From 9d30113fdde8f7468fb49ce8fd73e06a01cb60cd Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Tue, 8 Aug 2023 10:07:09 +0200
Subject: [PATCH 1/3] Refactor to prepare for follow-on change

---
 crates/fj-core/src/geometry/boundary.rs | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/crates/fj-core/src/geometry/boundary.rs b/crates/fj-core/src/geometry/boundary.rs
index bb5ed9935..6df775c22 100644
--- a/crates/fj-core/src/geometry/boundary.rs
+++ b/crates/fj-core/src/geometry/boundary.rs
@@ -34,9 +34,13 @@ impl<T: CurveBoundaryElement> CurveBoundary<T> {
     /// in a defined order. This can be used to compare a boundary while
     /// disregarding its direction.
     #[must_use]
-    pub fn normalize(mut self) -> Self {
-        self.inner.sort();
-        self
+    pub fn normalize(self) -> Self {
+        let [a, b] = &self.inner;
+        if a > b {
+            self.reverse()
+        } else {
+            self
+        }
     }
 }
 

From 6ed2aaa39711f07539d6308eea5fbaecf8ccc40e Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Tue, 8 Aug 2023 10:11:03 +0200
Subject: [PATCH 2/3] Return more info from `CurveBoundary::normalize`

---
 crates/fj-core/src/geometry/boundary.rs | 6 +++---
 crates/fj-core/src/validate/shell.rs    | 7 +++++--
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/crates/fj-core/src/geometry/boundary.rs b/crates/fj-core/src/geometry/boundary.rs
index 6df775c22..35a99d6cf 100644
--- a/crates/fj-core/src/geometry/boundary.rs
+++ b/crates/fj-core/src/geometry/boundary.rs
@@ -34,12 +34,12 @@ impl<T: CurveBoundaryElement> CurveBoundary<T> {
     /// in a defined order. This can be used to compare a boundary while
     /// disregarding its direction.
     #[must_use]
-    pub fn normalize(self) -> Self {
+    pub fn normalize(self) -> (Self, bool) {
         let [a, b] = &self.inner;
         if a > b {
-            self.reverse()
+            (self.reverse(), true)
         } else {
-            self
+            (self, false)
         }
     }
 }
diff --git a/crates/fj-core/src/validate/shell.rs b/crates/fj-core/src/validate/shell.rs
index eb1f1f328..c87b92542 100644
--- a/crates/fj-core/src/validate/shell.rs
+++ b/crates/fj-core/src/validate/shell.rs
@@ -235,6 +235,7 @@ impl ShellValidationError {
                                 .bounding_vertices_of_edge(edge)
                                 .expect("Expected edge to be part of shell")
                                 .normalize()
+                                .0
                         };
 
                         bounding_vertices_of(edge_a)
@@ -314,7 +315,8 @@ impl ShellValidationError {
                         .expect(
                             "Cycle should provide bounds of its own half-edge",
                         )
-                        .normalize();
+                        .normalize()
+                        .0;
 
                     let edge = (curve, bounding_vertices);
 
@@ -394,7 +396,8 @@ impl ShellValidationError {
                         .expect(
                             "Just got edge from this cycle; must be part of it",
                         )
-                        .normalize();
+                        .normalize()
+                        .0;
 
                     edges_by_coincidence
                         .entry((curve, boundary))

From c5cee37a9be9f63e948636217e7fa80fb4108299 Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Tue, 8 Aug 2023 10:12:32 +0200
Subject: [PATCH 3/3] Update doc comment

---
 crates/fj-core/src/geometry/boundary.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/crates/fj-core/src/geometry/boundary.rs b/crates/fj-core/src/geometry/boundary.rs
index 35a99d6cf..8a6eef11a 100644
--- a/crates/fj-core/src/geometry/boundary.rs
+++ b/crates/fj-core/src/geometry/boundary.rs
@@ -31,8 +31,10 @@ impl<T: CurveBoundaryElement> CurveBoundary<T> {
     /// Normalize the boundary
     ///
     /// Returns a new instance of this struct, which has the bounding elements
-    /// in a defined order. This can be used to compare a boundary while
-    /// disregarding its direction.
+    /// in a defined order, alongside a boolean that indicates whether the new
+    /// instance is different from the original one.
+    ///
+    /// This can be used to compare a boundary while disregarding its direction.
     #[must_use]
     pub fn normalize(self) -> (Self, bool) {
         let [a, b] = &self.inner;