From 27ec1980bcf62b8618182e9c6d73aa20452ada0c Mon Sep 17 00:00:00 2001
From: Noisyfox <timemanager.rick@gmail.com>
Date: Wed, 18 Dec 2024 21:32:41 +0800
Subject: [PATCH] Arachne: Fix an arithmetic overflow that causing extra points
 outside plate (#7330)

* Arachne: Fix an arithmetic overflow that causing extra points outside the plate (SoftFever/OrcaSlicer#7321)

* Better way of avoiding overflow, works in Release mode as well

* Fix debug build

* Fix build
---
 src/libslic3r/Arachne/utils/ExtrusionLine.cpp | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/libslic3r/Arachne/utils/ExtrusionLine.cpp b/src/libslic3r/Arachne/utils/ExtrusionLine.cpp
index ac7b88af833..35233f10751 100644
--- a/src/libslic3r/Arachne/utils/ExtrusionLine.cpp
+++ b/src/libslic3r/Arachne/utils/ExtrusionLine.cpp
@@ -153,10 +153,19 @@ void ExtrusionLine::simplify(const int64_t smallest_line_segment_squared, const
                 //                    ^ current
                 Point intersection_point;
                 bool has_intersection = Line(previous_previous.p, previous.p).intersection_infinite(Line(current.p, next.p), &intersection_point);
+                const auto dist_greater = [](const Point& p1, const Point& p2, const int64_t threshold) {
+                    const auto vec = (p1 - p2).cwiseAbs().cast<uint64_t>();
+                    if(vec.x() > threshold || vec.y() > threshold) {
+                        // If this condition is true, the distance is definitely greater than the threshold.
+                        // We don't need to calculate the squared norm at all, which avoid potential arithmetic overflow.
+                        return true;
+                    }
+                    return vec.squaredNorm() > threshold;
+                };
                 if (!has_intersection
                     || Line::distance_to_infinite_squared(intersection_point, previous.p, current.p) > double(allowed_error_distance_squared)
-                    || (intersection_point - previous.p).cast<int64_t>().squaredNorm() > smallest_line_segment_squared  // The intersection point is way too far from the 'previous'
-                    || (intersection_point - current.p).cast<int64_t>().squaredNorm() > smallest_line_segment_squared)  // and 'current' points, so it shouldn't replace 'current'
+                    || dist_greater(intersection_point, previous.p, smallest_line_segment_squared)  // The intersection point is way too far from the 'previous'
+                    || dist_greater(intersection_point, current.p, smallest_line_segment_squared))  // and 'current' points, so it shouldn't replace 'current'
                 {
                     // We can't find a better spot for it, but the size of the line is more than 5 micron.
                     // So the only thing we can do here is leave it in...