Return top edge from half-edge sweep

This is going to be required in the face sweep code, to make sure the
top of the solid is properly stitched up with the sides.

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

@@ -17,7 +17,7 @@ use crate::{
 use super::{Sweep, SweepCache};
 
 impl Sweep for (Handle<HalfEdge>, Color) {
- type Swept = Handle<Face>;
+ type Swept = (Handle<Face>, Handle<HalfEdge>);
 
  fn sweep_with_cache(
  self,
@@ -137,7 +137,7 @@ impl Sweep for (Handle<HalfEdge>, Color) {
  let cycle = {
  let a = bottom_edge;
  let [d, b] = side_edges;
- let c = top_edge;
+ let c = top_edge.clone();
 
  let mut edges = [a, b, c, d];
 
@@ -167,7 +167,9 @@ impl Sweep for (Handle<HalfEdge>, Color) {
  color: Some(color),
  ..Default::default()
  };
- face.build(objects).insert(objects)
+ let face = face.build(objects).insert(objects);
+
+ (face, top_edge)
  }
 }
 
@@ -202,7 +204,7 @@ mod tests {
  .insert(&mut services.objects)
  };
 
- let face = (half_edge, Color::default())
+ let (face, _) = (half_edge, Color::default())
  .sweep([0., 0., 1.], &mut services.objects);
 
  let expected_face = {

crates/fj-kernel/src/algorithms/sweep/face.rs

@@ -65,7 +65,7 @@ impl Sweep for Handle<Face> {
  let cycle = cycle.reverse(objects);
 
  for half_edge in cycle.half_edges().cloned() {
- let face = (half_edge, self.color())
+ let (face, _) = (half_edge, self.color())
  .sweep_with_cache(path, cache, objects);
 
  faces.push(face);
@@ -155,7 +155,9 @@ mod tests {
  .build(&mut services.objects)
  .insert(&mut services.objects)
  };
- (half_edge, Color::default()).sweep(UP, &mut services.objects)
+ let (face, _) =
+ (half_edge, Color::default()).sweep(UP, &mut services.objects);
+ face
  });
 
  assert!(side_faces
@@ -222,7 +224,9 @@ mod tests {
  .insert(&mut services.objects)
  .reverse(&mut services.objects)
  };
- (half_edge, Color::default()).sweep(DOWN, &mut services.objects)
+ let (face, _) = (half_edge, Color::default())
+ .sweep(DOWN, &mut services.objects);
+ face
  });
 
  assert!(side_faces