Filter with single scalar o/p

[Bill Lorensen]

<x-flowed>John,
         look in contrib/vtkMassProperties. It's an object that is not a 
filter, just computes some numbers.
Not everything needs to be a filter.

Bill

At 01:56 PM 8/19/99 +0100, John Biddiscombe wrote:
>Dear All,
>
>Suppose you have a filter which takes as input a (possibly very large)
>vtkStructuredPoints dataset and generates as its output a single value.
>(say) 5.334
>
>Is there any point making this a proper vtkFilter, rather than just a
>subroutine in some library of code.
>
>Clearly there's a lot of baggage associated with a vtkFilter - most of
>which in this case is not required.
>
>However....
>For programs dealing with large quantities of data and using the vtk
>Pipeline methodology, it does seem to be a useful thing to have.
>
>2 questions
>1) would a StructuredPoints dataset with 1 dimension and 1 scalar be the
>best storage facility for this (or a new DatasetToScalar filter superclass)
>
>2) Can anyone suggest a more efficient means of utilizing this kind of
>algorithm - by which I mean a better way of generating single valued
>outputs without losing the pipeline style.
>
>Perhaps other users have also required a parameter supplied to a filter (eg
>SetHeight(...) as opposed to a whole dataset) to change as a result of
>other pipeline changes. As yet, there only seems to be an ->Update() on
>Filters or ProcessObjects and not to parameters....
>
>Your views appreciated
>
>John B




-----------------------------------------------------------------------------
This is the private VTK discussion list.  Please keep messages on-topic.
Check the FAQ at: <http://www.automatrix.com/cgi-bin/vtkfaq>
To UNSUBSCRIBE, send message body containing "unsubscribe vtkusers" to
<majordomo at gsao.med.ge.com>.  For help, send message body containing
"info vtkusers" to the same address.     Live long and prosper.
-----------------------------------------------------------------------------


</x-flowed>