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martinb0820
28th September 2009, 17:38
I originally posted this under Installation and Deployment, but haven't had much in the way of responses there. I'm not sure whether this is a Qt-related issue, or associated with Open Inventor/Coin3D (but see the reference below to wglChoosePixelFormat() being called from inside Qt).

I'm using Qt 4.5 with both VSG Open Inventor and Coin3D, and also have a legacy application built with SGI Open Inventor and FLTK that are all capable of animating the same scene graph. The development environment is Qt Designer and 32-bit Visual Studio 2005 Sp1.

All of the applications run fine under 32-bit XP. When there is at least one very complex object in the scene graph, on a 64-bit system, with either ATI or NVIDEA graphics cards, the frame rate of both the Qt/OIV and Qt/Coin3D builds slows down to the point that updates are very choppy, about 1 fps or worse. The FLTK/SGI OIV build runs fine under 64-bit XP, however, and the Qt OpenGL examples also run fine under 64-bit XP.

Profiling the code, the Qt builds spend 75 to 90% of the time in wglChoosePixelFormat(), (called from inside of Qt) when running under 64-bit XP. This routine doesn't show up at all (it may be getting invoked but not accounting for enough time to appear) in the 32-bit profiles. This is true even when booting the same PC with 32- and 64-bit XP for testing.

I've tried every video card configuration I can find, have installed both new and various older video drivers, but nothing makes a difference.

Any help or ideas would be appreciated!

Thanks,
Martin

martinb0820
2nd October 2009, 20:23
Turned out to be incorrect OGL DLLs.