//*******************************************************************
//
// License:  See top level LICENSE.txt file.
// 
// Author:  Garrett Potts (gpotts@imagelinks.com)
//
// Description:
//
//*******************************************************************
//  $Id: ossimGnomonicProjection.h 17815 2010-08-03 13:23:14Z dburken $
#ifndef ossimGnomonicProjection_HEADER
#define ossimGnomonicProjection_HEADER

#include <ossim/projection/ossimMapProjection.h>

class OSSIMDLLEXPORT ossimGnomonicProjection : public ossimMapProjection
{
public:
   ossimGnomonicProjection(const ossimEllipsoid& ellipsoid = ossimEllipsoid(),
                                const ossimGpt& origin = ossimGpt());
   ossimGnomonicProjection(const ossimEllipsoid& ellipsoid,
                                const ossimGpt& origin,
                                const double falseEasting,
                                const double falseNorthing);
   ~ossimGnomonicProjection(){}
   virtual ossimObject *dup()const
      {
         return new ossimGnomonicProjection(*this);
      }
   
   virtual ossimGpt inverse(const ossimDpt &eastingNorthing)const;
   virtual ossimDpt forward(const ossimGpt &latLon)const;
   virtual void update();   
   

   /*!
    * SetFalseEasting.  The value is in meters.
    * Update is then called so we can pre-compute paramters
    */
   void setFalseEasting(double falseEasting);

   /*!
    * SetFalseNorthing.  The value is in meters.
    * Update is then called so we can pre-compute paramters
    */
   void setFalseNorthing(double falseNorthing);

   /*!
    * Sets both false easting and northing values.  The values are
    * expected to be in meters.
    * Update is then called so we can pre-compute paramters
    */
   void setFalseEastingNorthing(double falseEasting, double falseNorthing);

   void setDefaults();

   double getFalseEasting()const{return  Gnom_False_Easting;}
   double getFalseNorthing()const{return Gnom_False_Northing;}
   
   /*!
    * Method to save the state of an object to a keyword list.
    * Return true if ok or false on error.
    */
   virtual bool saveState(ossimKeywordlist& kwl,
                          const char* prefix=0)const;

   /*!
    * Method to the load (recreate) the state of an object from a keyword
    * list.  Return true if ok or false on error.
    */
   virtual bool loadState(const ossimKeywordlist& kwl,
                          const char* prefix=0);

protected:

   //__________________________GEOTRANS________________________
   mutable double Gnom_a;               /* Semi-major axis of ellipsoid in meters */
   mutable double Gnom_f;               /* Flattening of ellipsoid */
   mutable double Ra;                   /* Spherical Radius */
   mutable double Sin_Gnom_Origin_Lat;
   mutable double Cos_Gnom_Origin_Lat;
   
/* Gnomonic projection Parameters */
   mutable double Gnom_Origin_Lat;               /* Latitude of origin in radians */
   mutable double Gnom_Origin_Long;              /* Longitude of origin in radians */
   mutable double Gnom_False_Northing;           /* False northing in meters */
   mutable double Gnom_False_Easting;            /* False easting in meters */
   mutable double abs_Gnom_Origin_Lat;
   
   mutable double Gnom_Delta_Northing;
   mutable double Gnom_Delta_Easting;
   
/*
 * The function Set_Gnomonic_Parameters receives the ellipsoid parameters and
 * projection parameters as inputs, and sets the corresponding state
 * variables.  If any errors occur, the error code(s) are returned by the function, 
 * otherwise GNOM_NO_ERROR is returned.
 *
 *    a                 : Semi-major axis of ellipsoid, in meters   (input)
 *    f                 : Flattening of ellipsoid						        (input)
 *    Origin_Latitude   : Latitude in radians at which the          (input)
 *                          point scale factor is 1.0
 *    Central_Meridian  : Longitude in radians at the center of     (input)
 *                          the projection
 *    False_Easting     : A coordinate value in meters assigned to the
 *                          central meridian of the projection.     (input)
 *    False_Northing    : A coordinate value in meters assigned to the
 *                          origin latitude of the projection       (input)
 */
  long Set_Gnomonic_Parameters(double a,
                               double f,
                               double Origin_Latitude,
                               double Central_Meridian,
                               double False_Easting,
                               double False_Northing);

/*!
 * The function Get_Gnomonic_Parameters returns the current ellipsoid
 * parameters and Gnomonic projection parameters.
 *
 *    a                 : Semi-major axis of ellipsoid, in meters   (output)
 *    f                 : Flattening of ellipsoid						        (output)
 *    Origin_Latitude   : Latitude in radians at which the          (output)
 *                          point scale factor is 1.0
 *    Central_Meridian  : Longitude in radians at the center of     (output)
 *                          the projection
 *    False_Easting     : A coordinate value in meters assigned to the
 *                          central meridian of the projection.     (output)
 *    False_Northing    : A coordinate value in meters assigned to the
 *                          origin latitude of the projection       (output)
 */
  void Get_Gnomonic_Parameters(double *a,
                               double *f,
                               double *Origin_Latitude,
                               double *Central_Meridian,
                               double *False_Easting,
                               double *False_Northing)const;


/*!
 * The function Convert_Geodetic_To_Gnomonic converts geodetic (latitude and
 * longitude) coordinates to Gnomonic projection (easting and northing)
 * coordinates, according to the current ellipsoid and Gnomonic projection
 * parameters.  If any errors occur, the error code(s) are returned by the
 * function, otherwise GNOM_NO_ERROR is returned.
 *
 *    Latitude          : Latitude (phi) in radians           (input)
 *    Longitude         : Longitude (lambda) in radians       (input)
 *    Easting           : Easting (X) in meters               (output)
 *    Northing          : Northing (Y) in meters              (output)
 */
  long Convert_Geodetic_To_Gnomonic (double Latitude,
                                     double Longitude,
                                     double *Easting,
                                     double *Northing)const;


/*!
 * The function Convert_Gnomonic_To_Geodetic converts Gnomonic projection
 * (easting and northing) coordinates to geodetic (latitude and longitude)
 * coordinates, according to the current ellipsoid and Gnomonic projection
 * coordinates.  If any errors occur, the error code(s) are returned by the
 * function, otherwise GNOM_NO_ERROR is returned.
 *
 *    Easting           : Easting (X) in meters                  (input)
 *    Northing          : Northing (Y) in meters                 (input)
 *    Latitude          : Latitude (phi) in radians              (output)
 *    Longitude         : Longitude (lambda) in radians          (output)
 */
  long Convert_Gnomonic_To_Geodetic(double Easting,
                                    double Northing,
                                    double *Latitude,
                                    double *Longitude)const;


TYPE_DATA
};

#endif
