[vtk-developers] Performance tuning

[Ken Martin]

> I am not familiar the VTK 5 pipeline mechanism changes so perhaps
> someone could explain the implications on replacing or deleting a local
> section of a pipeline with little knowledge of the downstream filters.
> 
> Take for example, switching shrink on or off. This probably involves
> inserting or deleting a shrink filter and possibly switching between
> vtkShrinkPolyData or vtkShrinkFilter.
> 
> If the VTK 5 mechanism does not allow the shrink filter to be destroyed
> because it is somehow referenced by a downstream filter, I've got
> problems.
> 
> In VTK 4.4, my understanding is that just the filter output is
> registered by the next downstream filter and
> UnRegisterAllOutputs()allows the filter to be destroyed.

In either case a filter can be removed or added to the pipeline. This does
involve knowing about (and potentially holding references to, at least
temporarily) the two filters surrounding the one to be inserted/deleted.

> I would sooner be bitten by bad pointers rather than have orphaned
> filters consuming memory.

No matter what way we go there will not be orphaned filters consuming
memory.

Ken