Qt + Urho3D and threads

Hi,

I created an application which integrates Urho3D in a QML window via external window.
The problem I ran into is about threads. Indeed, in my code, I have :

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    QQmlApplicationEngine engine;

    //declaration of instances, ...
    ....

    //Urho3D
    mUrho3DContext = new Urho3D::Context();
    mUrho3DApplication = new Urho3DApplication(mUrho3DContext);

    //qml interface is loaded
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    mUrho3DApplication->Run();

    return app.exec();
}

The problem is that when Urho3D starts, it keeps the hand and consequently “return app.exec()” is never executed, which is a real problem for my Qt application which requires that instruction to run correctly.

So is it possible to run all Urho3D in a complete separated thread so that my main thread is handled by Qt, so no Urho3D in the main thread? For what I read, Urho3D needs the main thread so … not sure about the feasability of what I need.

Thanks.

I don’t think having multiple threads is really good idea. You need Qt and Urho3D both running main loop, and as I understand, common workaround is to call RunFrame() by hand via timer. Check out and how it is done in ParticleEditor2D:

You shall probably avoid using Appliaction if you don’t want Urho to be the ruler of application life.

Think twice before bringing multithread hell into your application.

@SteveU3D
Check Urho code for starting Emscripten or Ios. There’s a different launch procedure, because of same problem; i don’t remember the details, but emsc use web workers and cannot return directly, or so; and ios never return, because there’s no such thing as a “exit app” on ios…

I see multiple inheritance is another part of the key in the case of the ParticleEditor:

Thanks for your answer. I was able to do it like in the Particle example.

• a class which inherits from Urho3D::Object (the Urho3D class with the scene, all 3D objects, …) instead od Urho3D::Application, and with in particular a function to update the scene with engine_->RunFrame(),
• a class which inherits from QApplication with a slot which is executed all n milliseconds, this slot executes the update function of the Urho3D class.

And the

return app.exec();

of Qt is well executed.

Hey @SteveU3D, I’d be very interested to see a minimal example of how to integrate Urho into a QML application. If you’ve made any progress, posting some example code to GitHub would be greatly appreciated!

Thanks

EDIT: I’ll be trying this this week, so if I’m able to make a working example I’ll post here.

Hi,
@jonathan

Sorry for that late answer.
Here is a simple code integrating Urho3D in a QML application. I used it like that (with my own scene, objects, … not put in the code) but it needs to be improved, so don’t hesitate to do it .

In particular, one thing I didn’t succeed to do and I really need in my final application is to delete the Urho3DApplication class and create it again at runtime with Urho3DManager class (I deleted from the code on github the tests I did in Urho3DApplication destructor).

I wrote some explanations in README file but if you have questions, ask .

Repository : https://github.com/SteveTJS/urho3DInQML

Thanks.