Subpixel drawing of slow-moving sprites

Question

Hi.I've been working on an iOS game with Flash for a while. Now I'm stuck with a display problem.My game objects move very slowly and steadily and I notice pretty bad jittering/stuttering. This is GPU mode in Air 2.7, CPU mode is too slow. The cause of the jittering seems to be that Air moves my sprites (based on PNGs) only in full- and half-pixel steps, regardless of whether cacheAsBitmap/-Matrix are enabled. Is this an optimization by Adobe or can I get rid of this somehow? It's really annoying.Thank you!

Colin Holgate · Accepted Answer

This gave a new clue:"Just cacheAsBitmap looks much worse as it produces full-pixel stepping."What is your stage quality set to? Try:stage.quality = "high";

Colin Holgate · Answer

cacheasbitmap items are always drawn to the nearest pixel, that's one of the things that makes them be fast. You might try cacheasbitmapmtraix without cacheasbitmap, that could be enough so that the GPU handles them as floating point positions. Also, perhaps use a matrix that makes them be stored at higher resolution, so that the GPU has something to work with.

Are you seeing this just on old iPhone, or on iPad too? If it's also on iPhone 4, then make sure you're using High for the quality setting in publishing, because the Retina pixels are close enough together that you hopefully won't notice any stepping effect.

Also, make sure that your location math is floating point. If you're going math where the position gets rounded down, that would exaggerate the effect.

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