QOpenGLWindow - paintGL is never called

glararan

Hello,

I'm learning with new Qt classes like VAO, VBO, OpenGLWindow..

I took example and little bit rewrite it. Because example wasn't using paintGL but QPaintDevice.

Currently I have following code:

#include "glwindow.h"

#include <QCoreApplication>
#include <QDebug>

GLWindow::GLWindow()
: QOpenGLWindow(QOpenGLWindow::NoPartialUpdate)
{
}

GLWindow::~GLWindow()
{
}

void GLWindow::initializeGL()
{
    initializeOpenGLFunctions();

    connect(this, &GLWindow::frameSwapped, this, &GLWindow::renderNow); // use this or last commented out section in renderNow()?

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

    initialize();

    renderNow();
}

void GLWindow::paintGL()
{
    qDebug() << "c";
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

    render();

    painted = true;
}

void GLWindow::renderNow()
{
    if(!isExposed())
        return;

    /*if(!painted) // useless to continue when paint wasnt done yet
        return;

    painted = false;*/

    QOpenGLContext::currentContext()->makeCurrent(this);

    QOpenGLWindow::update(); // <---- this not calling paintGL at all :((

    QOpenGLContext::currentContext()->swapBuffers(this);

    qDebug() << "draw";

    // use connect or this? what is faster?
    /*if(draw && !pendingUpdate)
    {
        pendingUpdate = false;

        QCoreApplication::postEvent(this, new QEvent(QEvent::UpdateRequest));
    }*/
}

void GLWindow::resizeGL(int width, int height)
{
    const qreal pixelRatio = devicePixelRatio();

    glViewport(0, 0, width * pixelRatio, height * pixelRatio);
}

bool GLWindow::event(QEvent* event)
{
    switch(event->type())
    {
        case QEvent::UpdateRequest:
            {
                pendingUpdate = false;

                renderNow();

                return true;
            }

        default:
            return QWindow::event(event);
    }
}

void GLWindow::exposeEvent(QExposeEvent* event)
{
    Q_UNUSED(event);

    if(isExposed())
        renderNow();
}

void GLWindow::initialize() // virtual
{
}

void GLWindow::render() // virtual
{
}

This should be class which will be inherited.

What's the problem? I get from qDebug only "draw" not "paintGL" or "c". PaintGL should be called from line "QOpenGLWindow::update(); // <---- this not calling paintGL at all :((" or I had to missunderstand documentations.

Also last question, I did some comments to code, is better to use connect to repaint or QCoreApplication::postEvent?

Thanks

glararan

Ok I figured it out, there is broken code in example.

bool GLWindow::event(QEvent* event)
{
    switch(event->type())
    {
        case QEvent::UpdateRequest:
            {
                pendingUpdate = false;

                renderNow();

                return true;
            }

        default:
            return QWindow::event(event);
    }
}

Should be

bool GLWindow::event(QEvent* event)
{
    if(event->type() == QEvent::UpdateRequest)
    {
           pendingUpdate = false;

           renderNow();
    }

    return QWindow::event(event);
}

So there is only question which remains, what's better to use as update? PostEvent or connect?

Thanks

EDIT: next question, why is QOpenGLWindow limited to 30 frames per second? How to make 60fps?

EDIT 2: fps solved with setSwapInterval(0)
EDIT 3: I guess to FPS counter that QCoreApplication::PostEvent is 5 times faster than connect, but still give me your advice