libcruft-util/line.cpp

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/*
* This file is part of libgim.
*
* libgim 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.
*
* libgim 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 libgim. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2015 Danny Robson <danny@nerdcruft.net>
*/
#include "line.hpp"
#include "debug.hpp"
//-----------------------------------------------------------------------------
template <size_t S, typename T>
util::line<S,T>::line (util::point<S,T> _p,
util::vector<S,T> _d):
p (_p),
d (_d)
{
CHECK_EQ (d.magnitude2 (), 1);
}
///----------------------------------------------------------------------------
/// returns the distance along the line in a line-plane intersection
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///
/// returns inf if parallel
/// returns 0 if colinear
template <size_t S, typename T>
T
util::line<S,T>::intersect (plane<S,T> q) const
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{
return dot (q.p - p, q.n) / dot (d, q.n);
}
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///----------------------------------------------------------------------------
/// returns the distance from origin to AABB intersection
///
/// returns NaN on miss
/// returns -ve if behind
template <size_t S, typename T>
T
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util::line<S,T>::intersect (AABB<S,T> r) const
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{
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auto t1 = (r.p0 - p) / d;
auto t2 = (r.p1 - p) / d;
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auto vmin = min (t1, t2);
auto vmax = max (t1, t2);
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auto tmin = max (vmin);
auto tmax = min (vmax);
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if (tmax < 0)
return tmax;
if (tmin > tmax)
return std::numeric_limits<T>::quiet_NaN ();
return tmin;
}
///----------------------------------------------------------------------------
/// returns the closest parameter along the line to a given point
template <size_t S, typename T>
T
util::line<S,T>::closest (point<S,T> q) const
{
// project the origin-point difference onto the direction
return dot (p - q, d);
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}
//-----------------------------------------------------------------------------
template <size_t S, typename T>
util::point<S,T>
util::line<S,T>::at (T t) const
{
return p + d * t;
}
//-----------------------------------------------------------------------------
template struct util::line<2,float>;
template struct util::line<3,float>;