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Qt-interest Archive, July 2007
Transparent background in QGLWidget


Message 1 in thread

There is a way to make the background of a QGLWidget transparent?

I want to draw a 3D scene having the content of the screen (e.g. other windows) as background... It's possible?

Thanks!



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Message 2 in thread

I think it's not possible to set the background transparent (becase on every 
repaint of an opengl scene (the whole widget) you have to clear the whole 
color buffer).

But you can try one of those:
 - grabbing the widgets behind the QGLWidget and use that pixmap as a 
background texture for the QGLWidget
 - render the QGLWidget on a pbuffer (see the related qt class), then take the 
resulting pixmap and paint it on the top of your window
 - use the QGraphicsView framework over a QGLWidget. This way you can mix 
QGraphicsItems (drawn by QPainter) and native OpenGL calls [* best results]

Of course other ways to do that may exist, but that's what I can think about 
right now. If you can provide more details on your application we can try to 
give you better hints!

Ciao,
Enrico


On Sunday 15 July 2007 08:46:14 fabiodago@xxxxxxxxx wrote:
> There is a way to make the background of a QGLWidget transparent?
>
> I want to draw a 3D scene having the content of the screen (e.g. other
> windows) as background... It's possible?
>
> Thanks!
 
 
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