DCSOlympus/client/src/other/utils.ts

export function distance(lat1: number, lon1: number, lat2: number, lon2: number) {
    const R = 6371e3; // metres
    const φ1 = deg2rad(lat1); // φ, λ in radians
    const φ2 = deg2rad(lat2);
    const Δφ = deg2rad(lat2 - lat1);
    const Δλ = deg2rad(lon2 - lon1);

    const a = Math.sin(Δφ / 2) * Math.sin(Δφ / 2) + Math.cos(φ1) * Math.cos(φ2) * Math.sin(Δλ / 2) * Math.sin(Δλ / 2);
    const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

    const d = R * c; // in metres

    return d;
}

export function bearing(lat1: number, lon1: number, lat2: number, lon2: number) {
    const φ1 = deg2rad(lat1); // φ, λ in radians
    const φ2 = deg2rad(lat2);
    const λ1 = deg2rad(lon1); // φ, λ in radians
    const λ2 = deg2rad(lon2);
    const y = Math.sin(λ2 - λ1) * Math.cos(φ2);
    const x = Math.cos(φ1) * Math.sin(φ2) - Math.sin(φ1) * Math.cos(φ2) * Math.cos(λ2 - λ1);
    const θ = Math.atan2(y, x);
    const brng = (rad2deg(θ) + 360) % 360; // in degrees

    return brng;
}

const zeroPad = function (num: number, places: number) {
    var string = String(num);
    while (string.length < places) {
        string += "0";
    }
    return string;
}

export function ConvertDDToDMS(D: number, lng: boolean) {
    var dir = D < 0 ? (lng ? "W" : "S") : lng ? "E" : "N";
    var deg = 0 | (D < 0 ? (D = -D) : D);
    var min = 0 | (((D += 1e-9) % 1) * 60);
    var sec = (0 | (((D * 60) % 1) * 6000)) / 100;
    var dec = Math.round((sec - Math.floor(sec)) * 100);
    var sec = Math.floor(sec);
    if (lng)
        return dir + zeroPad(deg, 3) + "°" + zeroPad(min, 2) + "'" + zeroPad(sec, 2) + "." + zeroPad(dec, 2) + "\"";
    else
        return dir + zeroPad(deg, 2) + "°" + zeroPad(min, 2) + "'" + zeroPad(sec, 2) + "." + zeroPad(dec, 2) + "\"";
}

export function deg2rad(deg: number) {
    var pi = Math.PI;
    return deg * (pi / 180);
}

export function rad2deg(rad: number) {
    var pi = Math.PI;
    return rad / (pi / 180);
}