Draw 2D graphics onto a QOpenGLWidget subclass using QPainter

[ytyisme]

This URL (http://doc.qt.io/qt-5/qopenglwidget.html)show Draw 2D graphics onto a QOpenGLWidget subclass using QPainter.I don't konw why you reimplement the paintEvent() and call makeCurrent() and doneCurrent().

Install Qt5.9.1 with examples, you will find one example qopenglwidget in Qt5.9.1\Examples\Qt-5.9.1\opengl. qopenglwidget is a example show how to Draw 2D graphics onto a QOpenGLWidget subclass using QPainter.I tried to modify your code to make it look like that example. I remove paintEvent(),and put QPainter in paintGL(), but it not works.

You can try it.

[Pseudomanifold]

I am not sure what you mean in this issue. Do you want me to remove the paintEvent that I implemented in the widget? In my implementation, I need paintEvent in order to paint the selection rectangle with QPainter. Since the OSG widget displays a mixture of both 3D graphics (OpenSceneGraph) and 2D graphics (QPainter), I thought that this was the best solution. The Qt documentation states that this makes sense, as far as I understand.

[ytyisme]

Now, in the windows platform，can’t display the things QPainter draw when use your code. My English is poor. Most of them are from google translation

[Pseudomanifold]

I am sorry, I do not have much experience with programming for Microsoft Windows. I will try to look into this. Can you send me some screenshots maybe?

[ytyisme]

Now show the correct under Windows
I modified as follows

class OSGWidget : public QOpenGLWidget,protected QOpenGLFunctions

void OSGWidget::paintGL()
{
glPushAttrib(GL_ALL_ATTRIB_BITS);
glPushClientAttrib(GL_ALL_ATTRIB_BITS);
viewer_->frame();
glPopAttrib();
glPopClientAttrib();
}

Under Windows, you need to add the link library opengl32.lib

[Pseudomanifold]

Thank you for these modifications! Is the protected QOpenGLFunctions required?

[ytyisme]

If you do not inherit QOpenGLFunctions then the OpenGL function will not be declared. You may need to include the gl.h header file

[Pseudomanifold]

Thank you for the reply! I will refer to this discussion in the README file because, as I said, I do not have sufficient experience with programming for Microsoft Windows.