├── composer.json
└── src
    └── Geometry
        └── Polygon.php


/composer.json:
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 1 | {
 2 |     "name": "hannesvdvreken/pip",
 3 |     "description": "The Polygon class",
 4 |     "keywords": ["pip","GeoJSON","Polygon","Geometry","Geo","Point-in-polygon"],
 5 |     "authors": [
 6 |         {
 7 |             "name": "Hannes Van De Vreken",
 8 |             "email": "vandevreken.hannes@gmail.com"
 9 |         }
10 |     ],
11 |     "license" : "MIT",
12 |     "require": {
13 |         "php": ">=5.6.0"
14 |     },
15 |     "require-dev": {
16 |         "phpunit/phpunit": "^5.6.3||^8.2.3"
17 |     },
18 |     "autoload": {
19 |         "psr-4": {
20 |             "Geometry\\": "src/Geometry/"
21 |         }
22 |     }
23 | }
24 | 


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/src/Geometry/Polygon.php:
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  1 | <?php
  2 | 
  3 | namespace Geometry;
  4 | 
  5 | class Polygon
  6 | {
  7 |     /**
  8 |      * @var array
  9 |      */
 10 |     protected $coordinates = [];
 11 | 
 12 |     /**
 13 |      * @var bool
 14 |      */
 15 |     protected $valid;
 16 | 
 17 |     /**
 18 |      * @param array $coordinates
 19 |      */
 20 |     public function __construct(array $coordinates = null)
 21 |     {
 22 |         if ($coordinates) {
 23 |             $this->setOutline($coordinates);
 24 |         } else {
 25 |             $this->valid = false;
 26 |         }
 27 |     }
 28 | 
 29 |     /**
 30 |      * @param array $coordinates
 31 |      *
 32 |      * @return $this
 33 |      */
 34 |     public function setOutline(array $coordinates)
 35 |     {
 36 |         $points = [];
 37 |         $this->valid = true;
 38 | 
 39 |         // Check if it has at least 3 points.
 40 |         if (count($coordinates) >= 3) {
 41 |             // Check format
 42 |             foreach ($coordinates as $point) {
 43 |                 if ($this->validPoint($point)) {
 44 |                     $points[] = $point;
 45 |                 } else {
 46 |                     $this->valid = false;
 47 |                     return $this;
 48 |                 }
 49 |             }
 50 |         } else {
 51 |             $this->valid = false;
 52 |             return $this;
 53 |         }
 54 | 
 55 |         // Make sure the last one is the same as the first one.
 56 |         if ($this->firstAndLastEqual($points)) {
 57 |             $points[] = reset($points);
 58 |         }
 59 | 
 60 |         // Assign.
 61 |         $this->coordinates = $points;
 62 |     }
 63 | 
 64 |     /**
 65 |      * @return array
 66 |      */
 67 |     public function getOutline()
 68 |     {
 69 |         return $this->coordinates;
 70 |     }
 71 | 
 72 |     /**
 73 |      * @return bool
 74 |      */
 75 |     public function isValid()
 76 |     {
 77 |         return $this->valid;
 78 |     }
 79 | 
 80 |     /**
 81 |      * @param double $latitude
 82 |      * @param double $longitude
 83 |      *
 84 |      * @return bool
 85 |      */
 86 |     public function pip($latitude, $longitude)
 87 |     {
 88 |         // init
 89 |         $left = 0;
 90 |         $right = 0;
 91 |         $previous = reset($this->coordinates);
 92 | 
 93 |         // calculate
 94 |         while ($point = next($this->coordinates)) {
 95 |             $x1 = $previous[0];
 96 |             $y1 = $previous[1];
 97 | 
 98 |             $x2 = $point[0];
 99 |             $y2 = $point[1];
100 | 
101 |             // If the edge is on the same height.
102 |             if (max($x2, $x1) >= $latitude && min($x2, $x1) < $latitude) {
103 |                 // Change edge's direction if needed.
104 |                 if ($x2 > $x1) {
105 |                     list($x1, $y1, $x2, $y2) = [$x2, $y2, $x1, $y1];
106 |                 }
107 | 
108 |                 // Check position relative to the edge.
109 |                 $temp = ($x2 - $x1) * ($longitude - $y1) - ($y2 - $y1) * ($latitude - $x1);
110 |                 $left += ($temp < 0) ? 1 : 0;
111 |             }
112 | 
113 |             // Shift.
114 |             $previous = $point;
115 |         }
116 | 
117 |         // Return
118 |         return $left % 2 === 1;
119 |     }
120 | 
121 |     /**
122 |      * @return bool
123 |      */
124 |     public function isClockwise()
125 |     {
126 |         // Init
127 |         $sum = 0;
128 | 
129 |         // Get the first.
130 |         $previous = reset($this->coordinates);
131 | 
132 |         // Loop.
133 |         while ($point = next($this->coordinates)) {
134 |             $sum += ($point[0] - $previous[0]) * ($point[1] + $previous[1]);
135 | 
136 |             // Shift
137 |             $previous = $point;
138 |         }
139 | 
140 |         // Reset pointer.
141 |         reset($this->coordinates);
142 | 
143 |         // Return.
144 |         return $sum >= 0;
145 |     }
146 | 
147 |     /**
148 |      * @return array
149 |      */
150 |     public function centroid()
151 |     {
152 |         // Init
153 |         $cx = 0;
154 |         $cy = 0;
155 |         $a  = 0;
156 | 
157 |         // First point.
158 |         $previous = reset($this->coordinates);
159 | 
160 |         // Loop all points.
161 |         while ($point = next($this->coordinates)) {
162 |             $temp = ($previous[0] * $point[1]) - ($point[0] * $previous[1]);
163 |             $cx += (($previous[0] + $point[0]) * $temp);
164 |             $cy += (($previous[1] + $point[1]) * $temp);
165 |             $a += $temp * 3;
166 | 
167 |             // Shift
168 |             $previous = $point;
169 |         }
170 | 
171 |         // Reset the pointer.
172 |         reset($this->coordinates);
173 | 
174 |         // Return the centroid.
175 |         return [$cx / $a, $cy / $a];
176 |     }
177 | 
178 |     /**
179 |      * @param $point
180 |      *
181 |      * @return bool
182 |      */
183 |     protected function validPoint($point)
184 |     {
185 |         return is_array($point) &&
186 |             count($point) == 2 &&
187 |             is_numeric($point[0]) &&
188 |             is_numeric($point[1]);
189 |     }
190 | 
191 |     /**
192 |      * @param array $points
193 |      *
194 |      * @return bool
195 |      */
196 |     protected function firstAndLastEqual(array $points)
197 |     {
198 |         // Get first and last.
199 |         $first = reset($points);
200 |         $last = end($points);
201 | 
202 |         // Return if the first and the last are the same.
203 |         return $first[0] !== $last[0] || $first[1] !== $last[1];
204 |     }
205 | }
206 | 


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