vmag.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_VMAG_HPP
#define ANTKEEPER_PHYSICS_LIGHT_VMAG_HPP
 
#include <cmath>
 
namespace physics {
namespace light {
 
namespace vmag {
 
template <class T>
T to_brightness(T mv)
{
    // 100^(1/5)
    static constexpr T fifth_root_100 = T{2.5118864315095801110850320677993};
    return std::pow(fifth_root_100, -mv);
}
 
template <class T>
T to_illuminance(T mv)
{
    return std::pow(T{10}, (T{-14.18} - mv) * T{0.4});
}
 
template <class T>
T from_illuminance(T ev)
{
    return T{-14.18} - T{2.5} * std::log10(ev);
}
 
} // namespace vmag
} // namespace light
} // namespace physics
 
#endif // ANTKEEPER_PHYSICS_LIGHT_VMAG_HPP