[Qt 4.6.3/OpenGL 4.1] : Unrecognized OpenGL

**didier** · 4th August 2011, 22:50

Hi,

I'm encountering a problem with integrating a QGLWidget.

The message "Unrecognized OpenGL" appears on console.
And glGetString always returns NULL.

My graphic driver is up-to-date.

I success in compiling and running a trivial openGL program and glGetStrings works well.

Someone can tell me what to do ?
Thanks a lot.

**Dong Back Kim** · 5th August 2011, 01:03

Originally Posted by didier

Hi,

I'm encountering a problem with integrating a QGLWidget.

The message "Unrecognized OpenGL" appears on console.
And glGetString always returns NULL.

My graphic driver is up-to-date.

I success in compiling and running a trivial openGL program and glGetStrings works well.

Someone can tell me what to do ?
Thanks a lot.

Are you using overpainting with the QGLWidget?

**didier** · 5th August 2011, 11:11

Originally Posted by Dong Back Kim

Are you using overpainting with the QGLWidget?

A this time, no. I have just written this piece of code.

Qt Code:

Switch view

class GLWidget :public QGLWidget
{
Q_OBJECT
   public:
   GLWidget(QWidget* argParent = 0,
            const QGLWidget* argShareWidget = 0,
            Qt::WindowFlags argFlags = 0 );
 
    signals:
    void sizeChanges(QSize const&);
    void doubleClick(QPoint const&);
    void click(QPoint const&);
 
    protected:
    void initializeGL();
    void resizeGL(int argWidth, int argHeight);
    void mouseDoubleClickEvent(QMouseEvent* event);
    void mouseReleaseEvent(QMouseEvent* event);
    void paintGL();
 
};

class GLWidget :public QGLWidget
{
Q_OBJECT
   public:
   GLWidget(QWidget* argParent = 0,
            const QGLWidget* argShareWidget = 0,
            Qt::WindowFlags argFlags = 0 );

    signals:
    void sizeChanges(QSize const&);
    void doubleClick(QPoint const&);
    void click(QPoint const&);

    protected:
    void initializeGL();
    void resizeGL(int argWidth, int argHeight);
    void mouseDoubleClickEvent(QMouseEvent* event);
    void mouseReleaseEvent(QMouseEvent* event);
    void paintGL();

};

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Qt Code:

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#include "../include/GLWidget.h"
 
GLWidget::GLWidget(QWidget* argParent,
                    const QGLWidget* argShareWidget,
                    Qt::WindowFlags argFlags)
 
                    :QGLWidget(argParent,
                               argShareWidget,
                               argFlags)
{
}
 
void GLWidget::initializeGL()
{
}
 
void GLWidget::resizeGL(int argWidth, int argHeight)
{
   emit sizeChanges(QSize(argWidth, argHeight));
}
 
 
void GLWidget::paintGL()
{
}
 
void GLWidget::mouseDoubleClickEvent(QMouseEvent* event)
{
emit doubleClick(event->pos());
}
 
void GLWidget::mouseReleaseEvent(QMouseEvent* event)
{
   emit click(event->pos());
}

#include "../include/GLWidget.h"

GLWidget::GLWidget(QWidget* argParent,
                    const QGLWidget* argShareWidget,
                    Qt::WindowFlags argFlags)

                    :QGLWidget(argParent,
                               argShareWidget,
                               argFlags)
{
}

void GLWidget::initializeGL()
{
}

void GLWidget::resizeGL(int argWidth, int argHeight)
{
   emit sizeChanges(QSize(argWidth, argHeight));
}


void GLWidget::paintGL()
{
}

void GLWidget::mouseDoubleClickEvent(QMouseEvent* event)
{
emit doubleClick(event->pos());
}

void GLWidget::mouseReleaseEvent(QMouseEvent* event)
{
   emit click(event->pos());
}

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I've believed, an instant, it's because my OpenGL implementation is 4.1 and Qt 4.6.3 wouldn't recognize OpenGL 4.1 because of enum QGLFormat::OpenGLVersionFlag's definition.

About glGetString(). The problem is over. I've discovered glContext is inititialized in after QGLWidget() constructor. In paintGL(), it works well.

**Dong Back Kim** · 5th August 2011, 23:33

Originally Posted by didier

A this time, no. I have just written this piece of code.

Qt Code:

Switch view

class GLWidget :public QGLWidget
{
Q_OBJECT
   public:
   GLWidget(QWidget* argParent = 0,
            const QGLWidget* argShareWidget = 0,
            Qt::WindowFlags argFlags = 0 );
 
    signals:
    void sizeChanges(QSize const&);
    void doubleClick(QPoint const&);
    void click(QPoint const&);
 
    protected:
    void initializeGL();
    void resizeGL(int argWidth, int argHeight);
    void mouseDoubleClickEvent(QMouseEvent* event);
    void mouseReleaseEvent(QMouseEvent* event);
    void paintGL();
 
};

class GLWidget :public QGLWidget
{
Q_OBJECT
   public:
   GLWidget(QWidget* argParent = 0,
            const QGLWidget* argShareWidget = 0,
            Qt::WindowFlags argFlags = 0 );

    signals:
    void sizeChanges(QSize const&);
    void doubleClick(QPoint const&);
    void click(QPoint const&);

    protected:
    void initializeGL();
    void resizeGL(int argWidth, int argHeight);
    void mouseDoubleClickEvent(QMouseEvent* event);
    void mouseReleaseEvent(QMouseEvent* event);
    void paintGL();

};

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Qt Code:

Switch view

#include "../include/GLWidget.h"
 
GLWidget::GLWidget(QWidget* argParent,
                    const QGLWidget* argShareWidget,
                    Qt::WindowFlags argFlags)
 
                    :QGLWidget(argParent,
                               argShareWidget,
                               argFlags)
{
}
 
void GLWidget::initializeGL()
{
}
 
void GLWidget::resizeGL(int argWidth, int argHeight)
{
   emit sizeChanges(QSize(argWidth, argHeight));
}
 
 
void GLWidget::paintGL()
{
}
 
void GLWidget::mouseDoubleClickEvent(QMouseEvent* event)
{
emit doubleClick(event->pos());
}
 
void GLWidget::mouseReleaseEvent(QMouseEvent* event)
{
   emit click(event->pos());
}

#include "../include/GLWidget.h"

GLWidget::GLWidget(QWidget* argParent,
                    const QGLWidget* argShareWidget,
                    Qt::WindowFlags argFlags)

                    :QGLWidget(argParent,
                               argShareWidget,
                               argFlags)
{
}

void GLWidget::initializeGL()
{
}

void GLWidget::resizeGL(int argWidth, int argHeight)
{
   emit sizeChanges(QSize(argWidth, argHeight));
}


void GLWidget::paintGL()
{
}

void GLWidget::mouseDoubleClickEvent(QMouseEvent* event)
{
emit doubleClick(event->pos());
}

void GLWidget::mouseReleaseEvent(QMouseEvent* event)
{
   emit click(event->pos());
}

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I've believed, an instant, it's because my OpenGL implementation is 4.1 and Qt 4.6.3 wouldn't recognize OpenGL 4.1 because of enum QGLFormat::OpenGLVersionFlag's definition.

About glGetString(). The problem is over. I've discovered glContext is inititialized in after QGLWidget() constructor. In paintGL(), it works well.

Good to know about QGLFormat::OpenGLVersionFlag.