[vtkusers] Advice on mitigating choppy resize with Qt 5 + VTK 7.1

David Cole DLRdave at aol.com
Tue Mar 7 09:53:15 EST 2017


On Windows, we make resizing our windows interactive by getting the
vtkInteractorStyle associated with the render window containing the
volume rendering, and then calling StartState at resize begin time
(OnEnterSizeMove) and StopState at resize end time (OnExitSizeMove).

I suppose there may be a Qt equivalent which works on many platforms
for beginning and ending a resize action. If not, there are definitely
platform-specific hooks you can intercept to achieve smooth resizing
with this technique.

Wrapping anything in a StartState/StopState pair on the
vtkInteractorStyle will cause "interactive frame rate rendering" to be
in effect in between the calls. The volume rendering is not as nice
looking during interactions, but it is definitely speedier.


HTH,
David C.



On Tue, Mar 7, 2017 at 9:33 AM, Elvis Stansvik
<elvis.stansvik at orexplore.com> wrote:
> 2017-03-07 15:17 GMT+01:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
>> Hi all,
>>
>> I'm using Qt 5.5.1 and VTK 7.1. The program has a couple of VTKWidget
>> showing volume renderings, as well as a window with a chart.
>
> Actually, I'm able to reproduce this behavior when not using Qt at
> all, but just a regular render window + interactor setup with a single
> volume rendered. Camera interaction is nice and fast, but resizing the
> window, the rendering is very choppy. I'm also getting
>
> Warning: In /buildbot/vtk7-builder/build/Rendering/OpenGL2/vtkXOpenGLRenderWindow.cxx,
> line 1207
> vtkXOpenGLRenderWindow (0x1353a10): warning window did not resize in
> the allotted time
>
> printed to the console, so it seems VTK detects what I'm seeing
> visually. I did not get this warning printed in the Qt + VTK app.
>
> Elvis
>
>>
>> Have a look at the attached screen recording. Notice how camera
>> interaction in both VTK render windows is nice and smooth, but when
>> resizing the windows, the updating of the renderings is very
>> slow/choppy.
>>
>> I've been trying to debug this, or at least finding a way of
>> mitigating it. Could it be that Qt is delivering too many resize
>> events? Has anyone else dealt with this problem?
>>
>> Thanks in advance for any advice,
>> Elvis
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