175 lines
5.7 KiB
C++
175 lines
5.7 KiB
C++
/********************************************************************
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KWin - the KDE window manager
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This file is part of the KDE project.
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Copyright 2017 Roman Gilg <subdiff@gmail.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*********************************************************************/
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#include "suncalc.h"
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#include "constants.h"
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#include <QDateTime>
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#include <QTimeZone>
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#include <QtMath>
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namespace KWin {
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namespace ColorCorrect {
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#define TWILIGHT_NAUT -12.0
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#define TWILIGHT_CIVIL -6.0
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#define SUN_RISE_SET -0.833
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#define SUN_HIGH 2.0
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static QTime convertToLocalTime(const QDateTime &when, const QTime &utcTime)
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{
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const QTimeZone timeZone = QTimeZone::systemTimeZone();
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const int utcOffset = timeZone.offsetFromUtc(when);
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return utcTime.addSecs(utcOffset);
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}
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QPair<QDateTime, QDateTime> calculateSunTimings(const QDateTime &dateTime, double latitude, double longitude, bool morning)
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{
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// calculations based on https://aa.quae.nl/en/reken/zonpositie.html
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// accuracy: +/- 5min
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// positioning
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const double rad = M_PI / 180.;
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const double earthObliquity = 23.4397; // epsilon
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const double lat = latitude; // phi
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const double lng = -longitude; // lw
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// times
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const QDateTime utcDateTime = dateTime.toUTC();
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const double juPrompt = utcDateTime.date().toJulianDay(); // J
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const double ju2000 = 2451545.; // J2000
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// geometry
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auto mod360 = [](double number) -> double {
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return std::fmod(number, 360.);
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};
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auto sin = [&rad](double angle) -> double {
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return std::sin(angle * rad);
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};
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auto cos = [&rad](double angle) -> double {
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return std::cos(angle * rad);
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};
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auto asin = [&rad](double val) -> double {
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return std::asin(val) / rad;
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};
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auto acos = [&rad](double val) -> double {
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return std::acos(val) / rad;
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};
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auto anomaly = [&](const double date) -> double { // M
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return mod360(357.5291 + 0.98560028 * (date - ju2000));
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};
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auto center = [&sin](double anomaly) -> double { // C
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return 1.9148 * sin(anomaly) + 0.02 * sin(2 * anomaly) + 0.0003 * sin(3 * anomaly);
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};
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auto ecliptLngMean = [](double anom) -> double { // Mean ecliptical longitude L_sun = Mean Anomaly + Perihelion + 180°
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return anom + 282.9372; // anom + 102.9372 + 180°
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};
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auto ecliptLng = [&](double anom) -> double { // lambda = L_sun + C
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return ecliptLngMean(anom) + center(anom);
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};
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auto declination = [&](const double date) -> double { // delta
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const double anom = anomaly(date);
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const double eclLng = ecliptLng(anom);
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return mod360(asin(sin(earthObliquity) * sin(eclLng)));
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};
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// sun hour angle at specific angle
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auto hourAngle = [&](const double date, double angle) -> double { // H_t
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const double decl = declination(date);
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const double ret0 = (sin(angle) - sin(lat) * sin(decl)) / (cos(lat) * cos(decl));
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double ret = mod360(acos( ret0 ));
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if (180. < ret) {
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ret = ret - 360.;
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}
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return ret;
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};
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/*
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* Sun positions
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*/
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// transit is at noon
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auto getTransit = [&](const double date) -> double { // Jtransit
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const double juMeanSolTime = juPrompt - ju2000 - 0.0009 - lng / 360.; // n_x = J - J_2000 - J_0 - l_w / 360°
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const double juTrEstimate = date + qRound64(juMeanSolTime) - juMeanSolTime; // J_x = J + n - n_x
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const double anom = anomaly(juTrEstimate); // M
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const double eclLngM = ecliptLngMean(anom); // L_sun
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return juTrEstimate + 0.0053 * sin(anom) - 0.0068 * sin(2 * eclLngM);
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};
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auto getSunMorning = [&hourAngle](const double angle, const double transit) -> double {
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return transit - hourAngle(transit, angle) / 360.;
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};
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auto getSunEvening = [&hourAngle](const double angle, const double transit) -> double {
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return transit + hourAngle(transit, angle) / 360.;
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};
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/*
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* Begin calculations
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*/
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// noon - sun at the highest point
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const double juNoon = getTransit(juPrompt);
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double begin, end;
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if (morning) {
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begin = getSunMorning(TWILIGHT_CIVIL, juNoon);
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end = getSunMorning(SUN_HIGH, juNoon);
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} else {
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begin = getSunEvening(SUN_HIGH, juNoon);
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end = getSunEvening(TWILIGHT_CIVIL, juNoon);
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}
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// transform to QDateTime
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begin += 0.5;
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end += 0.5;
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QDateTime dateTimeBegin;
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QDateTime dateTimeEnd;
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if (!std::isnan(begin)) {
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const double dayFraction = begin - int(begin);
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const QTime utcTime = QTime::fromMSecsSinceStartOfDay(dayFraction * MSC_DAY);
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const QTime localTime = convertToLocalTime(dateTime, utcTime);
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dateTimeBegin = QDateTime(dateTime.date(), localTime);
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}
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if (!std::isnan(end)) {
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const double dayFraction = end - int(end);
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const QTime utcTime = QTime::fromMSecsSinceStartOfDay(dayFraction * MSC_DAY);
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const QTime localTime = convertToLocalTime(dateTime, utcTime);
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dateTimeEnd = QDateTime(dateTime.date(), localTime);
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}
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return { dateTimeBegin, dateTimeEnd };
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}
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}
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}
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