问题
I finished a breakout game tutorial in a book, but the ball, which is a 20x20 pixel image, was skipping frames and not moving very smoothly. That is the case on the Simulator as well as on an iPhone 4S (the real thing). The code wasn't using NSTimer (which may be slower), but was using CADisplayLink and UIImageView setFrame to do the animation.
Is Core Animation on iOS not very suitable for development animation type of games? Say if it is a game of
- Invaders (Space Invaders)
- Breakout (as a game in a tutorial)
- Arkanoid
- Angry Birds / Cut the Rope / Fruit Ninja
For these types of games, is Core Animation really suitable for writing (2) above? For (1), (3), and (4), either Cocos2D or OpenGL ES is more suitable of doing the job. And the performance of Cocos2D and OpenGL ES are very close. Is that true?
回答1:
Cocos2D is often looked at because of its ease for programming common game logic, like collision detection and sprite animations, frame-by-frame, scaling and other processes that are quite common in game development, where you string together multiple animations, combine then, sequence them, do call backs, and more. That is one of the big benefits of the engine.
However, performance is another. Cocos offers batch nodes, which combine all graphic elements into a single OpenGL call, rather than "drawing" each to the screen separately in each frame; this can dramatically improve performance, especially for large graphics. If you had skipping frames, I wonder if batch sprites in Cocos would have been the missing link.
I'm very impressed by Core Animation and want to hope that it can hold its own with performance issues in games. My understanding is that CA is, like Cocos, also built on top of OpenGL ES, so I'd expect it possible to achieve good results in either. It could be that doing so in Cocos is easier simply because it has been designed and optimized internally for game development.
回答2:
If you are having performance problems with a 2D app, this is likely caused by a lack of understanding of how to get the most efficient results from CoreGraphics as opposed to something that switching to OpenGL will fix. A 2D game will work just fine with CoreGraphics, you just need to start with the right approach. First off, you should not be rendering the entire view over again on each CADisplayLink callback. Instead, setup a UIView that contains multiple CALayer objects. Set the layer like so: CALayer.contents = (id) cgImage and then let the system take care of rendering it when the x, y, or animation elements change. You just need to position your elements and define the animations that move the elements around. With this approach, the system will cache the animating image on the graphics card behind the scenes and redraw using GPU operations.
来源：https://stackoverflow.com/questions/10234570/suitability-of-using-core-animation-on-ios-vs-using-cocos2d-and-opengl-es