primitives/ray.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_GEOM_PRIMITIVES_RAY_HPP
#define ANTKEEPER_GEOM_PRIMITIVES_RAY_HPP
 
#include <engine/math/vector.hpp>
#include <algorithm>
#include <cmath>
 
namespace geom {
namespace primitive {
 
template <class T, std::size_t N>
struct ray
{
    using vector_type = math::vector<T, N>;
    
    vector_type origin;
    
    vector_type direction;
    
    [[nodiscard]] inline constexpr vector_type extrapolate(T distance) const noexcept
    {
        return origin + direction * distance;
    }
    
    [[nodiscard]] inline constexpr vector_type closest_point(const vector_type& point) const noexcept
    {
        return extrapolate(std::max<T>(T{0}, math::dot(point - origin, direction)));
    }
    
    [[nodiscard]] inline constexpr T sqr_distance(const vector_type& point) const noexcept
    {
        return math::sqr_distance(point, closest_point(point));
    }
    
    [[nodiscard]] inline T distance(const vector_type& point) const noexcept
    {
        const T d = sqr_distance(point);
        return (d) ? std::sqrt(d) : d;
    }
};
 
} // namespace primitive
} // namespace geom
 
#endif // ANTKEEPER_GEOM_PRIMITIVES_RAY_HPP