Vsync in Flex/Flash/AS3?

Question

I work on a 2D shooter game with lots of moving objects on the screen (bullets etc).

I use BitmapData.copyPixels(...) to render entire screen to a buffer:BitmapData. Then I "copyPixels" from "buffer" to screen:BitmapData. The framerate is 60.

private var bitmap:Bitmap = new Bitmap();
private var buffer:Bitmap = new Bitmap();

private function start():void {
    addChild(bitmap);
}

private function onEnterFrame():void {
    // render into "buffer"
    // copy "buffer" -> "bitmap"
}

The problem is that the sprites are tearing apart: some part of a sprite got shifted horizontally.

It looks like a PC game with VSYNC turned off.

Did anyone solve this problem?

UPDATE: the question is not about performance, but about getting rid of screen tearing.

[!] UPDATE: I've created another question and here you may try both implementations: using Flash way or BitmapData+copyPixels()

the others are right, that this approach isn't very suitable for flash player ... still, i'm amazed, it doesn't work at all ... few questions: - did you try to lock the bitmapData you are drawing into? (if not, this may help a lot!) - are you using transparent bitmaps? (general performance killer) - dir you try Stage::invalidate and rendering on Event.RENDER instead of rendering? greetz back2dos — back2dos
- lock/unlock didn't help because copying "buffer" -> "bitmap" produces single event, so it is same single notification in both cases - I do use transparent bitmaps for projectiles - but, again, the problem is not in performance, the problem is in screen tearing - I tried to: * prepare "buffer" + stage.invalidate() in ENTER_EVENT and then * copy "buffer" -> "bitmap" in RENDER event Same result (screen tearing), but higher CPU consumption(I guess because it is because of events fired by stage.invalidate() ) — oshyshko
Screen tearing is related to performance. That's the only way to fix your tearing. — Kekoa
@Kekoa I can't agree. Performance has nothing to do with screen tearing, because I use double-buffer. In case of poor performance I would get lower FPS but not screen tearing. — oshyshko

Daniel Carvalho Daniel Carvalho · Accepted Answer · 2010-03-14T22:42:04

I feel your pain as I'm currently in the trenches developing my own game. At default settings, the Flash renderer produces horrible screen tearing / v-sync issues, regardless of what code you produce.

This is why I was pleased to have found the most simple, elegant answer, that wasn't re-factoring code (which doesn't help a single bit, the problem is the Flash player, not code).

Just enable Hardware Acceleration in your Publish Settings. There's two different options:

Level 1: Direct; and Level 2: GPU.

Read more about it at the official documentation: Specify publish settings for SWF files, and decide what option is best for your game.

Target market does play a factor here, if it's a serious game for gamers, you don't need to worry about possible performance issues, as most gamers have GPU's.

This article did not provide me with the solution specifically, but lead me in the right direction. BUT, if your game is going to be in a browser window, you might have to use the same technique of setting wmode to direct or gpu as well.

Vsync in Flex/Flash/AS3?

3 Answers