[vtkusers] set opacity to vtkActor2D

[Helmut Muehl]

Hi there,

i try to display two vtkActor2D in one renderwindow. The problem is that
i can either view actor1 or actor2 because they are layed one upon the
other. Now my idea is to set the opacity of the upper actor so that i
can see through to the lower one. My code therefore is:
            actor1->GetProperty()->SetOpacity(opacity);  //opacity is of
type float.
            interactor1->update();  // interactor1 is of type
renderwindowinteractor
Unfortunatley it dosn't work.
Maybe one of you have a idea how to solve this problem.
Best regards

Helmut