💿🐜 Antkeeper source code
https://antkeeper.com
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109 lines
3.4 KiB
109 lines
3.4 KiB
/*
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* Copyright (C) 2021 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 "entity/systems/orbit.hpp"
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#include "physics/orbit/orbit.hpp"
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#include <iostream>
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namespace entity {
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namespace system {
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orbit::orbit(entity::registry& registry):
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updatable(registry),
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universal_time(0.0),
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time_scale(1.0),
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ke_iterations(10),
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ke_tolerance(1e-6)
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{
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registry.on_construct<entity::component::orbit>().connect<&orbit::on_orbit_construct>(this);
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registry.on_replace<entity::component::orbit>().connect<&orbit::on_orbit_replace>(this);
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}
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void orbit::update(double t, double dt)
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{
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// Add scaled timestep to current time
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set_universal_time(universal_time + dt * time_scale);
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// Propagate orbits
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registry.view<component::orbit>().each(
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[&](entity::id entity_id, auto& orbit)
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{
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// Determine mean anomaly at current time
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const double ma = orbit.elements.ma + orbit.mean_motion * this->universal_time;
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// Solve Kepler's equation for eccentric anomaly (E)
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const double ea = physics::orbit::anomaly::mean_to_eccentric(orbit.elements.ec, ma, ke_iterations, ke_tolerance);
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// Calculate Cartesian orbital position in the PQW frame
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math::vector3<double> pqw_position = physics::orbit::frame::pqw::cartesian(orbit.elements.ec, orbit.elements.a, ea, orbit.semiminor_axis);
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// Transform orbital position from PQW frame to BCI frame
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orbit.bci_position = orbit.pqw_to_bci.transform(pqw_position);
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});
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// Update orbital positions in the ICRF frame
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registry.view<component::orbit>().each(
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[&](entity::id entity_id, auto& orbit)
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{
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orbit.icrf_position = orbit.bci_position;
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entity::id parent = orbit.parent;
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while (parent != entt::null)
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{
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const component::orbit& parent_orbit = registry.get<component::orbit>(parent);
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orbit.icrf_position += parent_orbit.bci_position;
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parent = parent_orbit.parent;
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}
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});
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}
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void orbit::set_universal_time(double time)
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{
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universal_time = time;
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}
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void orbit::set_time_scale(double scale)
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{
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time_scale = scale;
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}
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void orbit::on_orbit_construct(entity::registry& registry, entity::id entity_id, entity::component::orbit& component)
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{
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component.semiminor_axis = physics::orbit::semiminor_axis(component.elements.a, component.elements.ec);
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component.pqw_to_bci = physics::orbit::frame::pqw::to_bci
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(
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component.elements.om,
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component.elements.in,
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component.elements.w
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);
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}
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void orbit::on_orbit_replace(entity::registry& registry, entity::id entity_id, entity::component::orbit& component)
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{
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component.semiminor_axis = physics::orbit::semiminor_axis(component.elements.a, component.elements.ec);
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component.pqw_to_bci = physics::orbit::frame::pqw::to_bci
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(
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component.elements.om,
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component.elements.in,
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component.elements.w
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);
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}
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} // namespace system
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} // namespace entity
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