->SetInput(polydata);
#else
  mapper->SetInputData(polydata);
#endif

  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);

  renderer->AddActor(actor);
  renderWindow->Render();

  // Initialize must be called prior to creating timer events.
  renderWindowInteractor->Initialize();

  // Sign up to receive TimerEvent
  vtkSmartPointer<vtkTimerCallback2> cb = vtkSmartPointer<vtkTimerCallback2>::New();
  cb->actor = actor;
  cb->nd = nd;
  cb->nstrips = nstrips;
  cb->points = points;
  cb->strips = strips;
  cb->polydata = polydata;
  cb->mapper = mapper;
  renderWindowInteractor->AddObserver(vtkCommand::TimerEvent, cb);

  int timerId = renderWindowInteractor->CreateRepeatingTimer(1000);
  std::cout << "timerId: " << timerId << std::endl;

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

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