PHP determines whether a point is inside or outside the polygon area

PHP determines whether a point is inside or outside the polygon area;

According to the ray method of mathematical knowledge, if the number of points that the ray intersects with the geometric polygon is an odd number, it is inside the geometry;

An even number Externally;

/** * Created by PhpStorm. * function: inArea * Description: 判断点是否在多边形区域内 * User: Xiaoxie * @param $x * @param $y * @param $arr 几何订单坐标 * @return int * */ public function inArea($x,$y,$arr) { //点的数量 $count = count($arr); $n = 0; //点与线相交的个数 $bool = 0;//外 for ($i = 0, $j = $count - 1; $i < $count; $j = $i, $i++) { //两个点一条线 取出两个连接点的定点 $px1 = $arr[$i][0]; $py1 = $arr[$i][1]; $px2 = $arr[$j][0]; $py2 = $arr[$j][1]; //$x的水平位置画射线 if($x>=$px1 || $x>= $px2) { //判断$y 是否在线的区域 if(($y>=$py1 && $y<=$py2) || ($y>=$py2 && $y<= $py1)){ if (($y == $py1 && $x == $px1) || ($y == $py2 && $x == $px2)) { #如果$x的值和点的坐标相同 $bool = 2;//在点上 return $bool; }else{ $px = $px1+($y-$py1)/($py2-$py1)*($px2-$px1) ; if($px ==$x) { $bool = 3;//在线上 }elseif($px< $x){ $n++; } } } } } if ($n%2 != 0) { $bool = 1; } return $bool; }

Test Array

$arr = [ ['9.4','12.04'], ['6.68','8.61'], ['9.05','6.06'], ['6.24','3.87'], ['10.02','2.55'], ['14.06','4.13'], ['16.35','7.56'], ['11.69','8.35'], ]; $x =15.73; $y = 5.62; //在外 $x = 9.97; $y = 4.96; //在内

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