127 lines
3.3 KiB
C++
127 lines
3.3 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 Danny Robson <danny@nerdcruft.net>
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*/
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#include "ray.hpp"
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#include "debug.hpp"
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using util::ray;
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///////////////////////////////////////////////////////////////////////////////
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template <size_t S, typename T>
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ray<S,T>::ray (util::point<S,T> _origin,
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util::vector<S,T> _direction):
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origin (_origin),
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direction (_direction)
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{
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CHECK (direction.is_normalised ());
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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 corayar
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template <size_t S, typename T>
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T
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ray<S,T>::intersect (plane<S,T> q) const
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{
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return dot (q.p - origin, q.n) / dot (direction, q.n);
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}
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///----------------------------------------------------------------------------
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/// returns the distance from origin to AABB intersection
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///
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/// returns NaN on miss
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/// returns NaN if behind
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template <size_t S, typename T>
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T
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ray<S,T>::intersect (AABB<S,T> r) const
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{
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auto t1 = (r.p0 - origin) / direction;
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auto t2 = (r.p1 - origin) / direction;
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auto vmin = min (t1, t2);
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auto vmax = max (t1, t2);
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auto tmin = max (vmin);
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auto tmax = min (vmax);
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// closest intersection is behind us
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if (tmax < 0)
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return std::numeric_limits<T>::quiet_NaN ();
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// missed intersection
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if (tmin > tmax)
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return std::numeric_limits<T>::quiet_NaN ();
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return tmin;
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}
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///----------------------------------------------------------------------------
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/// returns the smallest distance from ray origin to a sphere intersection
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///
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/// returns NaN on miss
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/// returns NaN if behind
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template <size_t S, typename T>
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T
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ray<S,T>::intersect (sphere<S,T> s) const
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{
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T b = dot (direction, origin - s.centre);
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T c = dot (origin - s.centre, origin - s.centre) - s.radius * s.radius;
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T D = b * b - c;
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if (D < 0)
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return std::numeric_limits<T>::quiet_NaN ();
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auto t_ = std::sqrt (D);
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auto t0 = -b + t_;
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auto t1 = -b - t_;
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return t1 >= 0 ? t1 :
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t0 >= 0 ? t0 :
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std::numeric_limits<T>::quiet_NaN ();
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}
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///////////////////////////////////////////////////////////////////////////////
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/// returns the closest parameter along the ray to a given point
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template <size_t S, typename T>
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T
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ray<S,T>::closest (point<S,T> q) const
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{
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// project the origin-point difference onto the direction
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return dot (origin - q, direction);
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}
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//-----------------------------------------------------------------------------
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template <size_t S, typename T>
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util::point<S,T>
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ray<S,T>::at (T t) const
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{
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return origin + direction * t;
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}
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///////////////////////////////////////////////////////////////////////////////
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template struct util::ray<2,float>;
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template struct util::ray<3,float>;
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