From 2aa55ef950a5372d45a68a32b34d1d8e366dd945 Mon Sep 17 00:00:00 2001
From: Lukas Matena <lukasmatena@seznam.cz>
Date: Wed, 3 May 2023 16:14:26 +0200
Subject: [PATCH] Cut: fixed an issue when the view rotates to the other side
 of the plane

---
 src/slic3r/GUI/MeshUtils.cpp | 11 +++++------
 src/slic3r/GUI/MeshUtils.hpp |  2 +-
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/src/slic3r/GUI/MeshUtils.cpp b/src/slic3r/GUI/MeshUtils.cpp
index 99a241c48..60ea6c856 100644
--- a/src/slic3r/GUI/MeshUtils.cpp
+++ b/src/slic3r/GUI/MeshUtils.cpp
@@ -392,12 +392,11 @@ void MeshClipper::recalculate_triangles()
         }
 
         isl.expoly = std::move(exp);
-        isl.expoly_bb = get_extents(exp);
-        isl.hash = 0;
-        for (const Point& pt : isl.expoly.contour) {
-            isl.hash ^= pt.x();
-            isl.hash ^= pt.y();
-        }
+        isl.expoly_bb = get_extents(isl.expoly);
+
+        Point centroid_scaled = isl.expoly.contour.centroid();
+        Vec3d centroid_world = m_result->trafo * Vec3d(unscale(centroid_scaled).x(), unscale(centroid_scaled).y(), 0.);
+        isl.hash = isl.expoly.contour.size() + size_t(std::abs(100.*centroid_world.x())) + size_t(std::abs(100.*centroid_world.y())) + size_t(std::abs(100.*centroid_world.z()));
     }
 
     // Now sort the islands so they are in defined order. This is a hack needed by cut gizmo, which sometimes
diff --git a/src/slic3r/GUI/MeshUtils.hpp b/src/slic3r/GUI/MeshUtils.hpp
index e5fa97e39..3645ecc02 100644
--- a/src/slic3r/GUI/MeshUtils.hpp
+++ b/src/slic3r/GUI/MeshUtils.hpp
@@ -141,7 +141,7 @@ private:
         ExPolygon expoly;
         BoundingBox expoly_bb;
         bool disabled = false;
-        coord_t hash;
+        size_t hash;
     };
     struct ClipResult {
         std::vector<CutIsland> cut_islands;