mirror of https://github.com/CGAL/cgal
463 lines
15 KiB
C++
463 lines
15 KiB
C++
// Copyright (c) 2000
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// Utrecht University (The Netherlands),
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// ETH Zurich (Switzerland),
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// INRIA Sophia-Antipolis (France),
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// Max-Planck-Institute Saarbruecken (Germany),
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// and Tel-Aviv University (Israel). All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; either version 3 of the License,
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// or (at your option) any later version.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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// SPDX-License-Identifier: LGPL-3.0+
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//
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//
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// Author(s) : Geert-Jan Giezeman
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#ifndef CGAL_SEGMENT_2_SEGMENT_2_INTERSECTION_H
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#define CGAL_SEGMENT_2_SEGMENT_2_INTERSECTION_H
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#include <CGAL/Segment_2.h>
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#include <CGAL/Point_2.h>
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#include <CGAL/kernel_assertions.h>
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#include <CGAL/number_utils.h>
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#include <CGAL/predicates_on_points_2.h>
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#include <CGAL/Line_2.h>
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#include <CGAL/Line_2_Line_2_intersection.h>
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#include <CGAL/Uncertain.h>
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#include <CGAL/Intersection_traits_2.h>
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namespace CGAL {
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namespace internal {
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template <class K>
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inline bool
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do_intersect(const typename K::Segment_2 &seg1, const typename K::Segment_2 &seg2);
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template <class K>
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bool seg_seg_do_intersect_crossing(
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const typename K::Point_2 &p1, const typename K::Point_2 &p2,
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const typename K::Point_2 &p3, const typename K::Point_2 &p4,
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const K& k)
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{
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switch (make_certain(k.orientation_2_object()(p1,p2,p3))) {
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case LEFT_TURN:
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return ! (k.orientation_2_object()(p3,p4,p2) == RIGHT_TURN); // right_turn(p3,p4,p2);
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case RIGHT_TURN:
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return ! (k.orientation_2_object()(p3,p4,p2) == LEFT_TURN); //left_turn(p3,p4,p2);
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case COLLINEAR:
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return true;
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}
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CGAL_kernel_assertion(false);
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return false;
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}
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template <class K>
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bool seg_seg_do_intersect_contained(
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const typename K::Point_2 &p1, const typename K::Point_2 &p2,
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const typename K::Point_2 &p3, const typename K::Point_2 &p4,
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const K& k)
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{
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switch (make_certain(k.orientation_2_object()(p1,p2,p3))) {
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case LEFT_TURN:
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return ! (k.orientation_2_object()(p1,p2,p4) == LEFT_TURN); // left_turn(p1,p2,p4);
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case RIGHT_TURN:
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return ! (k.orientation_2_object()(p1,p2,p4) == RIGHT_TURN); // right_turn(p1,p2,p4);
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case COLLINEAR:
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return true;
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}
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CGAL_kernel_assertion(false);
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return false;
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}
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template <class K>
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bool
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do_intersect(const typename K::Segment_2 &seg1,
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const typename K::Segment_2 &seg2,
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const K& k)
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{
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typename K::Point_2 const & A1 = seg1.source();
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typename K::Point_2 const & A2 = seg1.target();
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typename K::Point_2 const & B1 = seg2.source();
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typename K::Point_2 const & B2 = seg2.target();
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typename K::Less_xy_2 less_xy;
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typename K::Compare_xy_2 compare_xy;
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if (less_xy(A1,A2)) {
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if (less_xy(B1,B2)) {
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if (less_xy(A2,B1)
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|| less_xy(B2,A1))
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return false;
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} else {
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if (less_xy(A2,B2)
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|| less_xy(B1,A1))
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return false;
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}
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} else {
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if (less_xy(B1,B2)) {
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if (less_xy(A1,B1)
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|| less_xy(B2,A2))
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return false;
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} else {
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if (less_xy(A1,B2)
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|| less_xy(B1,A2))
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return false;
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}
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}
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if (less_xy(A1,A2)) {
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if (less_xy(B1,B2)) {
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switch(make_certain(compare_xy(A1,B1))) {
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case SMALLER:
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switch(make_certain(compare_xy(A2,B1))) {
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case SMALLER:
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return false;
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(A2,B2))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(A1,A2,B1,B2, k);
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case EQUAL:
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return true;
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default: // LARGER
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return seg_seg_do_intersect_contained(A1,A2,B1,B2, k);
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}
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}
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(B2,A1))) {
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case SMALLER:
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return false;
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(B2,A2))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(B1,B2,A1,A2, k);
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case EQUAL:
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return true;
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default: // LARGER
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return seg_seg_do_intersect_contained(B1,B2,A1,A2, k);
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}
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}
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}
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} else {
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switch(make_certain(compare_xy(A1,B2))) {
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case SMALLER:
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switch(make_certain(compare_xy(A2,B2))) {
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case SMALLER:
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return false;
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(A2,B1))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(A1,A2,B2,B1, k);
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case EQUAL:
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return true;
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default: // LARGER
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return seg_seg_do_intersect_contained(A1,A2,B2,B1, k);
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}
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}
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(B1,A1))) {
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case SMALLER:
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return false;
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(B1,A2))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(B2,B1,A1,A2, k);
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case EQUAL:
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return true;
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default: // LARGER
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return seg_seg_do_intersect_contained(B2,B1,A1,A2, k);
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}
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}
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}
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}
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} else {
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if (less_xy(B1,B2)) {
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switch(make_certain(compare_xy(A2,B1))) {
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case SMALLER:
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switch(make_certain(compare_xy(A1,B1))) {
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case SMALLER:
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return false;
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(A1,B2))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(A2,A1,B1,B2, k);
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case EQUAL:
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return true;
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default: // LARGER
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return seg_seg_do_intersect_contained(A2,A1,B1,B2, k);
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}
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}
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(B2,A2))) {
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case SMALLER:
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return false;
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(B2,A1))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(B1,B2,A2,A1, k);
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case EQUAL:
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return true;
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default: // LARGER
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return seg_seg_do_intersect_contained(B1,B2,A2,A1, k);
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}
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}
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}
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} else {
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switch(make_certain(compare_xy(A2,B2))) {
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case SMALLER:
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switch(make_certain(compare_xy(A1,B2))) {
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case SMALLER:
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return false;
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(A1,B1))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(A2,A1,B2,B1, k);
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case EQUAL:
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return true;
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default: // LARGER
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return seg_seg_do_intersect_contained(A2,A1,B2,B1, k);
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}
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}
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(B1,A2))) {
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case SMALLER:
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return false;
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case EQUAL:
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return true;
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default: // LARGER
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switch(make_certain(compare_xy(B1,A1))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(B2,B1,A2,A1, k);
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case EQUAL:
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return true;
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default: // LARGER
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return seg_seg_do_intersect_contained(B2,B1,A2,A1, k);
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}
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}
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}
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}
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}
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CGAL_kernel_assertion(false);
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return false;
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}
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template <class K>
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class Segment_2_Segment_2_pair {
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public:
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enum Intersection_results {NO_INTERSECTION, POINT, SEGMENT};
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Segment_2_Segment_2_pair(typename K::Segment_2 const *seg1,
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typename K::Segment_2 const *seg2)
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: _seg1(seg1), _seg2(seg2), _known(false) {}
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Intersection_results intersection_type() const;
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typename K::Point_2 intersection_point() const;
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typename K::Segment_2 intersection_segment() const;
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protected:
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typename K::Segment_2 const* _seg1;
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typename K::Segment_2 const * _seg2;
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mutable bool _known;
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mutable Intersection_results _result;
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mutable typename K::Point_2 _intersection_point, _other_point;
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};
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template <class K>
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typename Segment_2_Segment_2_pair<K>::Intersection_results
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Segment_2_Segment_2_pair<K>::intersection_type() const
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{
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typename K::Construct_vector_2 construct_vector;
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if (_known)
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return _result;
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_known = true;
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if (!internal::do_intersect(*_seg1, *_seg2, K())) {
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_result = NO_INTERSECTION;
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return _result;
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}
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typename K::Line_2 const &l1 = _seg1->supporting_line();
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typename K::Line_2 const &l2 = _seg2->supporting_line();
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Line_2_Line_2_pair<K> linepair(&l1, &l2);
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switch ( linepair.intersection_type()) {
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case Line_2_Line_2_pair<K>::NO_INTERSECTION:
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_result = NO_INTERSECTION;
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break;
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case Line_2_Line_2_pair<K>::POINT:
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_intersection_point = linepair.intersection_point();
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_result = POINT;
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break;
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case Line_2_Line_2_pair<K>::LINE:
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{
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//typedef typename K::RT RT;
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typename K::Point_2 const &start1 = _seg1->source();
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typename K::Point_2 const &end1 = _seg1->target();
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typename K::Point_2 const &start2 = _seg2->source();
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typename K::Point_2 const &end2 = _seg2->target();
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typename K::Vector_2 diff1 = construct_vector(start1, end1);
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typename K::Point_2 const *minpt;
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typename K::Point_2 const *maxpt;
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if (CGAL_NTS abs(diff1.x()) > CGAL_NTS abs(diff1.y())) {
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if (start1.x() < end1.x()) {
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minpt = &start1;
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maxpt = &end1;
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} else {
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minpt = &end1;
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maxpt = &start1;
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}
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if (start2.x() < end2.x()) {
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if (start2.x() > minpt->x()) {
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minpt = &start2;
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}
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if (end2.x() < maxpt->x()) {
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maxpt = &end2;
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}
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} else {
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if (end2.x() > minpt->x()) {
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minpt = &end2;
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}
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if (start2.x() < maxpt->x()) {
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maxpt = &start2;
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}
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}
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if (maxpt->x() < minpt->x()) {
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_result = NO_INTERSECTION;
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return _result;
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}
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if (maxpt->x() == minpt->x()) {
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_intersection_point = *minpt;
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_result = POINT;
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return _result;
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}
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_intersection_point = *minpt;
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_other_point = *maxpt;
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_result = SEGMENT;
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return _result;
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} else {
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if (start1.y() < end1.y()) {
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minpt = &start1;
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maxpt = &end1;
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} else {
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minpt = &end1;
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maxpt = &start1;
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}
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if (start2.y() < end2.y()) {
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if (start2.y() > minpt->y()) {
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minpt = &start2;
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}
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if (end2.y() < maxpt->y()) {
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maxpt = &end2;
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}
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} else {
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if (end2.y() > minpt->y()) {
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minpt = &end2;
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}
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if (start2.y() < maxpt->y()) {
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maxpt = &start2;
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}
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}
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if (maxpt->y() < minpt->y()) {
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_result = NO_INTERSECTION;
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return _result;
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}
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if (maxpt->y() == minpt->y()) {
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_intersection_point = *minpt;
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_result = POINT;
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return _result;
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}
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_intersection_point = *minpt;
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_other_point = *maxpt;
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_result = SEGMENT;
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return _result;
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}
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}
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}
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return _result;
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}
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template <class K>
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typename K::Point_2
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Segment_2_Segment_2_pair<K>::intersection_point() const
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{
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if (!_known)
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intersection_type();
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CGAL_kernel_assertion(_result == POINT);
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return _intersection_point;
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}
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template <class K>
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typename K::Segment_2
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Segment_2_Segment_2_pair<K>::intersection_segment() const
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{
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typedef typename K::Segment_2 Segment_2;
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if (!_known)
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intersection_type();
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CGAL_kernel_assertion(_result == SEGMENT);
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return Segment_2(_intersection_point, _other_point);
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}
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template <class K>
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typename CGAL::Intersection_traits
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<K, typename K::Segment_2, typename K::Segment_2>::result_type
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intersection(const typename K::Segment_2 &seg1,
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const typename K::Segment_2 &seg2,
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const K&)
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{
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typedef Segment_2_Segment_2_pair<K> is_t;
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is_t ispair(&seg1, &seg2);
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switch (ispair.intersection_type()) {
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case is_t::NO_INTERSECTION:
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default:
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return intersection_return<typename K::Intersect_2, typename K::Segment_2, typename K::Segment_2>();
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case is_t::POINT:
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return intersection_return<typename K::Intersect_2, typename K::Segment_2, typename K::Segment_2>(ispair.intersection_point());
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case is_t::SEGMENT:
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return intersection_return<typename K::Intersect_2, typename K::Segment_2, typename K::Segment_2>(ispair.intersection_segment());
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}
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}
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} // namespace internal
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CGAL_INTERSECTION_FUNCTION_SELF(Segment_2, 2)
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CGAL_DO_INTERSECT_FUNCTION_SELF(Segment_2, 2)
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} //namespace CGAL
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#endif
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