💿🐜 Antkeeper source code
https://antkeeper.com
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207 lines
5.8 KiB
207 lines
5.8 KiB
/*
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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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#ifndef ANTKEEPER_GEOM_PRIMITIVE_INTERSECTION_HPP
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#define ANTKEEPER_GEOM_PRIMITIVE_INTERSECTION_HPP
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#include "geom/primitive/hyperplane.hpp"
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#include "geom/primitive/hyperrectangle.hpp"
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#include "geom/primitive/hypersphere.hpp"
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#include "geom/primitive/ray.hpp"
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#include <algorithm>
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#include <optional>
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namespace geom {
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namespace primitive {
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/**
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* Ray-hyperplane intersection test.
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*
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* @param ray Ray.
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* @param hyperplane Hyperplane.
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*
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* @return Distance along the ray to the point of intersection, or `std::nullopt` if no intersection occurred.
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*/
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/// @{
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template <class T, std::size_t N>
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constexpr std::optional<T> intersection(const ray<T, N>& ray, const hyperplane<T, N>& hyperplane) noexcept
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{
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const T cos_theta = math::dot(ray.direction, hyperplane.normal);
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if (cos_theta != T{0})
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{
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const T t = -hyperplane.distance(ray.origin) / cos_theta;
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if (t >= T{0})
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return t;
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}
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return std::nullopt;
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}
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template <class T, std::size_t N>
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constexpr inline std::optional<T> intersection(const hyperplane<T, N>& hyperplane, const ray<T, N>& ray) noexcept
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{
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return intersection<T, N>(ray, hyperplane);
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}
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/// @}
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/**
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* Ray-hyperrectangle intersection test.
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*
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* @param ray Ray.
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* @param hyperrectangle Hyperrectangle.
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*
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* @return Tuple containing the distances along the ray to the first and second points of intersection, or `std::nullopt` if no intersection occurred.
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*/
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/// @{
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template <class T, std::size_t N>
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constexpr std::optional<std::tuple<T, T>> intersection(const ray<T, N>& ray, const hyperrectangle<T, N>& hyperrectangle) noexcept
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{
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T t0 = -std::numeric_limits<T>::infinity();
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T t1 = std::numeric_limits<T>::infinity();
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for (std::size_t i = 0; i < N; ++i)
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{
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if (!ray.direction[i])
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{
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if (ray.origin[i] < hyperrectangle.min[i] || ray.origin[i] > hyperrectangle.max[i])
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return std::nullopt;
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}
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else
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{
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T min = (hyperrectangle.min[i] - ray.origin[i]) / ray.direction[i];
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T max = (hyperrectangle.max[i] - ray.origin[i]) / ray.direction[i];
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t0 = std::max(t0, std::min(min, max));
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t1 = std::min(t1, std::max(min, max));
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}
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}
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if (t0 > t1 || t1 < T{0})
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return std::nullopt;
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return {t0, t1};
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}
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template <class T, std::size_t N>
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constexpr inline std::optional<std::tuple<T, T>> intersection(const hyperrectangle<T, N>& hyperrectangle, const ray<T, N>& ray) noexcept
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{
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return intersection<T, N>(ray, hyperrectangle);
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}
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/// @}
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/**
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* Ray-hypersphere intersection test.
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*
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* @param ray Ray.
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* @param hypersphere Hypersphere.
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*
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* @return Tuple containing the distances along the ray to the first and second points of intersection, or `std::nullopt` if no intersection occurred.
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*/
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template <class T, std::size_t N>
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std::optional<std::tuple<T, T>> intersection(const ray<T, N>& ray, const hypersphere<T, N>& hypersphere) noexcept
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{
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const math::vector<T, N> displacement = ray.origin - hypersphere.center;
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const T b = math::dot(displacement, ray.direction);
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const T c = math::sqr_length(displacement) - hypersphere.radius * hypersphere.radius;
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T h = b * b - c;
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if (h < T{0})
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return std::nullopt;
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h = std::sqrt(h);
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T t0 = -b - h;
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T t1 = -b + h;
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if (t0 > t1)
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std::swap(t0, t1);
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if (t0 < T{0})
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return std::nullopt;
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return std::tuple<T, T>{t0, t1};
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}
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/**
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* Hyperrectangle-hyperrectangle intersection test.
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*
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* @param a First hyperrectangle.
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* @param b Second hyperrectangle.
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*
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* @return `true` if an intersection occurred, `false` otherwise.
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*/
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template <class T, std::size_t N>
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constexpr inline bool intersection(const hyperrectangle<T, N>& a, const hyperrectangle<T, N>& b) noexcept
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{
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return a.intersects(b);
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}
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/**
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* Hyperrectangle-hypersphere intersection test.
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*
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* @param hyperrectangle Hyperrectangle.
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* @param hypersphere Hypersphere.
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*
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* @return `true` if an intersection occurred, `false` otherwise.
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*/
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/// @{
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template <class T, std::size_t N>
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constexpr bool intersection(const hyperrectangle<T, N>& hyperrectangle, const hypersphere<T, N>& hypersphere) noexcept
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{
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T sqr_distance{0};
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for (std::size_t i = 0; i < N; ++i)
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{
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if (hypersphere.center[i] < hyperrectangle.min[i])
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{
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const T difference = hyperrectangle.min[i] - hypersphere.center[i];
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sqr_distance += difference * difference;
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}
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else if (hypersphere.center[i] > hyperrectangle.max[i])
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{
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const T difference = hypersphere.center[i] - hyperrectangle.max[i];
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sqr_distance += difference * difference;
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}
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}
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return sqr_distance <= hypersphere.radius * hypersphere.radius;
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}
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template <class T, std::size_t N>
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constexpr inline bool intersection(const hypersphere<T, N>& hypersphere, const hyperrectangle<T, N>& hyperrectangle) noexcept
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{
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return intersection<T, N>(hyperrectangle, hypersphere);
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}
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/// @}
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/**
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* Hypersphere-hypersphere intersection test.
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*
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* @param a First hypersphere.
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* @param b Second hypersphere.
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*
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* @return `true` if an intersection occurred, `false` otherwise.
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*/
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template <class T, std::size_t N>
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constexpr inline bool intersection(const hypersphere<T, N>& a, const hypersphere<T, N>& b) noexcept
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{
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return a.intersects(b);
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}
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} // namespace primitive
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} // namespace geom
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#endif // ANTKEEPER_GEOM_PRIMITIVE_INTERSECTION_HPP
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