[vtkusers] Getting point value on picking besides the coordinates

[abhinay]

HI 

I have a vtkwidget which i am using to show k means clustering in 3d , I am 
stuck with getting the value of the point which was clicked I am just able
to get the value of the pixel. Here is what I do 


vtkSmartPointer<vtkPoints> points = 
      vtkSmartPointer<vtkPoints>::New(); 

  points->InsertNextPoint ( 0.0, 0.0, 0.0 ); 
  points->InsertNextPoint ( 3.0, 3.0, 3.0 ); 
  points->InsertNextPoint ( 0.1, 0.1, 0.1 ); 
  . 
 . 

  //get the points into the format needed for KMeans 
  vtkSmartPointer<vtkTable> inputData = 
      vtkSmartPointer<vtkTable>::New(); 



//display 

  vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter = 
    vtkSmartPointer<vtkVertexGlyphFilter>::New(); 
  glyphFilter->SetInputConnection(polydata->GetProducerPort()); 
  glyphFilter->Update(); 

  //Create a mapper and actor 
  vtkSmartPointer<vtkPolyDataMapper> mapper = 
      vtkSmartPointer<vtkPolyDataMapper>::New(); 
  mapper->SetInputConnection(glyphFilter->GetOutputPort()); 

  vtkSmartPointer<vtkActor> actor = 
      vtkSmartPointer<vtkActor>::New(); 
  actor->SetMapper(mapper); 
  actor->GetProperty()->SetPointSize(3); 

  //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); 
  
   vtkSmartPointer<MouseInteractorStylePP> style = 
      vtkSmartPointer<MouseInteractorStylePP>::New(); 
    renderWindowInteractor->SetInteractorStyle( style );

Now in the mouse interactor I have the following :

class MouseInteractorStylePP : public vtkInteractorStyleTrackballCamera 
{ 
  public: 
    static MouseInteractorStylePP* New(); 
    vtkTypeMacro(MouseInteractorStylePP, vtkInteractorStyleTrackballCamera); 

    MouseInteractorStylePP() 
        { 
          this->SelectedMapper = vtkSmartPointer<vtkDataSetMapper>::New(); 
          this->SelectedActor = vtkSmartPointer<vtkActor>::New(); 
          this->SelectedActor->SetMapper(SelectedMapper); 
        } 

    virtual void OnLeftButtonDown() 
    { 
      std::cout << "Picking pixel: " <<
this->Interactor->GetEventPosition()[0] << " " <<
this->Interactor->GetEventPosition()[1]<< " " <<
this->Interactor->GetEventPosition()[2] << std::endl; 
     
this->Interactor->GetPicker()->Pick(this->Interactor->GetEventPosition()[0], 
                         this->Interactor->GetEventPosition()[1], 
                         this->Interactor->GetEventPosition()[2],  // always
zero. 
                        
this->Interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer()); 
      double picked[3],data; 
      this->Interactor->GetPicker()->GetPickPosition(picked); 
      std::cout << "Picked value: " << picked[0] << " " << picked[1] << " "
<< picked[2] << std::endl; 

     how do i get the polydata value associated with this pixel at the time
of the click?

==== 

Am i supposed to do something like th following? (and how?) 

 vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter = 
             vtkSmartPointer<vtkVertexGlyphFilter>::New(); 
          
glyphFilter->SetInputConnection(extractGeometry->GetOutputPort()); 
           glyphFilter->Update(); 

           vtkPolyData* selected = glyphFilter->GetOutput(); 
           std::cout << "Selected " << selected->GetNumberOfPoints() << "
points." << std::endl; 
           std::cout << "Selected " << selected->GetNumberOfCells() << "
cells." << std::endl; 
           this->SelectedMapper->SetInput(selected); 
          

Please advise 

Thanks and best regards 
abhinay 
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