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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 "ecs/systems/blackbody-system.hpp"
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#include "color/color.hpp"
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#include "physics/light/blackbody.hpp"
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#include "physics/light/photometry.hpp"
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#include "math/quadrature.hpp"
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namespace ecs {
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blackbody_system::blackbody_system(ecs::registry& registry):
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entity_system(registry)
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{
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// RGB wavelengths determined by matching wavelengths to XYZ, transforming XYZ to ACEScg, then selecting the max wavelengths for R, G, and B.
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rgb_wavelengths_nm = {602.224, 541.069, 448.143};
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rgb_wavelengths_m = rgb_wavelengths_nm * 1e-9;
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// Construct a range of sample wavelengths in the visible spectrum
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visible_wavelengths_nm.resize(780 - 280);
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std::iota(visible_wavelengths_nm.begin(), visible_wavelengths_nm.end(), 280);
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registry.on_construct<ecs::blackbody_component>().connect<&blackbody_system::on_blackbody_construct>(this);
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registry.on_replace<ecs::blackbody_component>().connect<&blackbody_system::on_blackbody_replace>(this);
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registry.on_construct<ecs::celestial_body_component>().connect<&blackbody_system::on_celestial_body_construct>(this);
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registry.on_replace<ecs::celestial_body_component>().connect<&blackbody_system::on_celestial_body_replace>(this);
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}
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void blackbody_system::update(double t, double dt)
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{}
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void blackbody_system::update_luminous_intensity(ecs::entity entity)
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{
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// Abort if entity has no blackbody component
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if (!registry.has<blackbody_component>(entity))
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return;
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// Get blackbody component of the entity
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blackbody_component& blackbody = registry.get<blackbody_component>(entity);
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// Clear luminous intensity
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blackbody.luminous_intensity = {0, 0, 0};
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// Abort if entity has no celestial body component
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if (!registry.has<celestial_body_component>(entity))
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return;
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// Get celestial body component of the entity
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const celestial_body_component& celestial_body = registry.get<celestial_body_component>(entity);
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// Calculate (spherical) surface area of the celestial body
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const double surface_area = 4.0 * math::pi<double> * celestial_body.radius * celestial_body.radius;
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// Construct a lambda function which calculates the blackbody's RGB luminous intensity of a given wavelength
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auto rgb_luminous_intensity = [blackbody, surface_area](double wavelength_nm) -> double3
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{
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// Convert wavelength from nanometers to meters
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const double wavelength_m = wavelength_nm * 1e-9;
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// Calculate the spectral intensity of the wavelength
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const double spectral_intensity = physics::light::blackbody::spectral_intensity<double>(blackbody.temperature, surface_area, wavelength_m);
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// Calculate the ACEScg color of the wavelength using CIE color matching functions
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double3 spectral_color = color::xyz::to_acescg(color::xyz::match(wavelength_nm));
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// Scale the spectral color by spectral intensity
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return spectral_color * spectral_intensity * 1e-9 * physics::light::max_luminous_efficacy<double>;
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};
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// Integrate the blackbody RGB luminous intensity over wavelengths in the visible spectrum
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blackbody.luminous_intensity = math::quadrature::simpson(rgb_luminous_intensity, visible_wavelengths_nm.begin(), visible_wavelengths_nm.end());
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}
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void blackbody_system::on_blackbody_construct(ecs::registry& registry, ecs::entity entity, ecs::blackbody_component& blackbody)
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{
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update_luminous_intensity(entity);
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}
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void blackbody_system::on_blackbody_replace(ecs::registry& registry, ecs::entity entity, ecs::blackbody_component& blackbody)
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{
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update_luminous_intensity(entity);
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}
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void blackbody_system::on_celestial_body_construct(ecs::registry& registry, ecs::entity entity, ecs::celestial_body_component& celestial_body)
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{
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update_luminous_intensity(entity);
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}
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void blackbody_system::on_celestial_body_replace(ecs::registry& registry, ecs::entity entity, ecs::celestial_body_component& celestial_body)
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{
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update_luminous_intensity(entity);
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}
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} // namespace ecs
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