Quote Originally Posted by unix7777 View Post
1.The difference in using QPaint and OpenGL?
QPainter is a painting frontend, OpenGL is a painting backend that can be used by QPainter.

2.What is the best approach if i want to make a game using raster graphic for example game like BigFishgames with background and another
pictures that move around?
Probably QGraphicsView.
3.Is OpenGL only for vector graphic?
Well.... in general yes. You can do raster graphics with it using shaders or keeping sprites as textures and manipulating rectangles but I wouldn't call it straightforward (but essentially if you use QPainter with OpenGL backend that's what you get).
4.Some examples of simple game made with QT?
There are some in Qt docs, there is Google Earth... ups... that's not a game..., also "WolfenQt" (it's on Qt Labs) is a nice example of what you can do with Qt.