File indexing completed on 2024-04-21 05:46:36

 // SPDX-License-Identifier: GPL-3.0-or-later
 /*
   Copyright 2021 Martin Koller, kollix@aon.at
 
   This file is part of liquidshell.
 
   liquidshell 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 3 of the License, or
   (at your option) any later version.
 
   liquidshell 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.
 
   You should have received a copy of the GNU General Public License
   along with liquidshell.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 // original code from http://www.voidware.com/phase.c
 // adjusted for liquidshell
 
 #include <Moon.hxx>
 #include <cmath>
 
 #define PI  3.1415926535897932384626433832795
 #define RAD  (PI/180.0)
 #define SMALL_FLOAT  (1e-12)
 
 //--------------------------------------------------------------------------------
 
 int Moon::phase(const QDate &date)
 {
   double j = date.toJulianDay() - 2444238.5;
   double ls = sun_position(j);
   double lm = moon_position(j, ls);
   double t = lm - ls;
 
   if (t < 0) t += 360;
   return static_cast<int>((t / 360.0) * 55);
 }
 
 //--------------------------------------------------------------------------------
 
 double Moon::sun_position(double j)
 {
   double n, x, e, l, dl, v;
   int i;
   n = 360 / 365.2422 * j;
   i = n / 360;
   n = n - i * 360.0;
   x = n - 3.762863;
 
   if (x < 0) x += 360;
 
   x *= RAD;
   e = x;
 
   do
   {
     dl = e - .016718 * std::sin(e) - x;
     e = e - dl / (1 - .016718 * std::cos(e));
   }
   while (std::fabs(dl) >= SMALL_FLOAT);
 
   v = 360 / PI * std::atan(1.01686011182 * std::tan(e / 2));
   l = v + 282.596403;
   i = l / 360;
   l = l - i * 360.0;
   return l;
 }
 
 //--------------------------------------------------------------------------------
 
 double Moon::moon_position(double j, double ls)
 {
   double ms, l, mm, n, ev, sms, ae, ec;
   int i;
   /* ls = sun_position(j) */
   ms = 0.985647332099 * j - 3.762863;
 
   if (ms < 0) ms += 360.0;
 
   l = 13.176396 * j + 64.975464;
   i = l / 360;
   l = l - i * 360.0;
 
   if (l < 0) l += 360.0;
 
   mm = l - 0.1114041 * j - 349.383063;
   i = mm / 360;
   mm -= i * 360.0;
   n = 151.950429 - 0.0529539 * j;
   i = n / 360;
   n -= i * 360.0;
   ev = 1.2739 * std::sin((2 * (l - ls) - mm) * RAD);
   sms =  std::sin(ms * RAD);
   ae = 0.1858 * sms;
   mm += ev - ae - 0.37 * sms;
   ec = 6.2886 * std::sin(mm * RAD);
   l += ev + ec - ae + 0.214 * std::sin(2 * mm * RAD);
   l = 0.6583 * std::sin(2 * (l - ls) * RAD) + l;
   return l;
 }
 
 //--------------------------------------------------------------------------------