[vtkusers] picking an actor with vtkPropPicker

[Lloyd Fenelon]

Hi,

I would like to get the position of an actor when I
pick it in the screen with the mouse and "p".
I am using vtkPropPicker but the method getActor()
always returns NULL..I don't know what I missed in the code.
I tried with vtkPicker but I got the same results.
Here is the callback function and the main I am using to try picking:


class vtkMyCallback : public vtkCommand
{
    public:
        static vtkMyCallback *New()
        {
            return new vtkMyCallback;
        }
        void Delete()
        {
            delete this;
        }
        virtual void Execute(vtkObject *caller, unsigned long, void*)
        {
            vtkPropPicker* picker
                  = reinterpret_cast<vtkPropPicker*>(caller);

            vtkSmartPointer<vtkActor> pickedActor
                  = vtkSmartPointer<vtkActor>::New();

            pickedActor = picker->GetActor();
            if ( pickedActor == NULL) cout << " nothing picked\n";

            //double actorCoord[3] = {0.0};
            //pickedActor->GetPosition(actorCoord);
            //cout << actorCoord[0] << "   \t" << actorCoord[1] << "   \t" << actorCoord[2] << "\n";
        }
};

int main()
{

      vtkSphereSource *sphere = vtkSphereSource::New();
      sphere->SetThetaResolution(10);
      sphere->SetPhiResolution(5);

      vtkPolyDataMapper *sphereMapper = vtkPolyDataMapper::New();
      sphereMapper->SetInputConnection(sphere->GetOutputPort());

      vtkActor *sphere1 = vtkActor::New();
      sphere1->SetMapper(sphereMapper);
      sphere1->GetProperty()->SetColor(1,0,0);

      vtkActor *sphere2 = vtkActor::New();
      sphere2->SetMapper(sphereMapper);
      sphere2->GetProperty()->SetColor(0,0,1);
      sphere2->AddPosition(1.25,0,0);

      vtkRenderer *ren1 = vtkRenderer::New();
      vtkRenderWindow *renWin = vtkRenderWindow::New();
      renWin->AddRenderer(ren1);
      vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
      iren->SetRenderWindow(renWin);

      ren1->AddActor(sphere1);
      ren1->AddActor(sphere2);
      ren1->SetBackground(1, 1, 1);
      renWin->SetSize(600, 400);

      ///////////////////////////////////////////////////////////////
      // Picker
      vtkSmartPointer<vtkPropPicker> picker
            = vtkSmartPointer<vtkPropPicker>::New();
      iren->SetPicker(picker);
      vtkMyCallback* updateCoord = vtkMyCallback::New();
      picker->AddObserver(vtkCommand::StartPickEvent, updateCoord);

      ///////////////////////////////////////////////////////////////

      iren->Initialize();
      iren->Start();

      sphere->Delete();
      sphereMapper->Delete();
      sphere1->Delete();
      sphere2->Delete();
      ren1->Delete();
      renWin->Delete();
      iren->Delete();

      return 0;
}

Thanks for your help
Lloyd
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