在多边形PHP中查找点 [英] Find Point in polygon PHP

问题描述

我有一个典型的问题，关于MySQL的几何数据类型，多边形.

i have a typical question with the Geometric datatype of mysql, polygon.

我具有经度和纬度数组形式的面数据，例如:

I have the polygon data, in the form of an array of latitudes and longitudes, ex:

[["x":37.628134,  "y":-77.458334],
["x":37.629867,   "y":-77.449021],
["x":37.62324,    "y":-77.445416],
["x":37.622424,   "y":-77.457819]]

我有一个点(顶点)，它具有经度和纬度坐标，例如:

And i have a point (Vertex) with coordinates of latitude and longitude, ex:

$location = new vertex($_GET["longitude"], $_GET["latitude"]);

现在，我想查找此顶点(点)是否在多边形内. 我如何在php中做到这一点?

Now i want to find whether this vertex (point) is inside the polygon. How can i do this in php ?

推荐答案

这是我从另一种语言转换为PHP的函数:

This is a function i converted from another language into PHP:

$vertices_x = array(37.628134, 37.629867, 37.62324, 37.622424);    // x-coordinates of the vertices of the polygon
$vertices_y = array(-77.458334,-77.449021,-77.445416,-77.457819); // y-coordinates of the vertices of the polygon
$points_polygon = count($vertices_x) - 1;  // number vertices - zero-based array
$longitude_x = $_GET["longitude"];  // x-coordinate of the point to test
$latitude_y = $_GET["latitude"];    // y-coordinate of the point to test

if (is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y)){
  echo "Is in polygon!";
}
else echo "Is not in polygon";


function is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y)
{
  $i = $j = $c = 0;
  for ($i = 0, $j = $points_polygon ; $i < $points_polygon; $j = $i++) {
    if ( (($vertices_y[$i]  >  $latitude_y != ($vertices_y[$j] > $latitude_y)) &&
     ($longitude_x < ($vertices_x[$j] - $vertices_x[$i]) * ($latitude_y - $vertices_y[$i]) / ($vertices_y[$j] - $vertices_y[$i]) + $vertices_x[$i]) ) )
       $c = !$c;
  }
  return $c;
}

其他: 有关更多功能，建议您使用polygon.php类此处可用. 使用顶点创建类，并以测试点作为输入调用函数isInside，以使另一个函数解决您的问题.

Additional: For more functions i advise you to use the polygon.php class available here. Create the Class using your vertices and call the function isInside with your testpoint as input to have another function solving your problem.

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