[vtkusers] Re: automatic update of objects generating a vtkAbstractTransform

[David Gobbi]

Hi Alexandre,

Yes, send me the changes.  I think that a vtkAbstractTransformSource
is a good solution, thanks for doing the work on this.  Debugging
can be a pain with VTK, because of all the interconnectedness, but
the pipeline architecture is what makes VTK what it is.

Eventually, vtkAbstractTransformSource should become a subclass of
vtkSource but for now I think I'll leave it as a separate class.

 - David

--
  David Gobbi, MSc                    dgobbi at irus.rri.on.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario

On 5 Apr 2001, Alexandre Guimond wrote:

> On Wed, 21 Mar 2001 11:44:00 -0500 (EST)
> David Gobbi <dgobbi at irus.rri.on.ca> writes:
>
> > Ah, I understand.  No, a transform does not have a 'source.'  I'll
> > have to think about this... it might be worthwhile to make
> > vtkAbstractTransform a subclass of vtkDataObject, but I'm reluctant to
> > do this because most of the methods/attributes of vtkDataObject
> > are irrelevant to transforms.  On the other hand, the concept of
> > 'UpdateExtent' does make sense for nonlinear transformations.
>
> I've been playing around with it for a couple of weeks.  It works ok,
> but it's pretty annoying (considering I'm not at ease with all the vtk
> concepts about times and extents).  First the source::Update method
> need to do quite a few things (checking pipeline times, setting
> extents, types, etc.).  Also, in source::Update you can't call many
> functions of the transform (like print) since they call source::update
> themselves and you end up in a lock.  It's also weird to call print on
> the source itself, since it will call update on the transform and
> hence update the source object (which is probably not what one wants
> when you calls print).  All in all, I think is ok as a temporary
> solution, but I'm hoping you can work out something more convinient in
> the future.
>
> If you're interested in what I did to vtkAbstractTransform, I can send
> them to you.  I've also come up with a vtkAbstractTransformSource.
> Pretty simple, but it might save you a bit of typing if you want
> something along those lines.
>