libcruft-util/ray.cpp
2015-04-15 18:00:37 +10:00

127 lines
3.3 KiB
C++

/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2015 Danny Robson <danny@nerdcruft.net>
*/
#include "ray.hpp"
#include "debug.hpp"
using util::ray;
///////////////////////////////////////////////////////////////////////////////
template <size_t S, typename T>
ray<S,T>::ray (util::point<S,T> _origin,
util::vector<S,T> _direction):
origin (_origin),
direction (_direction)
{
CHECK (direction.is_normalised ());
}
///////////////////////////////////////////////////////////////////////////////
/// returns the distance along the ray in a ray-plane intersection
///
/// returns inf if parallel
/// returns 0 if corayar
template <size_t S, typename T>
T
ray<S,T>::intersect (plane<S,T> q) const
{
return dot (q.p - origin, q.n) / dot (direction, q.n);
}
///----------------------------------------------------------------------------
/// returns the distance from origin to AABB intersection
///
/// returns NaN on miss
/// returns NaN if behind
template <size_t S, typename T>
T
ray<S,T>::intersect (AABB<S,T> r) const
{
auto t1 = (r.p0 - origin) / direction;
auto t2 = (r.p1 - origin) / direction;
auto vmin = min (t1, t2);
auto vmax = max (t1, t2);
auto tmin = max (vmin);
auto tmax = min (vmax);
// closest intersection is behind us
if (tmax < 0)
return std::numeric_limits<T>::quiet_NaN ();
// missed intersection
if (tmin > tmax)
return std::numeric_limits<T>::quiet_NaN ();
return tmin;
}
///----------------------------------------------------------------------------
/// returns the smallest distance from ray origin to a sphere intersection
///
/// returns NaN on miss
/// returns NaN if behind
template <size_t S, typename T>
T
ray<S,T>::intersect (sphere<S,T> s) const
{
T b = dot (direction, origin - s.centre);
T c = dot (origin - s.centre, origin - s.centre) - s.radius * s.radius;
T D = b * b - c;
if (D < 0)
return std::numeric_limits<T>::quiet_NaN ();
auto t_ = std::sqrt (D);
auto t0 = -b + t_;
auto t1 = -b - t_;
return t1 >= 0 ? t1 :
t0 >= 0 ? t0 :
std::numeric_limits<T>::quiet_NaN ();
}
///////////////////////////////////////////////////////////////////////////////
/// returns the closest parameter along the ray to a given point
template <size_t S, typename T>
T
ray<S,T>::closest (point<S,T> q) const
{
// project the origin-point difference onto the direction
return dot (origin - q, direction);
}
//-----------------------------------------------------------------------------
template <size_t S, typename T>
util::point<S,T>
ray<S,T>::at (T t) const
{
return origin + direction * t;
}
///////////////////////////////////////////////////////////////////////////////
template struct util::ray<2,float>;
template struct util::ray<3,float>;