Find Point in polygon PHP

If your polygons are self-closing, that is to say that it's final vertex is the line between it's last point and it's first point then you need to add a variable and a condition to your loop to deal with the final vertex. You also need to pass the number of vertices as being equal to the number of points.

Here is the accepted answer modified to deal with self-closing polygons:

$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);  // number vertices = number of points in a self-closing polygon
$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 = $point = 0;
  for ($i = 0, $j = $points_polygon ; $i < $points_polygon; $j = $i++) {
    $point = $i;
    if( $point == $points_polygon )
      $point = 0;
    if ( (($vertices_y[$point]  >  $latitude_y != ($vertices_y[$j] > $latitude_y)) &&
     ($longitude_x < ($vertices_x[$j] - $vertices_x[$point]) * ($latitude_y - $vertices_y[$point]) / ($vertices_y[$j] - $vertices_y[$point]) + $vertices_x[$point]) ) )
       $c = !$c;
  }
  return $c;
}

Thank you! I found this page and it's accepted answer very helpful and I am proud to offer this variation.

Above solution is not working as i expect, instead of using the above solution you can prefer below solutions

With PHP

function pointInPolygon($point, $polygon, $pointOnVertex = true) {
    $this->pointOnVertex = $pointOnVertex;

    // Transform string coordinates into arrays with x and y values
    $point = $this->pointStringToCoordinates($point);
    $vertices = array(); 
    foreach ($polygon as $vertex) {
        $vertices[] = $this->pointStringToCoordinates($vertex); 
    }

    // Check if the lat lng sits exactly on a vertex
    if ($this->pointOnVertex == true and $this->pointOnVertex($point, $vertices) == true) {
        return "vertex";
    }

    // Check if the lat lng is inside the polygon or on the boundary
    $intersections = 0; 
    $vertices_count = count($vertices);

    for ($i=1; $i < $vertices_count; $i++) {
        $vertex1 = $vertices[$i-1]; 
        $vertex2 = $vertices[$i];
        if ($vertex1['y'] == $vertex2['y'] and $vertex1['y'] == $point['y'] and $point['x'] > min($vertex1['x'], $vertex2['x']) and $point['x'] < max($vertex1['x'], $vertex2['x'])) { // Check if point is on an horizontal polygon boundary
            return "boundary";
        }
        if ($point['y'] > min($vertex1['y'], $vertex2['y']) and $point['y'] <= max($vertex1['y'], $vertex2['y']) and $point['x'] <= max($vertex1['x'], $vertex2['x']) and $vertex1['y'] != $vertex2['y']) { 
            $xinters = ($point['y'] - $vertex1['y']) * ($vertex2['x'] - $vertex1['x']) / ($vertex2['y'] - $vertex1['y']) + $vertex1['x']; 
            if ($xinters == $point['x']) { // Check if lat lng is on the polygon boundary (other than horizontal)
                return "boundary";
            }
            if ($vertex1['x'] == $vertex2['x'] || $point['x'] <= $xinters) {
                $intersections++; 
            }
        } 
    } 
    // If the number of edges we passed through is odd, then it's in the polygon. 
    if ($intersections % 2 != 0) {
        return "inside";
    } else {
        return "outside";
    }
}

function pointOnVertex($point, $vertices) {
  foreach($vertices as $vertex) {
      if ($point == $vertex) {
          return true;
      }
  }

}

function pointStringToCoordinates($pointString) {
    $coordinates = explode(" ", $pointString);
    return array("x" => $coordinates[0], "y" => $coordinates[1]);
}
// Function to check lat lng
function check(){
    $points = array("22.367582 70.711816", "21.43567582 72.5811816","22.367582117085913 70.71181669186944","22.275334996986643 70.88614147123701","22.36934302329968 70.77627818998701"); // Array of latlng which you want to find
    $polygon = array(
        "22.367582117085913 70.71181669186944",
        "22.225161442616514 70.65582486840117",
        "22.20736264867434 70.83229276390898",
        "22.18701840565626 70.9867880031668",
        "22.22452581029355 71.0918447658621",
        "22.382709129816103 70.98884793969023",
        "22.40112042636022 70.94078275414336",
        "22.411912121843205 70.7849142238699",
        "22.367582117085913 70.71181669186944"
    );
    // The last lat lng must be the same as the first one's, to "close the loop"
    foreach($points as $key => $point) {
        echo "(Lat Lng) " . ($key+1) . " ($point): " . $this->pointInPolygon($point, $polygon) . "<br>";
    }
}

With MySql

CREATE TABLE `TestPoly` (
   `id` int(11) NOT NULL,
   `name` varchar(255) NOT NULL,
   `pol` polygon NOT NULL
 )

SET @g = 'POLYGON((22.367582117085913 70.71181669186944, 22.225161442616514 70.65582486840117, 22.20736264867434 70.83229276390898, 22.18701840565626 70.9867880031668, 22.22452581029355 71.0918447658621, 22.382709129816103 70.98884793969023, 22.40112042636022 70.94078275414336, 22.411912121843205 70.7849142238699, 22.367582117085913 70.71181669186944))';
INSERT INTO TestPoly (pol) VALUES (ST_GeomFromText(@g))

set @p = GeomFromText('POINT(22.4053386588057 70.86240663480157)');
select * FROM TestPoly where ST_Contains(pol, @p);

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;
}

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.

The popular answer above contains typos. Elsewhere, this code has been cleaned up. The corrected code is as follows:

<?php
/**
  From: http://www.daniweb.com/web-development/php/threads/366489
  Also see http://en.wikipedia.org/wiki/Point_in_polygon
*/
$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); // number vertices
$longitude_x = $_GET["longitude"]; // x-coordinate of the point to test
$latitude_y = $_GET["latitude"]; // y-coordinate of the point to test
//// For testing.  This point lies inside the test polygon.
// $longitude_x = 37.62850;
// $latitude_y = -77.4499;

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-1 ; $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;
}
?>

Find Point in polygon PHP

Tags:

Mysql

Php

Polygon

Point In Polygon

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