[vtkusers] Notification after interaction with vtkComposite(TransferFunction|ControlPoints)Item

[Elvis Stansvik]

2016-06-27 15:55 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> 2016-06-22 12:23 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
>
>> 2016-06-22 11:07 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
>>
>>> 2016-06-22 10:36 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>
>>> :
>>>
>>>> 2016-06-21 16:02 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com
>>>> >:
>>>>
>>>>> Hi all,
>>>>>
>>>>> I'm using a vtkCompositeTransferFunctionItem +
>>>>> vtkCompositeControlPointsItem in a vtkChartXY to modify the transfer
>>>>> functions used for some volume rendering.
>>>>>
>>>>> Is there some event from one of these items I can observe that will
>>>>> fire once interaction has occurred? I know I can observe the ModifiedEvent
>>>>> of the vtkCompositeTransferFunctionItem, but when dragging points
>>>>> around, it will fire on each mouse move. I need to be notified only once
>>>>> the interaction has stopped.
>>>>>
>>>>
>>>> Looking at the code, I noticed that vtkControlPointsItem seem to emit
>>>> vtkCommand::StartInteractionEvent and vtkCommand::EndInteractionEvent
>>>> (though I'm not sure...), and since vtkCompositeControlPointsItem
>>>> indirectly inherits vtkControlPointsItem, I tried to observe vtkCommand::EndInteractionEvent
>>>> with
>>>>
>>>>         self._pointsItem.AddObserver(vtkCommand.EndInteractionEvent,
>>>>                                      lambda *_: print('interaction
>>>> ended'))
>>>>
>>>> where self._pointsItem is my vtkCompositeControlPointsItem.
>>>>
>>>> But it seems the event is not emitted when I interact with the points.
>>>>
>>>> Any ideas here? Surely there must be some way of being notified when
>>>> interaction with the color transfer functions has ended? My use case is
>>>> that I don't want to issue a re-render of my volume each time the mouse
>>>> moves when dragging a point around. Only when dragging finally stops do I
>>>> want to re-render.
>>>>
>>>> Any advice is much appriciated.
>>>>
>>>
>>> After some more experimentation, trying to observe various events on the
>>> items, the chart, the context view and the context scene, I've realized I
>>> can observe
>>>
>>> vtkCommand.LeftButtonReleaseEvent
>>> vtkCommand.RightButtonReleaseEvent
>>> vtkCommand.MiddleButtonReleaseEvent
>>>
>>> on the context scene. This will work as a workaround, but seems overly
>>> liberal and complicated. Is there no single event on the composite control
>>> points item or the composite transfer function item I could observe?
>>>
>>
>> Although I realized now that this approach won't work, since for some
>> reason, by the time I get the vtkCommand.MiddleButtonReleaseEvent, the
>> point has not yet been deleted. So still looking for a proper solution.
>>
>
> Noone knows how this can be done? I noticed that ParaView also has this
> behavior (that the rendering is updated on each mouse move when dragging a
> point in the transfer function). For me, this will be too heavy :/ Only
> once mouse movement stops do I want to re-render. But I can't seem to find
> a way to do this when using these VTK-bundled transfer function editing
> widgets.
>

Sorry to bump my own thread, but I'm still searching for a solution here. I
find it incredible that this wouldn't be possible. Anyone know how I can be
notified once editing of a transfer function stops when using these editor
widgets?

Thanks in advance,
Elvis


> Elvis
>
>
>>
>> Elvis
>>
>>
>>>
>>
>>> Elvis
>>>
>>>
>>>> Elvis
>>>>
>>>>
>>>>> Thanks in advance,
>>>>> Elvis
>>>>>
>>>>
>>>>
>>>
>>
>
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