LcShopBundle/ShopBundle/Services/PointLocationUtils.php

<?php

namespace Lc\ShopBundle\Services ;

class PointLocationUtils {

        var $pointOnVertex = true; // Check if the point sits exactly on one of the vertices?

        function pointLocation() {
        }

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

                // Check if the point 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 == $point['x']) { // Check if point is on the polygon boundary (other than horizontal)
                                        return "boundary";
                                }
                                if ($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]);
        }

}