计算两个经纬度之间的距离

//计算两个经纬度之间的距离

/**
 * 计算两点地理坐标之间的距离
 * @param  Decimal $longitude1 起点经度
 * @param  Decimal $latitude1  起点纬度
 * @param  Decimal $longitude2 终点经度
 * @param  Decimal $latitude2  终点纬度
 * @param  Int     $unit       单位 1:米 2:公里
 * @param  Int     $decimal    精度 保留小数位数
 * @return Decimal
 */

function getDistance($longitude1, $latitude1, $longitude2, $latitude2, $unit=2, $decimal=2){

    $EARTH_RADIUS = 6370.996; // 地球半径系数
    $PI = 3.1415926;

    $radLat1 = $latitude1 * $PI / 180.0;
    $radLat2 = $latitude2 * $PI / 180.0;

    $radLng1 = $longitude1 * $PI / 180.0;
    $radLng2 = $longitude2 * $PI /180.0;

    $a = $radLat1 - $radLat2;
    $b = $radLng1 - $radLng2;

    $distance = 2 * asin(sqrt(pow(sin($a/2),2) + cos($radLat1) * cos($radLat2) * pow(sin($b/2),2)));
    $distance = $distance * $EARTH_RADIUS * 1000;

    if($unit==2){
        $distance = $distance / 1000;
    }

    return round($distance, $decimal);

}



//根据给的距离算出自己附近的经纬度范围，算出距离后排序

public function vicinity()
{
    if (!request()->isPost()) {
        return result_set(-1);
    }
    $page = input('post.page/d');
    $page_num = input('post.page_num/d') ? input('post.page_num/d') : 10;
    if (isset($page) && NULL !== $page) {
        $current_page = $page;
    } else {
        $current_page = 1;
    }
    $options = [
        'page' => $current_page,
        'path' => url('index')
    ];
    $uid = $this->uid;
    $lng = trim(input("post.lng"));
    $lat = trim(input("post.lat"));
    $distance = config('distance');


    $degree = (24901*1609)/360.0;
    $dpmLat = 1/$degree;

    $radiusLat = $dpmLat*$distance;
    $minLat = $lat - $radiusLat;       // 最小纬度
    $maxLat = $lat + $radiusLat;       // 最大纬度

    $mpdLng = $degree*cos($lat * (M_PI/180));
    $dpmLng = 1 / $mpdLng;
    $radiusLng = $dpmLng*$distance;
    $minLng = $lng - $radiusLng;      // 最小经度
    $maxLng = $lng + $radiusLng;      // 最大经度
    $condition['p.lng'] = ['between', [$minLng, $maxLng]];
    $condition['p.lat'] = ['between', [$minLat, $maxLat ]];


    $data = db('member_position')                   ->alias('p')                  ->join('member m', 'p.uid=m.uid')       
           ->where('p.uid', '<>', $uid)
           ->where($condition) 
           ->field('p.lng,p.lat,p.uid,m.authentication_status,m.thumb as thumb,m.nickname,m.start,m.brief')
           ->paginate($page_num, false, $options);
           $data = $data->toArray();   
           foreach ($data['data'] as $k => $v) { 
               $data['data'][$k]['thumb'] = 'http://' . config('DOMAIN') . '/' . $v['thumb'];       
               $data['data'][$k]['distance'] = getDistance($lng, $lat, $v['lng'], $v['lat'], 1);   
           }  
      $arr = $data['data'];    $date = array_column($arr, 'distance');   
      array_multisort($date,SORT_ASC,$arr);    
      return result_set(1, '成功', $arr);}