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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                             ORTHOGRAPHIC
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  PURPOSE:	Transforms input longitude and latitude to Easting and
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  Northing for the Orthographic 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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  T. Mittan		Mar, 1993
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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.  Snyder, John P. and Voxland, Philip M., "An Album of Map Projections",
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  U.S. Geological Survey Professional Paper 1453 , United State Government
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  Printing Office, Washington D.C., 1989.
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 * ***************************************************************************** */
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class Proj4phpProjOrtho {
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    /* Initialize the Orthographic projection
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      ------------------------------------- */
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    public function init( $def ) {
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        //double temp;			/* temporary variable		*/
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        /* Place parameters in static storage for common use
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          ------------------------------------------------- */;
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        $this->sin_p14 = sin( $this->lat0 );
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        $this->cos_p14 = cos( $this->lat0 );
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    }
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    /* Orthographic forward equations--mapping lat,long to x,y
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      --------------------------------------------------- */
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    public function forward( $p ) {
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        /*
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        $sinphi;
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        $cosphi; // sin and cos value
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        $dlon;  // delta longitude value
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        $coslon;  // cos of longitude
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        $ksp;  // scale factor
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        $g;
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        */
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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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        $dlon = Proj4php::$common->adjust_lon( $lon - $this->long0 );
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        $sinphi = sin( $lat );
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        $cosphi = cos( $lat );
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        $coslon = cos( $dlon );
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        $g = $this->sin_p14 * sinphi + $this->cos_p14 * $cosphi * $coslon;
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        $ksp = 1.0;
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        if( ($g > 0) || (abs( $g ) <= Proj4php::$common->EPSLN) ) {
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            $x = $this->a * $ksp * $cosphi * sin( $dlon );
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            $y = $this->y0 + $this->a * $ksp * ($this->cos_p14 * $sinphi - $this->sin_p14 * $cosphi * $coslon);
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        } else {
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            Proj4php::reportError( "orthoFwdPointError" );
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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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        /*
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        $rh;  // height above ellipsoid
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        $z;  // angle
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        $sinz;
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        $cosz; // sin of z and cos of z
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        $temp;
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        $con;
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        $lon;
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        $lat;
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        */
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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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        $rh = sqrt( $p->x * $p->x + $p->y * $p->y );
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        if( $rh > $this->a + .0000001 ) {
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            Proj4php::reportError( "orthoInvDataError" );
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        }
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        $z = Proj4php::$common . asinz( $rh / $this->a );
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        $sinz = sin( $z );
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        $cosz = cos( $z );
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        $lon = $this->long0;
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        if( abs( $rh ) <= Proj4php::$common->EPSLN ) {
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            $lat = $this->lat0;
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        }
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        $lat = Proj4php::$common . asinz( $cosz * $this->sin_p14 + ($p->y * $sinz * $this->cos_p14) / $rh );
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        $con = abs( $this->lat0 ) - Proj4php::$common->HALF_PI;
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        if( abs( con ) <= Proj4php::$common->EPSLN ) {
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            if( $this->lat0 >= 0 ) {
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                $lon = Proj4php::$common->adjust_lon( $this->long0 + atan2( $p->x, -$p->y ) );
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            } else {
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                $lon = Proj4php::$common->adjust_lon( $this->long0 - atan2( -$p->x, $p->y ) );
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            }
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        }
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        $con = $cosz - $this->sin_p14 * sin( $lat );
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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['ortho'] = new Proj4phpProjOrtho();