Speaking of performance, how is xna/directx working for 2d?
Xna actually has surprisingly great support for 2D. Its not as simple as SFML, but one big thing they have going for them is their SpriteBatch class. There are 5 sorting methods:
1. Immediate: Draw whenever the state (texture) changes.
2. Texture: Draw everything at once, ordered by texture (for when stuff doesn't overlap).
3. Deferred: Draw all at once in the same order called (same as Immediate, but delayed, I believe - its so you can build up multiple batches at once without messing up the drawing).
4. Front-to-back: Deferred, but sorted by depth.
5. Back-to-front: Deferred, but sorted by depth (other direction).
I personally only really used Immediate, since I find it easy enough to handle the ordering myself. I assume this is pretty much like the batching Laurent added to SFML 2.0. If a call to draw uses the same state as the last call, you queue it into the batch. If the state changes, you flush the queue, clear it, then place the newest call in the front of the batch. Combined with texture atlases, I was able to render my whole scenes in under 30-or-so batches.
However, with XNA, you are in a load of hurt if you try to do things your own way. One reason I switch from XNA to SFML for my project was since I didn't like how XNA's ContentManager worked. Switching to SFML, I had a robust content manager that supports lazy-loading, only loading one instance of each asset, and automatic asset reloading (if you call an asset that has been disposed, it reloads from file transparently) done very quickly. Trying to do this with XNA, I gave up after about a full day of working on it, and tons of hacking with reflection.
In my project, since I just replaced XNA with SFML, things are being used pretty much the same way. From what I can see, the only real performance hits are coming from the fact that I no longer have any batching. But even still, I am hitting 60 FPS no sweat. I think the SFML version is running about 50%* slower while doing the exact same stuff (even using texture atlases still), but again, we're comparing no batching to batching, and I am still using SFML 1.5. And my rendering is still written with XNA in mind, not SFML.
*This is a complete guess from memory based purely on approximate numbers I remember when looking at the Task Manager. In no way have I EVER actually measured it.As far as simplicity goes, SFML beats XNA hands-down for 2D. Its quite scary how simple SFML is. And at least when you don't like how something works in SFML, you can roll your own without a fight.
