crash in VSGQt

[hasanshamsijeze]

I have a project where I'm using VSGQt, and everything was working fine until a few days ago. Today, when I tried to run it again, the application suddenly started crashing.

After debugging, I traced the issue to this section of code:

app = new rocky::Application(viewer);
//-----------------------setting---------------------------
app->mapNode->terrainSettings().concurrency = 32;
app->mapNode->terrainSettings().backgroundColor = rocky::Color::Gray;

app->renderContinuously = false;

viewer->frame = [this]() {
    this->frame();
    return app->frame();
};
viewer->setInterval(8);

rocky::Log()->set_level(rocky::log::level::info);

auto windowTraits = vsg::WindowTraits::create();
windowTraits->debugLayer = false;
windowTraits->x = SETTING->Screen.x();
windowTraits->y = SETTING->Screen.y();
windowTraits->width = SETTING->Screen.width();
windowTraits->height = SETTING->Screen.height();

auto window = new vsgQt2::Window(viewer, windowTraits);
MainViewController::GetInstance()->setting(this);

window->initializeWindow();
if (!windowTraits->device)
    windowTraits->device = window->windowAdapter->getOrCreateDevice();

window->windowAdapter->bufferedEvents.push_back(vsg::KeyReleaseEvent::create());
window->windowAdapter->bufferedEvents.push_back(vsg::KeyPressEvent::create());
window->windowAdapter->bufferedEvents.push_back(vsg::MoveEvent::create());

QWidget *widget = QWidget::createWindowContainer(window, this);

The crash happens specifically when I try to create a QWidget from the VSG window:

QWidget *widget = QWidget::createWindowContainer(window, this);

After more investigation, I found that the crash actually happens earlier, when calling:

window->initializeWindow();

Inside initializeWindow(), this section is executed:

#if defined(VK_USE_PLATFORM_WIN32_KHR)
    traits->nativeWindow = reinterpret_cast<HWND>(winId());
#elif defined(VK_USE_PLATFORM_XLIB_KHR)
    traits->nativeWindow = static_cast<::Window>(winId());
#elif defined(VK_USE_PLATFORM_XCB_KHR)
    traits->nativeWindow = static_cast<xcb_window_t>(winId());
#elif defined(VK_USE_PLATFORM_MACOS_MVK)
    traits->nativeWindow = winId();
#endif

On my system, this line is executed:

traits->nativeWindow = static_cast<xcb_window_t>(winId());

And that’s exactly what causes the crash.

If I comment out this line, the test version of the app runs without crashing (but of course nothing is rendered).
However, in my main project, the program freezes at:

windowAdapter = vsg::Window::create(traits);

inside initializeWindow().

What’s strange is that this exact code worked perfectly until 3 days ago, and I haven’t changed anything in the project. Now suddenly it crashes or freezes.

Please help me figure out what is causing this and how to fix it.

---

callstack

[hasanshamsijeze]

i use of qt 6.7.0 and 6.7.2

[vsg-dev]

No one else has reported vsgQt/Qt suddenly stopping working. Something must have changed on your system, a driver, VSG, Qt update?

I have just tried VSG, vsgXchange, vsgQt master and ran vsgqtviewer, vsgqtmdi and vsgqtwindows and all 3 run correctly.

I tried building against both Qt5 ( 5.15.13) and Qt6 (6.4.2) on Kubuntu 22.04 system and saw no differences in behavior in the vsgqt examples.

To configure the build with Qt5 and Qt6 respectively I used the QT_PACKAGE_NAME cmake var:

cmake . -DQT_PACKAGE_NAME=Qt5
make
vsgqtviewer models/teapot.vsgt
vsgqtwindows models/lz.vsgt
vsgqtmdi models/openstreetmap.vsgt

cmake . -DQT_PACKAGE_NAME=Qt6
make
vsgqtviewer models/teapot.vsgt
vsgqtwindows models/lz.vsgt
vsgqtmdi models/openstreetmap.vsgt

I have a Geforce 2060 and NVidia drivers installed.

As I can't reproduce any issues I can't do anything more at my end. I'm not a Qt/user developer so don't have a deep under understanding of the ins and outs of Qt so will likely have to defer to others to help you further.

[hasanshamsijeze]

OK, thanks. I also tested the program on another system and it worked correctly, so my guess is the same as what you mentioned.

[robertosfield]

Has the system been updated during the period where it stopped working? Perhaps drivers or Qt has been patched and broken something. Sometimes a reboot can help is an update hasn't been reconfigured everything correctly at runtime.