Booleans: a face crossed by nested intersection loops (both walls of a tube) gives each hole to the innermost piece holding it (vendored shapeops; tubes and tori cut across now work); revolved full circles start at an odd angle so their seams don't lie in common cut planes

Oracle: 70/76.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/kernel/src/build.rs

@@ -144,7 +144,42 @@ pub fn revolve(plane: &Plane, regions: &[Region2], axis_origin: Vec2, axis_dir:
                 })
                 .collect(),
         };
-        let r = &Region2 { outer: snap_loop(&r.outer), holes: r.holes.iter().map(snap_loop).collect() };
+        // Full circles start at an odd angle: their seam points then don't lie in the planes
+        // through the profile's centre that other bodies tend to cut along.
+        let reseam = |l: Loop2| -> Loop2 {
+            let c = match l.segs.first() {
+                Some(Seg2::Arc { center, radius, .. }) => Some((*center, *radius)),
+                _ => None,
+            };
+            // (A circle touching the axis keeps its vertex there.)
+            let touches = c.is_some_and(|(center, radius)| (d.cross(center - axis_origin).abs() - radius).abs() < 1e-7);
+            match c {
+                Some((center, radius))
+                    if !touches
+                        && l.segs.iter().all(
+                            |s| matches!(s, Seg2::Arc { center: c2, radius: r2, .. } if c2.dist(center) < 1e-9 && (r2 - radius).abs() < 1e-9),
+                        )
+                        && (l
+                            .segs
+                            .iter()
+                            .map(|s| match s {
+                                Seg2::Arc { sweep, .. } => *sweep,
+                                _ => 0.0,
+                            })
+                            .sum::<f64>()
+                            .abs()
+                            - std::f64::consts::TAU)
+                            .abs()
+                            < 1e-6 =>
+                {
+                    let ccw = l.signed_area() > 0.0;
+                    let n = Loop2::circle_from(center, radius, 0.4142);
+                    if ccw { n } else { n.reversed() }
+                }
+                _ => l,
+            }
+        };
+        let r = &Region2 { outer: reseam(snap_loop(&r.outer)), holes: r.holes.iter().map(|h| reseam(snap_loop(h))).collect() };
         // A half disc on the axis revolved fully is a sphere: build it without poles.
         if angle.abs() >= std::f64::consts::TAU - 1e-9
             && r.holes.is_empty()

crates/kernel/src/tests.rs

@@ -1037,3 +1037,26 @@ fn overlapping_holes_and_mirror_joins() {
     assert!(rel(u.volume, v1 * 5.0 / 3.0) < 2e-4, "{} (one: {v1})", u.volume);
     assert_eq!(u.merged.faces, 3, "{:?}", u.merged);
 }
+
+#[test]
+fn torus_cut_through_its_middle_plane() {
+    // A torus whose tube centre lies in a box's top face: the box's top cuts the torus where
+    // the tube is vertical. (The revolve profile's seam points used to lie in that plane.)
+    let bx = box_solid(Vec3::new(-30.0, -30.0, -10.0), Vec3::new(30.0, 30.0, 0.0)).unwrap();
+    let xz = Plane::new(Vec3::ZERO, Vec3::X, Vec3::new(0.0, 0.0, -1.0)).unwrap();
+    let ring = Region2 { outer: Loop2::circle(Vec2::new(22.0, 0.0), 4.0), holes: vec![] };
+    let torus = revolve(&xz, &[ring], Vec2::ZERO, Vec2::new(0.0, -1.0), 2.0 * PI).unwrap().pop().unwrap();
+    let c = boolean(&bx, &torus, BoolOp::Cut).unwrap().unwrap();
+    // Half the torus volume (2π²Rr²) is removed.
+    let want = 36000.0 - PI * PI * 22.0 * 16.0;
+    let v = measure(&c).unwrap().volume;
+    assert!(rel(v, want) < 1e-4, "{v} vs {want}");
+    // A revolved tube cut across: both walls cross the box's top face (nested loops on it).
+    let tube =
+        Region2 { outer: Loop2::polygon(&[Vec2::new(5.0, 0.0), Vec2::new(10.0, 0.0), Vec2::new(10.0, -30.0), Vec2::new(5.0, -30.0)]), holes: vec![] };
+    let t = revolve(&xz, &[tube], Vec2::ZERO, Vec2::new(0.0, -1.0), 2.0 * PI).unwrap().pop().unwrap();
+    let bx = box_solid(Vec3::new(-40.0, -40.0, -40.0), Vec3::new(40.0, 40.0, 10.0)).unwrap();
+    let i = boolean(&t, &bx, BoolOp::Intersect).unwrap().unwrap();
+    let v = measure(&i).unwrap().volume;
+    assert!(rel(v, PI * 75.0 * 10.0) < 1e-4, "{v}");
+}