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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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/*******************************************************************************
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  NAME                  		SINUSOIDAL
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  PURPOSE:	Transforms input longitude and latitude to Easting and
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  Northing for the Sinusoidal projection.  The
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  longitude and latitude must be in radians.  The Easting
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  and Northing values will be returned in meters.
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  PROGRAMMER              DATE
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  ----------              ----
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  D. Steinwand, EROS      May, 1991
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  This function was adapted from the Sinusoidal projection code (FORTRAN) in the
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  General Cartographic Transformation Package software which is available from
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  the U.S. Geological Survey National Mapping Division.
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  ALGORITHM REFERENCES
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  1.  Snyder, John P., "Map Projections--A Working Manual", U.S. Geological
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  Survey Professional Paper 1395 (Supersedes USGS Bulletin 1532), United
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  State Government Printing Office, Washington D.C., 1987.
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  2.  "Software Documentation for GCTP General Cartographic Transformation
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  Package", U.S. Geological Survey National Mapping Division, May 1982.
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 * ***************************************************************************** */
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class Proj4phpProjSinu {
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    /* Initialize the Sinusoidal projection
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      ------------------------------------ */
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    public function init() {
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        /* Place parameters in static storage for common use
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          ------------------------------------------------- */
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        #$this->R = 6370997.0; //Radius of earth
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        if( !$this->sphere ) {
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            $this->en = Proj4php::$common->pj_enfn( $this->es );
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        } else {
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            $this->n = 1.;
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            $this->m = 0.;
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            $this->es = 0;
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            $this->C_y = sqrt( ($this->m + 1.) / $this->n );
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            $this->C_x = $this->C_y / ($this->m + 1.);
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        }
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    }
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    /* Sinusoidal forward equations--mapping lat,long to x,y
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      ----------------------------------------------------- */
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    public function forward( $p ) {
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        #$x,y,delta_lon;
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        $lon = $p->x;
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        $lat = $p->y;
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        /* Forward equations
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          ----------------- */
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        $lon = Proj4php::$common->adjust_lon( $lon - $this->long0 );
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        if( isset($this->sphere) ) {
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            if( !$this->m ) {
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                $lat = $this->n != 1. ? asin( $this->n * sin( $lat ) ) : $lat;
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            } else {
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                $k = $this->n * sin( $lat );
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                for( $i = Proj4php::$common->MAX_ITER; $i; --$i ) {
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                    $V = ($this->m * $lat + sin( $lat ) - $k) / ($this->m + cos( $lat ));
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                    $lat -= $V;
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                    if( abs( $V ) < Proj4php::$common->EPSLN )
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                        break;
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                }
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            }
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            $x = $this->a * $this->C_x * $lon * ($this->m + cos( $lat ));
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            $y = $this->a * $this->C_y * $lat;
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        } else {
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            $s = sin( $lat );
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            $c = cos( $lat );
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            $y = $this->a * Proj4php::$common->pj_mlfn( $lat, $s, $c, $this->en );
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            $x = $this->a * $lon * $c / sqrt( 1. - $this->es * $s * $s );
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        }
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        $p->x = $x;
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        $p->y = $y;
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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 type
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     */
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    public function inverse( $p ) {
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        #$lat;
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        #$temp;
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        #$lon;
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        /* Inverse equations
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          ----------------- */
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        $p->x -= $this->x0;
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        $p->y -= $this->y0;
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        $lat = $p->y / $this->a;
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        if( isset($this->sphere) ) {
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            $p->y /= $this->C_y;
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            $lat = $this->m ? asin( ($this->m * $p->y + sin( $p->y )) / $this->n ) : ( $this->n != 1. ? asin( sin( $p->y ) / $this->n ) : $p->y );
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            $lon = $p->x / ($this->C_x * ($this->m + cos( $p->y )));
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        }
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        else {
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            $lat = Proj4php::$common->pj_inv_mlfn( $p->y / $this->a, $this->es, $this->en );
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            $s = abs( $lat );
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            if( $s < Proj4php::$common->HALF_PI ) {
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                $s = sin( $lat );
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                $temp = $this->long0 + $p->x * sqrt( 1. - $this->es * $s * $s ) / ($this->a * cos( $lat ));
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                //temp = $this->long0 + $p->x / ($this->a * cos($lat));
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                $lon = Proj4php::$common->adjust_lon( $temp );
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            } else if( ($s - Proj4php::$common->EPSLN) < Proj4php::$common->HALF_PI ) {
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                $lon = $this->long0;
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            }
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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['sinu'] = new Proj4phpProjSinu();