💿🐜 Antkeeper source code
https://antkeeper.com
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
101 lines
3.2 KiB
101 lines
3.2 KiB
/*
|
|
* Copyright (C) 2020 Christopher J. Howard
|
|
*
|
|
* This file is part of Antkeeper source code.
|
|
*
|
|
* Antkeeper source code 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.
|
|
*
|
|
* Antkeeper source code 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 Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include "game/systems/solar-system.hpp"
|
|
#include "game/astronomy/celestial-coordinates.hpp"
|
|
#include "game/astronomy/celestial-mechanics.hpp"
|
|
#include "game/astronomy/celestial-time.hpp"
|
|
#include "game/components/orbit-component.hpp"
|
|
#include "game/components/transform-component.hpp"
|
|
|
|
using namespace ecs;
|
|
|
|
static constexpr double seconds_per_day = 24.0 * 60.0 * 60.0;
|
|
|
|
solar_system::solar_system(entt::registry& registry):
|
|
entity_system(registry),
|
|
julian_date(0.0),
|
|
time_scale(1.0),
|
|
latitude(0.0),
|
|
longitude(0.0),
|
|
altitude(0.0)
|
|
{}
|
|
|
|
void solar_system::update(double t, double dt)
|
|
{
|
|
// Add scaled timestep to Julian date
|
|
set_julian_date(julian_date + (dt * time_scale) / seconds_per_day);
|
|
|
|
// Update horizontal (topocentric) positions of orbiting bodies
|
|
registry.view<orbit_component, transform_component>().each(
|
|
[&](auto entity, auto& orbit, auto& transform)
|
|
{
|
|
double a = orbit.a;
|
|
double ec = orbit.ec;
|
|
double w = orbit.w;
|
|
double ma = orbit.ma;
|
|
double i = orbit.i;
|
|
double om = orbit.om;
|
|
|
|
double3 ecliptic = ast::solve_kepler(a, ec, w, ma, i, om);
|
|
double3 horizontal = ecliptic_to_horizontal * ecliptic;
|
|
|
|
// Subtract Earth's radius (in AU), for positon of observer
|
|
horizontal.z -= 4.25875e-5;
|
|
|
|
// Transform into local right-handed coordinates
|
|
double3 translation = ast::horizontal_to_right_handed * horizontal;
|
|
double3x3 rotation = ast::horizontal_to_right_handed * ecliptic_to_horizontal;
|
|
|
|
transform.local.translation = math::type_cast<float>(translation);
|
|
transform.local.rotation = math::type_cast<float>(math::quaternion_cast(rotation));
|
|
});
|
|
}
|
|
|
|
void solar_system::set_julian_date(double jd)
|
|
{
|
|
julian_date = jd;
|
|
|
|
// Recalculate obliquity of the ecliptic
|
|
ecl = ast::approx_ecliptic_obliquity(julian_date);
|
|
|
|
// Recalculate LMST
|
|
lmst = ast::jd_to_lmst(julian_date, longitude);
|
|
|
|
// Recalculate ecliptic to horizontal transformation matrix
|
|
ecliptic_to_horizontal = ast::ecliptic_to_horizontal(ecl, latitude, lmst);
|
|
}
|
|
|
|
void solar_system::set_time_scale(double scale)
|
|
{
|
|
time_scale = scale;
|
|
}
|
|
|
|
void solar_system::set_observer_location(double latitude, double longitude, double altitude)
|
|
{
|
|
this->latitude = latitude;
|
|
this->longitude = longitude;
|
|
this->altitude = altitude;
|
|
|
|
// Recalculate LMST
|
|
lmst = ast::jd_to_lmst(julian_date, longitude);
|
|
|
|
// Recalculate ecliptic to horizontal transformation matrix
|
|
ecliptic_to_horizontal = ast::ecliptic_to_horizontal(ecl, latitude, lmst);
|
|
}
|