/**
* 計算兩個坐標之間的距離(米)
* @param float $fP1Lat 起點(緯度)
* @param float $fP1Lon 起點(經度)
* @param float $fP2Lat 終點(緯度)
* @param float $fP2Lon 終點(經度)
* @return int
*/
function distanceBetween($fP1Lat, $fP1Lon, $fP2Lat, $fP2Lon){
$fEARTH_RADIUS = 6378137;
//角度換算成弧度
$fRadLon1 = deg2rad($fP1Lon);
$fRadLon2 = deg2rad($fP2Lon);
$fRadLat1 = deg2rad($fP1Lat);
$fRadLat2 = deg2rad($fP2Lat);
//計算經緯度的差值
$fD1 = abs($fRadLat1 - $fRadLat2);
$fD2 = abs($fRadLon1 - $fRadLon2);
//距離計算
$fP = pow(sin($fD1/2), 2) +
cos($fRadLat1) * cos($fRadLat2) * pow(sin($fD2/2), 2);
return intval($fEARTH_RADIUS * 2 * asin(sqrt($fP)) + 0.5);
}
/**
* 百度坐標系轉換成標準GPS坐系
* @param float $lnglat 坐標(如:106.426, 29.553404)
* @return string 轉換后的標準GPS值:
*/
function BD09LLtoWGS84($fLng, $fLat){ // 經度,緯度
$lnglat = explode(',', $lnglat);
list($x,$y) = $lnglat;
$Baidu_Server = "http://api.map.baidu.com/ag/coord/convert?from=0&to=4&x={$x}&y={$y}";
$result = @file_get_contents($Baidu_Server);
$json = json_decode($result);
if($json->error == 0){
$bx = base64_decode($json->x);
$by = base64_decode($json->y);
$GPS_x = 2 * $x - $bx;
$GPS_y = 2 * $y - $by;
return $GPS_x.','.$GPS_y;//經度,緯度
}else
return $lnglat;
}
