Quote Originally Posted by wysota View Post
Well... you can't draw in the middle of a pixel. If you scale up the painter, the precision should increase.
I could suppose that QT can resample my pixmap using algorithm similar to one using for resizing...

Anyway, for now I've decided to use OpenGL which should be available in 90% cases with fallback to slow software rendering in other cases. On old machines without OpenGL even QPixmap approach can be too slow so I'll probably provide advances options to draw particles as points instead of circles.