144 lines
3.4 KiB
PHP
144 lines
3.4 KiB
PHP
<?php
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/**
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* Polygon: A polygon is a plane figure that is bounded by a closed path,
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* composed of a finite sequence of straight line segments
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*/
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class Polygon extends Collection
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{
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protected $geom_type = 'Polygon';
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public function area($exterior_only = FALSE, $signed = FALSE) {
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if ($this->isEmpty()) return 0;
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if ($this->geos() && $exterior_only == FALSE) {
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return $this->geos()->area();
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}
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$exterior_ring = $this->components[0];
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$pts = $exterior_ring->getComponents();
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$c = count($pts);
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if((int)$c == '0') return NULL;
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$a = '0';
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foreach($pts as $k => $p){
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$j = ($k + 1) % $c;
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$a = $a + ($p->getX() * $pts[$j]->getY()) - ($p->getY() * $pts[$j]->getX());
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}
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if ($signed) $area = ($a / 2);
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else $area = abs(($a / 2));
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if ($exterior_only == TRUE) {
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return $area;
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}
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foreach ($this->components as $delta => $component) {
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if ($delta != 0) {
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$inner_poly = new Polygon(array($component));
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$area -= $inner_poly->area();
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}
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}
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return $area;
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}
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public function centroid() {
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if ($this->isEmpty()) return NULL;
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if ($this->geos()) {
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return geoPHP::geosToGeometry($this->geos()->centroid());
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}
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$exterior_ring = $this->components[0];
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$pts = $exterior_ring->getComponents();
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$c = count($pts);
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if((int)$c == '0') return NULL;
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$cn = array('x' => '0', 'y' => '0');
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$a = $this->area(TRUE, TRUE);
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// If this is a polygon with no area. Just return the first point.
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if ($a == 0) {
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return $this->exteriorRing()->pointN(1);
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}
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foreach($pts as $k => $p){
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$j = ($k + 1) % $c;
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$P = ($p->getX() * $pts[$j]->getY()) - ($p->getY() * $pts[$j]->getX());
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$cn['x'] = $cn['x'] + ($p->getX() + $pts[$j]->getX()) * $P;
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$cn['y'] = $cn['y'] + ($p->getY() + $pts[$j]->getY()) * $P;
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}
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$cn['x'] = $cn['x'] / ( 6 * $a);
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$cn['y'] = $cn['y'] / ( 6 * $a);
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$centroid = new Point($cn['x'], $cn['y']);
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return $centroid;
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}
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/**
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* Find the outermost point from the centroid
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*
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* @returns Point The outermost point
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*/
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public function outermostPoint() {
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$centroid = $this->getCentroid();
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$max = array('length' => 0, 'point' => null);
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foreach($this->getPoints() as $point) {
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$lineString = new LineString(array($centroid, $point));
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if($lineString->length() > $max['length']) {
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$max['length'] = $lineString->length();
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$max['point'] = $point;
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}
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}
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return $max['point'];
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}
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public function exteriorRing() {
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if ($this->isEmpty()) return new LineString();
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return $this->components[0];
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}
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public function numInteriorRings() {
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if ($this->isEmpty()) return 0;
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return $this->numGeometries()-1;
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}
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public function interiorRingN($n) {
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return $this->geometryN($n+1);
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}
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public function dimension() {
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if ($this->isEmpty()) return 0;
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return 2;
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}
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public function isSimple() {
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if ($this->geos()) {
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return $this->geos()->isSimple();
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}
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$segments = $this->explode();
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foreach ($segments as $i => $segment) {
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foreach ($segments as $j => $check_segment) {
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if ($i != $j) {
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if ($segment->lineSegmentIntersect($check_segment)) {
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return FALSE;
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}
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}
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}
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}
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return TRUE;
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}
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// Not valid for this geometry type
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// --------------------------------
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public function length() { return NULL; }
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}
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