From 692323049594e1800e0981bac0349b985177a237 Mon Sep 17 00:00:00 2001
From: "jiangkai.zhao" <jiangkai.zhao@bambulab.com>
Date: Tue, 19 Aug 2025 11:24:39 +0800
Subject: [PATCH] Fix:path conflictcheck

Coincident lines are considered as intersecting
jira:STUDIO-14085

Change-Id: I1487e6e2479e2488a3fd55651b8b4fb1bc1f4ced
(cherry picked from commit 2348328a96a8d805c35cae8f03ebaa0869b1313e)
---
 src/libslic3r/GCode/ConflictChecker.cpp |  3 +++
 src/libslic3r/Line.cpp                  | 15 ++++++++++++++-
 src/libslic3r/Line.hpp                  |  2 +-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/libslic3r/GCode/ConflictChecker.cpp b/src/libslic3r/GCode/ConflictChecker.cpp
index 78a696f950..e8780a818c 100644
--- a/src/libslic3r/GCode/ConflictChecker.cpp
+++ b/src/libslic3r/GCode/ConflictChecker.cpp
@@ -288,6 +288,9 @@ ConflictComputeOpt ConflictChecker::line_intersect(const LineWithID &l1, const L
     constexpr double SUPPORT_THRESHOLD = 100;  // this large almost disables conflict check of supports
     constexpr double OTHER_THRESHOLD   = 0.01;
     if (l1._id == l2._id) { return {}; } // return true if lines are from same object
+    double overlap_length = 0.;
+    bool   overlap  = l1._line.overlap(l2._line, overlap_length);
+    if (overlap && overlap_length > scaled(OTHER_THRESHOLD)) return std::make_optional<ConflictComputeResult>(l1._id, l2._id);
     Point inter;
     bool  intersect = l1._line.intersection(l2._line, &inter);
 
diff --git a/src/libslic3r/Line.cpp b/src/libslic3r/Line.cpp
index 20591f0377..c74df3aa59 100644
--- a/src/libslic3r/Line.cpp
+++ b/src/libslic3r/Line.cpp
@@ -76,7 +76,20 @@ bool Line::parallel_to(const Line& line) const
     const Vec2d v2 = (line.b - line.a).cast<double>();
     return sqr(cross2(v1, v2)) < sqr(EPSILON) * v1.squaredNorm() * v2.squaredNorm();
 }
-
+bool Line::overlap(const Line &line, double &overlap_length) const
+{
+    if (!this->parallel_to(line)) return false;
+    Line line_(this->a, line.a);
+    if (line_.length() > scaled(EPSILON) && !this->parallel_to(line_)) return false;
+    coord_t a_min  = std::min(this->a.x(), this->b.x());
+    coord_t a_max  = std::max(this->a.x(), this->b.x());
+    coord_t b_min  = std::min(line.a.x(), line.b.x());
+    coord_t b_max  = std::max(line.a.x(), line.b.x());
+    if (a_min>b_max||a_max<b_min) return false;
+    overlap_length = std::max((coord_t)0, std::min(a_max, b_max) - std::max(a_min, b_min));
+    overlap_length /= ((double) a_max - a_min) / this->length();
+    return true;
+}
 bool Line::perpendicular_to(double angle) const
 {
     return Slic3r::Geometry::directions_perpendicular(this->direction(), angle);
diff --git a/src/libslic3r/Line.hpp b/src/libslic3r/Line.hpp
index 5c39f25faa..028ea2aafa 100644
--- a/src/libslic3r/Line.hpp
+++ b/src/libslic3r/Line.hpp
@@ -183,7 +183,7 @@ public:
 	bool   clip_with_bbox(const BoundingBox &bbox);
     // Extend the line from both sides by an offset.
     void   extend(double offset);
-
+    bool   overlap(const Line &line, double &overlap_length) const;
     static inline double distance_to_squared(const Point &point, const Point &a, const Point &b) { return line_alg::distance_to_squared(Line{a, b}, Vec<2, coord_t>{point}); }
     static double distance_to(const Point &point, const Point &a, const Point &b) { return sqrt(distance_to_squared(point, a, b)); }