[vtkusers] Any examples of using Pieces?

Berk Geveci berklist at nycap.rr.com
Wed Nov 6 08:47:29 EST 2002


> I would like to display sub-sets of a dataset (interactively chosen).  It
> looks like the "pieces" capabilities of the PolyDataMapper might be the 
> appropriate tool for selecting which portions of a dataset to display.  Does
> anyone have any examples of using this capability?  How does one
> identify/specify what constitutes each "piece"?

I don't think this is what you are looking for. Pieces are used
in parallel processing and are usually assigned by a reader or a
special filter. When you set the number of pieces/current piece on
the mapper, this information is propagated up the pipeline and 
some source/filter along the pipeline will break the data into
pieces (if possible). It is usually hard to control how the data
will be broken. Furthermore, you won't really be able to pick
these pieces separately.
 
> For example, I've got a dataset which is all of the parts of a vehicle.  I'd
> like to specify that these triangles are the brake, and those are the steering
> wheel, and then select one or the other or both for display.
> 
> The only alternative seems to be to create a really large number of actors,
> each of which represents a single "part" of the vehicle.  That seems less
> desireable.

It sounds like you have to use a separate actor for each object possibly
in combination with assemblies. How many parts are there on average ?
Having a large number of actors usually reduces performance but
there are ways of getting around this. 

-Berk






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