* September 1998. This code is based upon algorithms and data kindly
* provided by Mr. Paul Schlyter. (pausch@saaf.se).
*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of the
- * License, or (at your option) any later version.
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
*
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
+ * Library General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $Id$
**************************************************************************/
#include <simgear/debug/logstream.hxx>
-#ifdef FG_MATH_EXCEPTION_CLASH
-# define exception c_exception
-#endif
#include <math.h>
#include "celestialBody.hxx"
/**************************************************************************
- * void CelestialBody::updatePosition(fgTIME *t, Star *ourSun)
+ * void CelestialBody::updatePosition(double mjd, Star *ourSun)
*
* Basically, this member function provides a general interface for
* calculating the right ascension and declinaion. This function is
* position is calculated an a slightly different manner.
*
* arguments:
- * fgTIME t: provides the current time.
+ * double mjd: provides the modified julian date.
* Star *ourSun: the sun's position is needed to convert heliocentric
* coordinates into geocentric coordinates.
*
* return value: none
*
*************************************************************************/
-void CelestialBody::updatePosition(FGTime *t, Star *ourSun)
+void CelestialBody::updatePosition(double mjd, Star *ourSun)
{
double eccAnom, v, ecl, actTime,
xv, yv, xh, yh, zh, xg, yg, zg, xe, ye, ze;
- updateOrbElements(t);
- actTime = fgCalcActTime(t);
+ updateOrbElements(mjd);
+ actTime = sgCalcActTime(mjd);
// calcualate the angle bewteen ecliptic and equatorial coordinate system
- ecl = DEG_TO_RAD * (23.4393 - 3.563E-7 *actTime);
+ ecl = SGD_DEGREES_TO_RADIANS * (23.4393 - 3.563E-7 *actTime);
- eccAnom = fgCalcEccAnom(M, e); //calculate the eccentric anomaly
+ eccAnom = sgCalcEccAnom(M, e); //calculate the eccentric anomaly
xv = a * (cos(eccAnom) - e);
yv = a * (sqrt (1.0 - e*e) * sin(eccAnom));
v = atan2(yv, xv); // the planet's true anomaly
ze = yg * sin(ecl) + zg * cos(ecl);
rightAscension = atan2(ye, xe);
declination = atan2(ze, sqrt(xe*xe + ye*ye));
- FG_LOG(FG_GENERAL, FG_INFO, "Planet found at : "
- << rightAscension << " (ra), " << declination << " (dec)" );
+ /* SG_LOG(SG_GENERAL, SG_INFO, "Planet found at : "
+ << rightAscension << " (ra), " << declination << " (dec)" ); */
//calculate some variables specific to calculating the magnitude
//of the planet
tmp = -1.0;
}
- FV = RAD_TO_DEG * acos( tmp );
-};
+ FV = SGD_RADIANS_TO_DEGREES * acos( tmp );
+}
/****************************************************************************
- * double CelestialBody::fgCalcEccAnom(double M, double e)
+ * double CelestialBody::sgCalcEccAnom(double M, double e)
* this private member calculates the eccentric anomaly of a celestial body,
* given its mean anomaly and eccentricity.
*
* the eccentric anomaly
*
****************************************************************************/
-double CelestialBody::fgCalcEccAnom(double M, double e)
+double CelestialBody::sgCalcEccAnom(double M, double e)
{
double
eccAnom, E0, E1, diff;
diff = fabs(E0 - E1);
E0 = E1;
}
- while (diff > (DEG_TO_RAD * 0.001));
+ while (diff > (SGD_DEGREES_TO_RADIANS * 0.001));
return E0;
}
return eccAnom;
}
+/*****************************************************************************
+ * inline CelestialBody::CelestialBody
+ * public constructor for a generic celestialBody object.
+ * initializes the 6 primary orbital elements. The elements are:
+ * N: longitude of the ascending node
+ * i: inclination to the ecliptic
+ * w: argument of perihelion
+ * a: semi-major axis, or mean distance from the sun
+ * e: eccenticity
+ * M: mean anomaly
+ * Each orbital element consists of a constant part and a variable part that
+ * gradually changes over time.
+ *
+ * Argumetns:
+ * the 13 arguments to the constructor constitute the first, constant
+ * ([NiwaeM]f) and the second variable ([NiwaeM]s) part of the orbital
+ * elements. The 13th argument is the current time. Note that the inclination
+ * is written with a capital (If, Is), because 'if' is a reserved word in the
+ * C/C++ programming language.
+ ***************************************************************************/
+CelestialBody::CelestialBody(double Nf, double Ns,
+ double If, double Is,
+ double wf, double ws,
+ double af, double as,
+ double ef, double es,
+ double Mf, double Ms, double mjd)
+{
+ NFirst = Nf; NSec = Ns;
+ iFirst = If; iSec = Is;
+ wFirst = wf; wSec = ws;
+ aFirst = af; aSec = as;
+ eFirst = ef; eSec = es;
+ MFirst = Mf; MSec = Ms;
+ updateOrbElements(mjd);
+}
+CelestialBody::CelestialBody(double Nf, double Ns,
+ double If, double Is,
+ double wf, double ws,
+ double af, double as,
+ double ef, double es,
+ double Mf, double Ms)
+{
+ NFirst = Nf; NSec = Ns;
+ iFirst = If; iSec = Is;
+ wFirst = wf; wSec = ws;
+ aFirst = af; aSec = as;
+ eFirst = ef; eSec = es;
+ MFirst = Mf; MSec = Ms;
+}
+/****************************************************************************
+ * inline void CelestialBody::updateOrbElements(double mjd)
+ * given the current time, this private member calculates the actual
+ * orbital elements
+ *
+ * Arguments: double mjd: the current modified julian date:
+ *
+ * return value: none
+ ***************************************************************************/
+void CelestialBody::updateOrbElements(double mjd)
+{
+ double actTime = sgCalcActTime(mjd);
+ M = SGD_DEGREES_TO_RADIANS * (MFirst + (MSec * actTime));
+ w = SGD_DEGREES_TO_RADIANS * (wFirst + (wSec * actTime));
+ N = SGD_DEGREES_TO_RADIANS * (NFirst + (NSec * actTime));
+ i = SGD_DEGREES_TO_RADIANS * (iFirst + (iSec * actTime));
+ e = eFirst + (eSec * actTime);
+ a = aFirst + (aSec * actTime);
+}
+/*****************************************************************************
+ * inline double CelestialBody::sgCalcActTime(double mjd)
+ * this private member function returns the offset in days from the epoch for
+ * wich the orbital elements are calculated (Jan, 1st, 2000).
+ *
+ * Argument: the current time
+ *
+ * return value: the (fractional) number of days until Jan 1, 2000.
+ ****************************************************************************/
+double CelestialBody::sgCalcActTime(double mjd)
+{
+ return (mjd - 36523.5);
+}
+/*****************************************************************************
+ * inline void CelestialBody::getPos(double* ra, double* dec)
+ * gives public access to Right Ascension and declination
+ *
+ ****************************************************************************/
+void CelestialBody::getPos(double* ra, double* dec)
+{
+ *ra = rightAscension;
+ *dec = declination;
+}
-
-
-
-
-
-
-
-
-
-
-
-
+/*****************************************************************************
+ * inline void CelestialBody::getPos(double* ra, double* dec, double* magnitude
+ * gives public acces to the current Right ascension, declination, and
+ * magnitude
+ ****************************************************************************/
+void CelestialBody::getPos(double* ra, double* dec, double* magn)
+{
+ *ra = rightAscension;
+ *dec = declination;
+ *magn = magnitude;
+}
projects / simgear.git / blobdiff