[vtk-developers] Usage of filters inside filters

[Francisco Caraballo]

Thanks a lot for your answer David.

I have one doubt about it though, what are ivars?
Generally when I instantiate filters I assign them to vtkSmartPointers.
Are ivars something different?

Greetings.

Francisco Caraballo



On Tue, Feb 28, 2012 at 2:31 PM, David E DeMarle
<dave.demarle at kitware.com> wrote:
> It is fine to do so.
>
> In the outer filter, create the internal filters as ivars. You can
> New() into those pointers in your constructor and Delete() them in
> your destructor to keep it simple.
>
> In your RequestData method, set up the internal connections of the
> internal pipeline with SetInputConnection(GetOutputPort) like you
> would anywhere else. The only real trick is that you have have to
> ShallowCopy the outer filter's input into the first filter in the
> internal pipeline and ShallowCopy the last filter's output into the
> outer filter's output. Otherwise the Executives get confused about
> what is connected to what and how to schedule updates.
>
> If the internal filters are visible and controlled outside of the
> outer filter, you probably want to override the outer filter's
> ModififiedTime to take into account the MTimes of the internal ones
> too.
>
> David E DeMarle
> Kitware, Inc.
> R&D Engineer
> 21 Corporate Drive
> Clifton Park, NY 12065-8662
> Phone: 518-881-4909
>
>
>
> On Tue, Feb 28, 2012 at 8:10 AM, Francisco Caraballo
> <francisco.caraballo at gmail.com> wrote:
>> Hello everyone.
>>
>> I'm developing a filter for image segmentation and i'm rather new to
>> the VTK workflow and would like to ask you guys for some help.
>> It would help me a lot if I could call several other filters from
>> within my own filter (i.e Image Mathematics, Gaussian, Gradient). I
>> have searched in the mailing list archives and found some old messages
>> where some people was against doing it and other people was for it.
>> What is the current position of the community on this subject,
>> considering I'm using VTK 5.8? Is it an accepted practice? If
>> positive, could you give me some advice as to how to do it? I'm
>> particularly confused about the pipeline calls and how to go around
>> calling the filters outside of the "main" pipeline.
>>
>> Thanks a lot in advance.
>>
>> Francisco Caraballo
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