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/*
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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/astronomy.hpp"
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#include "astro/apparent-size.hpp"
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#include "entity/components/blackbody.hpp"
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#include "entity/components/transform.hpp"
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#include "entity/components/diffuse-reflector.hpp"
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#include "geom/intersection.hpp"
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#include "geom/cartesian.hpp"
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#include "color/color.hpp"
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#include "physics/orbit/orbit.hpp"
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#include "physics/time/ut1.hpp"
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#include "physics/light/photometry.hpp"
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#include "physics/light/luminosity.hpp"
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#include "physics/light/refraction.hpp"
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#include "physics/gas/atmosphere.hpp"
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#include "geom/cartesian.hpp"
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#include "astro/apparent-size.hpp"
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#include "geom/solid-angle.hpp"
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#include "math/polynomial.hpp"
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#include <iostream>
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namespace entity {
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namespace system {
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template <class T>
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math::vector3<T> transmittance(T depth_r, T depth_m, T depth_o, const math::vector3<T>& extinction_r, T extinction_m, const math::vector3<T>& extinction_o)
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{
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math::vector3<T> transmittance_r = extinction_r * depth_r;
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math::vector3<T> transmittance_m = math::vector3<T>{extinction_m, extinction_m, extinction_m} * depth_m;
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math::vector3<T> transmittance_o = extinction_o * depth_o;
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math::vector3<T> t = transmittance_r + transmittance_m + transmittance_o;
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t.x = std::exp(-t.x);
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t.y = std::exp(-t.y);
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t.z = std::exp(-t.z);
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return t;
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}
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astronomy::astronomy(entity::registry& registry):
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updatable(registry),
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time(0.0),
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time_scale(1.0),
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reference_entity(entt::null),
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observer_location{0, 0, 0},
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sun_light(nullptr),
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sky_light(nullptr),
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moon_light(nullptr),
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camera(nullptr),
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sky_pass(nullptr),
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exposure_offset(0.0),
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starlight_illuminance(0.0)
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{
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// Construct transformation which transforms coordinates from ENU to EUS
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enu_to_eus = math::transformation::se3<double>
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{
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{0, 0, 0},
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math::quaternion<double>::rotate_x(-math::half_pi<double>)
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};
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registry.on_construct<entity::component::celestial_body>().connect<&astronomy::on_celestial_body_construct>(this);
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registry.on_replace<entity::component::celestial_body>().connect<&astronomy::on_celestial_body_replace>(this);
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}
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astronomy::~astronomy()
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{
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registry.on_construct<entity::component::celestial_body>().disconnect<&astronomy::on_celestial_body_construct>(this);
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registry.on_replace<entity::component::celestial_body>().disconnect<&astronomy::on_celestial_body_replace>(this);
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}
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void astronomy::update(double t, double dt)
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{
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double total_illuminance = 0.0;
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double sky_light_illuminance = 0.0;
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// Add scaled timestep to current time
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set_time(time + dt * time_scale);
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// Abort if no reference body
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if (reference_entity == entt::null)
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return;
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// Abort if either reference body or orbit have not been set
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if (!registry.has<entity::component::orbit>(reference_entity) || !registry.has<entity::component::celestial_body>(reference_entity))
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return;
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const entity::component::orbit& reference_orbit = registry.get<entity::component::orbit>(reference_entity);
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const entity::component::celestial_body& reference_body = registry.get<entity::component::celestial_body>(reference_entity);
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math::transformation::se3<double> icrf_to_bci{{-reference_orbit.position}, math::quaternion<double>::identity};
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const double days_from_epoch = time;
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const double centuries_from_epoch = days_from_epoch / 36525.0;
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// Evaluate reference body orientation polynomials
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const double reference_body_pole_ra = math::polynomial::horner(reference_body.pole_ra.begin(), reference_body.pole_ra.end(), centuries_from_epoch);
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const double reference_body_pole_dec = math::polynomial::horner(reference_body.pole_dec.begin(), reference_body.pole_dec.end(), centuries_from_epoch);
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const double reference_body_prime_meridian = math::polynomial::horner(reference_body.prime_meridian.begin(), reference_body.prime_meridian.end(), days_from_epoch);
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// Construct transformation from the ICRF frame to the reference body BCBF frame
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icrf_to_bcbf = physics::orbit::frame::bci::to_bcbf
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(
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reference_body_pole_ra,
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reference_body_pole_dec,
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reference_body_prime_meridian
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);
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icrf_to_bcbf.t = icrf_to_bcbf.r * -reference_orbit.position;
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icrf_to_enu = icrf_to_bcbf * bcbf_to_enu;
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icrf_to_eus = icrf_to_enu * enu_to_eus;
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// Set the transform component translations of orbiting bodies to their topocentric positions
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registry.view<component::celestial_body, component::orbit, component::transform>().each(
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[&](entity::id entity_id, const auto& body, const auto& orbit, auto& transform)
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{
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// Skip reference entity
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if (entity_id == this->reference_entity)
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return;
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// Transform orbital Cartesian position (r) from the ICRF frame to the EUS frame
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const double3 r_eus = icrf_to_eus * orbit.position;
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// Evaluate body orientation polynomials
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const double body_pole_ra = math::polynomial::horner(body.pole_ra.begin(), body.pole_ra.end(), centuries_from_epoch);
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const double body_pole_dec = math::polynomial::horner(body.pole_dec.begin(), body.pole_dec.end(), centuries_from_epoch);
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const double body_prime_meridian = math::polynomial::horner(body.prime_meridian.begin(), body.prime_meridian.end(), days_from_epoch);
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// Determine body orientation in the ICRF frame
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math::quaternion<double> rotation_icrf = physics::orbit::frame::bcbf::to_bci
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(
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body_pole_ra,
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body_pole_dec,
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body_prime_meridian
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).r;
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// Transform body orientation from the ICRF frame to the EUS frame.
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math::quaternion<double> rotation_eus = math::normalize(icrf_to_eus.r * rotation_icrf);
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// Update local transform
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if (orbit.parent != entt::null)
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{
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transform.local.translation = math::normalize(math::type_cast<float>(r_eus));
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transform.local.rotation = math::type_cast<float>(rotation_eus);
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transform.local.scale = {1.0f, 1.0f, 1.0f};
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}
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/*
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if (orbit.parent != entt::null)
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{
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// RA-DEC
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const double3 r_bci = icrf_to_bci * orbit.position;
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double3 r_bci_spherical = physics::orbit::frame::bci::spherical(r_bci);
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if (r_bci_spherical.z < 0.0)
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r_bci_spherical.z += math::two_pi<double>;
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const double dec = math::degrees(r_bci_spherical.y);
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const double ra = math::degrees(r_bci_spherical.z);
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// AZ-EL
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const double3 r_enu = icrf_to_enu * orbit.position;
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double3 r_enu_spherical = physics::orbit::frame::enu::spherical(r_enu);
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if (r_enu_spherical.z < 0.0)
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r_enu_spherical.z += math::two_pi<double>;
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const double el = math::degrees(r_enu_spherical.y);
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const double az = math::degrees(r_enu_spherical.z);
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std::cout << "t: " << this->time << "; ra: " << ra << "; dec: " << dec << std::endl;
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std::cout << "t: " << this->time << "; az: " << az << "; el: " << el << std::endl;
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}
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*/
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});
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// Update blackbody lighting
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registry.view<component::celestial_body, component::orbit, component::blackbody>().each(
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[&](entity::id entity_id, const auto& body, const auto& orbit, const auto& blackbody)
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{
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// Calculate blackbody inertial basis
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//double3 blackbody_forward_icrf = math::normalize(reference_orbit.icrf_position - orbit.icrf_position);
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double3 blackbody_up_icrf = {0, 0, 1};
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// Transform blackbody ICRF position and basis into EUS frame
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double3 blackbody_position_eus = icrf_to_eus * orbit.position;
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double3 blackbody_position_enu = icrf_to_enu * orbit.position;
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double3 blackbody_forward_eus = math::normalize(-blackbody_position_eus);
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double3 blackbody_up_eus = icrf_to_eus.r * blackbody_up_icrf;
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// Calculate distance from observer to blackbody
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double blackbody_distance = math::length(blackbody_position_eus) - body.radius;
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// Calculate blackbody solid angle
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const double blackbody_angular_radius = astro::angular_radius(body.radius, blackbody_distance);
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const double blackbody_solid_angle = geom::solid_angle::cone(blackbody_angular_radius);
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// Calculate blackbody illuminance
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const double3 blackbody_illuminance = blackbody.luminance * blackbody_solid_angle;
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// Init atmospheric transmittance
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double3 atmospheric_transmittance = {1.0, 1.0, 1.0};
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// Get atmosphere component of reference body (if any)
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if (this->registry.has<entity::component::atmosphere>(reference_entity))
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{
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const entity::component::atmosphere& reference_atmosphere = registry.get<entity::component::atmosphere>(reference_entity);
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// Altitude of observer in meters
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geom::ray<double> sample_ray;
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sample_ray.origin = {0, reference_body.radius + observer_location[0], 0};
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sample_ray.direction = math::normalize(blackbody_position_eus);
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geom::sphere<double> exosphere;
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exosphere.center = {0, 0, 0};
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exosphere.radius = reference_body.radius + reference_atmosphere.upper_limit;
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auto intersection_result = geom::ray_sphere_intersection(sample_ray, exosphere);
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if (std::get<0>(intersection_result))
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{
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double3 sample_start = sample_ray.origin;
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double3 sample_end = sample_ray.extrapolate(std::get<2>(intersection_result));
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double optical_depth_r = physics::gas::atmosphere::optical_depth_exp(sample_start, sample_end, reference_body.radius, reference_atmosphere.rayleigh_scale_height, 16);
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double optical_depth_m = physics::gas::atmosphere::optical_depth_exp(sample_start, sample_end, reference_body.radius, reference_atmosphere.mie_scale_height, 16);
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double optical_depth_o = physics::gas::atmosphere::optical_depth_tri(sample_start, sample_end, reference_body.radius, reference_atmosphere.ozone_lower_limit, reference_atmosphere.ozone_upper_limit, reference_atmosphere.ozone_mode, 16);
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atmospheric_transmittance = transmittance(optical_depth_r, optical_depth_m, optical_depth_o, reference_atmosphere.rayleigh_scattering, reference_atmosphere.mie_scattering + reference_atmosphere.mie_absorption, reference_atmosphere.ozone_absorption);
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}
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// Add airglow to sky light illuminance
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sky_light_illuminance += reference_atmosphere.airglow;
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}
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// Blackbody illuminance transmitted through the atmosphere
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const double3 transmitted_blackbody_illuminance = blackbody_illuminance * atmospheric_transmittance;
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// Add atmosphere-transmitted blackbody illuminance to total illuminance
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total_illuminance += (transmitted_blackbody_illuminance.x + transmitted_blackbody_illuminance.y + transmitted_blackbody_illuminance.z) / 3.0;
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// Update sun light
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if (sun_light != nullptr)
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{
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sun_light->set_translation(math::normalize(math::type_cast<float>(blackbody_position_eus)));
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sun_light->set_rotation
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(
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math::look_rotation
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(
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math::type_cast<float>(blackbody_forward_eus),
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math::type_cast<float>(blackbody_up_eus)
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)
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);
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sun_light->set_color(math::type_cast<float>(transmitted_blackbody_illuminance));
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}
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// Update sky light
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if (sky_light != nullptr)
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{
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// Calculate sky illuminance
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double3 blackbody_position_enu_spherical = physics::orbit::frame::enu::spherical(blackbody_position_enu);
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const double sky_illuminance = 25000.0 * std::max<double>(0.0, std::sin(blackbody_position_enu_spherical.y));
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// Add sky illuminance to sky light illuminance
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sky_light_illuminance += sky_illuminance;
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// Add starlight illuminance to sky light illuminance
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sky_light_illuminance += starlight_illuminance;
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// Add sky light illuminance to total illuminance
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total_illuminance += sky_light_illuminance;
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//std::cout << "sky light illum: " << sky_light_illuminance << std::endl;
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// Update sky light
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sky_light->set_color(float3{1.0f, 1.0f, 1.0f} * static_cast<float>(sky_light_illuminance));
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}
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// Upload blackbody params to sky pass
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if (this->sky_pass)
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{
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this->sky_pass->set_sun_position(math::type_cast<float>(blackbody_position_eus));
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this->sky_pass->set_sun_luminance(math::type_cast<float>(blackbody.luminance));
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this->sky_pass->set_sun_illuminance(math::type_cast<float>(blackbody_illuminance));
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this->sky_pass->set_sun_angular_radius(static_cast<float>(blackbody_angular_radius));
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}
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const double3& blackbody_icrf_position = orbit.position;
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// Update diffuse reflectors
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this->registry.view<component::celestial_body, component::orbit, component::diffuse_reflector, component::transform>().each(
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[&](entity::id entity_id, const auto& reflector_body, const auto& reflector_orbit, const auto& reflector, const auto& transform)
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{
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// Calculate distance to blackbody and direction of incoming light
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double3 blackbody_light_direction_icrf = reflector_orbit.position - blackbody_icrf_position;
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double blackbody_distance = math::length(blackbody_light_direction_icrf);
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blackbody_light_direction_icrf = blackbody_light_direction_icrf / blackbody_distance;
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// Transform blackbody light direction from the ICRF frame to the EUS frame
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double3 blackbody_light_direction_eus = icrf_to_eus.r * blackbody_light_direction_icrf;
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// Calculate blackbody solid angle
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const double blackbody_angular_radius = astro::angular_radius(body.radius, blackbody_distance);
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const double blackbody_solid_angle = geom::solid_angle::cone(blackbody_angular_radius);
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// Calculate blackbody illuminance
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double3 view_direction_icrf = reflector_orbit.position - reference_orbit.position;
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const double reflector_distance = math::length(view_direction_icrf);
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view_direction_icrf = view_direction_icrf / reflector_distance;
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const double3 sunlight_illuminance = blackbody.luminance * blackbody_solid_angle;
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const double reflector_angular_radius = astro::angular_radius(reflector_body.radius, reflector_distance);
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const double reflector_solid_angle = geom::solid_angle::cone(reflector_angular_radius);
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const double reflector_phase_factor = dot(view_direction_icrf, blackbody_light_direction_icrf) * 0.5 + 0.5;
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const double3 planet_luminance = (sunlight_illuminance * reference_body.albedo) / math::pi<double>;
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const double planet_angular_radius = astro::angular_radius(reference_body.radius, reflector_distance);
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const double planet_solid_angle = geom::solid_angle::cone(planet_angular_radius);
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const double planet_phase_factor = math::dot(-view_direction_icrf, math::normalize(reference_orbit.position - blackbody_icrf_position)) * 0.5 + 0.5;
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const double3 planetlight_illuminance = planet_luminance * planet_solid_angle * planet_phase_factor;
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double3 planetlight_direction_eus = math::normalize(icrf_to_eus.r * view_direction_icrf);
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const double3 reflected_sunlight_luminance = (sunlight_illuminance * reflector.albedo) / math::pi<double>;
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const double3 reflected_sunlight_illuminance = reflected_sunlight_luminance * reflector_solid_angle * reflector_phase_factor;
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const double3 reflected_planetlight_luminance = (planetlight_illuminance * reflector.albedo) / math::pi<double>;
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const double3 reflected_planetlight_illuminance = reflected_planetlight_luminance * reflector_solid_angle;
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/*
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std::cout << "reflected sunlight illuminance: " << reflected_sunlight_illuminance << std::endl;
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std::cout << "planetlight illuminance: " << planetlight_illuminance << std::endl;
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std::cout << "planet luminance: " << planet_luminance << std::endl;
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std::cout << "reflected planetlight luminance: " << reflected_planetlight_luminance << std::endl;
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std::cout << "reflected planetlight illuminance: " << reflected_planetlight_illuminance << std::endl;
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std::cout << "reflector phase: " << reflector_phase_factor << std::endl;
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std::cout << "planet phase: " << planet_phase_factor << std::endl;
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*/
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if (this->sky_pass)
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{
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this->sky_pass->set_moon_position(transform.local.translation);
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this->sky_pass->set_moon_rotation(transform.local.rotation);
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this->sky_pass->set_moon_angular_radius(static_cast<float>(reflector_angular_radius));
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this->sky_pass->set_moon_sunlight_direction(math::type_cast<float>(blackbody_light_direction_eus));
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this->sky_pass->set_moon_sunlight_illuminance(math::type_cast<float>(sunlight_illuminance));
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this->sky_pass->set_moon_planetlight_direction(math::type_cast<float>(planetlight_direction_eus));
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this->sky_pass->set_moon_planetlight_illuminance(math::type_cast<float>(planetlight_illuminance));
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}
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if (this->moon_light)
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{
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float3 reflector_up_eus = math::type_cast<float>(icrf_to_eus.r * double3{0, 0, 1});
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double3 reflected_illuminance = reflected_sunlight_illuminance + reflected_planetlight_illuminance;
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//reflected_illuminance *= std::max<double>(0.0, std::sin(transform.local.translation.y));
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total_illuminance += (reflected_illuminance.x + reflected_illuminance.y + reflected_illuminance.z) / 3.0;
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this->moon_light->set_color(math::type_cast<float>(reflected_illuminance));
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this->moon_light->set_rotation
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(
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math::look_rotation
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(
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math::normalize(-transform.local.translation),
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reflector_up_eus
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)
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);
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}
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/*
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std::cout << "moon: sun solid angle: " << blackbody_solid_angle << std::endl;
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std::cout << "moon: sun illuminance: " << blackbody_illuminance << std::endl;
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std::cout << "moon: moon luminance: " << reflector_luminance << std::endl;
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std::cout << "sun brightness: " << sun_brightness << std::endl;
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std::cout << "vega brightness: " << vega_brightness << std::endl;
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std::cout << "earth: moon distance: " << reflector_distance << std::endl;
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std::cout << "earth: moon solid angle: " << reflector_solid_angle << std::endl;
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std::cout << "earth: moon phase: " << reflector_phase << std::endl;
|
|
std::cout << "earth: moon phase angle: " << math::degrees(reflector_phase_angle) << std::endl;
|
|
std::cout << "earth: moon illum %: " << reflector_illumination_factor * 100.0 << std::endl;
|
|
std::cout << "earth: moon illuminance: " << reflector_illuminance << std::endl;
|
|
std::cout << "earth: moon phase-modulated illuminance: " << reflector_illuminance * reflector_illumination_factor << std::endl;
|
|
*/
|
|
});
|
|
});
|
|
|
|
// Update sky pass topocentric frame
|
|
if (sky_pass != nullptr)
|
|
{
|
|
// Upload topocentric frame to sky pass
|
|
sky_pass->set_icrf_to_eus
|
|
(
|
|
math::transformation::se3<float>
|
|
{
|
|
math::type_cast<float>(icrf_to_eus.t),
|
|
math::type_cast<float>(icrf_to_eus.r)
|
|
}
|
|
);
|
|
|
|
// Upload observer elevation to sky pass
|
|
sky_pass->set_observer_elevation(observer_location[0]);
|
|
|
|
sky_pass->set_planet_radius(static_cast<float>(reference_body.radius));
|
|
}
|
|
|
|
// Auto-exposure
|
|
if (camera)
|
|
{
|
|
const double calibration = 250.0;
|
|
const double ev100 = std::log2((total_illuminance * 100.0) / calibration);
|
|
//std::cout << "LUX: " << total_illuminance << std::endl;
|
|
//std::cout << "EV100: " << ev100 << std::endl;
|
|
//camera->set_exposure(exposure_offset);
|
|
}
|
|
}
|
|
|
|
void astronomy::set_time(double time)
|
|
{
|
|
this->time = time;
|
|
}
|
|
|
|
void astronomy::set_time_scale(double scale)
|
|
{
|
|
time_scale = scale;
|
|
}
|
|
|
|
void astronomy::set_reference_body(entity::id entity_id)
|
|
{
|
|
reference_entity = entity_id;
|
|
update_bcbf_to_enu();
|
|
}
|
|
|
|
void astronomy::set_observer_location(const double3& location)
|
|
{
|
|
observer_location = location;
|
|
update_bcbf_to_enu();
|
|
}
|
|
|
|
void astronomy::set_sun_light(scene::directional_light* light)
|
|
{
|
|
sun_light = light;
|
|
}
|
|
|
|
void astronomy::set_sky_light(scene::ambient_light* light)
|
|
{
|
|
sky_light = light;
|
|
}
|
|
|
|
void astronomy::set_moon_light(scene::directional_light* light)
|
|
{
|
|
moon_light = light;
|
|
}
|
|
|
|
void astronomy::set_camera(scene::camera* camera)
|
|
{
|
|
this->camera = camera;
|
|
}
|
|
|
|
void astronomy::set_exposure_offset(float offset)
|
|
{
|
|
exposure_offset = offset;
|
|
}
|
|
|
|
void astronomy::set_starlight_illuminance(double illuminance)
|
|
{
|
|
starlight_illuminance = illuminance;
|
|
}
|
|
|
|
void astronomy::set_sky_pass(::render::sky_pass* pass)
|
|
{
|
|
this->sky_pass = pass;
|
|
}
|
|
|
|
void astronomy::on_celestial_body_construct(entity::registry& registry, entity::id entity_id, entity::component::celestial_body& celestial_body)
|
|
{
|
|
if (entity_id == reference_entity)
|
|
update_bcbf_to_enu();
|
|
}
|
|
|
|
void astronomy::on_celestial_body_replace(entity::registry& registry, entity::id entity_id, entity::component::celestial_body& celestial_body)
|
|
{
|
|
if (entity_id == reference_entity)
|
|
update_bcbf_to_enu();
|
|
}
|
|
|
|
void astronomy::update_bcbf_to_enu()
|
|
{
|
|
double radial_distance = observer_location[0];
|
|
|
|
if (reference_entity)
|
|
{
|
|
if (registry.has<entity::component::celestial_body>(reference_entity))
|
|
radial_distance += registry.get<entity::component::celestial_body>(reference_entity).radius;
|
|
}
|
|
|
|
// Construct reference frame which transforms coordinates from a BCBF frame to a horizontal frame
|
|
bcbf_to_enu = physics::orbit::frame::bcbf::to_enu
|
|
(
|
|
radial_distance,
|
|
observer_location[1],
|
|
observer_location[2]
|
|
);
|
|
}
|
|
|
|
} // namespace system
|
|
} // namespace entity
|