[Google Maps] - Google map API 위도경도 거리계산

function calcDistance(lat1, lon1, lat2, lon2){

            var EARTH_R, Rad, radLat1, radLat2, radDist; 

            var distance, ret;

            EARTH_R = 6371000.0;

            Rad = Math.PI/180;

            radLat1 = Rad * lat1;

            radLat2 = Rad * lat2;

            radDist = Rad * (lon1 - lon2);

            

            distance = Math.sin(radLat1) * Math.sin(radLat2);

            distance = distance + Math.cos(radLat1) * Math.cos(radLat2) * Math.cos(radDist);

            ret = EARTH_R * Math.acos(distance);

            var rtn = Math.round(Math.round(ret) / 1000);

            

            if(rtn <= 0)

            {

            rtn = Math.round(ret) + " m";

            }else

            {

            rtn = rtn + " km";

            }

            

            return  rtn;

        }