cesium 根据经纬度与距离计算另一个经纬度

/**
* 
* @param {*} lng 经度 122
* @param {*} lat 纬度 24
* @param {*} brng 方位角 0~360度
* @param {*} dist 90000距离(米)
*
*/
function (lng, lat, brng, dist) {
            var a = 6378137;
            var b = 6356752.3142;
            var f = 1 / 298.257223563;
        
            var lon1 = lng * 1;
            var lat1 = lat * 1;
            var s = dist;
            var alpha1 = brng * (Math.PI / 180)
            var sinAlpha1 = Math.sin(alpha1);
            var cosAlpha1 = Math.cos(alpha1);
            var tanU1 = (1 - f) * Math.tan(lat1 * (Math.PI / 180));
            var cosU1 = 1 / Math.sqrt((1 + tanU1 * tanU1)), sinU1 = tanU1 * cosU1;
            var sigma1 = Math.atan2(tanU1, cosAlpha1);
            var sinAlpha = cosU1 * sinAlpha1;
            var cosSqAlpha = 1 - sinAlpha * sinAlpha;
            var uSq = cosSqAlpha * (a * a - b * b) / (b * b);
            var A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)));
            var B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)));
            var sigma = s / (b * A), sigmaP = 2 * Math.PI;
            while (Math.abs(sigma - sigmaP) > 1e-12) {
                var cos2SigmaM = Math.cos(2 * sigma1 + sigma);
                var sinSigma = Math.sin(sigma);
                var cosSigma = Math.cos(sigma);
                var deltaSigma = B * sinSigma * (cos2SigmaM + B / 4 * (cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM) -
                    B / 6 * cos2SigmaM * (-3 + 4 * sinSigma * sinSigma) * (-3 + 4 * cos2SigmaM * cos2SigmaM)));
                sigmaP = sigma;
                sigma = s / (b * A) + deltaSigma;
            }
        
            var tmp = sinU1 * sinSigma - cosU1 * cosSigma * cosAlpha1;
            var lat2 = Math.atan2(sinU1 * cosSigma + cosU1 * sinSigma * cosAlpha1,
                (1 - f) * Math.sqrt(sinAlpha * sinAlpha + tmp * tmp));
            var lambda = Math.atan2(sinSigma * sinAlpha1, cosU1 * cosSigma - sinU1 * sinSigma * cosAlpha1);
            var C = f / 16 * cosSqAlpha * (4 + f * (4 - 3 * cosSqAlpha));
            var L = lambda - (1 - C) * f * sinAlpha *
                (sigma + C * sinSigma * (cos2SigmaM + C * cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM)));
        
            var revAz = Math.atan2(sinAlpha, -tmp); // final bearing
        
            var lngLatObj = { lng: lon1 + L * (180 / Math.PI), lat: lat2 * (180 / Math.PI) }
            return lngLatObj;
        }