From 9f309b65052f899e96e5e6b2188d398dac105e45 Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Mon, 19 Jun 2023 12:08:35 +0200
Subject: [PATCH 1/2] Add `BuildRegion::empty`

---
 crates/fj-core/src/operations/build/region.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/crates/fj-core/src/operations/build/region.rs b/crates/fj-core/src/operations/build/region.rs
index eacc85711..51c616e8f 100644
--- a/crates/fj-core/src/operations/build/region.rs
+++ b/crates/fj-core/src/operations/build/region.rs
@@ -8,6 +8,15 @@ use crate::{
 
 /// Build a [`Region`]
 pub trait BuildRegion {
+    /// Build an empty region
+    fn empty(services: &mut Services) -> Region {
+        let exterior = Cycle::empty().insert(services);
+        let interiors = [];
+        let color = None;
+
+        Region::new(exterior, interiors, color)
+    }
+
     /// Build a circle
     fn circle(
         center: impl Into<Point<2>>,

From 4bdf3949214abbe0ecb47727974acac78b2f13f4 Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Mon, 19 Jun 2023 12:21:23 +0200
Subject: [PATCH 2/2] Add `star` model

---
 Cargo.lock              |  7 ++++++
 Cargo.toml              |  1 +
 models/star/Cargo.toml  |  7 ++++++
 models/star/src/lib.rs  | 53 +++++++++++++++++++++++++++++++++++++++++
 models/star/src/main.rs |  7 ++++++
 5 files changed, 75 insertions(+)
 create mode 100644 models/star/Cargo.toml
 create mode 100644 models/star/src/lib.rs
 create mode 100644 models/star/src/main.rs

diff --git a/Cargo.lock b/Cargo.lock
index aba1d14f0..d9e84050a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2737,6 +2737,13 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "star"
+version = "0.1.0"
+dependencies = [
+ "fj",
+]
+
 [[package]]
 name = "static_assertions"
 version = "1.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index cced879a7..f2459e714 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,6 +11,7 @@ members = [
 
     "models/cuboid",
     "models/spacer",
+    "models/star",
 
     "tools/autolib",
     "tools/automator",
diff --git a/models/star/Cargo.toml b/models/star/Cargo.toml
new file mode 100644
index 000000000..0279bef41
--- /dev/null
+++ b/models/star/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "star"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies.fj]
+path = "../../crates/fj"
diff --git a/models/star/src/lib.rs b/models/star/src/lib.rs
new file mode 100644
index 000000000..9910cbead
--- /dev/null
+++ b/models/star/src/lib.rs
@@ -0,0 +1,53 @@
+use std::f64::consts::PI;
+
+use fj::{
+    core::{
+        algorithms::sweep::Sweep,
+        objects::{Cycle, Region, Sketch, Solid},
+        operations::{
+            BuildCycle, BuildRegion, BuildSketch, Insert, Reverse,
+            UpdateRegion, UpdateSketch,
+        },
+        services::Services,
+        storage::Handle,
+    },
+    math::Vector,
+};
+
+pub fn model(num_points: u64, r1: f64, r2: f64, h: f64) -> Handle<Solid> {
+    let mut services = Services::new();
+
+    let num_vertices = num_points * 2;
+    let vertex_iter = (0..num_vertices).map(|i| {
+        let angle_rad = 2. * PI / num_vertices as f64 * i as f64;
+        let radius = if i % 2 == 0 { r1 } else { r2 };
+        (angle_rad, radius)
+    });
+
+    let mut outer_points = Vec::new();
+    let mut inner_points = Vec::new();
+
+    for (angle_rad, radius) in vertex_iter {
+        let (sin, cos) = angle_rad.sin_cos();
+
+        let x = cos * radius;
+        let y = sin * radius;
+
+        outer_points.push([x, y]);
+        inner_points.push([x / 2., y / 2.]);
+    }
+
+    let sketch = Sketch::empty()
+        .add_region(
+            Region::polygon(outer_points, &mut services)
+                .add_interiors([Cycle::polygon(inner_points, &mut services)
+                    .reverse(&mut services)
+                    .insert(&mut services)])
+                .insert(&mut services),
+        )
+        .insert(&mut services);
+
+    let surface = services.objects.surfaces.xy_plane();
+    let path = Vector::from([0., 0., h]);
+    (sketch, surface).sweep(path, &mut services)
+}
diff --git a/models/star/src/main.rs b/models/star/src/main.rs
new file mode 100644
index 000000000..c6f11d59c
--- /dev/null
+++ b/models/star/src/main.rs
@@ -0,0 +1,7 @@
+use fj::handle_model;
+
+fn main() -> fj::Result {
+    let model = star::model(5, 1., 2., 1.);
+    handle_model(model)?;
+    Ok(())
+}