Fillet: refuse only crossed faces the round makes, not ones the body had (#1488) (#1517)

Thanks @erkexzcx.

crates/engine/src/tests.rs

@@ -316,6 +316,7 @@ mod loft_spacing;
 mod mirror_planes;
 #[cfg(not(target_arch = "wasm32"))]
 mod native_cad_import;
+mod nudge_slivers;
 mod path_scope;
 mod pleat_join;
 mod primitive_points;

crates/engine/src/tests/nudge_slivers.rs

@@ -0,0 +1,76 @@
+//! #1488: a loft joined into a slab, flush with the slab's outer face and its bottom, takes the
+//! boolean's last retry (the tool nudged a fraction of a micron). That leaves sliver faces
+//! along the flush faces, one of which reads as a face whose boundary crosses itself; every
+//! later round on the body was then refused for it ("the rounds would leave openings"), even
+//! one 36 mm away. A round is now refused only for crossed faces it makes.
+
+use serde_json::json;
+
+use super::run;
+use crate::Session;
+
+/// The issue's slab `width` thick with a window through it and the pleat loft joined into it.
+fn slab_with_pleat(width: f64) -> Session {
+    let mut s = Session::default();
+    run(&mut s, "solid.box", json!({"corner": [-60, 0, 0], "length": 120, "width": width, "height": 95, "body_name": "Wall"}));
+    run(
+        &mut s,
+        "solid.box",
+        json!({"corner": [-24, -0.5, -1], "length": 48, "width": width + 1.0, "height": 91, "operation": "cut", "targets": ["Wall"]}),
+    );
+    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "Bottom"}));
+    run(
+        &mut s,
+        "sketch.line",
+        json!({"closed": true, "infer": false, "connect": false, "points": [
+            [-26, 3], [-24.76384, 3], [-16.0568, 14.97217], [-8, 4.90117], [0, 14.90117], [8, 4.90117], [16.0568, 14.97217], [24.76384, 3], [26, 3],
+            [26, 0], [23.23616, 0], [15.9432, 10.02783], [8, 0.09883], [0, 10.09883], [-8, 0.09883], [-15.9432, 10.02783], [-23.23616, 0], [-26, 0]]}),
+    );
+    run(&mut s, "sketch.finish", json!({}));
+    run(&mut s, "sketch.create", json!({"plane": "XY", "offset": 90.5, "name": "Top"}));
+    run(
+        &mut s,
+        "sketch.line",
+        json!({"closed": true, "infer": false, "connect": false, "points": [
+            [-26, 3], [-24, 3], [-16, 3], [-8, 3], [0, 3], [8, 3], [16, 3], [24, 3], [26, 3],
+            [26, 0], [24, 0], [16, 0], [8, 0], [0, 0], [-8, 0], [-16, 0], [-24, 0], [-26, 0]]}),
+    );
+    run(&mut s, "sketch.finish", json!({}));
+    run(
+        &mut s,
+        "solid.loft",
+        json!({"sections": [{"sketch": "Bottom"}, {"sketch": "Top"}], "operation": "join", "targets": ["Wall"], "name": "Pleat"}),
+    );
+    s
+}
+
+fn wall(s: &Session) -> solidcraft_kernel::Body {
+    s.model.state().body("Wall").map(|b| b.body.clone()).unwrap()
+}
+
+/// The R1 round on the slab's end edge at x = −60 works after the join, as it does on the 3 mm
+/// slab (and on the 3.5 mm one before the loft), and adds no crossed face of its own.
+#[test]
+fn a_round_far_from_the_joined_loft_works() {
+    for (width, pick) in [(3.5, [-60.0, 1.75, 95.0]), (3.0, [-60.0, 1.5, 95.0])] {
+        let mut s = slab_with_pleat(width);
+        let before = wall(&s);
+        let r = s.execute("solid.fillet", &json!({"body": "Wall", "edges": [pick], "radius": 1}));
+        assert!(r.is_ok(), "{width} mm: {r:?}");
+        let after = wall(&s);
+        assert_eq!(after.face_count(), before.face_count() + 1, "{width} mm: one round face");
+        assert_eq!(after.crossed_faces().unwrap(), before.crossed_faces().unwrap(), "{width} mm");
+        // The round lies along the picked edge: the end face's top corner is gone.
+        let m = solidcraft_kernel::measure(&after).unwrap();
+        assert!((m.bbox.min.x + 60.0).abs() < 1e-6 && (m.bbox.max.z - 95.0).abs() < 1e-6, "{width} mm: {:?}", m.bbox);
+    }
+}
+
+/// A round that does cross faces is still refused, joined loft or not (#871's check stands).
+#[test]
+fn rounds_that_overlap_are_still_refused() {
+    let mut s = slab_with_pleat(3.5);
+    // Both long top edges of the 3.5 mm slab with a radius over half its thickness.
+    let r = s.execute("solid.fillet", &json!({"body": "Wall", "edges": [[-40, 0, 95], [-40, 3.5, 95]], "radius": 2}));
+    assert!(r.is_err(), "{r:?}");
+}

crates/kernel/src/blend.rs

@@ -1121,7 +1121,7 @@ pub fn fillet_g2(body: &Body, edges: &[Vec3], radius: f64) -> Result<Body> {
         let (made, rec) = guard("G2 fillet", || blend_one(&solid, &edge, size, radius, Shape::Curvature))?;
         cur = record::after(record::rebuilt(made, &[&solid], &rec)?, &cur, &counts);
     }
-    closed(cur)
+    closed(body, cur)
 }
 
 /// Most edges whose other orders are tried when the order given is refused.
@@ -1804,9 +1804,16 @@ fn loop_split(cur: &Body, pts: &[Vec3]) -> Result<Option<(Vec<Vec<Vec3>>, Vec<Ve
 /// A fillet's result, refused when a face's boundary crosses itself (#871): rounds that
 /// overlap where a wall is thinner than both leave such faces, which the topology checks
 /// don't see but which show as holes in the model. A fillet either closes the solid or is
-/// refused.
-fn closed(b: Body) -> Result<Body> {
-    match b.crossed_face_loops()? {
+/// refused. Faces of `input` that crossed already and that the fillet carried over unchanged
+/// (a sliver an earlier boolean left far from the rounds, #1488) are not the fillet's doing.
+fn closed(input: &Body, b: Body) -> Result<Body> {
+    let after = b.crossed_faces()?;
+    if after.is_empty() {
+        return Ok(b);
+    }
+    let before = input.crossed_faces()?;
+    let tol = (input.size().max(b.size()) * 1e-6).max(1e-9);
+    match after.iter().filter(|p| !before.iter().any(|q| q.dist(**p) <= tol)).count() {
         0 => Ok(b),
         _ => Err(KernelError::Failed(
             "fillet: the rounds would leave openings in the surface (they overlap where a wall or a face is narrower than both)".into(),
@@ -1832,17 +1839,17 @@ pub fn fillet(body: &Body, edges: &[Vec3], radius: f64) -> Result<Body> {
 fn fillet_built(body: &Body, edges: &[Vec3], radius: f64) -> Result<Body> {
     // Corners the local blends refuse (an earlier round at an edge's end): radius per edge.
     blend(body, edges, radius, Shape::Round, "fillet")
-        .and_then(closed)
+        .and_then(|b| closed(body, b))
         .or_else(|e| {
             let sel: Vec<(Vec3, f64)> = edges.iter().map(|p| (*p, radius)).collect();
             // The local blend's refusal, unless only the corner build found the radius too large.
             crate::blend_corner::fillet_radii(body, &sel)
-                .and_then(closed)
+                .and_then(|b| closed(body, b))
                 .map_err(|e2| keep_size(e, e2))
                 // Three edges at a vertex of any faces end in a sphere.
                 .or_else(|e| {
                     if edges.len() >= 3 {
-                        crate::blend_vertex::fillet_ball_vertices(body, edges, radius).and_then(closed).map_err(|_| e)
+                        crate::blend_vertex::fillet_ball_vertices(body, edges, radius).and_then(|b| closed(body, b)).map_err(|_| e)
                     } else {
                         Err(e)
                     }
@@ -1850,9 +1857,9 @@ fn fillet_built(body: &Body, edges: &[Vec3], radius: f64) -> Result<Body> {
         })
         // Straight edges ending at a curved face that isn't an earlier round's: a rolling ball
         // trimmed by the face. Refused, the refusal above stands.
-        .or_else(|e| blend_with(body, edges, radius, Shape::Round, "fillet", true).and_then(closed).map_err(|_| e))
+        .or_else(|e| blend_with(body, edges, radius, Shape::Round, "fillet", true).and_then(|b| closed(body, b)).map_err(|_| e))
         // Blends meeting at corners on curved faces: all at once.
-        .or_else(|e| corners(body, edges, radius, Shape::Round, "fillet").and_then(closed).map_err(|e2| keep_size(e, e2)))
+        .or_else(|e| corners(body, edges, radius, Shape::Round, "fillet").and_then(|b| closed(body, b)).map_err(|e2| keep_size(e, e2)))
 }
 
 /// The first refusal, unless only the second found the blend too large (a smaller one may fit).
@@ -1970,7 +1977,7 @@ pub fn fillet_each(body: &Body, edges: &[Vec3], radii: &[f64]) -> Result<Body> {
         }
         Ok(b)
     };
-    if let Ok(b) = crate::blend_corner::fillet_radii(body, &sel).and_then(closed).and_then(fit) {
+    if let Ok(b) = crate::blend_corner::fillet_radii(body, &sel).and_then(|b| closed(body, b)).and_then(fit) {
         return Ok(b);
     }
     let mut by_radius: Vec<(f64, Vec<Vec3>)> = Vec::new();

crates/kernel/src/body.rs

@@ -1165,15 +1165,21 @@ impl Body {
     /// (rounds that overlap where a wall is thinner than both, #871). Boundaries that only
     /// touch (at a vertex they share, or within the size's millionth) don't count.
     pub fn crossed_face_loops(&self) -> Result<usize> {
+        Ok(self.crossed_faces()?.len())
+    }
+
+    /// The faces [`Body::crossed_face_loops`] counts, each as the mean of its boundary's
+    /// points: the same for a face an operation carried over unchanged.
+    pub fn crossed_faces(&self) -> Result<Vec<Vec3>> {
         use mt::{BoundedCurve, ParameterDivision1D};
         if self.is_mesh() {
-            return Ok(0);
+            return Ok(Vec::new());
         }
         const MAX_SEGMENTS: usize = 20_000;
         let size = self.size();
         let tol = (size * 1e-6).max(1e-9);
         let chord = (size * 1e-3).max(1e-4);
-        let mut crossed = 0;
+        let mut crossed = Vec::new();
         for f in self.solid.face_iter() {
             let mt::Surface::Plane(pl) = f.oriented_surface() else { continue };
             let o = from_p3(pl.origin());
@@ -1226,7 +1232,10 @@ impl Body {
                 loops.iter().enumerate().flat_map(|(l, segs)| segs.iter().map(move |s| (l, s))).collect();
             let bad = all.iter().enumerate().any(|(i, (_, s))| all.iter().skip(i + 1).any(|(_, t)| cross(s, t)));
             if bad {
-                crossed += 1;
+                let ends: Vec<(f64, f64)> = all.iter().map(|(_, s)| s.0).collect();
+                let k = ends.len().max(1) as f64;
+                let (su, sv) = ends.iter().fold((0.0, 0.0), |acc, p| (acc.0 + p.0, acc.1 + p.1));
+                crossed.push(o + u * (su / k) + v * (sv / k));
             }
         }
         Ok(crossed)