M0: truck-based kernel with local fillets and chamfers, parametric document timeline

The kernel moved from monstertruck to truck: truck's booleans handle blind
holes, pockets and bosses that monstertruck's did not (see the ADR). Fillets
and chamfers on straight convex edges between planar faces are our own exact
local B-rep operation. The document holds parameters with unit-aware
expressions and a timeline that re-evaluates incrementally.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/kernel/src/blend.rs

@@ -0,0 +1,307 @@
+//! Edge fillets and chamfers as a local B-rep operation.
+//!
+//! Supported: a straight, convex edge between two planar faces whose two end vertices each
+//! touch exactly one more planar face perpendicular to the edge (the common case for edges of
+//! extruded and box-like parts). The two side faces are trimmed back, the end faces get an arc
+//! (fillet) or a line (chamfer) at the corner, and a cylindrical (or planar) face is inserted.
+//! The result is exact. Edges meeting at an already blended corner, curved edges and other
+//! configurations are reported as not supported yet.
+
+use std::collections::HashMap;
+
+use solvecraft_geom::Vec3;
+use truck_modeling::{self as mt, builder};
+
+use crate::body::{Body, Solid, from_p3, p3, v3};
+use crate::{KernelError, Result, guard};
+
+#[derive(Clone, Copy, PartialEq)]
+enum Shape {
+    Round,
+    Flat,
+}
+
+fn unsupported(msg: &str) -> KernelError {
+    KernelError::Failed(format!("not supported yet: {msg}"))
+}
+
+fn vtx(v: &mt::Vertex) -> Vec3 {
+    from_p3(v.point())
+}
+
+/// Outward unit normal of a planar face (from its oriented surface), if planar.
+fn plane_normal(f: &mt::Face) -> Option<Vec3> {
+    match f.oriented_surface() {
+        mt::Surface::Plane(p) => {
+            let n = p.normal();
+            Vec3::new(n.x, n.y, n.z).normalized()
+        }
+        _ => None,
+    }
+}
+
+/// Replace edges in a face's oriented boundary (by id, keeping orientation), and insert extra
+/// edges where consecutive edges no longer connect.
+fn rebuild_face(f: &mt::Face, subst: &HashMap<mt::EdgeID, mt::Edge>, connectors: &[mt::Edge]) -> Result<mt::Face> {
+    let mut wires = Vec::new();
+    for w in f.boundaries() {
+        let mut edges: Vec<mt::Edge> = Vec::new();
+        for e in w.edge_iter() {
+            let ne = match subst.get(&e.id()) {
+                Some(n) => {
+                    // `n` was built in the orientation of the stored edge; match this use.
+                    let stored_forward = e.front() == e.absolute_front();
+                    if stored_forward { n.clone() } else { n.inverse() }
+                }
+                None => e.clone(),
+            };
+            edges.push(ne);
+        }
+        // Close gaps with connector edges.
+        let n = edges.len();
+        let mut out: Vec<mt::Edge> = Vec::new();
+        for i in 0..n {
+            let (Some(cur), Some(next)) = (edges.get(i), edges.get((i + 1) % n)) else { continue };
+            out.push(cur.clone());
+            if cur.back() != next.front() {
+                let c = connectors
+                    .iter()
+                    .find_map(|c| {
+                        if c.front() == cur.back() && c.back() == next.front() {
+                            Some(c.clone())
+                        } else if c.back() == cur.back() && c.front() == next.front() {
+                            Some(c.inverse())
+                        } else {
+                            None
+                        }
+                    })
+                    .ok_or_else(|| KernelError::Failed("blend: could not close a face boundary".into()))?;
+                out.push(c);
+            }
+        }
+        wires.push(mt::Wire::from(out));
+    }
+    let surface = f.oriented_surface();
+    mt::Face::try_new(wires, surface).map_err(|e| KernelError::Failed(format!("blend: {e}")))
+}
+
+fn blend_one(solid: &Solid, edge: &mt::Edge, size: f64, r: f64, shape: Shape) -> Result<Solid> {
+    if !matches!(edge.curve(), mt::Curve::Line(_)) {
+        return Err(unsupported("only straight edges can be blended"));
+    }
+    let shells = solid.boundaries();
+    let (si, shell) = shells
+        .iter()
+        .enumerate()
+        .find(|(_, sh)| sh.edge_iter().any(|e| e.id() == edge.id()))
+        .ok_or_else(|| KernelError::Failed("edge not found".into()))?;
+    let faces: Vec<&mt::Face> = shell.face_iter().collect();
+    let on_edge: Vec<usize> = (0..faces.len()).filter(|i| faces.get(*i).is_some_and(|f| f.edge_iter().any(|e| e.id() == edge.id()))).collect();
+    let [i1, i2] = on_edge[..] else { return Err(unsupported("the edge is not between two faces")) };
+    let (Some(f1), Some(f2)) = (faces.get(i1), faces.get(i2)) else { return Err(KernelError::Failed("faces".into())) };
+    let (Some(n1), Some(n2)) = (plane_normal(f1), plane_normal(f2)) else { return Err(unsupported("both faces next to the edge must be planar")) };
+    let (v0, v1) = (edge.absolute_front().clone(), edge.absolute_back().clone());
+    let (p0, p1) = (vtx(&v0), vtx(&v1));
+    let d = (p1 - p0).normalized().ok_or_else(|| KernelError::Failed("zero-length edge".into()))?;
+    // In-face directions perpendicular to the edge, pointing away from it.
+    let mut t1 = n1.cross(d);
+    if t1.dot(n2) > 0.0 {
+        t1 = -t1;
+    }
+    let mut t2 = n2.cross(d);
+    if t2.dot(n1) > 0.0 {
+        t2 = -t2;
+    }
+    // Convex edge: the faces' outward normals point away from each other's interior.
+    let cos_phi = t1.dot(t2).clamp(-1.0, 1.0);
+    let phi = cos_phi.acos();
+    if !(phi > 1e-3 && phi < std::f64::consts::PI - 1e-3) || n1.dot(t2) > 1e-9 || n2.dot(t1) > 1e-9 {
+        return Err(unsupported("only convex edges can be blended"));
+    }
+    blend_geometry(solid, si, &faces, (i1, i2), edge, (v0, v1), (p0, p1, d), (n1, t1, t2, phi), size, r, shape)
+}
+
+/// Distance along each face from the edge to the blend boundary.
+fn setback(r: f64, phi: f64, shape: Shape) -> f64 {
+    match shape {
+        Shape::Round => r / (phi / 2.0).tan(),
+        Shape::Flat => r,
+    }
+}
+
+#[allow(clippy::too_many_arguments)]
+fn blend_geometry(
+    solid: &Solid,
+    si: usize,
+    faces: &[&mt::Face],
+    (i1, i2): (usize, usize),
+    edge: &mt::Edge,
+    (v0, v1): (mt::Vertex, mt::Vertex),
+    (p0, p1, d): (Vec3, Vec3, Vec3),
+    (n1, t1, t2, phi): (Vec3, Vec3, Vec3, f64),
+    size: f64,
+    r: f64,
+    shape: Shape,
+) -> Result<Solid> {
+    let s = setback(r, phi, shape);
+    let tol = (size * 1e-7).max(1e-9);
+    // End faces and the side edges at each end.
+    struct End {
+        v: mt::Vertex,
+        g: usize,
+        e1: mt::Edge,
+        e2: mt::Edge,
+    }
+    let mut ends: Vec<End> = Vec::new();
+    for (v, p) in [(&v0, p0), (&v1, p1)] {
+        let at_v: Vec<usize> = (0..faces.len()).filter(|i| faces.get(*i).is_some_and(|f| f.vertex_iter().any(|x| &x == v))).collect();
+        let others: Vec<usize> = at_v.iter().copied().filter(|i| *i != i1 && *i != i2).collect();
+        let [g] = others[..] else { return Err(unsupported("each end of the edge must touch exactly one more face")) };
+        let gf = faces.get(g).ok_or_else(|| KernelError::Failed("face".into()))?;
+        let ng = plane_normal(gf).ok_or_else(|| unsupported("the faces at the edge ends must be planar"))?;
+        if ng.dot(d).abs() < 1.0 - 1e-9 {
+            return Err(unsupported("the faces at the edge ends must be perpendicular to the edge"));
+        }
+        // Edges at v shared by g with f1 and with f2.
+        let shared = |fi: usize| -> Result<mt::Edge> {
+            let f = faces.get(fi).ok_or_else(|| KernelError::Failed("face".into()))?;
+            f.edge_iter()
+                .find(|e| e.id() != edge.id() && (e.front() == v || e.back() == v) && gf.edge_iter().any(|x| x.id() == e.id()))
+                .ok_or_else(|| unsupported("unexpected corner topology"))
+        };
+        let (e1, e2) = (shared(i1)?, shared(i2)?);
+        for (e, t) in [(&e1, t1), (&e2, t2)] {
+            if !matches!(e.curve(), mt::Curve::Line(_)) {
+                return Err(unsupported("the edges at the corners must be straight"));
+            }
+            let other = if e.front() == v { vtx(e.back()) } else { vtx(e.front()) };
+            let along = (other - p).dot(t);
+            if (other - p - t * along).len() > tol * 100.0 + 1e-7 || along <= s + tol {
+                return Err(unsupported("the blend is larger than the neighbouring faces"));
+            }
+        }
+        ends.push(End { v: v.clone(), g, e1, e2 });
+    }
+    let [end0, end1] = &ends[..] else { return Err(KernelError::Failed("ends".into())) };
+    if end0.g == end1.g {
+        return Err(unsupported("both ends touch the same face"));
+    }
+    let a0 = builder::vertex(p3(p0 + t1 * s));
+    let b0 = builder::vertex(p3(p0 + t2 * s));
+    let a1 = builder::vertex(p3(p1 + t1 * s));
+    let b1 = builder::vertex(p3(p1 + t2 * s));
+    // Corner curves on the end faces (A → B) and the blend surface.
+    let bisector = (t1 + t2).normalized().ok_or_else(|| KernelError::Failed("bisector".into()))?;
+    let corner = |a: &mt::Vertex, b: &mt::Vertex, p: Vec3| -> mt::Edge {
+        match shape {
+            Shape::Round => {
+                // Arc centre is r inside both faces; its mid point is on the bisector, toward the edge.
+                let c = p + t1 * s - n1 * r;
+                let mid = c - bisector * r;
+                builder::circle_arc(a, b, p3(mid))
+            }
+            Shape::Flat => builder::line(a, b),
+        }
+    };
+    let c0 = corner(&a0, &b0, p0);
+    let c1 = corner(&a1, &b1, p1);
+    let la = builder::line(&a0, &a1);
+    let lb = builder::line(&b0, &b1);
+
+    // Substitutions: side edges at the ends now stop at A/B; the blended edge moves to A or B.
+    let mut subst: HashMap<mt::EdgeID, mt::Edge> = HashMap::new();
+    for (end, a, b) in [(end0, &a0, &b0), (end1, &a1, &b1)] {
+        for (e, nv) in [(&end.e1, a), (&end.e2, b)] {
+            let (f, bk) = (e.absolute_front(), e.absolute_back());
+            let ne = if f == &end.v { builder::line(nv, bk) } else { builder::line(f, nv) };
+            subst.insert(e.id(), ne);
+        }
+    }
+    let mut new_faces: Vec<mt::Face> = Vec::with_capacity(faces.len() + 1);
+    for (i, f) in faces.iter().enumerate() {
+        let nf = if i == i1 {
+            let mut m = subst.clone();
+            m.insert(edge.id(), la.clone());
+            rebuild_face(f, &m, &[])?
+        } else if i == i2 {
+            let mut m = subst.clone();
+            m.insert(edge.id(), lb.clone());
+            rebuild_face(f, &m, &[])?
+        } else if i == end0.g {
+            rebuild_face(f, &subst, std::slice::from_ref(&c0))?
+        } else if i == end1.g {
+            rebuild_face(f, &subst, std::slice::from_ref(&c1))?
+        } else {
+            (*f).clone()
+        };
+        new_faces.push(nf);
+    }
+    // The blend face uses each new edge opposite to its neighbour.
+    let f1_forward = faces.get(i1).is_some_and(|f| f.boundaries().iter().any(|w| w.edge_iter().any(|e| e.id() == edge.id() && e.front() == &v0)));
+    let wire: mt::Wire = if f1_forward {
+        vec![c0.clone(), lb.clone(), c1.inverse(), la.inverse()].into()
+    } else {
+        vec![la.clone(), c1.clone(), lb.inverse(), c0.inverse()].into()
+    };
+    let blend_face = match shape {
+        Shape::Flat => builder::try_attach_plane(&[wire]).map_err(|e| KernelError::Failed(format!("chamfer face: {e}")))?,
+        Shape::Round => {
+            let swept: mt::Face = builder::tsweep(&c0, v3(p1 - p0));
+            let mut surf = swept.oriented_surface();
+            // Outward normal at the arc middle points away from the arc centre.
+            let c = p0 + t1 * s - n1 * r;
+            let mid = c - bisector * r;
+            use mt::{ParametricSurface3D, SearchParameter};
+            if let Some((u, v)) = surf.search_parameter(p3(mid), None, 100) {
+                let nn = surf.normal(u, v);
+                if Vec3::new(nn.x, nn.y, nn.z).dot(bisector) > 0.0 {
+                    surf = mt::Invertible::inverse(&surf);
+                }
+            }
+            mt::Face::try_new(vec![wire], surf).map_err(|e| KernelError::Failed(format!("fillet face: {e}")))?
+        }
+    };
+    new_faces.push(blend_face);
+    let mut shells = solid.boundaries().clone();
+    let new_shell: mt::Shell = new_faces.into();
+    if let Some(sh) = shells.get_mut(si) {
+        *sh = new_shell;
+    }
+    Solid::try_new(shells).map_err(|e| KernelError::Failed(format!("blend produced an invalid solid: {e}")))
+}
+
+fn blend(body: &Body, edges: &[Vec3], r: f64, shape: Shape, what: &str) -> Result<Body> {
+    if !(r.is_finite() && r > 1e-6 && r < 1e6) {
+        return Err(KernelError::Invalid(format!("{what} size must be positive")));
+    }
+    if edges.is_empty() {
+        return Err(KernelError::Invalid("no edges selected".into()));
+    }
+    if edges.len() > 1000 {
+        return Err(KernelError::Invalid("too many edges".into()));
+    }
+    let mut cur = body.clone();
+    for p in edges {
+        let size = cur.size();
+        let tol = (size * 2e-3).max(1e-3);
+        let Some((idx, dist)) = cur.nearest_edge(*p, tol)? else { return Err(KernelError::Invalid("the body has no edges".into())) };
+        if dist > size * 0.05 + 1e-3 {
+            return Err(KernelError::Invalid(format!("no edge near {:?}", [p.x, p.y, p.z])));
+        }
+        let solid = cur.deep_copy();
+        let edge = Body::unique_edges(&solid).into_iter().nth(idx).ok_or_else(|| KernelError::Invalid("edge index".into()))?;
+        let out = guard(what, || blend_one(&solid, &edge, size, r, shape))?;
+        cur = Body::new(out)?;
+    }
+    Ok(cur)
+}
+
+/// Constant-radius fillet of the edges nearest to the given points.
+pub fn fillet(body: &Body, edges: &[Vec3], radius: f64) -> Result<Body> {
+    blend(body, edges, radius, Shape::Round, "fillet")
+}
+
+/// Equal-distance chamfer of the edges nearest to the given points.
+pub fn chamfer(body: &Body, edges: &[Vec3], distance: f64) -> Result<Body> {
+    blend(body, edges, distance, Shape::Flat, "chamfer")
+}

crates/kernel/src/body.rs

@@ -1,7 +1,7 @@
-use monstertruck_meshing::prelude::*;
-use monstertruck_modeling as mt;
 use serde::Serialize;
 use solvecraft_geom::{Mesh, Vec3};
+use truck_meshalgo::prelude::*;
+use truck_modeling as mt;
 
 use crate::{KernelError, Result, guard};
 
@@ -61,7 +61,7 @@ fn polyline_mid(pts: &[Vec3]) -> (Vec3, f64) {
 
 impl Body {
     pub(crate) fn new(mut solid: Solid) -> Result<Body> {
-        if solid.is_empty() {
+        if solid.boundaries().is_empty() {
             return Err(KernelError::Failed("empty result".into()));
         }
         // Orient outward: a closed solid must have positive volume.
@@ -216,6 +216,11 @@ impl Body {
         Ok(best)
     }
 
+    /// Is the point inside the solid?
+    pub fn contains(&self, p: Vec3) -> bool {
+        self.tessellate(self.size() * 2e-3).map(|m| m.contains(p)).unwrap_or(false)
+    }
+
     pub fn face_count(&self) -> usize {
         self.solid.face_iter().count()
     }

crates/kernel/src/build.rs

@@ -1,8 +1,8 @@
 //! Building bodies: extrude and revolve planar regions, primitives.
 
-use monstertruck_modeling as mt;
 use mt::builder;
 use solvecraft_geom::{Loop2, Plane, Region2, Seg2, Vec2, Vec3};
+use truck_modeling as mt;
 
 use crate::body::{Body, Solid, p3, v3};
 use crate::{KernelError, Result, guard};
@@ -33,20 +33,12 @@ fn wire(plane: &Plane, lp: &Loop2) -> Result<mt::Wire> {
                     return Err(KernelError::Invalid("zero-length arc".into()));
                 }
                 // Split big arcs so every piece is well conditioned.
-                let mid = plane.to_world(s.mid());
                 if sweep.abs() > std::f64::consts::PI * 1.5 {
-                    let vm = builder::vertex(p3(mid));
-                    let q1 = plane.to_world(s.point_at(0.25));
-                    let q3 = plane.to_world(s.point_at(0.75));
-                    edges.push(
-                        builder::try_circle_arc(a, &vm, mt::builder::CircularArcConstraint::ThroughPoint(p3(q1)))
-                            .map_err(|e| KernelError::Invalid(e.to_string()))?,
-                    );
-                    builder::try_circle_arc(&vm, b, mt::builder::CircularArcConstraint::ThroughPoint(p3(q3)))
-                        .map_err(|e| KernelError::Invalid(e.to_string()))?
+                    let vm = builder::vertex(p3(plane.to_world(s.mid())));
+                    edges.push(builder::circle_arc(a, &vm, p3(plane.to_world(s.point_at(0.25)))));
+                    builder::circle_arc(&vm, b, p3(plane.to_world(s.point_at(0.75))))
                 } else {
-                    builder::try_circle_arc(a, b, mt::builder::CircularArcConstraint::ThroughPoint(p3(mid)))
-                        .map_err(|e| KernelError::Invalid(e.to_string()))?
+                    builder::circle_arc(a, b, p3(plane.to_world(s.mid())))
                 }
             }
         };
@@ -61,7 +53,7 @@ pub(crate) fn face(plane: &Plane, r: &Region2) -> Result<mt::Face> {
     for h in &r.holes {
         wires.push(wire(plane, &h.ccw().reversed())?);
     }
-    guard("face", || mt::profile::attach_plane_normalized(wires).map_err(|e| KernelError::Invalid(format!("profile: {e}"))))
+    guard("face", || builder::try_attach_plane(&wires).map_err(|e| KernelError::Invalid(format!("profile: {e}"))))
 }
 
 fn region_ok(r: &Region2) -> Result<()> {
@@ -98,7 +90,7 @@ pub fn extrude(plane: &Plane, regions: &[Region2], start: f64, end: f64) -> Resu
         region_ok(r)?;
         let base = plane.offset(lo);
         let f = face(&base, r)?;
-        let solid: Solid = guard("extrude", || Ok(builder::extrude(&f, v3(n * (hi - lo)))))?;
+        let solid: Solid = guard("extrude", || Ok(builder::tsweep(&f, v3(n * (hi - lo)))))?;
         out.push(Body::new(solid)?);
     }
     Ok(out)
@@ -130,16 +122,26 @@ pub fn revolve(plane: &Plane, regions: &[Region2], axis_origin: Vec2, axis_dir:
         if neg && pos {
             return Err(KernelError::Invalid("the profile crosses the revolve axis".into()));
         }
+        // Points on the axis (within solver tolerance) go exactly onto it, so the sweep does not
+        // create hair-thin faces.
+        let snap = |p: Vec2| {
+            let along = (p - axis_origin).dot(d);
+            let q = axis_origin + d * along;
+            if p.dist(q) < 1e-7 { q } else { p }
+        };
+        let snap_loop = |l: &Loop2| Loop2 {
+            segs: l
+                .segs
+                .iter()
+                .map(|s| match *s {
+                    Seg2::Line { a, b } => Seg2::Line { a: snap(a), b: snap(b) },
+                    arc => arc,
+                })
+                .collect(),
+        };
+        let r = &Region2 { outer: snap_loop(&r.outer), holes: r.holes.iter().map(snap_loop).collect() };
         let f = face(plane, r)?;
-        let full = angle.abs() >= std::f64::consts::TAU - 1e-9;
-        let solid: Solid = guard("revolve", || {
-            Ok(if full {
-                builder::revolve(&f, p3(o), v3(axis), builder::SweepAngle::Closed, 4)
-            } else {
-                let div = ((angle.abs() / std::f64::consts::FRAC_PI_2).ceil() as usize).clamp(1, 8);
-                builder::revolve(&f, p3(o), v3(axis), builder::SweepAngle::Partial(mt::Rad(angle)), div)
-            })
-        })?;
+        let solid: Solid = guard("revolve", || Ok(builder::rsweep(&f, p3(o), v3(axis), mt::Rad(angle))))?;
         out.push(Body::new(solid)?);
     }
     Ok(out)

crates/kernel/src/lib.rs

@@ -2,16 +2,17 @@
 //!
 //! Everything SolveCraft does with solids goes through this crate: building bodies from planar
 //! regions (extrude, revolve) and primitives, booleans, fillets and chamfers, tessellation,
-//! measurement and STEP export. The implementation uses the `monstertruck` crates (Apache-2.0,
-//! a maintained fork of `truck`; see `plan/adr/0001-geometry-kernel.md`), but no monstertruck
-//! type appears in the public API, so the kernel can be replaced without touching the rest of
-//! the workspace.
+//! measurement and STEP export. The implementation uses the `truck` crates (Apache-2.0; see
+//! `plan/adr/0001-geometry-kernel.md`) plus our own local operations (edge fillets and
+//! chamfers in `blend.rs`), but no truck type appears in the public API, so the kernel can be
+//! replaced without touching the rest of the workspace.
 //!
 //! Every call into the third-party kernel runs under [`guard`]: a panic inside it becomes a
 //! [`KernelError::Internal`] instead of taking the application down.
 #![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]
 #![forbid(unsafe_code)]
 
+mod blend;
 mod body;
 mod build;
 mod measure;
@@ -19,10 +20,11 @@ mod ops;
 mod step;
 mod topo;
 
+pub use blend::{chamfer, fillet};
 pub use body::{Body, EdgeInfo, FaceInfo};
 pub use build::{box_solid, cylinder, extrude, revolve, sphere, torus};
 pub use measure::{BodyMeasure, measure};
-pub use ops::{BoolOp, boolean, chamfer, fillet, transform};
+pub use ops::{BoolOp, boolean, transform};
 pub use step::step_export;
 pub use topo::{TopoCounts, merged_topology};
 

crates/kernel/src/ops.rs

@@ -1,10 +1,10 @@
-//! Operations on bodies: booleans, fillets, chamfers, rigid transforms.
+//! Operations on bodies: booleans and rigid transforms.
 
-use monstertruck_modeling as mt;
 use serde::{Deserialize, Serialize};
 use solvecraft_geom::Vec3;
+use truck_modeling as mt;
 
-use crate::body::{Body, Solid, v3};
+use crate::body::{Body, p3, v3};
 use crate::{KernelError, Result, guard};
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
@@ -15,84 +15,75 @@ pub enum BoolOp {
     Intersect,
 }
 
-/// Boolean of two bodies. Retries with a few tolerances; the result may be empty (`Ok(None)`)
-/// for a cut that removes everything or an intersection of disjoint bodies.
+/// Shifts applied to both operands on retries. The boolean classifies some faces by casting a
+/// ray whose direction is derived from point coordinates; moving both solids (and the result
+/// back) leaves the geometry unchanged but changes those rays.
+const JITTER: [[f64; 3]; 4] = [[0.0, 0.0, 0.0], [0.1373, 0.2719, 0.3911], [-0.5127, 0.0833, 0.2291], [0.6911, -0.3337, -0.6127]];
+
+fn volume(b: &Body) -> f64 {
+    b.tessellate(b.size() * 2e-3).map(|m| m.measure().volume).unwrap_or(f64::NAN)
+}
+
+/// Boolean of two bodies. The result may be empty (`Ok(None)`) for a cut that removes
+/// everything or an intersection of disjoint bodies. Results are checked against volume bounds
+/// and retried with shifted copies and other tolerances when they fail or look wrong.
 pub fn boolean(a: &Body, b: &Body, op: BoolOp) -> Result<Option<Body>> {
     let size = a.size().max(b.size());
+    let (va, vb) = (volume(a), volume(b));
+    let slack = 2e-3 * (va + vb) + 1e-9;
+    let plausible = |v: f64| match op {
+        BoolOp::Union => v >= va.max(vb) - slack && v <= va + vb + slack,
+        BoolOp::Cut => v >= va - vb - slack && v <= va + slack,
+        BoolOp::Intersect => v <= va.min(vb) + slack,
+    };
     let mut last = String::new();
-    for k in [1e-4, 1e-3, 5e-5, 5e-3] {
-        let tol = (size * k).max(1e-6);
-        let r = guard("boolean", || {
-            let (sa, sb) = (a.deep_copy(), b.deep_copy());
-            let res = match op {
-                BoolOp::Union => monstertruck_solid::or(&sa, &sb, tol),
-                BoolOp::Cut => monstertruck_solid::difference(&sa, &sb, tol),
-                BoolOp::Intersect => monstertruck_solid::and(&sa, &sb, tol),
-            };
-            res.map_err(|e| KernelError::Failed(format!("{e:?}")))
-        });
-        match r {
-            Ok(s) if s.is_empty() => return Ok(None),
-            Ok(s) => {
-                let body = Body::new(s)?;
-                if body.tessellate(size * 1e-2).map(|m| m.measure().volume > 0.0).unwrap_or(false) {
-                    return Ok(Some(body));
+    let mut empty_votes = 0;
+    for (attempt, j) in JITTER.iter().enumerate() {
+        let shift = mt::Vector3::new(j[0], j[1], j[2]) * (size * 0.01);
+        for k in [5e-4, 2e-3] {
+            let tol = (size * k).max(1e-5);
+            let r = guard("boolean", || {
+                let (mut sa, mut sb) = (a.deep_copy(), b.deep_copy());
+                if attempt > 0 {
+                    sa = mt::builder::translated(&sa, shift);
+                    sb = mt::builder::translated(&sb, shift);
                 }
-                last = "degenerate result".into();
+                let res = match op {
+                    BoolOp::Union => truck_shapeops::or(&sa, &sb, tol),
+                    BoolOp::Cut => {
+                        sb.not();
+                        truck_shapeops::and(&sa, &sb, tol)
+                    }
+                    BoolOp::Intersect => truck_shapeops::and(&sa, &sb, tol),
+                };
+                let s = res.ok_or_else(|| KernelError::Failed("no result".into()))?;
+                Ok(if attempt > 0 { mt::builder::translated(&s, -shift) } else { s })
+            });
+            match r {
+                Ok(s) if s.boundaries().is_empty() || s.face_iter().next().is_none() => {
+                    empty_votes += 1;
+                    last = "empty result".into();
+                }
+                Ok(s) => match Body::new(s) {
+                    Ok(body) => {
+                        let v = volume(&body);
+                        if v > 0.0 && plausible(v) {
+                            return Ok(Some(body));
+                        }
+                        last = format!("implausible result volume {v:.4}");
+                    }
+                    Err(e) => last = e.to_string(),
+                },
+                Err(e) => last = e.to_string(),
             }
-            Err(e) => last = e.to_string(),
+        }
+        if empty_votes >= 2 && op != BoolOp::Union {
+            return Ok(None);
         }
     }
     Err(KernelError::Failed(format!("boolean {op:?}: {last}")))
 }
 
-fn blend(body: &Body, edges: &[Vec3], radius: f64, profile: mt::FilletProfile, what: &str) -> Result<Body> {
-    if !(radius.is_finite() && radius > 1e-6 && radius < 1e6) {
-        return Err(KernelError::Invalid(format!("{what} size must be positive")));
-    }
-    if edges.is_empty() {
-        return Err(KernelError::Invalid("no edges selected".into()));
-    }
-    let tol = (body.size() * 2e-3).max(1e-3);
-    let mut cur = body.clone();
-    // One edge at a time: re-find each edge on the current body by its reference point.
-    for p in edges {
-        let Some((idx, d)) = cur.nearest_edge(*p, tol)? else { return Err(KernelError::Invalid("body has no edges".into())) };
-        if d > cur.size() * 0.05 + 1e-3 {
-            return Err(KernelError::Invalid(format!("no edge near {:?}", [p.x, p.y, p.z])));
-        }
-        let mut solid = cur.deep_copy();
-        let shape = profile.clone();
-        let res = guard(what, || {
-            let edge = Body::unique_edges(&solid).into_iter().nth(idx).ok_or_else(|| KernelError::Invalid("edge index".into()))?;
-            let shell_i = solid
-                .boundaries()
-                .iter()
-                .position(|sh| sh.edge_iter().any(|e| e.id() == edge.id()))
-                .ok_or_else(|| KernelError::Failed("edge not in a shell".into()))?;
-            let mut shells = solid.boundaries().clone();
-            let shell = shells.get_mut(shell_i).ok_or_else(|| KernelError::Failed("shell".into()))?;
-            let opts = mt::FilletOptions { radius: mt::RadiusSpec::Constant(radius), profile: shape, ..Default::default() };
-            mt::fillet_edges(shell, &[edge], Some(&opts)).map_err(|e| KernelError::Failed(format!("{what}: {e:?}")))?;
-            solid = Solid::try_new(shells).map_err(|e| KernelError::Failed(format!("{what} left an open shell: {e:?}")))?;
-            Ok(())
-        });
-        res?;
-        cur = Body::new(solid)?;
-    }
-    Ok(cur)
-}
-
-/// Constant-radius fillet of the edges nearest to the given points.
-pub fn fillet(body: &Body, edges: &[Vec3], radius: f64) -> Result<Body> {
-    blend(body, edges, radius, mt::FilletProfile::Round, "fillet")
-}
-
-/// Equal-distance chamfer of the edges nearest to the given points.
-pub fn chamfer(body: &Body, edges: &[Vec3], distance: f64) -> Result<Body> {
-    blend(body, edges, distance, mt::FilletProfile::Chamfer, "chamfer")
-}
-
 /// Rigid transform: rotate about `axis` through `origin` by `angle` radians, then translate.
 pub fn transform(body: &Body, translate: Vec3, origin: Vec3, axis: Vec3, angle: f64) -> Result<Body> {
     if !(translate.is_finite() && origin.is_finite() && angle.is_finite()) {
@@ -102,7 +93,7 @@ pub fn transform(body: &Body, translate: Vec3, origin: Vec3, axis: Vec3, angle:
         let mut s = body.deep_copy();
         if angle.abs() > 1e-12 {
             let ax = axis.normalized().ok_or_else(|| KernelError::Invalid("rotation axis".into()))?;
-            s = mt::builder::rotated(&s, crate::body::p3(origin), v3(ax), mt::Rad(angle));
+            s = mt::builder::rotated(&s, p3(origin), v3(ax), mt::Rad(angle));
         }
         if translate.len() > 0.0 {
             s = mt::builder::translated(&s, v3(translate));

crates/kernel/src/step.rs

@@ -1,18 +1,17 @@
-use monstertruck_io::step::save;
+use truck_stepio::out;
 
 use crate::body::Body;
 use crate::{KernelError, Result, guard};
 
-/// STEP (ISO 10303-21, AP203-style geometry) text for the given bodies.
+/// STEP (ISO 10303-21) text for the given bodies.
 pub fn step_export(bodies: &[&Body], system: &str) -> Result<String> {
     if bodies.is_empty() {
         return Err(KernelError::Invalid("nothing to export".into()));
     }
     guard("step export", || {
         let cs: Vec<_> = bodies.iter().map(|b| b.solid.compress()).collect();
-        let models = save::StepModels::from_iter(cs.iter());
-        let header = save::StepHeaderDescriptor { organization_system: system.to_owned(), ..Default::default() };
-        let out = save::CompleteStepDisplay::new(models, header).to_string();
-        Ok(out)
+        let models: out::StepModels<_, _, _> = cs.iter().collect();
+        let header = out::StepHeaderDescriptor { organization_system: system.to_owned(), ..Default::default() };
+        Ok(out::CompleteStepDisplay::new(models, header).to_string())
     })
 }

crates/kernel/src/tests.rs

@@ -119,6 +119,32 @@ fn hostile_inputs_are_errors() {
     assert!(transform(&b, Vec3::new(f64::NAN, 0.0, 0.0), Vec3::ZERO, Vec3::Z, 0.0).is_err());
 }
 
+#[test]
+fn fillets_on_several_edges_and_angles() {
+    let b = box_solid(Vec3::ZERO, Vec3::new(40.0, 30.0, 20.0)).unwrap();
+    // Two opposite vertical edges, then a horizontal top edge between them is not touching either.
+    let f = fillet(&b, &[Vec3::new(0.0, 0.0, 10.0), Vec3::new(40.0, 30.0, 10.0)], 4.0).unwrap();
+    let corner = 16.0 - PI * 4.0;
+    assert!(rel(measure(&f).unwrap().volume, 24000.0 - 2.0 * corner * 20.0) < 2e-4);
+    let top = fillet(&b, &[Vec3::new(20.0, 0.0, 20.0)], 2.0).unwrap();
+    assert!(rel(measure(&top).unwrap().volume, 24000.0 - (4.0 - PI) * 40.0) < 2e-4);
+    // Triangular prism: 60° edges.
+    let tri = Region2 { outer: Loop2::polygon(&[Vec2::new(0.0, 0.0), Vec2::new(30.0, 0.0), Vec2::new(15.0, 25.980762113533)]), holes: vec![] };
+    let p = extrude(&Plane::XY, &[tri], 0.0, 10.0).unwrap().pop().unwrap();
+    let r = 2.0;
+    let fp = fillet(&p, &[Vec3::new(0.0, 0.0, 5.0)], r).unwrap();
+    // Removed area for interior angle φ: r²(cot(φ/2)) − r²(π − φ)/2.
+    let phi = PI / 3.0;
+    let removed = r * r / (phi / 2.0).tan() - r * r * (PI - phi) / 2.0;
+    let v0 = measure(&p).unwrap().volume;
+    assert!(rel(measure(&fp).unwrap().volume, v0 - removed * 10.0) < 2e-4, "{} vs {}", measure(&fp).unwrap().volume, v0 - removed * 10.0);
+    // Adjacent edges at a blended corner are not supported yet (an error, not a crash).
+    assert!(fillet(&b, &[Vec3::new(0.0, 0.0, 10.0), Vec3::new(0.0, 15.0, 20.0)], 2.0).is_err());
+    // Concave edge: not supported.
+    let u = boolean(&b, &box_solid(Vec3::new(10.0, 10.0, 15.0), Vec3::new(20.0, 20.0, 30.0)).unwrap(), BoolOp::Union).unwrap().unwrap();
+    assert!(fillet(&u, &[Vec3::new(15.0, 10.0, 20.0)], 1.0).is_err());
+}
+
 #[test]
 #[ignore]
 fn debug_convergence() {
@@ -135,3 +161,58 @@ fn debug_convergence() {
         println!("face {f}: {} normals, first {:?}, max |n.z| {}", ns.len(), ns.first(), ns.iter().map(|n| n.z.abs()).fold(0.0, f64::max));
     }
 }
+
+#[test]
+#[ignore]
+fn debug_coplanar() {
+    let b = box_solid(Vec3::ZERO, Vec3::new(40.0, 30.0, 20.0)).unwrap();
+    for (z0, z1) in [(0.0, 20.0), (-5.0, 20.0), (0.0, 25.0), (-5.0, 25.0), (5.0, 20.0), (5.0, 25.0)] {
+        let c = cylinder(Vec3::new(20.0, 15.0, z0), Vec3::Z, 5.0, z1 - z0).unwrap();
+        let r = boolean(&b, &c, BoolOp::Cut);
+        println!("cut z {z0}..{z1}: {:?}", r.map(|o| o.map(|b| measure(&b).unwrap().volume)));
+        let r = boolean(&b, &c, BoolOp::Union);
+        println!("union z {z0}..{z1}: {:?}", r.map(|o| o.map(|b| measure(&b).unwrap().volume)));
+    }
+    let r =
+        Region2 { outer: Loop2::polygon(&[Vec2::new(0.0, 0.0), Vec2::new(40.0, 0.0), Vec2::new(40.0, 30.0), Vec2::new(0.0, 30.0)]), holes: vec![] };
+    for ang in [PI / 2.0, PI, 1.5 * PI, 2.0 * PI] {
+        let q = revolve(&Plane::XY, std::slice::from_ref(&r), Vec2::ZERO, Vec2::Y, ang).unwrap().pop().unwrap();
+        let m = measure(&q).unwrap();
+        println!("revolve {ang}: vol {} expect {} faces {}", m.volume, ang / 2.0 * 1600.0 * 30.0, m.faces);
+    }
+}
+
+#[test]
+#[ignore]
+fn debug_blind() {
+    let b = box_solid(Vec3::ZERO, Vec3::new(40.0, 30.0, 20.0)).unwrap();
+    let t = box_solid(Vec3::new(10.0, 10.0, 5.0), Vec3::new(20.0, 20.0, 25.0)).unwrap();
+    println!("box pocket: {:?}", boolean(&b, &t, BoolOp::Cut).map(|o| o.map(|b| measure(&b).unwrap().volume)));
+    let t = box_solid(Vec3::new(10.0, 10.0, 5.0), Vec3::new(20.0, 20.0, 15.0)).unwrap();
+    println!("box void: {:?}", boolean(&b, &t, BoolOp::Cut).map(|o| o.map(|b| measure(&b).unwrap().volume)));
+    for r in [5.0, 4.3] {
+        for z in [5.0, 7.3, 13.1] {
+            let c = cylinder(Vec3::new(20.3, 15.1, z), Vec3::Z, r, 30.0).unwrap();
+            println!("cyl r{r} z{z}: {:?}", boolean(&b, &c, BoolOp::Cut).map(|o| o.map(|b| measure(&b).unwrap().volume)));
+        }
+    }
+    let c = cylinder(Vec3::new(20.0, 15.0, 25.0), -Vec3::Z, 5.0, 20.0).unwrap();
+    println!("cyl down: {:?}", boolean(&b, &c, BoolOp::Cut).map(|o| o.map(|b| measure(&b).unwrap().volume)));
+    let s = sphere(Vec3::new(20.0, 15.0, 20.0), 5.0).unwrap();
+    println!("sphere: {:?}", boolean(&b, &s, BoolOp::Cut).map(|o| o.map(|b| measure(&b).unwrap().volume)));
+}
+
+#[test]
+#[ignore]
+fn debug_revolve_doc_case() {
+    let r =
+        Region2 { outer: Loop2::polygon(&[Vec2::new(0.0, 0.0), Vec2::new(40.0, 0.0), Vec2::new(40.0, 30.0), Vec2::new(0.0, 30.0)]), holes: vec![] };
+    for ang in [PI / 2.0, -PI / 2.0] {
+        let q = revolve(&Plane::XY, std::slice::from_ref(&r), Vec2::ZERO, Vec2::Y, ang).unwrap().pop().unwrap();
+        let m = measure(&q).unwrap();
+        println!("ang {ang}: vol {} bbox {:?}", m.volume, m.bbox);
+    }
+    let r2 = Region2 { outer: r.outer.reversed(), holes: vec![] };
+    let q = revolve(&Plane::XY, std::slice::from_ref(&r2), Vec2::ZERO, Vec2::Y, PI / 2.0).unwrap().pop().unwrap();
+    println!("reversed: {}", measure(&q).unwrap().volume);
+}

crates/kernel/src/topo.rs

@@ -174,7 +174,7 @@ pub fn merged_topology(b: &Body, mesh: &Mesh) -> Result<TopoCounts> {
             if !faces.contains(&fi) {
                 faces.push(fi);
             }
-            let mut vix = |v: &monstertruck_modeling::Vertex| {
+            let mut vix = |v: &truck_modeling::Vertex| {
                 let k = format!("{:?}", v.id());
                 let n = vid.len();
                 let i = *vid.entry(k).or_insert(n);