[vtkusers] HELP!! vtkActorCollection

[marisa aurelio]

Hi vtkUsers,

When I do:

vtkActor *imageActor1 = vtkActor::New();
vtkActor *imageActor2 = vtkActor::New();

vtkActorCollection *imageActorCollection = vtkActorCollection::New();

// Add the first actor
imageActorCollection->AddItem(imageActor1);
// Add the second actor
imageActorCollection->AddItem(imageActor2);

When I'm adding the second actor, does it add it to the first position,
deleting the actor that was already on the list ???
Or add it to the next position, maintaining the first actor???

I'm asking this because, I've several images of whitch I want to obtain
their contour and show all the contours in the same image. The problem is
that I don't know how many images I have because they can be in a different
number.

So I create a list that keeps the images. Than I obtained the contour and
kept it in a vtkActor which I add to vtkActorCollection. For this I use a
cicle 'for', that do this for all the images:

vtkMarchingSquares *imageSquares = vtkMarchingSquares::New();
vtkPolyDataMapper *imageMapper = vtkPolyDataMapper::New();

for(int i = 0; i < ImageNumber; i++)
{
   // some code...............

   //vtkImporter - contain the image

   imageSquares->SetInput(vtkImporter->GetOutput());
   imageSquares->SetValue(0,63);
   imageSquares->Update();

   vtkPolyData *maskMesh = imageSquares->GetOutput();

   imageMapper->SetInput(maskMesh );
   imageMapper->ScalarVisibilityOff();

   imageActor->SetMapper(imageMapper);

   imageActorCollection->AddItem(imageActor);
}

But, when I ask to show the contours it just shows the contour of the last
image from the list.

vtkRenderer* renderer = vtkRenderer::New();
vtkRenderWindow* renWin = vtkRenderWindow::New();

imageActorCollection ->InitTraversal();
while (imageActor = imageActorCollection ->GetNextActor())
{
     renderer->AddActor(imageActor);
}

renWin->AddRenderer(renderer);

Why???


Thanks in advance,

Marisa

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