From 13bd1a4d6841a341401ef66a75ca4dbbece46c8c Mon Sep 17 00:00:00 2001
From: SoftFever <softfeverever@gmail.com>
Date: Wed, 30 Jul 2025 23:33:21 +0800
Subject: [PATCH] Revert "Refactor stagger concentric seams (#6432)"

This reverts commit bd8c2ffaeb4c7c747ed253cc629ba85b307efd35.
---
 src/libslic3r/Fill/FillConcentric.cpp | 36 ++++++---------------------
 1 file changed, 7 insertions(+), 29 deletions(-)

diff --git a/src/libslic3r/Fill/FillConcentric.cpp b/src/libslic3r/Fill/FillConcentric.cpp
index 33863d4575..f7fe82ad5f 100644
--- a/src/libslic3r/Fill/FillConcentric.cpp
+++ b/src/libslic3r/Fill/FillConcentric.cpp
@@ -10,15 +10,12 @@
 namespace Slic3r {
 
 template<typename LINE_T>
-int stagger_seam_index(int ind, LINE_T line, double shift, bool dir)
+int stagger_seam_index(int ind, LINE_T line)
 {
     Point const *point = &line.points[ind];
     double dist = 0;
-    while (dist < shift / SCALING_FACTOR) {
-        if (dir)
-            ind = (ind + 1) % line.points.size();
-        else
-            ind = ind > 0 ? --ind : line.points.size() - 1;
+    while (dist < 0.5 / SCALING_FACTOR) {
+        ind = (ind + 1) % line.points.size();
         Point const &next = line.points[ind];
         dist += point->distance_to(next);
         point = &next;
@@ -26,8 +23,6 @@ int stagger_seam_index(int ind, LINE_T line, double shift, bool dir)
     return ind;
 }
 
-#define STAGGER_SEAM_THRESHOLD 0.9
-
 void FillConcentric::_fill_surface_single(
     const FillParams                &params, 
     unsigned int                     thickness_layers,
@@ -60,20 +55,8 @@ void FillConcentric::_fill_surface_single(
     // split paths using a nearest neighbor search
     size_t iPathFirst = polylines_out.size();
     Point last_pos(0, 0);
-    
-    double min_nozzle_diameter = 0.0;
-    bool dir = false;
-    if (this->print_config != nullptr && params.density >= STAGGER_SEAM_THRESHOLD) {
-        min_nozzle_diameter = *std::min_element(print_config->nozzle_diameter.values.begin(), print_config->nozzle_diameter.values.end());
-        dir = rand() % 2;
-    }
-    
     for (const Polygon &loop : loops) {
-        int ind = (this->print_config != nullptr && params.density > STAGGER_SEAM_THRESHOLD) ?
-                    stagger_seam_index(last_pos.nearest_point_index(loop.points), loop, min_nozzle_diameter / 2, dir) :
-                    last_pos.nearest_point_index(loop.points);
-
-        polylines_out.emplace_back(loop.split_at_index(ind));
+        polylines_out.emplace_back(loop.split_at_index(stagger_seam_index(last_pos.nearest_point_index(loop.points), loop)));
         last_pos = polylines_out.back().last_point();
     }
 
@@ -135,18 +118,13 @@ void FillConcentric::_fill_surface_single(const FillParams& params,
         // Split paths using a nearest neighbor search.
         size_t firts_poly_idx = thick_polylines_out.size();
         Point  last_pos(0, 0);
-        bool dir = rand() % 2;
         for (const Arachne::ExtrusionLine* extrusion : all_extrusions) {
             if (extrusion->empty())
                 continue;
+
             ThickPolyline thick_polyline = Arachne::to_thick_polyline(*extrusion);
-            
-            if (extrusion->is_closed) {
-                int ind = (params.density >= STAGGER_SEAM_THRESHOLD) ?
-                            stagger_seam_index(last_pos.nearest_point_index(thick_polyline.points), thick_polyline, min_nozzle_diameter / 2, dir) :
-                            last_pos.nearest_point_index(thick_polyline.points);
-                thick_polyline.start_at_index(ind);
-            }
+            if (extrusion->is_closed)
+                thick_polyline.start_at_index(stagger_seam_index(last_pos.nearest_point_index(thick_polyline.points), thick_polyline));
             thick_polylines_out.emplace_back(std::move(thick_polyline));
             last_pos = thick_polylines_out.back().last_point();
         }