geokit/bearing

Initial and final compass bearing between two LatLng points.

Bearings are reported in degrees clockwise from true north, in [0, 360). The initial bearing is the direction of travel when departing a along the great-circle route to b; the final bearing is the direction of arrival at b. The two differ along any route except along a meridian or the equator (where they are equal).

Formula: https://www.movable-type.co.uk/scripts/latlong.html.

Values

final

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pub fn final(
  from from: latlng.LatLng,
  to to: latlng.LatLng,
) -> Float

Final bearing when arriving at to along the great-circle route from from, in degrees in [0, 360). Computed as the reverse of initial(from: to, to: from) plus 180°.

initial

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pub fn initial(
  from from: latlng.LatLng,
  to to: latlng.LatLng,
) -> Float

Initial bearing (forward azimuth) from a to b, in degrees in [0, 360).

import geokit/bearing
import geokit/latlng

let assert Ok(tokyo) = latlng.new(lat: 35.6812, lng: 139.7671)
let assert Ok(osaka) = latlng.new(lat: 34.6937, lng: 135.5023)
bearing.initial(from: tokyo, to: osaka)
// ~= 254.0