[vtk-developers] vtkSelectPolyData don't give accses to cell information !!

[Youness BENCHRIFA]

Hello,
I'm using "vtkSelectPolyData"
I want to know please if we can get access to information about cells in 
the smallest region cut from the sphere(as example) ?

when I compute the number of cells :
polyData =  loop2->GetSelectionEdges ();
polyData->GetNumberOfCells();
i got 0 cell.

Here is the code giving as example in vtk.
---------------------------------------------------------------------------
package require vtk
package require vtkinteraction
package require vtktesting

# Define loop to clip with
#
vtkPoints selectionPoints
     selectionPoints InsertPoint 0 -0.16553 0.135971 0.451972
     selectionPoints InsertPoint 1 -0.0880123 -0.134952 0.4747
     selectionPoints InsertPoint 2  0.00292618 -0.134604 0.482459
     selectionPoints InsertPoint 3 0.0641941 0.067112 0.490947
     selectionPoints InsertPoint 4 0.15577 0.0734765 0.469245
     selectionPoints InsertPoint 5 0.166667 -0.129217 0.454622
     selectionPoints InsertPoint 6 0.241259 -0.123363 0.420581
     selectionPoints InsertPoint 7  0.240334 0.0727106 0.432555



vtkSphereSource sphere
     sphere SetPhiResolution 50
     sphere SetThetaResolution 100
     sphere SetStartPhi 0
     sphere SetEndPhi 90
vtkSelectPolyData loop
     loop SetInputConnection [sphere GetOutputPort]
     loop SetLoop selectionPoints
     loop GenerateSelectionScalarsOn
     loop SetSelectionModeToSmallestRegion; #negative scalars inside
vtkClipPolyData clip; #clips out positive region
     clip SetInputConnection [loop GetOutputPort]
vtkPolyDataMapper clipMapper
     clipMapper SetInputConnection [clip GetOutputPort]
vtkLODActor clipActor
     clipActor SetMapper clipMapper

vtkSelectPolyData loop2
     loop2 SetInputConnection [sphere GetOutputPort]
     loop2 SetLoop selectionPoints
     loop2 SetSelectionModeToSmallestRegion
vtkPolyDataMapper selectMapper
     selectMapper SetInputConnection [loop2 GetOutputPort]
vtkLODActor selectActor
     selectActor SetMapper selectMapper
     selectActor AddPosition 1 0 0
     eval [selectActor GetProperty] SetColor $peacock



# Create graphics stuff
#
vtkRenderer ren1
vtkRenderWindow renWin
     renWin AddRenderer ren1
vtkRenderWindowInteractor iren
     iren SetRenderWindow renWin

# Add the actors to the renderer, set the background and size
#
ren1 AddActor clipActor
ren1 AddActor selectActor
ren1 SetBackground .1 .2 .4

renWin SetSize 500 250
set cam1 [ren1 GetActiveCamera]
$cam1 SetClippingRange 0.236644 11.8322
$cam1 SetFocalPoint 0.542809 -0.0166201 0.183931
$cam1 SetPosition 1.65945 0.364443 2.29141
$cam1 SetViewUp -0.0746604 0.986933 -0.14279

iren Initialize

# render the image
#
iren AddObserver UserEvent {wm deiconify .vtkInteract}

# prevent the tk window from showing up then start the event loop
wm withdraw .