From 9e2ed0b2c4dd06624e5cb4e4515a241e1fb15db0 Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Tue, 24 Oct 2023 10:50:13 +0200
Subject: [PATCH 1/2] Move `are_siblings` method to query trait

---
 crates/fj-core/src/objects/kinds/shell.rs     | 27 +--------------
 crates/fj-core/src/queries/mod.rs             |  2 ++
 .../src/queries/sibling_of_half_edge.rs       | 33 +++++++++++++++++++
 crates/fj-core/src/validate/shell.rs          |  4 ++-
 4 files changed, 39 insertions(+), 27 deletions(-)
 create mode 100644 crates/fj-core/src/queries/sibling_of_half_edge.rs

diff --git a/crates/fj-core/src/objects/kinds/shell.rs b/crates/fj-core/src/objects/kinds/shell.rs
index 261783517..c905cf70b 100644
--- a/crates/fj-core/src/objects/kinds/shell.rs
+++ b/crates/fj-core/src/objects/kinds/shell.rs
@@ -1,6 +1,5 @@
 use crate::{
-    objects::{handles::Handles, Face, HalfEdge},
-    queries::BoundingVerticesOfHalfEdge,
+    objects::{handles::Handles, Face},
     storage::Handle,
 };
 
@@ -22,28 +21,4 @@ impl Shell {
     pub fn faces(&self) -> &Handles<Face> {
         &self.faces
     }
-
-    /// Indicate whether the provided half-edges are siblings
-    pub fn are_siblings(
-        &self,
-        a: &Handle<HalfEdge>,
-        b: &Handle<HalfEdge>,
-    ) -> bool {
-        let same_curve = a.curve().id() == b.curve().id();
-        let same_boundary = a.boundary() == b.boundary().reverse();
-        let same_vertices = {
-            let Some(a_vertices) = self.bounding_vertices_of_half_edge(a)
-            else {
-                return false;
-            };
-            let Some(b_vertices) = self.bounding_vertices_of_half_edge(b)
-            else {
-                return false;
-            };
-
-            a_vertices == b_vertices.reverse()
-        };
-
-        same_curve && same_boundary && same_vertices
-    }
 }
diff --git a/crates/fj-core/src/queries/mod.rs b/crates/fj-core/src/queries/mod.rs
index 03ac82d26..6f6488caf 100644
--- a/crates/fj-core/src/queries/mod.rs
+++ b/crates/fj-core/src/queries/mod.rs
@@ -11,8 +11,10 @@
 
 mod all_half_edges_with_surface;
 mod bounding_vertices_of_half_edge;
+mod sibling_of_half_edge;
 
 pub use self::{
     all_half_edges_with_surface::AllHalfEdgesWithSurface,
     bounding_vertices_of_half_edge::BoundingVerticesOfHalfEdge,
+    sibling_of_half_edge::SiblingOfHalfEdge,
 };
diff --git a/crates/fj-core/src/queries/sibling_of_half_edge.rs b/crates/fj-core/src/queries/sibling_of_half_edge.rs
new file mode 100644
index 000000000..2e84913d9
--- /dev/null
+++ b/crates/fj-core/src/queries/sibling_of_half_edge.rs
@@ -0,0 +1,33 @@
+use crate::{
+    objects::{HalfEdge, Shell},
+    storage::Handle,
+};
+
+use super::BoundingVerticesOfHalfEdge;
+
+/// Queries related to the sibling of a [`HalfEdge`]
+pub trait SiblingOfHalfEdge {
+    /// Indicate whether the provided half-edges are siblings
+    fn are_siblings(&self, a: &Handle<HalfEdge>, b: &Handle<HalfEdge>) -> bool;
+}
+
+impl SiblingOfHalfEdge for Shell {
+    fn are_siblings(&self, a: &Handle<HalfEdge>, b: &Handle<HalfEdge>) -> bool {
+        let same_curve = a.curve().id() == b.curve().id();
+        let same_boundary = a.boundary() == b.boundary().reverse();
+        let same_vertices = {
+            let Some(a_vertices) = self.bounding_vertices_of_half_edge(a)
+            else {
+                return false;
+            };
+            let Some(b_vertices) = self.bounding_vertices_of_half_edge(b)
+            else {
+                return false;
+            };
+
+            a_vertices == b_vertices.reverse()
+        };
+
+        same_curve && same_boundary && same_vertices
+    }
+}
diff --git a/crates/fj-core/src/validate/shell.rs b/crates/fj-core/src/validate/shell.rs
index 571aaf40b..a6dde5b6b 100644
--- a/crates/fj-core/src/validate/shell.rs
+++ b/crates/fj-core/src/validate/shell.rs
@@ -5,7 +5,9 @@ use fj_math::{Point, Scalar};
 use crate::{
     geometry::SurfaceGeometry,
     objects::{HalfEdge, Shell, Surface},
-    queries::{AllHalfEdgesWithSurface, BoundingVerticesOfHalfEdge},
+    queries::{
+        AllHalfEdgesWithSurface, BoundingVerticesOfHalfEdge, SiblingOfHalfEdge,
+    },
     storage::{Handle, HandleWrapper},
 };
 

From bcc9467a517d08528cd82aa3f3063f8dcbc92029 Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Tue, 24 Oct 2023 10:55:47 +0200
Subject: [PATCH 2/2] Add `SiblingOfHalfEdge::get_sibling_of`

---
 .../src/queries/sibling_of_half_edge.rs       | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/crates/fj-core/src/queries/sibling_of_half_edge.rs b/crates/fj-core/src/queries/sibling_of_half_edge.rs
index 2e84913d9..5c5dd2314 100644
--- a/crates/fj-core/src/queries/sibling_of_half_edge.rs
+++ b/crates/fj-core/src/queries/sibling_of_half_edge.rs
@@ -9,6 +9,16 @@ use super::BoundingVerticesOfHalfEdge;
 pub trait SiblingOfHalfEdge {
     /// Indicate whether the provided half-edges are siblings
     fn are_siblings(&self, a: &Handle<HalfEdge>, b: &Handle<HalfEdge>) -> bool;
+
+    /// Retrieve the sibling of this half-edge
+    ///
+    /// Returns `None`, if the provided half-edge is not part of the object this
+    /// method is called on, or if the provided half-edge has no sibling within
+    /// the object.
+    fn get_sibling_of(
+        &self,
+        half_edge: &Handle<HalfEdge>,
+    ) -> Option<Handle<HalfEdge>>;
 }
 
 impl SiblingOfHalfEdge for Shell {
@@ -30,4 +40,21 @@ impl SiblingOfHalfEdge for Shell {
 
         same_curve && same_boundary && same_vertices
     }
+
+    fn get_sibling_of(
+        &self,
+        half_edge: &Handle<HalfEdge>,
+    ) -> Option<Handle<HalfEdge>> {
+        for face in self.faces() {
+            for cycle in face.region().all_cycles() {
+                for h in cycle.half_edges() {
+                    if self.are_siblings(half_edge, h) {
+                        return Some(h.clone());
+                    }
+                }
+            }
+        }
+
+        None
+    }
 }