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- /*
- * Copyright (C) 2021 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_PRIMITIVE_HYPERSPHERE_HPP
- #define ANTKEEPER_GEOM_PRIMITIVE_HYPERSPHERE_HPP
-
- #include "math/constants.hpp"
- #include "math/vector.hpp"
-
- namespace geom {
- namespace primitive {
-
- /**
- * *n*-dimensional sphere.
- *
- * @tparam T Real type.
- * @tparam N Number of dimensions.
- */
- template <class T, std::size_t N>
- struct hypersphere
- {
- typedef math::vector<T, N> vector_type;
-
- /// Hypersphere center.
- vector_type center;
-
- /// Hypersphere radius.
- T radius;
-
- /**
- * Tests whether a point is contained within this hypersphere.
- *
- * @param point Point to test for containment.
- *
- * @return `true` if the point is contained within this hypersphere, `false` otherwise.
- */
- constexpr bool contains(const vector_type& point) const noexcept
- {
- return math::sqr_distance(center, point) <= radius * radius;
- }
-
- /**
- * Tests whether another hypersphere is contained within this hypersphere.
- *
- * @param other Hypersphere to test for containment.
- *
- * @return `true` if the hypersphere is contained within this hypersphere, `false` otherwise.
- */
- constexpr bool contains(const hypersphere& other) const noexcept
- {
- const T containment_radius = radius - other.radius;
- if (containment_radius < T{0})
- return false;
-
- return math::sqr_distance(center, other.center) <= containment_radius * containment_radius;
- }
-
- /**
- * Calculates the signed distance from the hypersphere to a point.
- *
- * @param point Input point.
- *
- * @return Signed distance from the hypersphere to @p point.
- */
- T distance(const vector_type& point) const noexcept
- {
- return math::distance(center, point) - radius;
- }
-
- /**
- * Tests whether another hypersphere intersects this hypersphere.
- *
- * @param other Hypersphere to test for intersection.
- *
- * @return `true` if the hypersphere intersects this hypersphere, `false` otherwise.
- */
- constexpr bool intersects(const hypersphere& other) const noexcept
- {
- const T intersection_radius = radius + other.radius;
- return math::sqr_distance(center, other.center) <= intersection_radius * intersection_radius;
- }
-
- /**
- * Volume calculation helper function.
- *
- * @tparam M Dimension.
- *
- * @param r Radius.
- *
- * @return Volume.
- */
- /// @private
- /// @{
- template <std::size_t M>
- static constexpr T volume(T r) noexcept
- {
- return (math::two_pi<T> / static_cast<T>(M)) * r * r * volume<M - 2>(r);
- }
-
- template <>
- static constexpr T volume<1>(T r) noexcept
- {
- return r * T{2};
- }
-
- template <>
- static constexpr T volume<0>(T r) noexcept
- {
- return T{1};
- }
- /// @}
-
- /// Calculates the volume of the hypersphere.
- inline constexpr T volume() const noexcept
- {
- return volume<N>(radius);
- }
- };
-
- } // namespace primitive
- } // namespace geom
-
- #endif // ANTKEEPER_GEOM_PRIMITIVE_HYPERSPHERE_HPP
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