[vtkusers] How to obtain the coordinates (double and not int type) mouse picking over an image?

[Georges]

Hi everybody, I'm new in vtk, this is my first vtk project. I'm working over
C++ in VisualStudio with vtk 5.10.1 version. I'm making a SDI-MFC aplication
and I'm trying to obtain the coordinates (image coordinates) of the left
mouse click event when this click is over an image. I've reviewed the
examples pickpixel, pickpixel2 and picking, but pickpixel2 gave me the
coordiantes in int type variable and I need the coordinates in double type
variable. I've implemented the picking example (link:
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/Picking) but when I run
the app over my program I get an Assertion and I can´t find the error. I now
attach my programm. I appreciate your help in explaining  how could I make
the picking detection event or find the program mistake.

*//
*************************************************************************
// FUNCTION TO LOAD AN IMAGE IN FORMATS *,jpg. *.bmp, *.tiff, *.png
//
**************************************************************************
void COSSysView::OssysLoadImagevtk(CString m_ImagePath)
{
  //Create an image reader 
  vtkImageFileReader *ImageReader = vtkImageFileReader::New();
  ImageReader->SetFileName(m_ImagePath);
  ImageReader->Update();

  // ###Create an image mapper
  vtkImageMapper3D *imageMapper;
  vtkImageSliceMapper *imageSMapper = vtkImageSliceMapper::New();
  imageMapper = imageSMapper;
  imageMapper->SetInputConnection(ImageReader->GetOutputPort());
			  			  			  			  
  // Create an actor
  vtkImageActor *ImageActor = vtkImageActor::New();
  ImageActor->SetInput(ImageReader->GetOutput());
  ImageActor->SetPosition(0,0,0);
  ImageActor->SetMapper(imageMapper); 
			  
  GetRenderer()->RemoveAllViewProps(); // Remove all the actors
		  
  // Setup renderer
  GetRenderer()->AddActor(ImageActor);
  GetRenderer()->ResetCamera();

  // Setup render window
  GetRenderer()->GetRenderWindow()->Render();

  // Setup render window interactor
  vtkRenderWindowInteractor *renderWindowInteractor =
vtkRenderWindowInteractor::New();
  MouseInteractorStyle2        *style			   = MouseInteractorStyle2::New();

  renderWindowInteractor->SetInteractorStyle(style);

  // Render and start interaction
  renderWindowInteractor->SetRenderWindow(GetRenderer()->GetRenderWindow());  
  renderWindowInteractor->Initialize();
  renderWindowInteractor->Start();

}
*//
**************************************************************************

*//
*************************************************************************
// CLASS TO HANDLE MOUSE EVENT
//
**************************************************************************

class MouseInteractorStyle2 : public vtkInteractorStyleTrackballCamera
{
  public:
    static MouseInteractorStyle2* New();
    vtkTypeMacro(MouseInteractorStyle2, vtkInteractorStyleTrackballCamera);
 
    virtual void OnLeftButtonDown()
    {
      int* clickPos = this->GetInteractor()->GetEventPosition();
 
      // Pick from this location.
      vtkSmartPointer<vtkPropPicker>  picker =  
vtkSmartPointer<vtkPropPicker>::New();
      picker->Pick(clickPos[0], clickPos[1], 0, this->GetDefaultRenderer());
// IN THIS PART THE ASSERTION APPEARS
 
      double* pos = picker->GetPickPosition();
      std::cout << "Pick position (world coordinates) is: "
                << pos[0] << " " << pos[1]
                << " " << pos[2] << std::endl;
 
      std::cout << "Picked actor: " << picker->GetActor() << std::endl;
      
//Create a sphere
      vtkSmartPointer<vtkSphereSource> sphereSource = 
vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetCenter(pos[0], pos[1], pos[2]);
      sphereSource->SetRadius(0.1);
 
      //Create a mapper and actor
      vtkSmartPointer<vtkPolyDataMapper> mapper = 
vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(sphereSource->GetOutputPort());
 
      vtkSmartPointer<vtkActor> actorsphere = 
vtkSmartPointer<vtkActor>::New();
      actorsphere->SetMapper(mapper);
      this->GetDefaultRenderer()->AddActor(actorsphere);
      // Forward events
      vtkInteractorStyleTrackballCamera::OnLeftButtonDown();
    }

};
 
vtkStandardNewMacro(MouseInteractorStyle2);




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