meili-epfl/Meili

package com.github.epfl.meili.util

import com.google.android.gms.maps.model.LatLng
import kotlin.math.*

object CustomMath {
    private const val EARTH_R = 6378100.0

    /**
     * Distance computed using Harversine's formula, for more details: https://en.wikipedia.org/wiki/Haversine_formula
     *
     * @return distance in meters between the two points
     */
    fun distanceOnSphere(from: LatLng, to: LatLng): Double {
        val dLat = Math.toRadians(to.latitude - from.latitude)
        val dLon = Math.toRadians(to.longitude - from.longitude)

        val originLat = Math.toRadians(from.latitude)
        val destinationLat = Math.toRadians(to.latitude)

        val a = sin(dLat / 2).pow(2.0) + sin(dLon / 2.0).pow(2.0) * cos(
            originLat
        ) * cos(destinationLat)
        val c = 2 * asin(sqrt(a))

        return EARTH_R * c
    }
}