From a8a4a7e404e8b4846be9c616159dcc20c0f38da8 Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Tue, 28 Nov 2023 17:44:56 +0100
Subject: [PATCH 1/3] Add `SweepFaceOfShell`

---
 crates/fj-core/src/operations/sweep/mod.rs    |  2 +
 .../src/operations/sweep/shell_face.rs        | 65 +++++++++++++++++++
 2 files changed, 67 insertions(+)
 create mode 100644 crates/fj-core/src/operations/sweep/shell_face.rs

diff --git a/crates/fj-core/src/operations/sweep/mod.rs b/crates/fj-core/src/operations/sweep/mod.rs
index 17d80e13b..729307455 100644
--- a/crates/fj-core/src/operations/sweep/mod.rs
+++ b/crates/fj-core/src/operations/sweep/mod.rs
@@ -8,6 +8,7 @@ mod face;
 mod half_edge;
 mod path;
 mod region;
+mod shell_face;
 mod sketch;
 mod vertex;
 
@@ -17,6 +18,7 @@ pub use self::{
     half_edge::SweepHalfEdge,
     path::SweepSurfacePath,
     region::SweepRegion,
+    shell_face::SweepFaceOfShell,
     sketch::SweepSketch,
     vertex::SweepVertex,
 };
diff --git a/crates/fj-core/src/operations/sweep/shell_face.rs b/crates/fj-core/src/operations/sweep/shell_face.rs
new file mode 100644
index 000000000..5632c295e
--- /dev/null
+++ b/crates/fj-core/src/operations/sweep/shell_face.rs
@@ -0,0 +1,65 @@
+use fj_math::Vector;
+
+use crate::{
+    objects::{Face, Region, Shell},
+    operations::{
+        insert::Insert,
+        reverse::Reverse,
+        sweep::{SweepCache, SweepRegion},
+        update::UpdateShell,
+    },
+    services::Services,
+    storage::Handle,
+};
+
+/// # Sweep a [`Face`] that is part of a [`Shell`]
+///
+/// See [module documentation] for more information.
+///
+/// [module documentation]: super
+pub trait SweepFaceOfShell {
+    /// # Sweep the [`Face`] of the [`Shell`]
+    ///
+    /// Extends the shell, adding the new faces to it.
+    ///
+    /// # Panics
+    ///
+    /// Panics, if the face has interior cycles. This is not a fundamental
+    /// limitation, but none the less not yet supported.
+    fn sweep_face_of_shell(
+        &self,
+        face: Handle<Face>,
+        path: impl Into<Vector<3>>,
+        services: &mut Services,
+    ) -> Self;
+}
+
+impl SweepFaceOfShell for Shell {
+    fn sweep_face_of_shell(
+        &self,
+        face: Handle<Face>,
+        path: impl Into<Vector<3>>,
+        services: &mut Services,
+    ) -> Self {
+        let path = path.into();
+
+        if !face.region().interiors().is_empty() {
+            todo!(
+                "Sweeping shell faces with interior cycles is not yet \
+                supported."
+            )
+        }
+
+        let mut cache = SweepCache::default();
+
+        let exterior =
+            face.region().exterior().reverse(services).insert(services);
+        let region = Region::new(exterior, [], face.region().color());
+        let faces = region
+            .sweep_region(face.surface(), path, &mut cache, services)
+            .into_iter()
+            .map(|face| face.insert(services));
+
+        self.remove_face(&face).add_faces(faces)
+    }
+}

From 69caaf94e8ed30c0427dd1aad117af4b18d6eaf6 Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Tue, 28 Nov 2023 17:52:12 +0100
Subject: [PATCH 2/3] Refactor to prepare for follow-on change

---
 models/split/src/lib.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/models/split/src/lib.rs b/models/split/src/lib.rs
index 96a8f2e15..c576b72fc 100644
--- a/models/split/src/lib.rs
+++ b/models/split/src/lib.rs
@@ -46,7 +46,8 @@ pub fn model(
                 (cycle.half_edges().nth(2).unwrap(), [split_pos]),
             ];
 
-            shell.split_face(face, line, services).0.insert(services)
+            let (shell, _) = shell.split_face(face, line, services);
+            shell.insert(services)
         })
         .insert(services)
 }

From ad0e25b439c912d125aedc0c84003c2a1c6bdb6c Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Tue, 28 Nov 2023 17:55:15 +0100
Subject: [PATCH 3/3] Sweep half of split face in `split` model

---
 models/split/src/lib.rs | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/models/split/src/lib.rs b/models/split/src/lib.rs
index c576b72fc..d58003683 100644
--- a/models/split/src/lib.rs
+++ b/models/split/src/lib.rs
@@ -5,7 +5,7 @@ use fj::{
             build::{BuildRegion, BuildSketch},
             insert::Insert,
             split::SplitFace,
-            sweep::SweepSketch,
+            sweep::{SweepFaceOfShell, SweepSketch},
             update::{UpdateSketch, UpdateSolid},
         },
         services::Services,
@@ -46,8 +46,11 @@ pub fn model(
                 (cycle.half_edges().nth(2).unwrap(), [split_pos]),
             ];
 
-            let (shell, _) = shell.split_face(face, line, services);
-            shell.insert(services)
+            let (shell, [face, _]) = shell.split_face(face, line, services);
+
+            shell
+                .sweep_face_of_shell(face, [0., 0., -size / 2.], services)
+                .insert(services)
         })
         .insert(services)
 }