A CALayer class to help doing frame animation quickly by using a sliding window (or door?) technique. This avoids something slower like calling drawInContext frequently. So far it seems to perform pretty well with several sprites on screen, both on iPhone & OS X.
A super simple example is included that has a basic cube rotating, animating via a timer.
The sliding window/door technique is done by turning on masksToBounds and putting a large layer in the sublayers which contains all the frames in 1 image. The masking of the sprite layer hides everything else, showing only the sprite frame you want to show at the time. Tie this in with a timer like in the example and you have a looping animation.
This was an attempt to try to use CoreAnimation for a 2D game where there would be a lot more frame animation than just one. The idea to try CoreAnimation for a game came from the CoreAnimation Asteroids posts from Cocoa With Love.
Asteroids in CoreAnimation posts:
- An Asteroids-style game in CoreAnimation, Part One.
- An Asteroids-style game in CoreAnimation, Part Two.
- An Asteroids-style game in CoreAnimation, Part Three.
- An Asteroids-style game in CoreAnimation, Part Four.
His example only had 1 sprite I believe that animated frames instead of just movement & rotation. Once I had a lot more on the screen, all calling drawInContext to update their frame would cause pretty poor performance.
- Support non-symmetrically laid out charsets/tilesets like seen in some 8-bit sprite sets
- Support non-square sprite sheets (though square might be best? at least thought so for GL)
- Ability to have a sprite change its frame based upon its own time setting, see updateWithTimeInterval & age in the cocoa with love posts
- I haven't thought about what would aid animating things like characters where they have different actions that might all loop a certain subset of frames
Feel free to contact me with ideas, send patches, or fork and send pull requests.
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