From d3d48e98955303181cd228729fd88a4cc0cedf50 Mon Sep 17 00:00:00 2001
From: Vojtech Bubnik <bubnikv@gmail.com>
Date: Wed, 12 Apr 2023 16:17:28 +0200
Subject: [PATCH] Fixed long standing bug in elephant foot compensation of
 holes.

---
 src/libslic3r/ClipperUtils.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/libslic3r/ClipperUtils.cpp b/src/libslic3r/ClipperUtils.cpp
index ed76fc66a..9dfee3813 100644
--- a/src/libslic3r/ClipperUtils.cpp
+++ b/src/libslic3r/ClipperUtils.cpp
@@ -1317,8 +1317,12 @@ ExPolygons variable_offset_inner_ex(const ExPolygon &expoly, const std::vector<s
 	// 2) Offset the holes one by one, collect the results.
 	ClipperLib::Paths holes;
 	holes.reserve(expoly.holes.size());
-	for (const Polygon& hole : expoly.holes)
-		append(holes, fix_after_outer_offset(mittered_offset_path_scaled(hole.points, deltas[1 + &hole - expoly.holes.data()], miter_limit), ClipperLib::pftNegative, false));
+    for (const Polygon &hole : expoly.holes) {
+        ClipperLib::Path offsetted = mittered_offset_path_scaled(hole.points, deltas[1 + &hole - expoly.holes.data()], miter_limit);
+        // Make it CCW.
+        std::reverse(offsetted.begin(), offsetted.end());
+        append(holes, fix_after_outer_offset(offsetted, ClipperLib::pftNegative, false));
+    }
 #ifndef NDEBUG
 	for (auto &c : holes)
 		assert(ClipperLib::Area(c) > 0.);