    overlay = vtkOverlayPass()

    passes = vtkRenderPassCollection()
    passes.AddItem(lights)
    passes.AddItem(opaque)
    passes.AddItem(overlay)
--
    overlay = vtkOverlayPass()

    passes = vtkRenderPassCollection()
    passes.AddItem(lights)
    passes.AddItem(opaque)
    passes.AddItem(overlay)
--
    overlay = vtkOverlayPass()

    passes = vtkRenderPassCollection()
    passes.AddItem(lights)
    passes.AddItem(opaque)
    passes.AddItem(overlay)
