And the root node's FrameAction component will trigger the single every frame. In practice, I think you can probably also get about the same effect by making a QTimer with zero timeout. After rendering a frame, the mainloop will be idle and trigger the idle timer. But it won't be guaranteed to be entirely in sync.
The name "Iris GL" is going to be super confusing to anybody who remembers IrisGL on Irix workstations. Might be a good idea to consider using a name not already associated with a well known thing in the are of 3D graphics.
Just if somebody is wondering I tried to use qGraphicsView/qGraphicsScene/qGraphicsItem and the performance are even much much worse.
I recommend you build, run, and study the "40000 Chips" example. (Search Qt Creator for the examples)
The key points are:
Make each ground tile an individual QGraphicsPixmapItem. (It might help to aggregate the tiles to bigger images)
Make your character sprite another QGraphicsPixmapItem.
Add all the ground tiles to your QGraphicsScene. You only need to do this once at startup, and you don't need to destroy them until your program quits.
For the Age of Empires-style fog-of-war, call QGraphicsView::setBackgroundBrush() once to make your background black. During the game, call setOpacity() to make the tiles around your character fully opaque, and make all the other tiles fully transparent. The transparent tiles will show the black background instead of the image.
To scroll, move your character sprite and call QGraphicsView::centerOn() to move the viewport.
This is an interesting topic.
I am porting a computer emulator (AppleWin) to Linux using Qt.
Qt is fit for this purpose and I managed to do most things without too much hassle.
Timers probably is where I found most issues as their accuracy is in the region of 10ms at best, while in the original Windows project one can achieve 1ms without problems.
Haven't dealt with audio yet so can't comment.
But which features people need from SDL which are not already in Qt?
I see a lot of overlapping in the 2 APIs with Qt the clear winner for all Dialog / Form / Button and traditional GUI components.
If I had to provide a blind answer I would say speed.
I guess this shows my ignorance of both Qt and SDL...