[vtkusers] Problem with vtkPointPicker

[Łukasz Tutaj]

Hi vtk Users.

I want to know the pointId of picked point. I wrote some test program 
but it doesn't work, m_picker->Pick(...) method returns 0 (nothing was 
picked) and pointId is -1. I don't know why it doesn't  work. Could 
anyone help me?

Thanks in advance.
Łukasz Tutaj

Here is my source code:

#include <vtkDICOMImageReader.h>
#include <vtkPointPicker.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkImageMapper.h>
#include <vtkActor2D.h>
#include <vtkCommand.h>

// Callback for the interaction
class vtkMyCallback : public vtkCommand
{
public:
    vtkPointPicker * m_picker;
    vtkRenderer *m_ren;

    int x, y;
  static vtkMyCallback *New()
    { return new vtkMyCallback; }
  virtual void Execute(vtkObject *caller, unsigned long, void*)
    {
            double *ptActual, *ptMapped;
      vtkRenderWindowInteractor *iren = 
reinterpret_cast<vtkRenderWindowInteractor*>(caller);
            x = iren->GetEventPosition()[0];
            y = iren->GetEventPosition()[1];
            int succed = m_picker->Pick(x, y, 0, m_ren);
            int pointId = m_picker->GetPointId();
            m_picker->GetPickedPositions();
            cout << "(" << x << ", " << y << ") " << succed << " " << 
pointId << endl;
    }
        void SetPicker(vtkPointPicker *picker)
        {
            m_picker = picker;
        }
        void SetRenderer(vtkRenderer *ren)
        {
            m_ren = ren;
        }
};

int main()
{
    vtkRenderWindow *renwin = vtkRenderWindow::New();
    vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
    vtkRenderer *ren = vtkRenderer::New();
    vtkPointPicker *picker = vtkPointPicker::New();
    iren->SetPicker(picker);
    renwin->AddRenderer(ren);
    renwin->SetInteractor(iren);
    vtkDICOMImageReader *reader = vtkDICOMImageReader::New();
  reader->SetFileName("D:\\PRACA MAGISTERSKA\\dane381\\46009361");
    vtkImageMapper *mapper = vtkImageMapper::New();
    mapper->SetInput(reader->GetOutput());
    mapper->SetColorWindow(300);
    mapper->SetColorLevel(40);
    vtkActor2D *actor = vtkActor2D::New();
    actor->SetMapper(mapper);
    ren->AddActor2D(actor);
    renwin->SetSize(512,512);
    vtkMyCallback *mo1 = vtkMyCallback::New();
    mo1->SetPicker(picker);
    mo1->SetRenderer(ren);
    iren->AddObserver(vtkCommand::LeftButtonPressEvent,mo1);
  mo1->Delete();
    iren->Initialize();
    iren->Start();
    return 0;
}