How Connect Two Timed Methods in sequence

wwolff

Hi!
I have a simple doubt here , and i dont know if it´s possible with Qt:

I have a simple OpelGL Window where i use a Render method to update the rendering using a timer as below:

    connect(this, SIGNAL(widthChanged (int)), this, SLOT(resizeGl()));
    connect(this, SIGNAL(heightChanged(int)), this, SLOT(resizeGl()));

    timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(RenderScene()));
    timer->start(0);

My doubt is:
It´s possible i connect another method like "UpdateScene" slot that be executed only after RenderScene finish it´s job?

Any help will be much appreciated becouse i´m having syncronization issues between the rendering being performed in the screen and the data being updated on the aplication, since the GPU´s are rendering in threads.

Kind Regards.

Paul Colby

Hi @wwolff

I might be missing the point of what you're asking, but as slots are just regular functions, you can always call one from the other, eg:

void MyClass::RenderScene() {
    // do whatever RenderScene does.
    UpdateScene(); // invoke the UpdateScene slot directly.
}

If you're bothered by the added coupling, you can emit your own signal as a go-between, eg:

void MyClass::MyClas(...) {
    connect(this, SIGNAL(sceneRendered()), this, SLOT(UpdateScene()));
    // the rest of your sample code from above here...
}

void MyClass::RenderScene() {
    // do whatever RenderScene does.
    emit sceneRendered();
}

Since you've specifically mentioned using threads, you probably want to use the signal/slot separation, because that allows you to use Qt's queued connections (or other connection types as appropriate) if signalling from one thread, to another's slot... have a read of Signals and Slots Across Threads.

Cheers.

wwolff

Thanks so much!
This is exactly what´s i´m looking for (A way to fire up a signal to inform that my UpdateScene Method need be executed).

I will try it!