137 lines
3.8 KiB
C++
137 lines
3.8 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2015-2018 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef __UTIL_GEOM_RAY_HPP
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#define __UTIL_GEOM_RAY_HPP
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#include "aabb.hpp"
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#include "plane.hpp"
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#include "../vector.hpp"
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#include "../point.hpp"
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#include <iosfwd>
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///////////////////////////////////////////////////////////////////////////////
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namespace util::geom {
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template <size_t S, typename T>
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struct ray {
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// queries
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T closest (point<S,T>) const;
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util::point<S,T> at (T) const;
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// data members
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point<S,T> origin;
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vector<S,T> direction;
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};
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template <size_t S, typename T>
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ray (point<S,T>,vector<S,T>) -> ray<S,T>;
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///////////////////////////////////////////////////////////////////////////
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typedef ray<2,float> ray2f;
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typedef ray<3,float> ray3f;
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///////////////////////////////////////////////////////////////////////////
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template <size_t S, typename T>
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ray<S,T>
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operator* (matrix<S+1,S+1,T> lhs, ray<S,T> rhs)
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{
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return {
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lhs * rhs.origin,
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normalised (lhs * rhs.direction)
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};
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}
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///////////////////////////////////////////////////////////////////////////
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/// returns the distance along the ray in a ray-plane intersection
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///
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/// returns inf if parallel
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/// returns 0 if coplanar
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template <size_t S, typename T>
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constexpr T
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distance (const ray<S,T> r, const plane<S,T> p)
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{
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CHECK_SANITY (r);
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return -dot (p.coefficients, r.origin. template redim<S+1> (1)) /
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dot (p.coefficients, r.direction.template redim<S+1> (0));
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}
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//-------------------------------------------------------------------------
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template <size_t S, typename T>
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constexpr bool
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intersects (const ray<S,T> r, const plane<S,T> p)
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{
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const auto d = distance (r, p);
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return d >= 0 && std::isfinite (d);
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}
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///////////////////////////////////////////////////////////////////////////
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// returns the distance along a ray to an aabb
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//
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// the return value may be negative if the plane lies behind the ray.
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// the return value may be infinity in the case the ray and plane are parallel
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template <size_t S, typename T>
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constexpr T
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distance (const ray<S,T> r, const aabb<S,T> b)
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{
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CHECK_SANITY (r);
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const auto t1 = (b.lo - r.origin) / r.direction;
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const auto t2 = (b.hi - r.origin) / r.direction;
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const auto tmin = max (min (t1, t2));
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const auto tmax = min (max (t1, t2));
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// did not intersect
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if (tmin > tmax)
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return std::numeric_limits<T>::infinity ();
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// closest is behind us
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if (tmin < 0)
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return tmax;
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// closest is in front of us
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return tmin;
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}
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//-------------------------------------------------------------------------
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// convenience method to test a ray intersects an aabb
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template <size_t S, typename T>
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constexpr bool
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intersects (const ray<S,T> r, const aabb<S,T> b)
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{
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return distance (r, b) >= 0;
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}
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///////////////////////////////////////////////////////////////////////////
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template <size_t S, typename T>
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std::ostream&
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operator<< (std::ostream&, ray<S,T>);
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}
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#endif
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