[Interest] Qt 5.1.1 render with both - OpenGL and QPainter - in one window?

[Till Oliver Knoll]

Am 24.09.2013 um 16:36 schrieb Bob Hood <bhood2 at comcast.net>:

> On 9/24/2013 8:15 AM, Thomas Meyer wrote:
>> Hi,
>> is it possible to use OpenGL and QPainter in one window (Qt 5.1.1)?
>> And if it is possible, how and is it recommended?
>> Example:
>> I want to render the word "Triangle" into the 'OpenGL Window Example'
>> (please see Qt Creator - Welcome - Examples).
>> 
>> My first guess is, that it is not possible. I can only render with OpenGL or
>> with QPainter, like the example shows.
> 
> Off the top of my head, have OpenGL render to a buffer, use QPainter to draw
> on the buffer contents, then blit the result to the window.

At least with Qt 4.x there was (at least one) an example which showed how to "mix" a QPainter with (raw) OpenGL.

IIRC you always paint on a QGLWidget and the QPainter would translate paint commands (lines etc.) directly into GL commands, or first paint into a QImage and convert that into a texture (or the like).

The magic keywords when switching from/to the GL context to/from the QPainter context (view, transformation matrix etc.) are QPainter::begin|endNativePainting, I believe.

Cheers,
  Oliver