- From: Rick Waldron via GitHub <sysbot+gh@w3.org>
- Date: Tue, 20 Sep 2016 21:55:15 +0000
- To: public-device-apis-log@w3.org
@marcoscaceres sorry I missed the original post. `Compass` &
`Magnetometer` in J5 don't expose raw xyz magnetometer data (though
they surely could), because generally the developer really just wants
a heading in degrees, which is be computed from x and y.
```
let heading = Math.atan2(y, x);
let pi_2 = Math.PI * 2;
if (heading < 0) {
heading += pi_2;
}
if (heading > pi_2) {
heading -= pi_2;
}
let degrees = heading * (180 / Math.PI);
```
I view that as an undue burden on the developer. For true-north
heading, just subtract a declination angle.
The **z** in x, y, z is used for computing the earth's magnetic
field—I've written a robot that can navigate from any lat/lon point to
any _other_ lat/lon point using a gps and compass/magnetometer—no
**z** necessary.
--
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Received on Tuesday, 20 September 2016 21:55:23 UTC