Using box2d flash as3 engine for iphone apps

Question

Hi
have any body tried box2d flash as3 libraries working with flsh cs5 iphone apps.? when i compile app it give many errors, using flash player 9 give one error b2fixture undefined type error. any body developing physics base games as3 for iphone please share any good as3 physics base game engine.
Thanks

Answer 1

If you are targeting all iDevices I strongly suggest to forget about the Box2D. There is absolutely no way you can get (almost) any kind of physics simulation running smoothly with 1st and 2nd generation iDevices with current version of Packager for iPhone.
And it really is graphics that is the problem more than anything else. Forget about caching Sprites or MovieClips. Actually don't use MovieClips and Sprites at all, it's just too slow. Instead start extending Bitmap class with your own animation system (swapping BitmapData) and mouse handling (hitTestPoint), there's plenty of examples.
And then if you write really really optimized code you can get one fluently moving and animated sprite object running on your iPhone or iPhone 3G (with out doing anything else than just moving and animating that one object). More than one (animated and/or moving) object causes serious performance problems. You don't notice this as linear slowing in FPS (which would still be kind of ok), but it's more like skipping frames every now and then. This looks and feels really disturbing and makes designing of games pretty hard...Using GPU mode doesn't make any difference.
But to answer the question, I'm pretty convinced that you can get (simple) Box2D simulation running smoothly on iPhone if you:
1. Target only 3rd generation iDevices and above
2. Use only Bitmaps as graphics
3. Do rotations with pre-rendered frames (or don't use rotation at all)
4. Optimize Box2D and your code thoroughly
Just for **** and giggles I think I try to get some kind of physics simulation running on 3G too...
By the way, comparing performance of 1st generation iPhone to HTC Desire (I happen to own both too) is like comparing C-64 to my shiny new Phenom II X6 rig. If you just look at the specs:
HTC Desire:
1 GH ARM v7
AMD Z430 GPU
576 Mb DRAM
iPhone 3G:
ARM 1176JZ(F)-S (underclocked to 412 MHz)
PowerVR MBX Lite 3D
128 Mb DRAM