Is it real to write threaded opengl app, which uses basic initialization (QGLWidget::initializeGL()) and painting (QGLWidget::paintGL()), but threaded drawing with glDrawPixels() ??
Not quite sure what you’re asking, but you can use GL from a separate thread if you’re careful.
I found this thread useful: http://www.gamedev.net/community/forums/topic.asp?topic_id=260982
I’d be very cautious of QGLWidget.
I got multithreaded rendering working today with a bit of hackery in my QGLWidget subclass – working, that is, on Windows and Linux. On Mac OS X the computer crashed hard 
– probably something I was doing was more than a little dodgy 
Writing a simple QGLWidget replacement seems pretty easy. QGLWidget does a bunch of stuff you don’t really care about most of the time… I have the most basic of basic ones working on X11 now. Mac OS X is first up tomorrow.
OneSadCookie: Please, send me your example at squirrel-sf at yandex.ru.
Thanks.
Basically I just used the code in the GameDev.net thread I linked above, in a QWidget subclass. Not sure how robust it is without a bit more testing, and I have to jump through some hoops to get things like resize messages through to the thread. You’re probably better off doing this yourself…
In other interesting news, I implemented the Mac OS X and Win32 versions of said QWidget subclass. The three systems are somewhat differently powered, but here are the performance numbers I gathered today. This is the FPS per-thread, two-thread test, each thread drawing a single triangle, half of a 1280x1024 screen:
Linux (Dell Precision 360, GeForce 6800 Ultra): 380
Mac OS X (Dual 2GHz G5, Radeon 9600): 450
Win32 (Dell Precision 360, GeForce 5900): 580
Just one thing - I need not two threads rendering two separate windows, I need two threads rendering the same window, but only one thread a time. I’ll look at example at gamedev.net, but I don’t hope that it is suitable for me 
You probably don’t want to get into trying to make GL calls to the same context from two different threads simultaneously…
If you do, you can only do it with a mutex, ensuring the two threads can never make GL calls at the same time as each other.
No, not ‘simultaneously’. I mean Main thread creates QGLWidget, drawes something on it, then creates QThread’s instance and this instance should draw something by itself, then exit. Main thread continues drawing …
You mean that two threads renders in the same buffer ?!
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