[vtkusers] Use transfer function editors from Python?

[Elvis Stansvik]

2016-05-23 15:42 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> 2016-05-23 15:38 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
>
>> 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?
>>
>
> Ah, I think I found the answer to both questions in vtkRenderViewBase
> (which vtkContextView inherit):
>
> "In order to use the view with a QVTKWidget the following code is required
> to ensure the interactor and render window are initialized properly.
>
> QVTKWidget *widget = new QVTKWidget;
> vtkContextView *view = vtkContextView::New();
> view->SetInteractor(widget->GetInteractor());
> widget->SetRenderWindow(view->GetRenderWindow());"
>

How would this work in the context of a QVTKRenderWindowInteractor (the
Python Qt widget/interactor)? It does not have a SetRenderWindow(...),
instead it takes a rw keyword parameter to its constructor.

Does this mean I have to construct the context view before the Qt widget?
That feels backwards :/ I think I'd want the context view completely
contained within the Qt widget (an implementation detail so to speak).

Elvis


>
> So I'll give that a try. Sorry for the noise.
>
> Of course interested in if there are any other (undocumented) gotchas here.
>
> Elvis
>
>
>
>>
>> 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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