Greetings OpenSceneGraph/Qt users,
I, also, noticed bad behavior (blinking and such) with the QOSGWidget
example code. It has been a while since I last worked with it, but I
believe that after digging around in the documentation and deep in the
source code that I (partially) corrected the problem by overriding the
virtual QWidget function, paintEngine:
QPaintEngine* QOSGWidget::paintEngine () const
{
return 0;
}
Check your documentation for QWidget::paintEngine, and then give my
suggestion a try; it seems to work for me.
I am currently using OpenSceneGraph 2.8.2 with Qt 4.5.2 on 32 bit
Windows XP Professional. I am building my project with Visual Studio
2005. I believe my fix may also work for linux users, but I haven't
tested it.
Good luck...
D.J.
On Mon, Dec 14, 2009 at 1:05 PM, Don Leich <[email protected]> wrote:
> I've run across the flickering problem before. There seems to be various
> side effects with certain Qt attributes, but I got better results changing
> setAttribute(Qt::WA_NoSystemBackground);
> to
> setAttribute(Qt::WA_OpaquePaintEvent);
> in QOSGWidget.cpp.
>
> You can follow the thread below or dig up the "QOSGWidget demo with a 4-way
> split window" I submitted for more help with Qt atttributes.
>
> // Date: Tue, 16 Jun 2009 10:07:16 +0000
> // From: "Eric Pouliquen" <[email protected]>
> // Subject: Re: [osg-submissions] New QOSGWidget demo with a 4-way split
> // window and bonus outboard window.
> // Suggested replacing the two setAttribute calls with this...
> // setAttribute(Qt::WA_OpaquePaintEvent);
> // This solverd a flickering problem on Windows
> // 8600 GT (185.85) and a Quadro FX1400 (182.65)
> // but causes a visible black border to be visible in the rendering
> // windows on Linux. This problem gone when WA_PaintOnScreen
> // is used in combination.
>
> // Hmmm...
> // According to Qt doc, WA_PaintOnScreen is X11 only and disables
> // double-buffering. I think this just means it disables a
> // buffer swap under Qt control. We want OSG to have full control.
> //
> // Equivalent to qt_x11_set_global_double_buffer(false)?
> //
> // Tried turning it off and got severe flashing on Linux.
> // Looks like without this we get an extraneous clear and
> // buffer swap form Qt.
> setAttribute(Qt::WA_PaintOnScreen);
> // This flags that something other than Qt is responsible for
> // all rendering in the window under the widget's control.
> setAttribute(Qt::WA_OpaquePaintEvent);
> // This seems superfluous now.
> // setAttribute(Qt::WA_NoSystemBackground);
>
>
> -Don Leich
>
>
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