<?php

/**

 * @name 围栏算法，判断一个坐标，是否在围栏里面.如：['113.664673,34.810146','113.681667,34.796896','113.69231,34.794711','113.702009,34.809159']

 * @author macnie <mac@lenmy.com>

 * @param array $fences 围栏，是一组坐标数组 如：113.674458,34.804719

 * @param string $point 要判断的坐标

 * @return bool

 */

function in_fences($fences, $point) {

    $nvert = count($fences);

    $vertx = [];

    $verty = [];

    list($testy, $testx) = explode(',', $point);

    foreach ($fences as $r) {

        list($lng, $lat) = explode(',', $r);

        $vertx[] = $lat;

        $verty[] = $lng;

    }

    $i = $j = $c = 0;

    for ($i = 0, $j = $nvert - 1; $i < $nvert; $j = $i++) {

        if (( ($verty[$i] > $testy) != ($verty[$j] > $testy) ) &&

            ($testx < ($vertx[$j] - $vertx[$i]) * ($testy - $verty[$i]) / ($verty[$j] - $verty[$i]) + $vertx[$i]))

            $c = !$c;

    }

    return $c;

}

//围栏map数据

$fences=[

'113.626809,34.75027',

    '113.630975,34.752162',

    '113.626102,34.753941'

];

$p="113.633093,34.751396"; //当前的位置

$res = in_fences($fences,$p);

var_dump($res);