Pause shift-scale during interaction

@ken-martin We have a customer with some large-ish, multi-scale data. They definitely want the focal-point shift-scale enabled on their mappers, but have noticed unwanted pauses during interaction when a VBO gets re-uploaded to the GPU. It doesn’t look like there’s a way to avoid calling vtkOpenGLPolyDataMapper::UpdateCameraShiftScale and vtkCompositeMapperHelper2::UpdateCameraShiftScale during interactive renders.

Do you have any objections to me adding an ivar to the mappers to disable calls to UpdateCameraShiftScale for a render (while continuing to use existing shift-scale values)? Is there a better way to do this?

No concerns. Sounds fine to me

Great! MR here: .