[vtkusers] Getting point value on picking besides the coordinates

[David Doria]

On Sat, Nov 20, 2010 at 9:49 PM, abhinay <abhinaynagpal at gmail.com> wrote:
>
> 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

Take a look at these examples:

http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/PointPicker
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/WorldPointPicker
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/MoveAVertex

David