luminosity.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_PHYSICS_LIGHT_LUMINOSITY_HPP
#define ANTKEEPER_PHYSICS_LIGHT_LUMINOSITY_HPP
 
#include <cmath>
 
namespace physics {
namespace light {
 
namespace luminosity {
 
template <class T>
T photopic(T lambda)
{
    const T t0 = (lambda - T(568.8)) * ((lambda < T(568.8)) ? T(0.0213) : T(0.0247));
    const T t1 = (lambda - T(530.9)) * ((lambda < T(530.9)) ? T(0.0613) : T(0.0322));
    
    const T y0 = T(0.821) * std::exp(T(-0.5) * t0 * t0);
    const T y1 = T(0.286) * std::exp(T(-0.5) * t1 * t1);
    
    return y0 + y1;
}
 
} // namespace luminosity
 
} // namespace light
} // namespace physics
 
#endif // ANTKEEPER_PHYSICS_LIGHT_LUMINOSITY_HPP