radar-wp/vendor/phayes/geophp/lib/geometry/LineString.class.php

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2015-02-24 16:25:12 +01:00
<?php
/**
* LineString. A collection of Points representing a line.
* A line can have more than one segment.
*/
class LineString extends Collection
{
protected $geom_type = 'LineString';
/**
* Constructor
*
* @param array $points An array of at least two points with
* which to build the LineString
*/
public function __construct($points = array()) {
if (count($points) == 1) {
throw new Exception("Cannot construct a LineString with a single point");
}
// Call the Collection constructor to build the LineString
parent::__construct($points);
}
// The boundary of a linestring is itself
public function boundary() {
return $this;
}
public function startPoint() {
return $this->pointN(1);
}
public function endPoint() {
$last_n = $this->numPoints();
return $this->pointN($last_n);
}
public function isClosed() {
return ($this->startPoint()->equals($this->endPoint()));
}
public function isRing() {
return ($this->isClosed() && $this->isSimple());
}
public function numPoints() {
return $this->numGeometries();
}
public function pointN($n) {
return $this->geometryN($n);
}
public function dimension() {
if ($this->isEmpty()) return 0;
return 1;
}
public function area() {
return 0;
}
public function length() {
if ($this->geos()) {
return $this->geos()->length();
}
$length = 0;
foreach ($this->getPoints() as $delta => $point) {
$previous_point = $this->geometryN($delta);
if ($previous_point) {
$length += sqrt(pow(($previous_point->getX() - $point->getX()), 2) + pow(($previous_point->getY()- $point->getY()), 2));
}
}
return $length;
}
public function greatCircleLength($radius = 6378137) {
$length = 0;
$points = $this->getPoints();
for($i=0; $i<$this->numPoints()-1; $i++) {
$point = $points[$i];
$next_point = $points[$i+1];
if (!is_object($next_point)) {continue;}
// Great circle method
$lat1 = deg2rad($point->getY());
$lat2 = deg2rad($next_point->getY());
$lon1 = deg2rad($point->getX());
$lon2 = deg2rad($next_point->getX());
$dlon = $lon2 - $lon1;
$length +=
$radius *
atan2(
sqrt(
pow(cos($lat2) * sin($dlon), 2) +
pow(cos($lat1) * sin($lat2) - sin($lat1) * cos($lat2) * cos($dlon), 2)
)
,
sin($lat1) * sin($lat2) +
cos($lat1) * cos($lat2) * cos($dlon)
);
}
// Returns length in meters.
return $length;
}
public function haversineLength() {
$degrees = 0;
$points = $this->getPoints();
for($i=0; $i<$this->numPoints()-1; $i++) {
$point = $points[$i];
$next_point = $points[$i+1];
if (!is_object($next_point)) {continue;}
$degree = rad2deg(
acos(
sin(deg2rad($point->getY())) * sin(deg2rad($next_point->getY())) +
cos(deg2rad($point->getY())) * cos(deg2rad($next_point->getY())) *
cos(deg2rad(abs($point->getX() - $next_point->getX())))
)
);
$degrees += $degree;
}
// Returns degrees
return $degrees;
}
public function explode() {
$parts = array();
$points = $this->getPoints();
foreach ($points as $i => $point) {
if (isset($points[$i+1])) {
$parts[] = new LineString(array($point, $points[$i+1]));
}
}
return $parts;
}
public function isSimple() {
if ($this->geos()) {
return $this->geos()->isSimple();
}
$segments = $this->explode();
foreach ($segments as $i => $segment) {
foreach ($segments as $j => $check_segment) {
if ($i != $j) {
if ($segment->lineSegmentIntersect($check_segment)) {
return FALSE;
}
}
}
}
return TRUE;
}
// Utility function to check if any line sigments intersect
// Derived from http://stackoverflow.com/questions/563198/how-do-you-detect-where-two-line-segments-intersect
public function lineSegmentIntersect($segment) {
$p0_x = $this->startPoint()->x();
$p0_y = $this->startPoint()->y();
$p1_x = $this->endPoint()->x();
$p1_y = $this->endPoint()->y();
$p2_x = $segment->startPoint()->x();
$p2_y = $segment->startPoint()->y();
$p3_x = $segment->endPoint()->x();
$p3_y = $segment->endPoint()->y();
$s1_x = $p1_x - $p0_x; $s1_y = $p1_y - $p0_y;
$s2_x = $p3_x - $p2_x; $s2_y = $p3_y - $p2_y;
$fps = (-$s2_x * $s1_y) + ($s1_x * $s2_y);
$fpt = (-$s2_x * $s1_y) + ($s1_x * $s2_y);
if ($fps == 0 || $fpt == 0) {
return FALSE;
}
$s = (-$s1_y * ($p0_x - $p2_x) + $s1_x * ($p0_y - $p2_y)) / $fps;
$t = ( $s2_x * ($p0_y - $p2_y) - $s2_y * ($p0_x - $p2_x)) / $fpt;
if ($s > 0 && $s < 1 && $t > 0 && $t < 1) {
// Collision detected
return TRUE;
}
return FALSE;
}
}