Check which OpenGL engine is used by Qt at runtime for release builds

Question

In QML applications there are 3 rendering types:

• Native OpenGL: "desktop"
• ANGLE Direct3D: "angle"
• A software renderer: "software"

We use the automatic loading mechanism of the supported type.

How can I programmatically determine which rendering type is used at runtime?

I know of QT_LOGGING_RULES=qt.qpa.gl=true but this produces a lot of noise and DEBUG messages, which are not logged in our release build. Is there another simple way to just get the rendering type?

Volumed

With "software" do you mean through a software OpenGL renderer like Mesa's llvmpipe, or the 2D renderer of Qt Quick? – Transpontine

@Transpontine Mesa's llvmpipe via the shipped opengl32sw.dll – Volumed

Then can you just check GL_VENDOR, GL_VERSION etc.? You'll get ANGLE, Mesa, etc. – Transpontine

@Transpontine How do I do that? glGetString(GL_VENDOR) gives me null (on Linux). – Volumed

Answer 1

Got it thanks to @peppe and some additional research:

// this connection must be established before show() is called
QObject::connect(window, &QQuickWindow::sceneGraphInitialized,
                 [=] () -> void {
    auto context = window->openglContext();
    auto functions = context->functions();
    const std::string vendor = reinterpret_cast<const char*>(functions->glGetString(GL_VENDOR));
    const std::string renderer = reinterpret_cast<const char*>(functions->glGetString(GL_RENDERER));
    const std::string version = reinterpret_cast<const char*>(functions->glGetString(GL_VERSION));
    qDebug() << "OpenGL vendor: " << vendor << " "
             << "renderer: " << renderer << " "
             << "version: " << version;
});

where window is my main QQuickWindow*.

Volumed