From 9a0ce083a419edb724c9f79a2a8507fa199004f3 Mon Sep 17 00:00:00 2001
From: Ioannis Giannakas <59056762+igiannakas@users.noreply.github.com>
Date: Thu, 6 Mar 2025 12:30:57 +0000
Subject: [PATCH] Bug fix: Removed expand factor from IOI as it was incorrectly
 causing perimeter failing to observe IOI reordering. (#8682)

* Removed expand factor from IOI as it was incorrectly causing perimeter failing to observe IOI reordering.

* Merge branch 'main' into Bug-Fix-IOI-re-ordering-failing-to-reorder-in-certain-edge-cases
---
 src/libslic3r/PerimeterGenerator.cpp | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/src/libslic3r/PerimeterGenerator.cpp b/src/libslic3r/PerimeterGenerator.cpp
index c08c822e89..ffda2b50d8 100644
--- a/src/libslic3r/PerimeterGenerator.cpp
+++ b/src/libslic3r/PerimeterGenerator.cpp
@@ -3188,9 +3188,6 @@ void PerimeterGenerator::process_arachne()
                 
                 // Debug statement to print spacing values:
                 //printf("External threshold - Ext perimeter: %d Ext spacing: %d Int perimeter: %d Int spacing: %d\n", this->ext_perimeter_flow.scaled_width(),this->ext_perimeter_flow.scaled_spacing(),this->perimeter_flow.scaled_width(), this->perimeter_flow.scaled_spacing());
-               
-                // Expand by 3% to cover rounding issues
-                const float expand_factor = 1.03f;
 
                 // Get searching thresholds. For an external perimeter we take the external perimeter spacing/2 plus the internal perimeter spacing/2 and expand by the factor
                 // rounding errors. When precise wall is enabled, the external perimeter full spacing is used.
@@ -3201,10 +3198,9 @@ void PerimeterGenerator::process_arachne()
                     // Normal ⇒ half ext spacing + half int spacing
                     : ( this->ext_perimeter_flow.scaled_spacing()/2.0
                         + this->perimeter_flow.scaled_spacing()/2.0 );
-                threshold_external *= expand_factor;
                 
                 // For the intenal perimeter threshold, the distance is the internal perimeter spacing expanded by the factor to cover rounding errors.
-                coord_t threshold_internal = this->perimeter_flow.scaled_spacing() * expand_factor;
+                coord_t threshold_internal = this->perimeter_flow.scaled_spacing();
                 
                 // Re-order extrusions based on distance
                 // Alorithm will aggresively optimise for the appearance of the outermost perimeter