[vtkusers] Use transfer function editors from Python?

[Elvis Stansvik]

2016-04-15 18:54 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> 2016-04-15 18:51 GMT+02:00 Cory Quammen <cory.quammen at kitware.com>:
>
>> On Fri, Apr 15, 2016 at 11:46 AM, Elvis Stansvik
>> <elvis.stansvik at orexplore.com> wrote:
>> > 2016-04-15 16:36 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com
>> >:
>> >>
>> >> 2016-04-15 16:09 GMT+02:00 Cory Quammen <cory.quammen at kitware.com>:
>> >>>
>> >>> Hi Elvis,
>> >>>
>> >>> Have a look at
>> >>>
>> >>>
>> >>>
>> http://www.vtk.org/gitweb?p=VTK.git;a=blob;f=Charts/Core/Testing/Cxx/TestScalarsToColors.cxx
>> >>>
>> >>> for an example of how to set up the transfer function editors used in
>> >>> ParaView.
>> >>>
>> >>> You can eliminate the check at the end for vtkOpenGL2ContextDevice2D -
>> >>> make sure to initialize and start the interactor, though.
>> >>>
>> >>> I don't see anything in this example that won't work in Python - if
>> >>> there is, please report back any problems you encounter.
>> >>
>> >>
>> >> Excellent, thanks a lot. I'll report back how it went.
>> >
>> >
>> > Worked like a charm :) It's not quite the same as the editors in
>> ParaView
>> > though. In ParaView, the opacity and color transfer functions are edited
>> > separately, like this:
>> >
>> >     https://blog.kitware.com/blog/files/48_1536770536.png
>> >
>> > Do you know if it's possible to get that kind of editing through VTK
>> > classes, with the color transfer function edited using a gradient editor
>> > below and the X/Y editor only for the the opacity transfer function, or
>> is
>> > ParaView doing something custom here?
>>
>> Yes. You can use a vtkPiecewiseFunctionItem and
>> vtkPiecewiseControlePointsItem to edit the opacity function and a
>> vtkColorTransferFunctionItem and a vtkColorTransferControlPointsItem
>> to edit the color transfer function. These can be displayed in two
>> separate widgets, much like ParaView does. In each widget, you can
>> have a vtkContextView. This is probably the easiest implementation for
>> what you are after.
>>
>
> Ah, excellent. Thanks. It was the vtkPiecewiseFunctionItem I was missing.
> Was searching for something called "opacity" or somesuch, but makes sense
> it's just a general piecewise function editor class.
>

Had to take a long break from this particular task, but now I'm back.

I have a short and hopefully simple question about the above: When you say

    "In each widget, you can have a vtkContextView."

I'm not quite sure how I add a vtkContextView to my widget
(QVTKRenderWindowInteractor). I mean, how I establish a link between them.

Should I

 * Set the render window of the context view to the render window of the
QVTKRenderWindowInteractor using SetRenderView(...)?
 * Get the renderer of the context view with GetRenderer() and add it to
the render window of the QVTKRenderWindowInteractor using AddRenderer(...)?
 * Something else?

Sorry if this is obvious, but it's a little hard to navigate the VTK
classes and figure out how they are to be used together :)

Thanks in advance,
Elvis


> Elvis
>
>
>> Cory
>>
>> > (I the class vtkCompositeTransferFunctionItem has "composite" in its
>> name
>> > precisely because it provides editing of both color/opacity in the same
>> > editor, while I would like the separated approach that ParaView has.)
>> >
>> > Elvis
>> >
>> >>
>> >> Elvis
>> >>
>> >>>
>> >>>
>> >>> HTH,
>> >>> Cory
>> >>>
>> >>> On Fri, Apr 15, 2016 at 8:54 AM, Elvis Stansvik
>> >>> <elvis.stansvik at orexplore.com> wrote:
>> >>> > Hi all,
>> >>> >
>> >>> > I'd like to use the transfer function editors that VTK seems to
>> provide
>> >>> > (used by e.g. Paraview) from Python. Is it possible?
>> >>> >
>> >>> > Looking at
>> >>> >
>> >>> >    http://www.vtk.org/pipermail/vtkusers/2013-December/082410.html
>> >>> >
>> >>> > I read the slightly worrying:
>> >>> >
>> >>> >     "[...] Save/restore state and python interface are not working
>> as
>> >>> > expected. [...]"
>> >>> >
>> >>> > Though that was an old message when the new editors were first
>> >>> > introduced in
>> >>> > 2013. Is it still the case that the Python interface for the editor
>> >>> > classes
>> >>> > is not working as expected?
>> >>> >
>> >>> > Does anyone know of a Python application/example that makes use of
>> the
>> >>> > editors? (I'm using VTK 6.2 and PyQt 5.5.1).
>> >>> >
>> >>> > Thanks,
>> >>> > Elvis
>> >>> >
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>> >>>
>> >>>
>> >>>
>> >>> --
>> >>> Cory Quammen
>> >>> R&D Engineer
>> >>> Kitware, Inc.
>> >>
>> >>
>> >
>>
>>
>>
>> --
>> Cory Quammen
>> R&D Engineer
>> Kitware, Inc.
>>
>
>
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