Remove end_vertex fields of HalfEdge/PartialHalfEdge

crates/fj-kernel/src/algorithms/approx/edge.rs

@@ -357,7 +357,7 @@ mod tests {
             half_edge.update_as_circle_from_radius(1.);
             half_edge.infer_vertex_positions_if_necessary(
                 &surface.geometry(),
-                half_edge.end_vertex.clone(),
+                half_edge.start_vertex.clone(),
             );
 
             half_edge

crates/fj-kernel/src/algorithms/reverse/cycle.rs

@@ -25,7 +25,6 @@ impl Reverse for Handle<Cycle> {
                     current.curve(),
                     boundary,
                     next.start_vertex().clone(),
-                    current.start_vertex().clone(),
                     current.global_form().clone(),
                 )
                 .insert(objects)

crates/fj-kernel/src/algorithms/transform/edge.rs

@@ -22,16 +22,12 @@ impl TransformObject for HalfEdge {
             .start_vertex()
             .clone()
             .transform_with_cache(transform, objects, cache);
-        let end_vertex = self
-            .end_vertex()
-            .clone()
-            .transform_with_cache(transform, objects, cache);
         let global_form = self
             .global_form()
             .clone()
             .transform_with_cache(transform, objects, cache);
 
-        Self::new(curve, boundary, start_vertex, end_vertex, global_form)
+        Self::new(curve, boundary, start_vertex, global_form)
     }
 }
 

crates/fj-kernel/src/builder/cycle.rs

@@ -92,21 +92,17 @@ impl CycleBuilder for PartialCycle {
         {
             let shared_surface_vertex =
                 new_half_edge.read().start_vertex.clone();
-
-            let mut last_half_edge = last_half_edge.write();
-
-            last_half_edge.end_vertex = shared_surface_vertex.clone();
-            last_half_edge.infer_global_form(shared_surface_vertex);
+            last_half_edge
+                .write()
+                .infer_global_form(shared_surface_vertex);
         }
 
         {
             let shared_surface_vertex =
                 first_half_edge.read().start_vertex.clone();
-
-            let mut new_half_edge = new_half_edge.write();
-
-            new_half_edge.end_vertex = shared_surface_vertex.clone();
-            new_half_edge.infer_global_form(shared_surface_vertex);
+            new_half_edge
+                .write()
+                .infer_global_form(shared_surface_vertex);
         }
 
         self.half_edges.push(new_half_edge.clone());
@@ -152,9 +148,9 @@ impl CycleBuilder for PartialCycle {
     where
         O: ObjectArgument<Partial<HalfEdge>>,
     {
-        edges.map(|other| {
+        edges.map_with_prev(|other, prev| {
             let mut this = self.add_half_edge();
-            this.write().update_from_other_edge(&other, surface);
+            this.write().update_from_other_edge(&other, &prev, surface);
             this
         })
     }

crates/fj-kernel/src/builder/edge.rs

@@ -64,6 +64,7 @@ pub trait HalfEdgeBuilder {
     fn update_from_other_edge(
         &mut self,
         other: &Partial<HalfEdge>,
+        other_prev: &Partial<HalfEdge>,
         surface: &SurfaceGeometry,
     );
 }
@@ -81,7 +82,6 @@ impl HalfEdgeBuilder for PartialHalfEdge {
 
         self.start_vertex.write().position =
             Some(path.point_from_path_coords(a_curve));
-        self.end_vertex = self.start_vertex.clone();
 
         for (point_boundary, point_curve) in
             self.boundary.each_mut_ext().zip_ext([a_curve, b_curve])
@@ -233,6 +233,7 @@ impl HalfEdgeBuilder for PartialHalfEdge {
     fn update_from_other_edge(
         &mut self,
         other: &Partial<HalfEdge>,
+        other_prev: &Partial<HalfEdge>,
         surface: &SurfaceGeometry,
     ) {
         self.curve = other.read().curve.as_ref().and_then(|path| {
@@ -309,15 +310,13 @@ impl HalfEdgeBuilder for PartialHalfEdge {
             }
         });
 
-        let other = other.read();
-
-        for (this, other) in [&mut self.start_vertex, &mut self.end_vertex]
-            .iter_mut()
-            .zip([&other.end_vertex, &other.start_vertex])
-        {
-            this.write().global_form.write().position =
-                other.read().global_form.read().position;
-        }
+        self.start_vertex.write().global_form.write().position = other_prev
+            .read()
+            .start_vertex
+            .read()
+            .global_form
+            .read()
+            .position;
     }
 }
 

crates/fj-kernel/src/builder/mod.rs

@@ -53,6 +53,14 @@ pub trait ObjectArgument<T>: IntoIterator<Item = T> {
     where
         F: FnMut(T) -> R;
 
+    /// Create a return value by mapping the implementing type
+    ///
+    /// Provides access to the (circular) next item.
+    fn map_with_prev<F, R>(self, f: F) -> Self::SameSize<R>
+    where
+        F: FnMut(T, T) -> R,
+        T: Clone;
+
     /// Create a return value with one more element
     fn map_plus_one<F, R>(self, item: R, f: F) -> Self::SizePlusOne<R>
     where
@@ -80,6 +88,25 @@ impl<T> ObjectArgument<T> for Vec<T> {
         ret
     }
 
+    fn map_with_prev<F, R>(self, mut f: F) -> Self::SameSize<R>
+    where
+        F: FnMut(T, T) -> R,
+        T: Clone,
+    {
+        let mut prev = Vec::new();
+        for i in 0..self.len() {
+            prev.push(self[(i + self.len() - 1) % self.len()].clone());
+        }
+
+        let mut ret = Vec::new();
+        for (i, item) in self.into_iter().enumerate() {
+            let prev = prev[i].clone();
+            ret.push(f(item, prev));
+        }
+
+        ret
+    }
+
     fn map_plus_one<F, R>(self, item: R, f: F) -> Self::SizePlusOne<R>
     where
         F: FnMut(T) -> R,
@@ -112,6 +139,24 @@ macro_rules! impl_object_argument_for_arrays {
                     self.map(f)
                 }
 
+                fn map_with_prev<F, R>(self, mut f: F) -> Self::SameSize<R>
+                where
+                    F: FnMut(T, T) -> R,
+                    T: Clone,
+                {
+                    let prev: [_; $len] = array::from_fn(|i| {
+                        self[(i + self.len() - 1) % self.len()].clone()
+                    });
+
+                    let mut i = 0;
+                    self.map(|item| {
+                        let prev = prev[i].clone();
+                        i += 1;
+
+                        f(item, prev)
+                    })
+                }
+
                 fn map_plus_one<F, R>(self, item: R, mut f: F)
                     -> Self::SizePlusOne<R>
                 where

crates/fj-kernel/src/objects/full/edge.rs

@@ -47,7 +47,6 @@ pub struct HalfEdge {
     curve: Curve,
     boundary: [Point<1>; 2],
     start_vertex: Handle<SurfaceVertex>,
-    end_vertex: Handle<SurfaceVertex>,
     global_form: Handle<GlobalEdge>,
 }
 
@@ -57,14 +56,12 @@ impl HalfEdge {
         curve: Curve,
         boundary: [Point<1>; 2],
         start_vertex: Handle<SurfaceVertex>,
-        end_vertex: Handle<SurfaceVertex>,
         global_form: Handle<GlobalEdge>,
     ) -> Self {
         Self {
             curve,
             boundary,
             start_vertex,
-            end_vertex,
             global_form,
         }
     }
@@ -94,11 +91,6 @@ impl HalfEdge {
         &self.start_vertex
     }
 
-    /// Access the vertex from where this half-edge ends
-    pub fn end_vertex(&self) -> &Handle<SurfaceVertex> {
-        &self.end_vertex
-    }
-
     /// Access the global form of the half-edge
     pub fn global_form(&self) -> &Handle<GlobalEdge> {
         &self.global_form

crates/fj-kernel/src/partial/objects/edge.rs

@@ -18,9 +18,6 @@ pub struct PartialHalfEdge {
     /// The surface vertex where the half-edge starts
     pub start_vertex: Partial<SurfaceVertex>,
 
-    /// The surface vertex where the half-edge ends
-    pub end_vertex: Partial<SurfaceVertex>,
-
     /// The global form of the half-edge
     pub global_form: Partial<GlobalEdge>,
 }
@@ -46,10 +43,6 @@ impl PartialObject for PartialHalfEdge {
                 half_edge.start_vertex().clone(),
                 cache,
             ),
-            end_vertex: Partial::from_full(
-                half_edge.end_vertex().clone(),
-                cache,
-            ),
             global_form: Partial::from_full(
                 half_edge.global_form().clone(),
                 cache,
@@ -70,10 +63,9 @@ impl PartialObject for PartialHalfEdge {
             point.expect("Can't build `HalfEdge` without boundary positions")
         });
         let start_vertex = self.start_vertex.build(objects);
-        let end_vertex = self.end_vertex.build(objects);
         let global_form = self.global_form.build(objects);
 
-        HalfEdge::new(curve, boundary, start_vertex, end_vertex, global_form)
+        HalfEdge::new(curve, boundary, start_vertex, global_form)
     }
 }
 
@@ -99,7 +91,6 @@ impl Default for PartialHalfEdge {
             curve,
             boundary: [None; 2],
             start_vertex,
-            end_vertex,
             global_form,
         }
     }

crates/fj-kernel/src/validate/cycle.rs

@@ -15,7 +15,6 @@ impl Validate for Cycle {
         config: &ValidationConfig,
         errors: &mut Vec<ValidationError>,
     ) {
-        CycleValidationError::check_half_edge_connections(self, errors);
         CycleValidationError::check_half_edge_boundaries(self, config, errors);
     }
 }
@@ -69,26 +68,6 @@ pub enum CycleValidationError {
 }
 
 impl CycleValidationError {
-    fn check_half_edge_connections(
-        cycle: &Cycle,
-        errors: &mut Vec<ValidationError>,
-    ) {
-        for (a, b) in cycle.half_edges().circular_tuple_windows() {
-            let prev = a.end_vertex();
-            let next = b.start_vertex();
-
-            if prev.id() != next.id() {
-                errors.push(
-                    Self::HalfEdgeConnection {
-                        prev: prev.clone(),
-                        next: next.clone(),
-                    }
-                    .into(),
-                );
-            }
-        }
-    }
-
     fn check_half_edge_boundaries(
         cycle: &Cycle,
         config: &ValidationConfig,
@@ -138,52 +117,6 @@ mod tests {
         validate::{CycleValidationError, Validate, ValidationError},
     };
 
-    #[test]
-    fn cycle_half_edge_connections() -> anyhow::Result<()> {
-        let mut services = Services::new();
-
-        let valid = {
-            let surface = services.objects.surfaces.xy_plane();
-
-            let mut cycle = PartialCycle::default();
-            cycle.update_as_polygon_from_points([[0., 0.], [1., 0.], [0., 1.]]);
-            cycle.infer_vertex_positions_if_necessary(&surface.geometry());
-            cycle.build(&mut services.objects)
-        };
-        let invalid = {
-            let mut half_edges = valid
-                .half_edges()
-                .map(|half_edge| Partial::from(half_edge.clone()))
-                .collect::<Vec<_>>();
-
-            // Sever connection between the last and first half-edge in the
-            // cycle.
-            {
-                let first_half_edge = half_edges.first_mut().unwrap();
-                let first_vertex = &mut first_half_edge.write().start_vertex;
-                let surface_vertex =
-                    Partial::from_partial(first_vertex.read().clone());
-                *first_vertex = surface_vertex;
-            }
-
-            let half_edges = half_edges
-                .into_iter()
-                .map(|half_edge| half_edge.build(&mut services.objects));
-
-            Cycle::new(half_edges)
-        };
-
-        valid.validate_and_return_first_error()?;
-        assert!(matches!(
-            invalid.validate_and_return_first_error(),
-            Err(ValidationError::Cycle(
-                CycleValidationError::HalfEdgeConnection { .. }
-            ))
-        ));
-
-        Ok(())
-    }
-
     #[test]
     fn vertex_position_mismatch() -> anyhow::Result<()> {
         let mut services = Services::new();

crates/fj-kernel/src/validate/edge.rs

@@ -175,7 +175,6 @@ mod tests {
                 valid.curve(),
                 valid.boundary(),
                 valid.start_vertex().clone(),
-                valid.end_vertex().clone(),
                 global_form,
             )
         };
@@ -216,7 +215,6 @@ mod tests {
                 valid.curve(),
                 boundary,
                 valid.start_vertex().clone(),
-                valid.end_vertex().clone(),
                 valid.global_form().clone(),
             )
         };