Add BuildCycle::polygon

crates/fj-kernel/src/operations/build/cycle.rs

@@ -1,11 +1,39 @@
-use crate::objects::Cycle;
+use fj_math::Point;
+use itertools::Itertools;
+
+use crate::{
+    objects::{Cycle, HalfEdge},
+    operations::Insert,
+    services::Services,
+};
+
+use super::BuildHalfEdge;
 
 /// Build a [`Cycle`]
 pub trait BuildCycle {
     /// Build an empty cycle
     fn empty() -> Cycle {
         Cycle::new([])
     }
+
+    /// Build a polygon
+    fn polygon<P, Ps>(points: Ps, services: &mut Services) -> Cycle
+    where
+        P: Into<Point<2>>,
+        Ps: IntoIterator<Item = P>,
+        Ps::IntoIter: Clone + ExactSizeIterator,
+    {
+        let half_edges = points
+            .into_iter()
+            .map(Into::into)
+            .circular_tuple_windows()
+            .map(|(start, end)| {
+                HalfEdge::line_segment([start, end], None, services)
+                    .insert(services)
+            });
+
+        Cycle::new(half_edges)
+    }
 }
 
 impl BuildCycle for Cycle {}