Is it possible to add GUI for QOpenGLWindow? The button should be in the center of the OpenGL canvas.

[JoeCFD]

@8Observer8 said in Is it possible to add GUI for QOpenGLWindow?:

m_pOpenGLWindow

m_pOpenGLWindow is not created. Is its header included? QOpenGLWidget is a widget. Sure you can add it to the layout.

[8Observer8]

I posted all the example code above.

[8Observer8]

@JoeCFD said in Is it possible to add GUI for QOpenGLWindow?:

QOpenGLWidget is a widget. Sure you can add it to the layout.

I just replaced QOpenGLWidget to QOpenGLWindow in your example. I don't need QOpenGLWidget.

[JoeCFD]

@8Observer8 You can not add it to the layout. I use QOpenGLWidget. You can overlay your button to any widget which holds QOpenGLWindow.

https://stackoverflow.com/questions/32593428/add-qwidget-on-top-of-qopenglwindow

[8Observer8]

@JoeCFD said in Is it possible to add GUI for QOpenGLWindow?:

https://stackoverflow.com/questions/32593428/add-qwidget-on-top-of-qopenglwindow

This is the only information I found on my topic through Google. But this question on StackOverflow doesn't have a solution, so I forgot about it. Now I noticed QWidget::createWindowContainer. But the question remains open. I'm trying to position a button in the center of an OpenGL window:

main_window.h

#ifndef MAIN_WINDOW_H
#define MAIN_WINDOW_H

#include <QtCore/QSize>
#include <QtCore/QString>
#include <QtWidgets/QHBoxLayout>
#include <QtWidgets/QVBoxLayout>
#include <QtWidgets/QPushButton>
#include <QtWidgets/QWidget>

#include "opengl_window.h"

class MainWindow : public QWidget
{
public:
    explicit MainWindow(QWidget *parent=nullptr) : QWidget(parent)
    {
        setFixedSize(QSize(300, 300));
        setWindowTitle("OpenGL 2.1, Qt6, C++");

        // m_pStartGameButton->move(center);

        QVBoxLayout *rootLayout = new QVBoxLayout();
        setLayout(rootLayout);

        m_pOpenGLWindow = new OpenGLWindow();
        QWidget *container = QWidget::createWindowContainer(m_pOpenGLWindow);
        rootLayout->addWidget(container);

        m_pStartGameButton = new QPushButton(QString("Start Game"));
        QHBoxLayout *startButtonLayout = new QHBoxLayout();
        startButtonLayout->setAlignment(Qt::AlignmentFlag::AlignHCenter);
        startButtonLayout->addWidget(m_pStartGameButton);
        rootLayout->addLayout(startButtonLayout);
    }

    ~MainWindow()
    {
        delete m_pOpenGLWindow;
    }

private:
    OpenGLWindow *m_pOpenGLWindow {};
    QPushButton *m_pStartGameButton {};
};

#endif // MAIN_WINDOW_H

[8Observer8]

I found my mistake:

        // rootLayout->addLayout(startButtonLayout);
        container->setLayout(startButtonLayout);

But it looks like the button is behind the OpenGL canvas like in the topic: https://stackoverflow.com/questions/32593428/add-qwidget-on-top-of-qopenglwindow
Is it a bug?

[8Observer8]

Current code:

        QVBoxLayout *rootLayout = new QVBoxLayout();
        setLayout(rootLayout);

        m_pOpenGLWindow = new OpenGLWindow();
        QWidget *container = QWidget::createWindowContainer(m_pOpenGLWindow);
        rootLayout->addWidget(container);

        m_pStartGameButton = new QPushButton(QString("Start Game"));
        QHBoxLayout *startButtonLayout = new QHBoxLayout();
        startButtonLayout->setAlignment(Qt::AlignmentFlag::AlignHCenter);
        startButtonLayout->addWidget(m_pStartGameButton);
        // rootLayout->addLayout(startButtonLayout);
        container->setLayout(startButtonLayout);

[JoeCFD]

@8Observer8
Do not put it in the layout.

       m_pStartGameButton = new QPushButton(QString("Start Game"), this );
       m_pStartGameButton->move( 150, 150 );

[8Observer8]

@JoeCFD I don't see the button again:

        QVBoxLayout *rootLayout = new QVBoxLayout();
        setLayout(rootLayout);

        m_pOpenGLWindow = new OpenGLWindow();
        QWidget *container = QWidget::createWindowContainer(m_pOpenGLWindow);
        rootLayout->addWidget(container);

        m_pStartGameButton = new QPushButton(QString("Start Game"), this);
        // QHBoxLayout *startButtonLayout = new QHBoxLayout();
        // startButtonLayout->setAlignment(Qt::AlignmentFlag::AlignHCenter);
        // startButtonLayout->addWidget(m_pStartGameButton);
        // container->setLayout(startButtonLayout);
        m_pStartGameButton->move(150, 150);

[8Observer8]

@JoeCFD I see part of it:

m_pStartGameButton->move(0, 0);

[JoeCFD]

@8Observer8
Read the link I posted. Raise your button. Call button->raise();

Qt cannot divine what Z order you want if you don't create the widgets in Z order. You need to raise the widget. The whole hiding rigmarole is completely unnecessary anyway. Simply create the widget where you need it.

[8Observer8]

@JoeCFD said in Is it possible to add GUI for QOpenGLWindow? The button should be in the center of the OpenGL canvas.:

Raise your button. Call button->raise();

It doesn't work:

    m_pStartGameButton = new QPushButton(QString("Start Game"), this);
    m_pStartGameButton->raise();
    m_pStartGameButton->move(0, 0);

[8Observer8]

Current code:

        QVBoxLayout *rootLayout = new QVBoxLayout();
        setLayout(rootLayout);

        m_pOpenGLWindow = new OpenGLWindow();
        QWidget *container = QWidget::createWindowContainer(m_pOpenGLWindow);
        rootLayout->addWidget(container);

        m_pStartGameButton = new QPushButton(QString("Start Game"), this);
        m_pStartGameButton->raise();
        m_pStartGameButton->move(0, 0);

[JoeCFD]

@8Observer8

    m_pStartGameButton = new QPushButton(QString("Start Game"), this);
    m_pStartGameButton->move(0, 0);
    m_pStartGameButton->setWindowFlags(m_pStartGameButton->windowFlags() | Qt::WindowStaysOnTopHint);

[8Observer8]

@JoeCFD unfortunately it doesn't work:

        QVBoxLayout *rootLayout = new QVBoxLayout();
        setLayout(rootLayout);

        m_pOpenGLWindow = new OpenGLWindow();
        QWidget *container = QWidget::createWindowContainer(m_pOpenGLWindow);
        rootLayout->addWidget(container);

        m_pStartGameButton = new QPushButton(QString("Start Game"), this);
        // m_pStartGameButton->raise();
        m_pStartGameButton->move(0, 0);
        m_pStartGameButton->setWindowFlags(m_pStartGameButton->windowFlags() | Qt::WindowStaysOnTopHint);

[JoeCFD]

@8Observer8
Sorry. I will make a test case later.

[8Observer8]

@JoeCFD this is my current project: start-button-qopenglwindow-opengl21-qt6-cpp.zip

main.cpp

/*
.pro file:
QT += core gui opengl widgets
win32: LIBS += -lopengl32
HEADERS += main_window.h opengl_window.h
SOURCES += main.cpp
TARGET = app
-------------------------------
Build and run commands for CMD:
> qmake -makefile
> mingw32-make
> "release/app"
*/

#ifdef _WIN32
#include <windows.h>
extern "C" __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
extern "C" __declspec(dllexport) DWORD AmdPowerXpressRequestHighPerformance = 0x00000001;
#endif

#include <QtWidgets/QApplication>
#include <iostream>
#include "main_window.h"

int main(int argc, char *argv[])
{
#ifdef _WIN32
    if (AttachConsole(ATTACH_PARENT_PROCESS))
    {
        freopen("CONOUT$", "w", stdout);
        freopen("CONOUT$", "w", stderr);
    }
#endif
    std::cout << std::endl;

    QApplication app(argc, argv);
    MainWindow w;
    w.show();
    return app.exec();
}

main_window.h

#ifndef MAIN_WINDOW_H
#define MAIN_WINDOW_H

#include <QtCore/QSize>
#include <QtCore/QString>
#include <QtWidgets/QHBoxLayout>
#include <QtWidgets/QVBoxLayout>
#include <QtWidgets/QPushButton>
#include <QtWidgets/QWidget>

#include "opengl_window.h"

class MainWindow : public QWidget
{
public:
    explicit MainWindow(QWidget *parent=nullptr) : QWidget(parent)
    {
        setFixedSize(QSize(300, 300));
        setWindowTitle("OpenGL 2.1, Qt6, C++");

        // m_pStartGameButton->move(center);
        // QHBoxLayout *startButtonLayout = new QHBoxLayout();
        // startButtonLayout->setAlignment(Qt::AlignmentFlag::AlignHCenter);
        // startButtonLayout->addWidget(m_pStartGameButton);
        // container->setLayout(startButtonLayout);

        QVBoxLayout *rootLayout = new QVBoxLayout();
        setLayout(rootLayout);

        m_pOpenGLWindow = new OpenGLWindow();
        QWidget *container = QWidget::createWindowContainer(m_pOpenGLWindow, this);
        rootLayout->addWidget(container);

        m_pStartGameButton = new QPushButton(QString("Start Game"), this);
        // m_pStartGameButton->raise();
        m_pStartGameButton->move(0, 0);
        m_pStartGameButton->setWindowFlags(m_pStartGameButton->windowFlags() | Qt::WindowStaysOnTopHint);
    }

    ~MainWindow()
    {
        delete m_pOpenGLWindow;
    }

private:
    OpenGLWindow *m_pOpenGLWindow {};
    QPushButton *m_pStartGameButton {};
};

#endif // MAIN_WINDOW_H

opengl_window.h

#ifndef OPENGL_WINDOW_H
#define OPENGL_WINDOW_H

#include <QtCore/QSize>
#include <QtGui/QOpenGLFunctions>
#include <QtGui/QSurfaceFormat>
#include <QtOpenGL/QOpenGLWindow>

#include <iostream>

class OpenGLWindow : public QOpenGLWindow, private QOpenGLFunctions
{
public:
    OpenGLWindow()
    {
        resize(QSize(300, 300));
        setTitle("OpenGL 2.1, Qt6, C++");

        // Set format
        QSurfaceFormat format;
        format.setSamples(4);
        format.setSwapInterval(1);
        setFormat(format);
        connect(this, SIGNAL(frameSwapped()), this, SLOT(update()));
    }

private:
    void initializeGL() override
    {
        initializeOpenGLFunctions();
        glClearColor(0.2, 0.5, 0.2, 1);
    }

    void paintGL() override
    {
        glClear(GL_COLOR_BUFFER_BIT);
        // std::cout << "paintGL" << std::endl;
    }
};

#endif // OPENGL_WINDOW_H

start-button-qopenglwindow-opengl21-qt6-cpp.pro

QT += core gui opengl widgets
win32: LIBS += -lopengl32
HEADERS += main_window.h opengl_window.h
SOURCES += main.cpp
TARGET = app

[SimonSchroeder]

I distinctly remember that Qt at one point announced support for QWidgets within OpenGL. However, I am not quite able to find that announcement again. Maybe support has been discontinued with Qt 6.

What I have found so far is this: https://docs.huihoo.com/qt/5.x/qtwidgets-graphicsview-boxes-example.html
I haven't read through the entire code to make sure that the widgets are drawn on some OpenGL canvas. Having a quick look at QGraphicsProxyWidget suggests that it might help with what you are trying to achieve. It still seems to exist in Qt 6.

[JoeCFD]

@8Observer8 Sorry I could not make it with QOpenGLWindow. I use QOpenGLWidget which is ok.

You also need to add a parent to the container in order to avoid leak.
QWidget *container = QWidget::createWindowContainer(m_pOpenGLWindow, this );

[8Observer8]

If QOpenGLWindow is inherited from QWindow, does that mean I can use the QML GUI in QOpenGLWindow?

@JoeCFD said in Is it possible to add GUI for QOpenGLWindow? The button should be in the center of the OpenGL canvas.:

You also need to add a parent to the container in order to avoid leak.
QWidget *container = QWidget::createWindowContainer(m_pOpenGLWindow, this );

Fixed in the message above and in the archive.