Re: [w3c/touch-events] Add touchType, altitudeAngle, azimuthAngle (Safari iOS 10.3 extensions for stylus) (#81)

> am i right in assuming that the Apple Pencil has no concept of "twist" (i.e. that both the altitudeAngle and azimuthAngle remain unchanged if i simply spin the Pencil along its lengthwise/z axis while keeping its overall position/attitude towards the digitizer surface the same)?

Sorry for the delay.  Yes, AFAIK there's no notion of twist (I think that's the same as MS Surface, right?).  But Twist is entirely separate I think (unless you're thinking about the special case of the stylus pointing straight up and down).

altitudeAngle/azimuthAngle are mathematically just an alternate representation of tiltX/tiltY.  Android has basically the same thing with [AXIS_TILT](https://developer.android.com/reference/android/view/MotionEvent.html#AXIS_TILT) (altitudeAngle) and [AXIS_ORIENTATION](https://developer.android.com/reference/android/view/MotionEvent.html#AXIS_ORIENTATION) (for stylus only, equivalent of azimuthAngle).  In Chrome we just do some trigonometry to convert between the [one](https://cs.chromium.org/chromium/src/ui/events/blink/blink_event_util.cc?sq=package:chromium&dr=CSs&l=907) representation and [the other](https://cs.chromium.org/chromium/src/content/browser/renderer_host/input/motion_event_web.cc?sq=package:chromium&dr=CSs&l=143).

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3c/touch-events/pull/81#issuecomment-298401520