edit2: Is accepted as a bug by the QA Team and forwarded to developers.
This is not so easy to pin down or explain, but i tested it on 5.5 and 5.4f1 in remote, and built with xcode on 5.5…
edit: now i tested further - and this happens also with only one touch. in editor and build. Summary of the text below: each time you go from stationary to moved, there is a slight jump in the position coords of the touch.
the best description i can give is:
if two fingers are active, and one is moving while the second is stationary, the second wont update its position properly until it leaves the ‘dead zone’ of stationary, leading to a jump in magnitude within one frame.
again a bit more detailed:
- When two (or more?) touches are registered, and the touchphase of one of them is going from stationary to moved, a spike in magnitude (jump) is happening.
- It only happens at the beginning of a touch - so the first transition from stationary to moved!
- most prominent when one finger moves, and the second finger starts moving with a short delay - the second finger experiences the jump.
- happens with position and rawposition
It is possible to compensate that within the code, and unless someone stumbled upon the same bug(?), i don’t think there is much that can be done at that point as the code to reproduce this is literally 2 lines in a empty project.
Still I post it here in case someone may know what i am talking about…
How i came to this point - i wrote pinch to zoom method and often got unexplained jumps when the pinch move started, or more precise - when the second finger started to move.
But with an empty project and two debug.log lines it behaves the same…
i think most of the time this problem does not appear, as usually you start methods with touchphase.moved, and as i said the problem appears only in the first transition of stationary to moved. The pinch zoom is a special case where one finger already starts moving, taking the stationary other finger into account to calculate the zoom, and once the other finger starts moving the ‘spike’ appears.
Maybe this is just how ios works and unity can do nothing about it… it would certainly explain why most apps like maps, google earth etc. have quite a big artificial dead zone when it comes to pinch-zoom