astronomy-system.hpp

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/*
 * Copyright (C) 2023  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/>.
 */
 
#ifndef ANTKEEPER_GAME_ASTRONOMY_SYSTEM_HPP
#define ANTKEEPER_GAME_ASTRONOMY_SYSTEM_HPP
 
#include "game/systems/updatable-system.hpp"
#include <engine/entity/id.hpp>
#include <engine/scene/directional-light.hpp>
#include <engine/math/vector.hpp>
#include <engine/math/se3.hpp>
#include <engine/render/passes/sky-pass.hpp>
#include "game/components/observer-component.hpp"
#include "game/components/atmosphere-component.hpp"
#include "game/components/celestial-body-component.hpp"
#include "game/components/orbit-component.hpp"
#include <engine/geom/primitives/ray.hpp>
 
 
class astronomy_system:
    public updatable_system
{
public:
    explicit astronomy_system(entity::registry& registry);
    ~astronomy_system();
    
    virtual void update(float t, float dt);
    
    void set_time(double t);
    
    void set_time_scale(double scale);
    
    void set_observer(entity::id eid);
    
    void set_transmittance_samples(std::size_t samples);
    
    void set_sun_light(scene::directional_light* light);
    void set_moon_light(scene::directional_light* light);
    void set_starlight_illuminance(const math::dvec3& illuminance);
    void set_sky_pass(::render::sky_pass* pass);
    
    [[nodiscard]] inline double get_time() const noexcept
    {
        return time_days;
    }
    
private:
    void on_observer_modified(entity::registry& registry, entity::id entity_id);
    void on_observer_destroyed(entity::registry& registry, entity::id entity_id);
    void on_celestial_body_modified(entity::registry& registry, entity::id entity_id);
    void on_celestial_body_destroyed(entity::registry& registry, entity::id entity_id);
    void on_orbit_modified(entity::registry& registry, entity::id entity_id);
    void on_orbit_destroyed(entity::registry& registry, entity::id entity_id);
    void on_atmosphere_modified(entity::registry& registry, entity::id entity_id);
    void on_atmosphere_destroyed(entity::registry& registry, entity::id entity_id);
    
    void observer_modified();
    
    void reference_body_modified();
    
    void reference_orbit_modified();
    
    void reference_atmosphere_modified();
 
    void update_bcbf_to_eus(const ::observer_component& observer, const ::celestial_body_component& body);
    
    void update_icrf_to_eus(const ::celestial_body_component& body, const ::orbit_component& orbit);
    
    math::dvec3 integrate_transmittance(const ::observer_component& observer, const ::celestial_body_component& body, const ::atmosphere_component& atmosphere, geom::ray<double, 3> ray) const;
    
    double time_days;
    
    double time_centuries;
    
    double time_scale;
    
    std::size_t transmittance_samples;
    
    entity::id observer_eid;
    
    entity::id reference_body_eid;
    
    math::se3<double> enu_to_eus;
    
    math::se3<double> bcbf_to_eus;
    
    math::se3<double> icrf_to_eus;
    
    scene::directional_light* sun_light;
    scene::directional_light* moon_light;
    ::render::sky_pass* sky_pass;
    math::dvec3 starlight_illuminance;
};
 
 
#endif // ANTKEEPER_GAME_ASTRONOMY_SYSTEM_HPP