From 0ef8a79cd23dda1ef8bb023a312e87aad12cc100 Mon Sep 17 00:00:00 2001
From: Rodrigo Faselli <162915171+RF47@users.noreply.github.com>
Date: Sat, 28 Feb 2026 18:52:05 -0300
Subject: [PATCH] Fix missing infill layers (fill_surface_by_multilines &
 fill_surface_trapezoidal bug fix) (#12516)

* FillRectilinear bugfix

* cleaning

* Revert "cleaning"

This reverts commit 0de21ada78649a3a9ca44adb773d6e98c4f2f776.

* Filltrapezoidal is OK

* Filltrapezoidal fix 2
---
 src/libslic3r/Fill/FillRectilinear.cpp | 28 +++++++++++++++++---------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/libslic3r/Fill/FillRectilinear.cpp b/src/libslic3r/Fill/FillRectilinear.cpp
index 775b3e8b42..59c69a9d32 100644
--- a/src/libslic3r/Fill/FillRectilinear.cpp
+++ b/src/libslic3r/Fill/FillRectilinear.cpp
@@ -3021,24 +3021,25 @@ bool FillRectilinear::fill_surface_by_multilines(const Surface *surface, FillPar
     multiline_fill(fill_lines, params, spacing);
  
     // Contract surface polygon by half line width to avoid excesive overlap with perimeter
-    ExPolygons contracted = offset_ex(surface->expolygon, -float(scale_(0.5 * this->spacing)));
-    
-    // if contraction results in empty polygon, use original surface
-    const ExPolygon &intersection_surface = contracted.empty() ? surface->expolygon : contracted.front();
+    const ExPolygons contracted = offset_ex(surface->expolygon, -float(scale_(0.5 * this->spacing)));
+
+    // if contraction results in empty ExPolygons, use original surface
+    const ExPolygons& intersection_surface = contracted.empty() ? ExPolygons{surface->expolygon} : contracted;
 
     // Intersect polylines with perimeter
     fill_lines = intersection_pl(std::move(fill_lines), intersection_surface);
 
-    if ((params.pattern == ipLateralLattice || params.pattern == ipLateralHoneycomb ) && params.multiline >1 )
-    remove_overlapped(fill_lines, line_width);
+    if ((params.pattern == ipLateralLattice || params.pattern == ipLateralHoneycomb) && params.multiline > 1)
+        remove_overlapped(fill_lines, line_width);
 
     if (!fill_lines.empty()) {
-        if (params.dont_connect()) { 
+        if (params.dont_connect()) {
             if (fill_lines.size() > 1)
                 fill_lines = chain_polylines(std::move(fill_lines));
             append(polylines_out, std::move(fill_lines));
         } else
-             connect_infill(std::move(fill_lines), intersection_surface, polylines_out, this->spacing, params);
+            connect_infill(std::move(fill_lines), to_polygons(intersection_surface), get_extents(surface->expolygon.contour), polylines_out,
+                           this->spacing, params);
     }
 
     return true;
@@ -3268,7 +3269,7 @@ bool FillRectilinear::fill_surface_trapezoidal(
     ExPolygons contracted = offset_ex(expolygon, -float(scale_(0.5 * this->spacing)));
 
     // if contraction results in empty polygon, use original surface
-    const ExPolygon &intersection_surface = contracted.empty() ? expolygon : contracted.front();
+    const ExPolygons& intersection_surface = contracted.empty() ? ExPolygons{expolygon} : contracted;
 
     // Intersect polylines with offset expolygon
     polylines = intersection_pl(std::move(polylines), intersection_surface);
@@ -3284,7 +3285,14 @@ bool FillRectilinear::fill_surface_trapezoidal(
     // Connect infill lines using offset expolygon
     int infill_start_idx = polylines_out.size();
     if (!polylines.empty()) {
-        Slic3r::Fill::chain_or_connect_infill(std::move(polylines), intersection_surface, polylines_out, this->spacing, params);
+        if (params.dont_connect()) {
+            if (polylines.size() > 1)
+                polylines = chain_polylines(std::move(polylines));
+            append(polylines_out, std::move(polylines));
+        } else {
+            connect_infill(std::move(polylines), to_polygons(intersection_surface), get_extents(intersection_surface), polylines_out,
+                           this->spacing, params);
+        }
 
         // Rotate back the infill lines to original orientation
         if (std::abs(base_angle) >= EPSILON) {