MathUtil.kt

object MathUtil {
    fun computeHeading(from: LatLng, to: LatLng): Double {
        val fromLat = Math.toRadians(from.latitude)
        val fromLng = Math.toRadians(from.longitude)
        val toLat = Math.toRadians(to.latitude)
        val toLng = Math.toRadians(to.longitude)
        val dLng = toLng - fromLng
        val heading = atan2(
            sin(dLng) * cos(toLat),
            cos(fromLat) * sin(toLat) - sin(fromLat) * cos(toLat) * cos(dLng)
        )
        return wrap(Math.toDegrees(heading))
    }

    private fun wrap(n: Double): Double {
        val min = -180.0
        val max = 180.0
        return if (n >= min && n < max) n else mod(n - -180.0) + min
    }

    private fun mod(x: Double): Double {
        val m = 360.0
        return (x % m + m) % m
    }
}