💿🐜 Antkeeper source code
https://antkeeper.com
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486 lines
15 KiB
486 lines
15 KiB
/*
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* Copyright (C) 2020 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code 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 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code 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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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "game/systems/weather-system.hpp"
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#include "scene/directional-light.hpp"
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#include "scene/ambient-light.hpp"
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#include "renderer/passes/sky-pass.hpp"
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#include "renderer/passes/shadow-map-pass.hpp"
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#include "renderer/passes/material-pass.hpp"
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#include "utility/gamma.hpp"
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#include "resources/image.hpp"
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#include "game/astronomy/celestial-coordinates.hpp"
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#include <cmath>
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#include <iostream>
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static constexpr double hours_per_day = 24.0;
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static constexpr double minutes_per_day = hours_per_day * 60.0;
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static constexpr double seconds_per_day = minutes_per_day * 60.0;
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/**
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*
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* @param year Gregorian year
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* @param month Month (1 = January, 12 = December)
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* @param day Day (1-31)
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* @param time Universal time in decimal hours.
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*/
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static double julian_day(int year, int month, int day, double time)
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{
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if (month < 3)
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{
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month += 12;
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year -= 1;
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}
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double y = static_cast<double>(year);
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double m = static_cast<double>(month);
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double d = static_cast<double>(day);
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return std::floor(365.25 * y) + std::floor(30.6001 * (m + 1.0)) - 15.0 + 1720996.5 + d + time;
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}
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/**
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* Calculates the ecliptic rectangular geocentric coordinates of the sun, with distance in AU.
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*/
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double3 calculate_sun_ecliptic(double jd)
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{
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const double t = (jd - 2451545.0) / 36525.0;
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const double m = 6.24 + 628.302 * t;
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const double longitude = 4.895048 + 628.331951 * t + (0.033417 - 0.000084 * t) * std::sin(m) + 0.000351 * std::sin(m * 2.0);
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const double latitude = 0.0;
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const double distance = 1.000140 - (0.016708 - 0.000042 * t) * std::cos(m) - 0.000141 * std::cos(m * 2.0);
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double3 ecliptic;
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ecliptic.x = distance * std::cos(longitude) * std::cos(latitude);
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ecliptic.y = distance * std::sin(longitude) * std::cos(latitude);
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ecliptic.z = distance * std::sin(latitude);
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return ecliptic;
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}
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/**
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* Calculates the ecliptic rectangular geocentric coordinates of the moon, with distance in Earth radii.
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*/
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double3 calculate_moon_ecliptic(double jd)
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{
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const double t = (jd - 2451545.0) / 36525.0;
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const double l1 = 3.8104 + 8399.7091 * t;
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const double m1 = 2.3554 + 8328.6911 * t;
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const double m = 6.2300 + 628.3019 * t;
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const double d = 5.1985 + 7771.3772 * t;
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const double d2 = d * 2.0;
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const double f = 1.6280 + 8433.4663 * t;
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const double longitude = l1
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+ 0.1098 * std::sin(m1)
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+ 0.0222 * std::sin(d2 - m1)
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+ 0.0115 * std::sin(d2)
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+ 0.0037 * std::sin(m1 * 2.0)
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- 0.0032 * std::sin(m)
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- 0.0020 * std::sin(d2)
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+ 0.0010 * std::sin(d2 - m1 * 2.0)
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+ 0.0010 * std::sin(d2 - m - m1)
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+ 0.0009 * std::sin(d2 + m1)
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+ 0.0008 * std::sin(d2 - m)
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+ 0.0007 * std::sin(m1 - m)
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- 0.0006 * std::sin(d)
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- 0.0005 * std::sin(m + m1);
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const double latitude = 0.0895 * sin(f)
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+ 0.0049 * std::sin(m1 + f)
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+ 0.0048 * std::sin(m1 - f)
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+ 0.0030 * std::sin(d2 - f)
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+ 0.0010 * std::sin(d2 + f - m1)
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+ 0.0008 * std::sin(d2 - f - m1)
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+ 0.0006 * std::sin(d2 + f);
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const double r = 1.0 / (0.016593
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+ 0.000904 * std::cos(m1)
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+ 0.000166 * std::cos(d2 - m1)
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+ 0.000137 * std::cos(d2)
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+ 0.000049 * std::cos(m1 * 2.0)
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+ 0.000015 * std::cos(d2 + m1)
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+ 0.000009 * std::cos(d2 - m));
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double3 ecliptic;
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ecliptic.x = r * std::cos(longitude) * std::cos(latitude);
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ecliptic.y = r * std::sin(longitude) * std::cos(latitude);
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ecliptic.z = r * std::sin(latitude);
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return ecliptic;
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}
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double3x3 find_moon_ecliptic_rotation(double jd)
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{
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const double t = (jd - 2451545.0) / 36525.0;
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const double l1 = 3.8104 + 8399.7091 * t;
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const double f = 1.6280 + 8433.4663 * t;
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const double az0 = f + math::pi<double>;
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const double ax = 0.026920;
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const double az1 = l1 - f;
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double3x3 rz0 =
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{
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cos(az0), -sin(az0), 0,
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sin(az0), cos(az0), 0,
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0, 0, 1
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};
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double3x3 rx =
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{
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1, 0, 0,
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0, cos(ax), -sin(ax),
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0, sin(ax), cos(ax)
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};
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double3x3 rz1 =
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{
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cos(az1), -sin(az1), 0,
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sin(az1), cos(az1), 0,
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0, 0, 1
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};
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return rz0 * rx * rz1;
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}
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/// @see http://www.stjarnhimlen.se/comp/ppcomp.html
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/// @see http://www.geoastro.de/elevazmoon/basics/index.htm
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void ecliptic_to_equatorial(double longitude, double latitude, double ecl, double* right_ascension, double* declination)
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{
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double eclip_x = std::cos(longitude) * std::cos(latitude);
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double eclip_y = std::sin(longitude) * std::cos(latitude);
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double eclip_z = std::sin(latitude);
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double equat_x = eclip_x;
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double equat_y = eclip_y * std::cos(ecl) - eclip_z * std::sin(ecl);
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double equat_z = eclip_y * std::sin(ecl) + eclip_z * std::cos(ecl);
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*right_ascension = std::atan2(equat_y, equat_x);
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*declination = std::atan2(equat_z, sqrt(equat_x * equat_x + equat_y * equat_y));
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}
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/// @see http://www.stjarnhimlen.se/comp/ppcomp.html
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/// @see http://www.geoastro.de/elevazmoon/basics/index.htm
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void equatorial_to_horizontal(double right_ascension, double declination, double lmst, double latitude, double* azimuth, double* elevation)
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{
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double hour_angle = lmst - right_ascension;
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double x = std::cos(hour_angle) * std::cos(declination);
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double y = std::sin(hour_angle) * std::cos(declination);
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double z = std::sin(declination);
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double horiz_x = x * std::cos(math::half_pi<double> - latitude) - z * std::sin(math::half_pi<double> - latitude);
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double horiz_y = y;
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double horiz_z = x * std::sin(math::half_pi<double> - latitude) + z * std::cos(math::half_pi<double> - latitude);
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*azimuth = math::wrap_radians<double>(std::atan2(horiz_y, horiz_x) + math::pi<double>);
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*elevation = math::wrap_radians<double>(std::atan2(horiz_z, std::sqrt(horiz_x * horiz_x + horiz_y * horiz_y)));
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}
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double3x3 horizontal_to_right_handed()
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{
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return double3x3
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{
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0.0, 0.0, 1.0,
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1.0, 0.0, 0.0,
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0.0, -1.0, 0.0
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};
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}
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/**
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* Calculates the Greenwich mean sidereal time (GMST) from a Julian day.
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*
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* @param jd Julian day.
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* @return GMST, in radians.
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*/
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static double jd_to_gmst(double jd)
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{
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return math::wrap_radians<double>(4.894961212 + 6.300388098 * (jd - 2451545.0));
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}
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weather_system::weather_system(entt::registry& registry):
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entity_system(registry),
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ambient_light(nullptr),
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sun_light(nullptr),
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moon_light(nullptr),
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shadow_light(nullptr),
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sky_pass(nullptr),
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shadow_map_pass(nullptr),
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material_pass(nullptr),
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time_scale(1.0f),
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sun_direction{0.0f, -1.0f, 0.0f},
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location{0.0f, 0.0f, 0.0f},
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jd(0.0)
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{}
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void weather_system::update(double t, double dt)
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{
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jd += (dt * time_scale) / seconds_per_day;
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const float latitude = location[0];
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const float longitude = location[1];
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// Calculate local mean sidereal time (LMST)
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double time_correction = longitude / (math::two_pi<double> / 24.0);
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double local_jd = jd + time_correction / 24.0 - 0.5;
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double local_time = (local_jd - std::floor(local_jd)) * 24.0;
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double hour = local_time;
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double gmst = jd_to_gmst(jd);
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double lmst = gmst + longitude;
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// Obliquity of the ecliptic
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double ecl = math::radians<double>(23.4393 - 3.563e-7 * (jd - 2451545.0));
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// Solar distance in AU
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//double sr = ...
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// Apparent radius in degrees
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//double sradius = 0.2666 / sr;
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double3x3 ecliptic_to_horizontal = ast::ecliptic_to_horizontal(ecl, latitude, lmst);
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double3 sun_ecliptic = calculate_sun_ecliptic(jd);
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double3 sun_horizontal = ecliptic_to_horizontal * sun_ecliptic;
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double3 sun_spherical = ast::rectangular_to_spherical(sun_horizontal);
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double3 sun_positiond = horizontal_to_right_handed() * sun_horizontal;
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float2 sun_az_el = {static_cast<float>(sun_spherical.z) - math::pi<float>, static_cast<float>(sun_spherical.y)};
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float3 sun_position = math::normalize(float3{static_cast<float>(sun_positiond.x), static_cast<float>(sun_positiond.y), static_cast<float>(sun_positiond.z)});
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double3 moon_ecliptic = calculate_moon_ecliptic(jd);
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double3 moon_horizontal = ecliptic_to_horizontal * moon_ecliptic;
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moon_horizontal.z -= 1.0; // Subtract one earth radius, for position of observer
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double3 moon_spherical = ast::rectangular_to_spherical(moon_horizontal);
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double3 moon_positiond = horizontal_to_right_handed() * moon_horizontal;
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float2 moon_az_el = {static_cast<float>(moon_spherical.z) - math::pi<float>, static_cast<float>(moon_spherical.y)};
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float3 moon_position = math::normalize(float3{static_cast<float>(moon_positiond.x), static_cast<float>(moon_positiond.y), static_cast<float>(moon_positiond.z)});
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//std::cout << "new moon: " << math::degrees(moon_az_el[0]) << ", " << math::degrees(moon_az_el[1]) << std::endl;
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double3x3 moon_rotation_matrix = horizontal_to_right_handed() * ecliptic_to_horizontal;
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math::quaternion<double> moon_rotationd = math::normalize(math::quaternion_cast(moon_rotation_matrix) * math::angle_axis(math::half_pi<double>, double3{0, 1, 0}) * math::angle_axis(-math::half_pi<double>, double3{0, 0, -1}));
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math::quaternion<float> moon_rotation =
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{
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static_cast<float>(moon_rotationd.w),
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static_cast<float>(moon_rotationd.x),
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static_cast<float>(moon_rotationd.y),
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static_cast<float>(moon_rotationd.z)
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};
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if (sun_light)
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{
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math::quaternion<float> sun_azimuth_rotation = math::angle_axis(sun_az_el[0], float3{0, 1, 0});
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math::quaternion<float> sun_elevation_rotation = math::angle_axis(sun_az_el[1], float3{-1, 0, 0});
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math::quaternion<float> sun_az_el_rotation = math::normalize(sun_azimuth_rotation * sun_elevation_rotation);
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sun_light->set_rotation(sun_az_el_rotation);
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}
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if (moon_light)
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{
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math::quaternion<float> moon_azimuth_rotation = math::angle_axis(moon_az_el[0], float3{0, 1, 0});
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math::quaternion<float> moon_elevation_rotation = math::angle_axis(moon_az_el[1], float3{-1, 0, 0});
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math::quaternion<float> moon_az_el_rotation = math::normalize(moon_azimuth_rotation * moon_elevation_rotation);
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moon_light->set_rotation(moon_az_el_rotation);
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}
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std::size_t hour_index = static_cast<std::size_t>(hour);
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float lerp_factor = hour - std::floor(hour);
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float sun_gradient_position = static_cast<float>(std::max<double>(0.0, ((sun_az_el[1] + math::half_pi<double>) / math::pi<double>)));
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float moon_gradient_position = static_cast<float>(std::max<double>(0.0, ((moon_az_el[1] + math::half_pi<double>) / math::pi<double>)));
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float sky_gradient_position = sun_gradient_position;
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float ambient_gradient_position = sun_gradient_position;
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if (sky_pass)
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{
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float3 horizon_color = interpolate_gradient(horizon_colors, sun_gradient_position);
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float3 zenith_color = interpolate_gradient(zenith_colors, sun_gradient_position);
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float3 sun_color = interpolate_gradient(sun_colors, sun_gradient_position);
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float3 moon_color = interpolate_gradient(moon_colors, moon_gradient_position);
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float3 ambient_color = interpolate_gradient(ambient_colors, ambient_gradient_position);
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sun_light->set_color(sun_color);
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sun_light->set_intensity(1.0f);
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moon_light->set_color(moon_color);
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moon_light->set_intensity(1.0f);
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ambient_light->set_color(ambient_color);
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ambient_light->set_intensity(0.5f);
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sky_pass->set_horizon_color(horizon_color);
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sky_pass->set_zenith_color(zenith_color);
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sky_pass->set_time_of_day(static_cast<float>(hour * 60.0 * 60.0));
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sky_pass->set_observer_location(location[0], location[1], location[2]);
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sky_pass->set_sun_coordinates(sun_position, sun_az_el);
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sky_pass->set_moon_coordinates(moon_position, moon_az_el);
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sky_pass->set_julian_day(static_cast<float>(jd));
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sky_pass->set_moon_rotation(moon_rotation);
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}
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shadow_light = sun_light;
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if (shadow_map_pass)
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{
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if (sun_az_el[1] < 0.0f)
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{
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shadow_map_pass->set_light(moon_light);
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}
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else
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{
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shadow_map_pass->set_light(sun_light);
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}
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}
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if (material_pass)
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{
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float shadow_strength = interpolate_gradient(shadow_strengths, sun_gradient_position).x;
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material_pass->set_shadow_strength(shadow_strength);
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}
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}
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void weather_system::set_location(float latitude, float longitude, float altitude)
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{
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location = {latitude, longitude, altitude};
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}
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void weather_system::set_ambient_light(::ambient_light* light)
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{
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ambient_light = light;
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}
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void weather_system::set_sun_light(directional_light* light)
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{
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sun_light = light;
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}
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void weather_system::set_moon_light(directional_light* light)
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{
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moon_light = light;
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}
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void weather_system::set_sky_pass(::sky_pass* pass)
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{
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sky_pass = pass;
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if (sky_pass)
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{
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sky_pass->set_moon_angular_radius(math::radians(1.0f));
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sky_pass->set_sun_angular_radius(math::radians(1.1f));
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}
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}
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void weather_system::set_shadow_map_pass(::shadow_map_pass* pass)
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{
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shadow_map_pass = pass;
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if (shadow_map_pass)
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{
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shadow_map_pass->set_light(shadow_light);
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}
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}
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void weather_system::set_material_pass(::material_pass* pass)
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{
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material_pass = pass;
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}
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void weather_system::set_time(int year, int month, int day, int hour, int minute, int second, double tc)
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{
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double time = ((static_cast<double>(hour) - tc) + ((static_cast<double>(minute) + static_cast<double>(second) / 60.0) / 60.0)) / 24.0;
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jd = julian_day(year, month, day, time);
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}
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void weather_system::set_time_scale(float scale)
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{
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time_scale = scale;
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}
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void weather_system::set_sky_palette(const ::image* image)
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{
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load_palette(&horizon_colors, image, 0);
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load_palette(&zenith_colors, image, 1);
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}
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void weather_system::set_sun_palette(const ::image* image)
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{
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load_palette(&sun_colors, image, 0);
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}
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void weather_system::set_moon_palette(const ::image* image)
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{
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load_palette(&moon_colors, image, 0);
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}
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void weather_system::set_ambient_palette(const ::image* image)
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{
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load_palette(&ambient_colors, image, 0);
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}
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void weather_system::set_shadow_palette(const ::image* image)
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{
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load_palette(&shadow_strengths, image, 0);
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}
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void weather_system::load_palette(std::vector<float3>* palette, const ::image* image, unsigned int row)
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{
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unsigned int w = image->get_width();
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unsigned int h = image->get_height();
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unsigned int c = image->get_channels();
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unsigned int y = std::min<unsigned int>(row, h - 1);
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palette->clear();
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if (image->is_hdr())
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{
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const float* pixels = static_cast<const float*>(image->get_pixels());
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for (unsigned int x = 0; x < w; ++x)
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{
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unsigned int i = y * w * c + x * c;
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float r = pixels[i];
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float g = pixels[i + 1];
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float b = pixels[i + 2];
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palette->push_back(float3{r, g, b});
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}
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}
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else
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{
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const unsigned char* pixels = static_cast<const unsigned char*>(image->get_pixels());
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for (unsigned int x = 0; x < w; ++x)
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{
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unsigned int i = y * w * c + x * c;
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float r = srgb_to_linear(static_cast<float>(pixels[i]) / 255.0f);
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float g = srgb_to_linear(static_cast<float>(pixels[i + 1]) / 255.0f);
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float b = srgb_to_linear(static_cast<float>(pixels[i + 2]) / 255.0f);
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palette->push_back(float3{r, g, b});
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}
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}
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}
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float3 weather_system::interpolate_gradient(const std::vector<float3>& gradient, float position)
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{
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position *= static_cast<float>(gradient.size() - 1);
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int index0 = static_cast<int>(position) % gradient.size();
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int index1 = (index0 + 1) % gradient.size();
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return math::lerp<float3>(gradient[index0], gradient[index1], position - std::floor(position));
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}
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