From 769cad1e3e9c7c0160a916e5d80b8b0f9da9431b Mon Sep 17 00:00:00 2001
From: Hanno Braun <hello@hannobraun.com>
Date: Fri, 21 Mar 2025 21:35:21 +0100
Subject: [PATCH] Fix assumption that is no longer valid

---
 crates/fj-core/src/algorithms/triangulate/delaunay.rs |  7 ++++++-
 crates/fj-math/src/triangle.rs                        | 11 ++++-------
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/crates/fj-core/src/algorithms/triangulate/delaunay.rs b/crates/fj-core/src/algorithms/triangulate/delaunay.rs
index c6e0f1b7f..e0e2ce7ae 100644
--- a/crates/fj-core/src/algorithms/triangulate/delaunay.rs
+++ b/crates/fj-core/src/algorithms/triangulate/delaunay.rs
@@ -61,7 +61,12 @@ pub fn triangulate(
             Handedness::LeftHanded => Winding::Cw,
             Handedness::RightHanded => Winding::Ccw,
         };
-        let actual_winding = triangle.winding();
+        let Some(actual_winding) = triangle.winding() else {
+            unreachable!(
+                "Just asserted that the triangle is valid. Therefore it must \
+                have a winding."
+            );
+        };
 
         let triangle = if actual_winding == required_winding {
             [v0, v1, v2]
diff --git a/crates/fj-math/src/triangle.rs b/crates/fj-math/src/triangle.rs
index 1cea0b0ff..cced92bb1 100644
--- a/crates/fj-math/src/triangle.rs
+++ b/crates/fj-math/src/triangle.rs
@@ -69,7 +69,7 @@ impl<const D: usize> Triangle<D> {
 
 impl Triangle<2> {
     /// # Compute the winding of the triangle
-    pub fn winding(&self) -> Winding {
+    pub fn winding(&self) -> Option<Winding> {
         let [pa, pb, pc] = self.points.map(|point| robust::Coord {
             x: point.u,
             y: point.v,
@@ -77,16 +77,13 @@ impl Triangle<2> {
         let orient2d = robust::orient2d(pa, pb, pc);
 
         if orient2d < 0. {
-            return Winding::Cw;
+            return Some(Winding::Cw);
         }
         if orient2d > 0. {
-            return Winding::Ccw;
+            return Some(Winding::Ccw);
         }
 
-        unreachable!(
-            "Points don't form a triangle, but this was verified in the \
-            constructor."
-        )
+        None
     }
 }