[vtkusers] Use transfer function editors from Python?

[Elvis Stansvik]

2016-05-23 15:35 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> 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?
>

Another question that comes up is if I need to set the interactor of the
context view to the QVTKRenderWindowInteractor using SetInteractor for the
interaction to work?

Elvis


> 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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