[Paraview] What part of the pipeline is producing the request for UPDATE_EXTENT?

[Kent Eschenberg]

Indeed, each of the my routines to set the VOI bounds (one each for the min/max 
in X/Y/Z) calls Modified().

During development I had temporary print statements everywhere and as I 
remember it these routines to set the VOI were called both before and after 
RequestInformation.

Kent
Pittsburgh Supercomputing Center

Moreland, Kenneth wrote:
> I belive it is supposed to work that your SetVOI() method should call 
> modified, which will in turn cause the pipeline to call 
> RequestInformation() on the next update.  Make sure that SetVOI() is 
> actually calling Modified().
> 
> -Ken
> 
> 
> On 2/12/08 9:26 PM, "Mike Jackson" <imikejackson at gmail.com> wrote:
> 
>     Pretty sure that was where we were going to end up BUT as far as I
>     can tell, the order of execution is :
>     RequestInformation()
>     SetVOI() // From the GUI in ParaView
>     RequestData();
> 
>     So we never really get a chance to get the VOI until RequestData
>     fires.. Is that what you have seen?
> 
>     Mike
>     On Feb 12, 2008, at 11:21 PM, Kent Eschenberg wrote:
> 
>     >  Mike,
>     >
>     >  I accomplished what you want with one of our custom readers. In my
>     >  opinion the documentation for RequestInformation, RequestData,
>     >  extents, etc. is so poor that it is useless.
>     >
>     >  At RequestInformation I read enough of the input to get the overall
>     >  input array size; apply the user-selected VOI; and return the
>     >  desired subset as the whole extent. At RequestData I read the rest.
>     >  I just don't bother letting VTK/ParaView manage the selection of
>     >  the VOI. This has worked for 2.6.1 through 3.2.1.
>     >
>     >  Kent
>     >  Pittsburgh Supercomputing Center
>     >
>     >  Mike Jackson wrote:
>     > > I can do that but I don't think it will work.
>     > > In paraview, I have managed to set an auto-generated UI for the
>     > > VOI. Now, the user opens our file, RequestInformation is run (I
>     > > can put some sane defaults for the VOI) and things are ok so far.
>     > > Now the user clicks "Apply" and then SetVOI is called with the
>     > > values from the GUI and then RequestData() is called after that.
>     > > So where do I update WHOLE_EXTENT? Or just take the values from
>     > > the VOI, create a vtkImageObject from that, and then just
>     > > ShallowCopy to the output object?
>     > > I'm a bit confused at this point. If our case is NOT a standard
>     > > use case for the pipeline than I guess I can look more seriously
>     > > into developing a full blown Plugin for our data file.
>     > > Mike