在我的webapp中,从数据库查询中获取
JSON数据响应,其中包括1到n个位置的纬度/经度坐标.我想计算从data [i]位置到当前位置的方位.
//starting lat/long along with converting lat to rads
var endLat = toRad(location.lat());
var endLong = location.lng();
//loop over response,calculate new headings for links and add link to array
for(var i=0; i<data.length; i++){
//this link's lat/long coordinates,convert lat to rads
var startLat = toRad(data[i].lat);
var startLong = data[i].lon;
//get the delta values between start and end coordinates in rads
var dLong = toRad(endLong - startLong);
//calculate
var y = Math.sin(dLong)*Math.cos(endLong);
var x = Math.cos(startLat)*Math.sin(endLat)-Math.sin(startLat)*Math.cos(endLat)*Math.cos(dLong);
var bearing = Math.atan(y,x);
bearing = (toDeg(bearing) + 360) % 360;
panoLinks.push({'heading': bearing,'description': data[i].description,'pano': data[i].description});
}
//radian/degree conversions
function toRad(convert){
return convert * Math.PI/180;
}
function toDeg(convert){
return convert * 180/Math.PI;
}
使用上面的函数和值
startLat= 43.6822,converts to 0.7623982145146669 radians startLong= -70.450769 endLat= 43.682211,converts to 0.7623984065008848 radians endLong= -70.45070 dLong = startLong - endLong,converts to 0.0000011170107216805305 radians
导致罗盘度
bearing= 0.000014910023935499339
这肯定是关闭的.我哪里出错了？
解决方法
尝试一下,我不能为我的生活记住我得到它的地方……
/**
* Calculate the bearing between two positions as a value from 0-360
*
* @param lat1 - The latitude of the first position
* @param lng1 - The longitude of the first position
* @param lat2 - The latitude of the second position
* @param lng2 - The longitude of the second position
*
* @return int - The bearing between 0 and 360
*/
bearing : function (lat1,lng1,lat2,lng2) {
var dLon = (lng2-lng1);
var y = Math.sin(dLon) * Math.cos(lat2);
var x = Math.cos(lat1)*Math.sin(lat2) - Math.sin(lat1)*Math.cos(lat2)*Math.cos(dLon);
var brng = this._toDeg(Math.atan2(y,x));
return 360 - ((brng + 360) % 360);
},/**
* Since not all browsers implement this we have our own utility that will
* convert from degrees into radians
*
* @param deg - The degrees to be converted into radians
* @return radians
*/
_toRad : function(deg) {
return deg * Math.PI / 180;
},/**
* Since not all browsers implement this we have our own utility that will
* convert from radians into degrees
*
* @param rad - The radians to be converted into degrees
* @return degrees
*/
_toDeg : function(rad) {
return rad * 180 / Math.PI;
},
