# Help : need to convert rotation in radians to "8" directions

but here is the kicker… it is NOT a simple convert radians to nearest multple of 45 degrees.

I have a control that has 8 allowed directions (corresponding to compass points)

If I do a touch gesture on an iPhone, it returns delta radians as I rotate my two fingers.
I need to figure out somehow when during that event to issue a +1 or -1 to the control

The gesture turns in fractional degrees but the control needs to “click” at the right time.

One idea (which I havent tested yet) is to do nothing until the gesture delta is exactly 45 degrees either direction. then tell the control to move 1 compass point … and reset the gesture delta to zero.

any other ideas?

It may be just me not understanding but I don’t know what you want to do.

I get what you don’t want to do,

But I don’t know what your question is here:

Are you asking how to make the transition feel right?

Why not program it to change only when the new position is “close” to the next one, as defined by a certain angle difference, and try how it feels varying that angle?

What I mean is that the control would switch to the new position when delta is above a certain threshold (below 45) that you can set to check how the control responds for different values of that threshold.

yes, you did understand

But for now I’ve decided the leave this out of the app… it isn’t natural to turn a gesture 360deg. you’d break your wrist… and doing it in increments took longer than tapping a designated “button”

When the user rotate to 15° or more, set the rotation to the next value 45°.
Once implemented, you will be able to decide if 15° is enough (I think so. 15° is a good value to avoid an user error and help the user to rotate).

it isn’t natural… Button
iPhone is more finger move than finger tap (IMHO, but I have none, so I may be wrong), so a single movement; and the movement can be done in anti-clock rotation, so only 180°… ;-