[pointerevents] tiltX and tiltY aren't as helpful as just having altitude angle (#274)

grorg has just created a new issue for https://github.com/w3c/pointerevents:

== tiltX and tiltY aren't as helpful as just having altitude angle ==
Pointer Events for a stylus currently use `tiltX`, `tiltY` and `twist` to give the orientation of the stylus in space. I believe that just `twist` and `altitude` would be sufficient for most cases, and easier to understand.

`altitude` is the angle between the screen surface and the stylus, ignoring the rotation or twist. Many styluses don't have an "up" direction around the barrel (e.g. Apple Pencil), so spinning the stylus in your fingers shouldn't change any values. Most drawing applications therefore just use the angle between the screen and the stylus to determine the angle of the painting nib, and the direction in which the stylus is "falling" for direction. Mapping those from `tiltX` and `tiltY` is confusing. It also makes those values dependent on the twist.

Please view or discuss this issue at https://github.com/w3c/pointerevents/issues/274 using your GitHub account

Received on Monday, 28 January 2019 21:41:06 UTC