96 lines
2.4 KiB
C++
96 lines
2.4 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2018 Danny Robson <danny@nerdcruft.net>
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*/
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#pragma once
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#include "../point.hpp"
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namespace cruft::geom {
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/// Represents a line that has a start and an end.
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///
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/// It is not valid to create an unbounded segment by fixing one of the
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/// points at infinity.
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template <size_t S, typename T>
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struct segment {
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cruft::point<S,T> a; /// The start of the segment.
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cruft::point<S,T> b; /// The end of the segment.
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/// Return a copy of this object with the underlying type casted to
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/// the specified type.
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template <typename CastT>
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segment<S,CastT>
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cast (void) const {
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return {
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.a = a.template cast<CastT> (),
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.b = b.template cast<CastT> ()
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};
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}
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};
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/// Return the squared distance from the closest point of the segment `s`
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/// to the point `p`.
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template <size_t S, typename T>
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T
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distance2 (segment<S,T> s, point<S,T> p)
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{
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const auto dir = s.b - s.a;
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const auto t1 = dot (p - s.a, dir);
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if (t1 < 0)
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return distance2 (p, s.a);
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const auto t2 = dot (dir, dir);
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if (t2 < t1)
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return distance2 (p, s.b);
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auto t = t1 / t2;
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return distance2 (p, s.a + t * dir);
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}
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/// Return the distance from a the closest point of the segment `s` to
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/// the point `p`.
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template <size_t S, typename T>
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T
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distance (segment<S,T> s, point<S,T> p)
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{
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return std::sqrt (distance2 (s, p));
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}
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/// Returns the un-normalised direction of the segment from its start to
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/// end components. ie, `a' to `b'.
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template <size_t S, typename T>
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cruft::vector<S,T>
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udirection (segment<S,T> const &val)
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{
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return val.b - val.a;
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}
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/// Returns the normalised direction of the segment.
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template <size_t S, typename T>
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cruft::vector<S,T>
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ndirection (segment<S,T> const &val)
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{
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return normalised (udirection (val));
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}
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using segment2i = segment<2,int>;
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using segment3i = segment<3,int>;
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using segment2f = segment<2,float>;
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using segment3f = segment<3,float>;
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template <size_t S, typename T>
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segment (point<S,T>, point<S,T>) -> segment<S,T>;
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}
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