graphicsview performance problem

[kernel_panic]

Hi all!
I have a problem with the performance of a QGraphicsView.
I made a small example and attached it. For the animation i have to do i need more than 1000 particles.
I tried it qith OpenGL viewport, optimazion flags and buffers. finally i put the particle system into a thread... nothing helped.
Im new with QGraphicsView and im sure some of you gurus can help me.

[wysota]

The example you provided works quite fast on my computer (with the GL viewport). Could you specify what exactly is the problem?

[kernel_panic]

try with 2000 particles.
int calcthread.cpp:
Init(2000,n_forces,f,Create,vel,pos1,pos2,128,QCol or(0,0,255,255),4);

[wysota]

I did. 2000 is still quite fast. With 10000 it's slow, but drawing 10k pixmaps is quite an effort, so I can understand it.

[kernel_panic]

?? for me is quiet slow....
and my dualcore has over 50% processor load.

[jacek]

Use a profiler. It will show you where you should improve your application.

[wysota]

I have a single core Athlon 2.5+ with hardware accelerated OpenGL implementation under Linux/X11 and Qt 4.3.3.

If rendering is too slow for you, try using OpenGL calls to render your items. It should be very fast - after all it's just a bunch of quads with the same texture applied.

[kernel_panic]

ah!
i forgott one thing!
on linux, bsd and mac its quiet fast... but under windows....puah!

you mean i should implement it fully in opengl? i never worked with opengl.... dou you know any good tutorials?

[jacek]

First try the profiler. By adding "const &" in certain place and changing one constant you can save about 30% of the CPU time.

[kernel_panic]

I never used a profiler.
i tried it with "sleepy", an oo project, but he said 47% of 50% processor load are from KiFastSystemCallRet.
WTF IS THAT? I think i know now why i hate developing under windows....

[wysota]

I suggest trying callgrind or gprof under Linux.

[Uwe]

I suggest trying callgrind or gprof under Linux.

Well, the problem was described as a Windows only problem.

Try to render the scene to a QImage, because QImage uses the same paint engine on all platforms, that is used on Windows. If you see the same performance problems with QImage/Linux you can use the tools Witold recommended.

Most paint engines are frontends to native paint subsystems like X11, but the raster paint engine is a new development in Qt4. So its no surprise, that many problems ( and performance issues ) are related to it.

Uwe