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5b89cb9 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | // This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2019 Hanxiao Shen <hanxiao@cs.nyu.edu>
//
// This Source Code Form is subject to the terms of the Mozilla Public License
// v. 2.0. If a copy of the MPL was not distributed with this file, You can
// obtain one at http://mozilla.org/MPL/2.0/.
#include "segment_segment_intersect.h"
// https://www.geeksforgeeks.org/check-if-two-given-line-segments-intersect/
template <typename DerivedP>
IGL_INLINE bool igl::predicates::segment_segment_intersect(
const Eigen::MatrixBase<DerivedP>& a,
const Eigen::MatrixBase<DerivedP>& b,
const Eigen::MatrixBase<DerivedP>& c,
const Eigen::MatrixBase<DerivedP>& d
)
{
typename DerivedP::Scalar Scalar;
auto t1 = igl::predicates::orient2d(a,b,c);
auto t2 = igl::predicates::orient2d(b,c,d);
auto t3 = igl::predicates::orient2d(a,b,d);
auto t4 = igl::predicates::orient2d(a,c,d);
// assume m,n,p are colinear, check whether p is in range [m,n]
auto on_segment = [](
const Eigen::MatrixBase<DerivedP>& m,
const Eigen::MatrixBase<DerivedP>& n,
const Eigen::MatrixBase<DerivedP>& p
){
return ((p(0) >= std::min(m(0),n(0))) &&
(p(0) <= std::max(m(0),n(0))) &&
(p(1) >= std::min(m(1),n(1))) &&
(p(1) <= std::max(m(1),n(1))));
};
// colinear case
if((t1 == igl::predicates::Orientation::COLLINEAR && on_segment(a,b,c)) ||
(t2 == igl::predicates::Orientation::COLLINEAR && on_segment(c,d,b)) ||
(t3 == igl::predicates::Orientation::COLLINEAR && on_segment(a,b,d)) ||
(t4 == igl::predicates::Orientation::COLLINEAR && on_segment(c,d,a)))
return true;
// ordinary case
return (t1 != t3 && t2 != t4);
}
#ifdef IGL_STATIC_LIBRARY
template bool igl::predicates::segment_segment_intersect<Eigen::Matrix<double, 1, 2, 1, 1, 2> >(Eigen::MatrixBase<Eigen::Matrix<double, 1, 2, 1, 1, 2> > const&, Eigen::MatrixBase<Eigen::Matrix<double, 1, 2, 1, 1, 2> > const&, Eigen::MatrixBase<Eigen::Matrix<double, 1, 2, 1, 1, 2> > const&, Eigen::MatrixBase<Eigen::Matrix<double, 1, 2, 1, 1, 2> > const&);
#endif
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