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delphine |
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<?php
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/**
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* Author : Julien Moquet
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*
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* Inspired by Proj4php from Mike Adair madairATdmsolutions.ca
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* and Richard Greenwood rich@greenwoodma$p->com
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* License: LGPL as per: http://www.gnu.org/copyleft/lesser.html
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*/
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class Proj4phpProjGauss {
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/**
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*
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*/
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public function init() {
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$sphi = sin( $this->lat0 );
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$cphi = cos( $this->lat0 );
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$cphi *= $cphi;
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$this->rc = sqrt( 1.0 - $this->es ) / (1.0 - $this->es * $sphi * $sphi);
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$this->C = sqrt( 1.0 + $this->es * $cphi * $cphi / (1.0 - $this->es) );
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$this->phic0 = asin( $sphi / $this->C );
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$this->ratexp = 0.5 * $this->C * $this->e;
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$this->K = tan( 0.5 * $this->phic0 + Proj4php::$common->FORTPI ) / (pow( tan( 0.5 * $this->lat0 + Proj4php::$common->FORTPI ), $this->C ) * Proj4php::$common->srat( $this->e * $sphi, $this->ratexp ));
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}
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/**
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*
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* @param type $p
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* @return type
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*/
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public function forward( $p ) {
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$lon = $p->x;
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$lat = $p->y;
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$p->y = 2.0 * atan( $this->K * pow( tan( 0.5 * $lat + Proj4php::$common->FORTPI ), $this->C ) * Proj4php::$common->srat( $this->e * sin( $lat ), $this->ratexp ) ) - Proj4php::$common->HALF_PI;
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$p->x = $this->C * $lon;
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return $p;
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}
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/**
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*
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* @param type $p
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* @return null
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*/
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public function inverse( $p ) {
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$DEL_TOL = 1e-14;
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$lon = $p->x / $this->C;
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$lat = $p->y;
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$num = pow( tan( 0.5 * $lat + Proj4php::$common . FORTPI ) / $this->K, 1. / $this->C );
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for( $i = Proj4php::$common . MAX_ITER; $i > 0; --$i ) {
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$lat = 2.0 * atan( $num * Proj4php::$common->srat( $this->e * sin( $p->y ), -0.5 * $this->e ) ) - Proj4php::$common->HALF_PI;
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if( abs( $lat - $p->y ) < $DEL_TOL )
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break;
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$p->y = $lat;
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}
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/* convergence failed */
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if( !$i ) {
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Proj4php::reportError( "gauss:inverse:convergence failed" );
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return null;
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}
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$p->x = $lon;
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$p->y = $lat;
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return $p;
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}
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}
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Proj4php::$proj['gauss'] = new Proj4phpProjGauss();
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