Polygon_2 intersection precondition violation

[jdmarsh]

Issue Details

When performing an intersection of two Polygon_2 objects I get a precondition violation with no other information other than reporting the bug.

Source Code

void bug_repro()
{
	using Kernel = CGAL::Exact_predicates_inexact_constructions_kernel;
	CGAL::Polygon_2<Kernel> polygon1;
	polygon1.push_back(Kernel::Point_2{-647.57122802734375, -96.856353759765625});
	polygon1.push_back(Kernel::Point_2{-649.41784667968750, -94.705856323242188});
	polygon1.push_back(Kernel::Point_2{-648.98065185546875, -96.118194580078125});
	polygon1.push_back(Kernel::Point_2{-648.97912597656250, -96.121437072753906});
	polygon1.push_back(Kernel::Point_2{-648.97521972656250, -96.124404907226562});
	CGAL::Polygon_2<Kernel> polygon2;
	polygon2.push_back(Kernel::Point_2{-649.41784667968750, -96.856353759765625});
	polygon2.push_back(Kernel::Point_2{-649.04852294921875, -96.856353759765625});
	polygon2.push_back(Kernel::Point_2{-649.04852294921875, -94.705856323242188});
	polygon2.push_back(Kernel::Point_2{-649.41784667968750, -94.705856323242188});
	std::vector<CGAL::Polygon_with_holes_2<Kernel>> intersecting;
	CGAL::intersection(polygon1, polygon2, std::back_inserter(intersecting));
}

Runtime output:

CGAL error: precondition violation!
Expression : (m_traits.compare_y_at_x_2_object()(p, cv) == EQUAL) && compare_xy(cv.left(), p) == SMALLER && compare_xy(cv.right(), p) == LARGER
File       : C:\repos\project\out\build\x64-debug\vcpkg_installed\x64-windows\include\CGAL\Arr_segment_traits_2.h
Line       : 610
Explanation:
Refer to the bug-reporting instructions at https://www.cgal.org/bug_report.html

Environment

• Operating system: Windows 64bit
• Compiler: MSVC in VS 2022 version 17.6.5
• Release or debug mode: Debug
• Specific flags used (if any): using C++latest
• CGAL version: 5.5.1 (installed through vcpkg)
• Boost version: 1.81 (installed as a dependency automatically through vcpkg)
• Other libraries versions if used (Eigen, TBB, etc.): N/A

[efifogel]

Use an exact construction exa t predicate kernel!!!

…

On Fri, Jul 14, 2023, 13:40 James Marsh ***@***.***> wrote: Issue Details When performing an intersection of two Polygon_2 objects I get a precondition violation with no other information other than reporting the bug. Source Code void bug_repro() { using Kernel = CGAL::Exact_predicates_inexact_constructions_kernel; CGAL::Polygon_2<Kernel> polygon1; polygon1.push_back(Kernel::Point_2{-647.57122802734375, -96.856353759765625}); polygon1.push_back(Kernel::Point_2{-649.41784667968750, -94.705856323242188}); polygon1.push_back(Kernel::Point_2{-648.98065185546875, -96.118194580078125}); polygon1.push_back(Kernel::Point_2{-648.97912597656250, -96.121437072753906}); polygon1.push_back(Kernel::Point_2{-648.97521972656250, -96.124404907226562}); CGAL::Polygon_2<Kernel> polygon2; polygon2.push_back(Kernel::Point_2{-649.41784667968750, -96.856353759765625}); polygon2.push_back(Kernel::Point_2{-649.04852294921875, -96.856353759765625}); polygon2.push_back(Kernel::Point_2{-649.04852294921875, -94.705856323242188}); polygon2.push_back(Kernel::Point_2{-649.41784667968750, -94.705856323242188}); std::vector<CGAL::Polygon_with_holes_2<Kernel>> intersecting; CGAL::intersection(polygon1, polygon2, std::back_inserter(intersecting)); } Runtime output: CGAL error: precondition violation! Expression : (m_traits.compare_y_at_x_2_object()(p, cv) == EQUAL) && compare_xy(cv.left(), p) == SMALLER && compare_xy(cv.right(), p) == LARGER File : C:\repos\project\out\build\x64-debug\vcpkg_installed\x64-windows\include\CGAL\Arr_segment_traits_2.h Line : 610 Explanation: Refer to the bug-reporting instructions at https://www.cgal.org/bug_report.html Environment - Operating system: Windows 64bit - Compiler: MSVC in VS 2022 version 17.6.5 - Release or debug mode: Debug - Specific flags used (if any): using C++latest - CGAL version: 5.5.1 (installed through vcpkg) - Boost version: 1.81 (installed as a dependency automatically through vcpkg) - Other libraries versions if used (Eigen, TBB, etc.): N/A — Reply to this email directly, view it on GitHub <#7598>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABVBNOCIC6Z4Y6UQGEIGLWLXQEO3HANCNFSM6AAAAAA2KE7I74> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[jdmarsh]

Yeah that works. Would be nice having a proper error message though.