[vtkusers] vtkInteractorStyleTrackballCamera renders unnecessarily

[David Cole]

> ... an additional render call
> is issued within StopState() at the
> end of an Interaction.

The second-to-last rendering is done while the interactor is still in 
an interactive state, and will therefore possibly be at a lower 
resolution/level-of-detail for volume rendering, or for level of detail 
actors. (Fast, interactive speed renderings, but possibly of lower 
quality...)

The last rendering, issued during the StopState call, is made after the 
interactor is taken out of its interactive state, and will therefore be 
a full rendering, at highest level of detail. (Best quality rendering 
possible, but might be much slower...)

If you are not taking advantage of any fast interactive renders with 
any actors in your scene, then you will not appreciate the difference. 
But for those of us who use the level of detail functionality, with 
lower quality fast renderings when interacting, and higher quality 
slower renderings when not interacting, *both* Render calls are 
definitely required.


HTH,
David C.