[vtkusers] Advice on mitigating choppy resize with Qt 5 + VTK 7.1
Elvis Stansvik
elvis.stansvik at orexplore.com
Wed Jun 7 08:15:41 EDT 2017
2017-03-13 10:37 GMT+01:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
> 2017-03-13 10:32 GMT+01:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
> > 2017-03-07 16:10 GMT+01:00 Elvis Stansvik <elvis.stansvik at orexplore.com>
> :
> >> 2017-03-07 15:58 GMT+01:00 Elvis Stansvik <elvis.stansvik at orexplore.com
> >:
> >>> 2017-03-07 15:53 GMT+01:00 David Cole <DLRdave at aol.com>:
> >>>> 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.
> >>>
> >>> Ah, I was just about to reply to myself with some further information:
> >>>
> >>> I know that during interaction, the quality of the rendering is
> >>> decreased, and that this can account for some of the performance
> >>> discrepancy I'm seeing between camera movement vs window resize.
> >>>
> >>> But, I've experimented with disabling the quality degradation during
> >>> interactions (so that the two should be on "equal footing"), and the
> >>> resizing is still much more choppy than when interacting with the
> >>> camera. So there must be something else.
> >>>
> >>> In fact, in the screencast I showed, I wasn't using the volume
> >>> renderer's default built-in quality degradation during interaction.
> >>> I'm using my own since I've found that VTKs own is a little too
> >>> aggressive in degrading the quality to maintain frame rate.
> >>
> >> To illustrate, look at the attached screen recording. In this test
> >> case, I'm using
> >>
> >> mapper->AutoAdjustSampleDistancesOff();
> >> mapper->SetSampleDistance(0.0002);
> >>
> >> on my vtkGPUVolumeRayCastMapper, to turn off the automatic adjustment
> >> of sample distance during interactions, and hardcode the sample
> >> distance to 0.0002.
> >>
> >> Notice how the rendering is still reasonably smooth during
> >> interaction, but during resize, the rendering sometimes lags with 100s
> >> of milliseconds. During the resizing I was getting warnings like
> >>
> >> Warning: In /buildbot/vtk7-builder/build/Rendering/OpenGL2/
> vtkXOpenGLRenderWindow.cxx,
> >> line 1207
> >> vtkXOpenGLRenderWindow (0x2a629d0): warning window did not resize in
> >> the allotted time
> >>
> >> printed.
> >
> > No ideas where this discrepancy in refresh rate, despite automatic
> > adjustment of sample distance being turned off, comes from?
> >
> > At the moment I've worked around it by simply resorting to bounding
> > box rendering when my VTK windows are resized, since the choppy resize
> > behavior was quite jarring. But that's a kludge and I'd much rather
> > find the real problem :/
> >
> > Below is a minimal test case, and I'm attaching a video where I first
> > interact with the volume rendering, giving a smooth albeit a little
> > slow frame rate, and then resizing the window, which gives a jerky and
> > choppy rendering.
> >
> > This was on a Thinkpad T440s laptop with Intel HD 4400 graphics. VTK
> > 7.1 and Qt 5.5.1 running on Kubuntu 16.04.
> >
> > Elvis
> >
> >
> > main.cpp:
> >
> > #include <random>
> >
> > #include <vtkCamera.h>
> > #include <vtkColorTransferFunction.h>
> > #include <vtkGPUVolumeRayCastMapper.h>
> > #include <vtkImageData.h>
> > #include <vtkNew.h>
> > #include <vtkPiecewiseFunction.h>
> > #include <vtkRenderer.h>
> > #include <vtkRenderWindow.h>
> > #include <vtkRenderWindowInteractor.h>
> > #include <vtkVolume.h>
> > #include <vtkVolumeProperty.h>
> >
> > int main(int argc, char *argv[])
> > {
> > vtkNew<vtkColorTransferFunction> colorFunction;
> > colorFunction->AddRGBPoint(0.0, 0.0, 0.0, 0.0);
> > colorFunction->AddRGBPoint(1.0, 0.0, 0.0, 0.0);
> >
> > vtkNew<vtkPiecewiseFunction> opacityFunction;
> > opacityFunction->AddPoint(0.0, 0.0);
> > opacityFunction->AddPoint(1.0, 0.02);
> >
> > vtkNew<vtkImageData> data;
> > data->SetExtent(0, 250, 0, 250, 0, 500);
> > data->AllocateScalars(VTK_FLOAT, 1);
> > std::random_device device;
> > std::mt19937 engine(device());
> > std::uniform_real_distribution<> distribution(0, 1);
> > auto dataPointer = static_cast<float *>(data->GetScalarPointer());
> > for (int i = 0; i < 250*250*500; ++i) {
> > *dataPointer = distribution(engine);
> > ++dataPointer;
> > }
> >
> > vtkNew<vtkGPUVolumeRayCastMapper> mapper;
> > mapper->SetInputData(data.Get());
>
> Sorry, the test case should have had
>
> mapper->AutoAdjustSampleDistancesOff();
> mapper->SetSampleDistance(1);
>
> here, to show that the discrepancy is there even when automatic
> adjustment of sample distance is turned off.
>
> The result is the same, the rendering is keeping up much better during
> interaction that it is during window resize.
>
> I can understand if it's a little heavier to re-render after window
> resize, but not by that much, so I think something is wrong
>
Anybody have some more advise on this? I'm seeing the same problem in PV
5.4.
I had hoped that maybe the new QVTKOpenGLWidget would change things, but it
hasn't. I would really like to remove the workarounds I have in place that
degrades the rendering to bounding boxes during widget resizing.
Elvis
>
> Elvis
>
> >
> > vtkNew<vtkVolumeProperty> property;
> > property->SetScalarOpacity(opacityFunction.Get());
> > property->SetColor(colorFunction.Get());
> >
> > vtkNew<vtkVolume> volume;
> > volume->SetMapper(mapper.Get());
> > volume->SetProperty(property.Get());
> >
> > vtkNew<vtkRenderer> renderer;
> > renderer->AddVolume(volume.Get());
> > renderer->SetBackground(1.0, 1.0, 1.0);
> >
> > vtkNew<vtkRenderWindow> window;
> > window->AddRenderer(renderer.Get());
> >
> > renderer->ResetCamera();
> >
> > vtkNew<vtkRenderWindowInteractor> interactor;
> > interactor->SetRenderWindow(window.Get());
> > interactor->Start();
> >
> > return 0;
> > }
> >
> >
> > CMakeLists.txt:
> >
> > cmake_minimum_required(VERSION 3.1)
> >
> > project(TestCase)
> >
> > set(CMAKE_PREFIX_PATH ${CMAKE_PREFIX_PATH} /opt/VTK7)
> >
> > find_package(VTK 7.1 COMPONENTS
> > vtkCommonCore
> > vtkCommonDataModel
> > vtkCommonExecutionModel
> > vtkCommonMath
> > vtkInteractionStyle
> > vtkRenderingCore
> > vtkRenderingOpenGL2
> > vtkRenderingVolume
> > vtkRenderingVolumeOpenGL2
> > REQUIRED
> > )
> >
> > add_executable(TestCase WIN32 main.cpp)
> >
> > target_link_libraries(TestCase PUBLIC
> > vtkCommonCore
> > vtkCommonDataModel
> > vtkCommonExecutionModel
> > vtkCommonMath
> > vtkInteractionStyle
> > vtkRenderingCore
> > vtkRenderingOpenGL2
> > vtkRenderingVolume
> > vtkRenderingVolumeOpenGL2
> > )
> >
> > target_include_directories(TestCase PUBLIC
> > ${VTK_INCLUDE_DIRS}
> > )
> >
> > target_compile_definitions(TestCase PUBLIC
> > ${VTK_DEFINITIONS}
> > )
> >
> > set_target_properties(TestCase PROPERTIES
> > CXX_STANDARD 14
> > CXX_STANDARD_REQUIRED ON
> > )
> >
> >>
> >> Elvis
> >>
> >>>
> >>> Elvis
> >>>
> >>>>
> >>>>
> >>>> 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
> >>>>> _______________________________________________
> >>>>> Powered by www.kitware.com
> >>>>>
> >>>>> Visit other Kitware open-source projects at http://www.kitware.com/
> opensource/opensource.html
> >>>>>
> >>>>> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
> >>>>>
> >>>>> Search the list archives at: http://markmail.org/search/?q=vtkusers
> >>>>>
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>
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