STEP import: read HYPERBOLA and PARABOLA edges exactly (#1832)

Thanks @NOWN-DEV.

crates/kernel/src/step_in/conic_tests.rs

@@ -0,0 +1,197 @@
+//! Hyperbola and parabola edges (ISO 10303-42 HYPERBOLA, PARABOLA): a cone cut by a plane
+//! parallel to its axis meets it in a hyperbola, by a plane parallel to a generator in a
+//! parabola. Hand-written files, volumes against closed forms.
+
+use std::f64::consts::{FRAC_PI_4, PI};
+
+use mt::{BoundedCurve, InnerSpace, ParametricCurve};
+use truck_modeling as mt;
+
+use super::geom::{Frame, hyperbola_arc, parabola_arc};
+use super::*;
+use crate::{measure, step_export};
+
+const HEAD: &str = "ISO-10303-21;\nHEADER;\nFILE_DESCRIPTION((''),'2;1');\nFILE_NAME('t','',(''),(''),'','hand','');\nFILE_SCHEMA(('AUTOMOTIVE_DESIGN { 1 0 10303 214 1 1 1 1 }'));\nENDSEC;\nDATA;\n";
+const TAIL: &str = "ENDSEC;\nEND-ISO-10303-21;\n";
+const CONTEXT: &str = "#90=ADVANCED_BREP_SHAPE_REPRESENTATION('',(#81),#91);\n#91=(GEOMETRIC_REPRESENTATION_CONTEXT(3)GLOBAL_UNCERTAINTY_ASSIGNED_CONTEXT((#92))GLOBAL_UNIT_ASSIGNED_CONTEXT((#93,#94))REPRESENTATION_CONTEXT('',''));\n#92=UNCERTAINTY_MEASURE_WITH_UNIT(LENGTH_MEASURE(1.E-6),#93,'','');\n#93=(LENGTH_UNIT()NAMED_UNIT(*)SI_UNIT(.MILLI.,.METRE.));\n#94=(NAMED_UNIT(*)PLANE_ANGLE_UNIT()SI_UNIT($,.RADIAN.));\n";
+
+/// Height of the cone pieces: the 45° cone `x² + y² = z²` up to `z = H`.
+const H: f64 = 10.0;
+
+fn rel(a: f64, b: f64) -> f64 {
+    (a - b).abs() / b.abs().max(1e-9)
+}
+
+/// A solid bounded by the 45° cone (apex at the origin, axis Z), its top plane `z = H` and a
+/// cutting plane. `curve` defines `#30` (the conic edge from `v1` to `v2`, rising parameter) and
+/// `#41`, the cutting plane's placement (normal pointing out of the solid). The top circle runs
+/// `#51` from `circle_from` to the other vertex counter-clockwise seen from above; the loops say
+/// which way each face uses each edge.
+fn cone_piece(curve: &str, v1: [f64; 3], v2: [f64; 3], circle_from_v1: bool, loops: [&str; 3]) -> String {
+    let mut t = String::from(HEAD);
+    t += "#1=CARTESIAN_POINT('',(0.,0.,10.));\n#2=DIRECTION('',(0.,0.,1.));\n#3=DIRECTION('',(1.,0.,0.));\n#4=AXIS2_PLACEMENT_3D('',#1,#2,#3);\n";
+    t += &format!("#5=CONICAL_SURFACE('',#4,10.,{FRAC_PI_4:.15});\n#6=PLANE('',#4);\n");
+    t += &format!("#10=CARTESIAN_POINT('',({:.15},{:.15},{:.15}));\n#11=VERTEX_POINT('',#10);\n", v1[0], v1[1], v1[2]);
+    t += &format!("#12=CARTESIAN_POINT('',({:.15},{:.15},{:.15}));\n#13=VERTEX_POINT('',#12);\n", v2[0], v2[1], v2[2]);
+    t += curve;
+    t += "#31=EDGE_CURVE('',#11,#13,#30,.T.);\n#42=PLANE('',#41);\n";
+    t += "#50=CIRCLE('',#4,10.);\n";
+    t += if circle_from_v1 { "#51=EDGE_CURVE('',#11,#13,#50,.T.);\n" } else { "#51=EDGE_CURVE('',#13,#11,#50,.T.);\n" };
+    t += "#52=VECTOR('',#3,1.);\n#53=LINE('',#10,#52);\n#54=EDGE_CURVE('',#11,#13,#53,.T.);\n";
+    // Faces: the cone, the cutting plane, the top.
+    for (k, (lp, surface)) in loops.iter().zip(["#5", "#42", "#6"]).enumerate() {
+        let b = 60 + 6 * k;
+        let edges: Vec<&str> = lp.split(' ').collect();
+        let mut oes = Vec::new();
+        for (j, e) in edges.iter().enumerate() {
+            let (id, fwd) = e.split_at(e.len() - 1);
+            t += &format!("#{}=ORIENTED_EDGE('',*,*,{id},{});\n", b + j, if fwd == "+" { ".T." } else { ".F." });
+            oes.push(format!("#{}", b + j));
+        }
+        t += &format!("#{}=EDGE_LOOP('',({}));\n#{}=FACE_OUTER_BOUND('',#{},.T.);\n", b + 3, oes.join(","), b + 4, b + 3);
+        t += &format!("#{}=ADVANCED_FACE('',(#{}),{surface},.T.);\n", b + 5, b + 4);
+    }
+    t += "#80=CLOSED_SHELL('',(#65,#71,#77));\n#81=MANIFOLD_SOLID_BREP('Piece',#80);\n";
+    t += CONTEXT;
+    t += TAIL;
+    t
+}
+
+/// The cone inside `z ≤ H` cut by the plane `y = D` (parallel to the axis), keeping `y ≥ D`:
+/// the cut meets the cone in the hyperbola `z² − x² = D²`, centre `(0, D, 0)`, both semi axes D.
+fn hyperbola_piece() -> String {
+    const D: f64 = 4.0;
+    let w = (H * H - D * D).sqrt();
+    // Real axis up the plane (X = +z), normal +y, so the imaginary axis is +x:
+    // (x, y, z) = (D·sinh t, D, D·cosh t).
+    let curve = "#20=CARTESIAN_POINT('',(0.,4.,0.));\n#21=DIRECTION('',(0.,1.,0.));\n#22=AXIS2_PLACEMENT_3D('',#20,#21,#2);\n#30=HYPERBOLA('',#22,4.,4.);\n#40=DIRECTION('',(0.,-1.,0.));\n#41=AXIS2_PLACEMENT_3D('',#20,#40,#3);\n";
+    // Cone: up the hyperbola from +x to −x, back along the arc; the plane (seen from −y):
+    // the hyperbola from −x to +x, back along the line; the top: the arc, then the line.
+    cone_piece(curve, [-w, D, H], [w, D, H], false, ["#31- #51-", "#31+ #54-", "#51+ #54+"])
+}
+
+/// The cone inside `z ≤ H` cut by the plane `z − y = C` (parallel to the generator in the
+/// x = 0, y > 0 half plane), keeping `z − y ≥ C`: the cut meets the cone in a parabola with its
+/// vertex at `(0, −C/2, C/2)`, axis along (0, 1, 1) and focal distance `C·√2 / 4`.
+fn parabola_piece() -> String {
+    const C: f64 = 8.0;
+    let w = (H * H - (H - C) * (H - C)).sqrt();
+    // Normal (0, 1, −1) out of the solid, axis X = (0, 1, 1), so Y = Z × X = +x:
+    // (x, y, z) = (4√2·t, −4 + 2t², 4 + 2t²).
+    let curve = format!(
+        "#20=CARTESIAN_POINT('',(0.,-4.,4.));\n#21=DIRECTION('',(0.,1.,-1.));\n#23=DIRECTION('',(0.,1.,1.));\n#22=AXIS2_PLACEMENT_3D('',#20,#21,#23);\n#30=PARABOLA('',#22,{:.15});\n#41=AXIS2_PLACEMENT_3D('',#20,#21,#23);\n",
+        C * 2f64.sqrt() / 4.0
+    );
+    // Cone (seen from −y): the parabola from −x to +x, back along the arc; the plane (seen from
+    // outside, +x on the left): the parabola from +x to −x, back along the line; the top: the
+    // arc round through −y, then the line back.
+    cone_piece(&curve, [-w, H - C, H], [w, H - C, H], true, ["#31+ #51-", "#31- #54+", "#51+ #54-"])
+}
+
+/// ∫ from D to H of the circular segment `y ≥ D` of the disc of radius z.
+fn hyperbola_piece_volume() -> f64 {
+    let d = 4.0;
+    let s = (H * H - d * d).sqrt();
+    H.powi(3) / 3.0 * (d / H).acos() - 2.0 / 3.0 * d * H * s + d.powi(3) / 3.0 * ((H + s) / d).ln()
+}
+
+/// ∫ from C/2 to H of the part `y ≤ z − C` of the disc of radius z.
+fn parabola_piece_volume() -> f64 {
+    let c = 8.0;
+    let q: f64 = 2.0 * c * H - c * c;
+    H.powi(3) / 3.0 * (PI - (1.0 - c / H).acos())
+        - (0.4 * q.powf(2.5) + 4.0 / 3.0 * c * c * q.powf(1.5) + 2.0 * c.powi(4) * q.sqrt()) / (24.0 * c * c)
+        + (0.4 * q.powf(2.5) - 2.0 / 3.0 * c * c * q.powf(1.5)) / (4.0 * c * c)
+}
+
+fn import_piece(text: &str, want: f64) -> StepImport {
+    assert_eq!(step_orientation_errors(text).unwrap(), Vec::<String>::new());
+    let imp = step_import(text).unwrap();
+    assert!(imp.warnings.is_empty(), "{:?}", imp.warnings);
+    assert_eq!(imp.bodies.len(), 1);
+    assert!(imp.bodies[0].closed);
+    let m = measure(&imp.bodies[0].body).unwrap();
+    assert_eq!(m.faces, 3);
+    assert!(rel(m.volume, want) < 1e-4, "volume {} vs {want}", m.volume);
+    imp
+}
+
+/// Export the imported piece and read it back: the conic edges are written as exact rational
+/// B-splines and come back as the same solid.
+fn round_trip(imp: &StepImport, want: f64) {
+    let text = step_export(&[&imp.bodies[0].body], "conic").unwrap();
+    step_validate(&text).unwrap();
+    let back = step_import(&text).unwrap();
+    assert!(back.warnings.is_empty(), "{:?}", back.warnings);
+    assert_eq!(back.bodies.len(), 1);
+    assert!(back.bodies[0].closed);
+    let v = measure(&back.bodies[0].body).unwrap().volume;
+    assert!(rel(v, want) < 1e-4, "round trip volume {v} vs {want}");
+}
+
+#[test]
+fn hyperbola_bounded_faces_import() {
+    let want = hyperbola_piece_volume();
+    assert!(rel(want, 175.447_506_9) < 1e-9, "{want}");
+    let imp = import_piece(&hyperbola_piece(), want);
+    round_trip(&imp, want);
+}
+
+#[test]
+fn parabola_bounded_faces_import() {
+    let want = parabola_piece_volume();
+    assert!(rel(want, 447.014_684_29) < 1e-9, "{want}");
+    let imp = import_piece(&parabola_piece(), want);
+    round_trip(&imp, want);
+}
+
+/// The kernel curves lie exactly on the conics, end to end, whichever way they run.
+#[test]
+fn conic_arcs_are_exact() {
+    let f = Frame { o: mt::Point3::new(1.0, 2.0, 3.0), x: mt::Vector3::unit_y(), y: mt::Vector3::unit_z(), z: mt::Vector3::unit_x() };
+    let local = |p: mt::Point3| ((p - f.o).dot(f.x), (p - f.o).dot(f.y), (p - f.o).dot(f.z));
+    for (t0, t1) in [(-1.5, 2.0), (3.0, -0.25), (0.0, 7.5)] {
+        let c = hyperbola_arc(&f, 3.0, 2.0, t0, t1);
+        let (s0, s1) = c.range_tuple();
+        for i in 0..=200 {
+            let (x, y, z) = local(c.subs(s0 + (s1 - s0) * i as f64 / 200.0));
+            assert!((x * x / 9.0 - y * y / 4.0 - 1.0).abs() < 1e-9 && x > 0.0 && z.abs() < 1e-12, "{x} {y}");
+        }
+        let (x, y, _) = local(c.subs(s0));
+        assert!((x - 3.0 * f64::cosh(t0)).abs() < 1e-9 && (y - 2.0 * f64::sinh(t0)).abs() < 1e-9);
+        let (x, y, _) = local(c.subs(s1));
+        assert!((x - 3.0 * f64::cosh(t1)).abs() < 1e-9 && (y - 2.0 * f64::sinh(t1)).abs() < 1e-9);
+
+        let c = parabola_arc(&f, 1.5, t0, t1);
+        let (s0, s1) = c.range_tuple();
+        for i in 0..=200 {
+            let (x, y, z) = local(c.subs(s0 + (s1 - s0) * i as f64 / 200.0));
+            assert!((y * y - 4.0 * 1.5 * x).abs() < 1e-9 * (1.0 + x.abs()) && z.abs() < 1e-12, "{x} {y}");
+        }
+        let (x, y, _) = local(c.subs(s1));
+        assert!((x - 1.5 * t1 * t1).abs() < 1e-9 && (y - 3.0 * t1).abs() < 1e-9);
+    }
+}
+
+/// Hostile conics are errors (the face is reported and left out), never panics.
+#[test]
+fn hostile_conics_never_panic() {
+    let good = hyperbola_piece();
+    for bad in [
+        good.replace("HYPERBOLA('',#22,4.,4.)", "HYPERBOLA('',#22,0.,4.)"),
+        good.replace("HYPERBOLA('',#22,4.,4.)", "HYPERBOLA('',#22,4.,-1.)"),
+        good.replace("HYPERBOLA('',#22,4.,4.)", "HYPERBOLA('',#22,4.)"),
+        good.replace("HYPERBOLA('',#22,4.,4.)", "HYPERBOLA('',#22,1.E300,4.)"),
+        good.replace("HYPERBOLA('',#22,4.,4.)", "HYPERBOLA('',#22,1.E-300,1.E-300)"),
+        good.replace("HYPERBOLA('',#22,4.,4.)", "HYPERBOLA('',#22,5.,4.)"),
+        good.replace("HYPERBOLA('',#22,4.,4.)", "PARABOLA('',#22,0.)"),
+        good.replace("HYPERBOLA('',#22,4.,4.)", "PARABOLA('',#22,1.)"),
+        good.replace("#31=EDGE_CURVE('',#11,#13,#30,.T.)", "#31=EDGE_CURVE('',#11,#11,#30,.T.)"),
+    ] {
+        let r = std::panic::catch_unwind(|| step_import(&bad));
+        let Ok(r) = r else { panic!("STEP import panicked") };
+        if let Ok(imp) = r {
+            assert!(!imp.warnings.is_empty(), "a broken conic imported silently");
+        }
+    }
+}

crates/kernel/src/step_in/geom.rs

@@ -1,6 +1,6 @@
 //! STEP geometry (ISO 10303-42 entities) to kernel curves and surfaces.
 //!
-//! Points, placements, lines, conics, B-splines (plain and rational), elementary surfaces and
+//! Points, placements, lines, conics (ellipses, hyperbolas and parabolas), B-splines (plain and rational), elementary surfaces and
 //! swept surfaces, with exact offsets of planes, cylinders, cones, spheres and regular tori.
 //! Free-form offsets and offsets through collapsed radii remain explicit import warnings.
 //! Edge curves are trimmed to their vertices here, so every kernel edge runs
@@ -54,6 +54,17 @@ pub(crate) enum CurveGeo {
         a: f64,
         b: f64,
     },
+    /// Hyperbola branch `o + a·cosh t·x + b·sinh t·y` in the frame's XY plane.
+    Hyperbola {
+        f: Frame,
+        a: f64,
+        b: f64,
+    },
+    /// Parabola `o + focal·(t²·x + 2t·y)` in the frame's XY plane.
+    Parabola {
+        f: Frame,
+        focal: f64,
+    },
     BSpline(mt::BSplineCurve<mt::Point3>),
     Nurbs(mt::NurbsCurve<mt::Vector4>),
 }
@@ -295,6 +306,22 @@ pub(crate) fn curve(cx: &Ctx, id: u64, depth: usize) -> R<CurveGeo> {
             }
             Ok(CurveGeo::Conic { f, a, b })
         }
+        "HYPERBOLA" => {
+            let f = frame(cx, p.get(1).and_then(Param::as_ref_id).ok_or("HYPERBOLA without placement")?)?;
+            let (a, b) = (length(cx, p.get(2), "semi axis")?, length(cx, p.get(3), "semi imaginary axis")?);
+            if a <= 0.0 || b <= 0.0 {
+                return Err("hyperbola axes must be positive".into());
+            }
+            Ok(CurveGeo::Hyperbola { f, a, b })
+        }
+        "PARABOLA" => {
+            let f = frame(cx, p.get(1).and_then(Param::as_ref_id).ok_or("PARABOLA without placement")?)?;
+            let focal = length(cx, p.get(2), "focal distance")?;
+            if focal == 0.0 {
+                return Err("parabola focal distance must not be zero".into());
+            }
+            Ok(CurveGeo::Parabola { f, focal })
+        }
         "B_SPLINE_CURVE_WITH_KNOTS" | "BEZIER_CURVE" | "UNIFORM_CURVE" | "QUASI_UNIFORM_CURVE" => bspline_curve(cx, e),
         "POLYLINE" => {
             let pts: Vec<mt::Point3> = p
@@ -346,6 +373,76 @@ pub(crate) fn conic_arc(f: &Frame, a: f64, b: f64, t0: f64, sweep: f64) -> mt::N
     mt::NurbsCurve::new(mt::BSplineCurve::new(mt::KnotVec::from(knots), ctrl))
 }
 
+/// Largest hyperbola parameter step one rational quadratic piece spans (keeps its weight
+/// `cosh(step / 2)` near 1).
+const HYPERBOLA_STEP: f64 = 1.0;
+
+/// Exact rational quadratic NURBS of the hyperbola branch from parameter `t0` to `t1` (either
+/// order): pieces whose middle control point is the meeting point of the end tangents, weighted
+/// `cosh` of the half step (the hyperbolic counterpart of [`conic_arc`]).
+pub(crate) fn hyperbola_arc(f: &Frame, a: f64, b: f64, t0: f64, t1: f64) -> mt::NurbsCurve<mt::Vector4> {
+    let n = (((t1 - t0).abs() / HYPERBOLA_STEP).ceil() as usize).clamp(1, 64);
+    let dt = (t1 - t0) / n as f64;
+    let w = (dt * 0.5).cosh();
+    let at = |c: f64, s: f64| f.at(a * c, b * s, 0.0);
+    let mut ctrl = Vec::with_capacity(2 * n + 1);
+    ctrl.push(at(t0.cosh(), t0.sinh()).to_homogeneous());
+    let mut knots = vec![0.0, 0.0, 0.0];
+    for i in 0..n {
+        let ta = t0 + dt * i as f64;
+        let tm = ta + dt * 0.5;
+        let tb = ta + dt;
+        let m = at(tm.cosh() / w, tm.sinh() / w);
+        ctrl.push(mt::Vector4::new(m.x * w, m.y * w, m.z * w, w));
+        ctrl.push(at(tb.cosh(), tb.sinh()).to_homogeneous());
+        let k = (i + 1) as f64 / n as f64;
+        knots.push(k);
+        knots.push(k);
+    }
+    knots.push(1.0);
+    mt::NurbsCurve::new(mt::BSplineCurve::new(mt::KnotVec::from(knots), ctrl))
+}
+
+/// The parabola from parameter `t0` to `t1` (either order): one quadratic Bézier, exact.
+pub(crate) fn parabola_arc(f: &Frame, focal: f64, t0: f64, t1: f64) -> mt::BSplineCurve<mt::Point3> {
+    let at = |t: f64| f.at(focal * t * t, 2.0 * focal * t, 0.0);
+    // The end tangents meet above the parameter midpoint: o + focal·(t0·t1, t0 + t1).
+    let mid = f.at(focal * t0 * t1, focal * (t0 + t1), 0.0);
+    mt::BSplineCurve::new(mt::KnotVec::bezier_knot(2), vec![at(t0), mid, at(t1)])
+}
+
+/// Parameter of the open conic at `p`, a point on (or within `tol` of) the curve.
+fn open_conic_param(g: &CurveGeo, p: mt::Point3, tol: f64) -> R<f64> {
+    let (t, q) = match g {
+        CurveGeo::Hyperbola { f, a, b } => {
+            let t = ((p - f.o).dot(f.y) / b).asinh();
+            (t, f.at(a * t.cosh(), b * t.sinh(), 0.0))
+        }
+        CurveGeo::Parabola { f, focal } => {
+            let t = (p - f.o).dot(f.y) / (2.0 * focal);
+            (t, f.at(focal * t * t, 2.0 * focal * t, 0.0))
+        }
+        _ => return Err("not an open conic".into()),
+    };
+    let d = q.distance(p);
+    if !t.is_finite() || !(d <= tol) {
+        return Err(format!(
+            "edge vertex is {d:.3e} mm off its {} curve",
+            if matches!(g, CurveGeo::Parabola { .. }) { "parabola" } else { "hyperbola" }
+        ));
+    }
+    Ok(t)
+}
+
+/// The open conic between parameters `t0` and `t1` as a kernel curve.
+fn open_conic_curve(g: &CurveGeo, t0: f64, t1: f64) -> R<mt::Curve> {
+    match g {
+        CurveGeo::Hyperbola { f, a, b } => Ok(mt::Curve::NurbsCurve(hyperbola_arc(f, *a, *b, t0, t1))),
+        CurveGeo::Parabola { f, focal } => Ok(mt::Curve::BSplineCurve(parabola_arc(f, *focal, t0, t1))),
+        _ => Err("not an open conic".into()),
+    }
+}
+
 fn conic_angle(f: &Frame, a: f64, b: f64, p: mt::Point3) -> f64 {
     let d = p - f.o;
     (d.dot(f.y) / b).atan2(d.dot(f.x) / a)
@@ -473,6 +570,19 @@ pub(crate) fn edge_pieces(g: &CurveGeo, ps: mt::Point3, pe: mt::Point3, sense: b
                 })
                 .collect())
         }
+        CurveGeo::Hyperbola { .. } | CurveGeo::Parabola { .. } => {
+            if closed {
+                return Err("closed edge on an open conic".into());
+            }
+            // The curve is open, so the edge is the parameters between its vertices: rising
+            // for the same sense, falling for the opposite one.
+            let (ts, te) = (open_conic_param(g, ps, tol)?, open_conic_param(g, pe, tol)?);
+            let scale = 1.0 + ts.abs().max(te.abs());
+            if (te - ts).abs() <= 1e-9 * scale {
+                return Err("degenerate conic edge".into());
+            }
+            Ok(vec![open_conic_curve(g, ts, te)?])
+        }
         CurveGeo::BSpline(c) => Ok(spline_pieces(c, ps, pe, sense, closed, tol)?.into_iter().map(mt::Curve::BSplineCurve).collect()),
         CurveGeo::Nurbs(c) => Ok(spline_pieces(c, ps, pe, sense, closed, tol)?.into_iter().map(mt::Curve::NurbsCurve).collect()),
     }
@@ -486,6 +596,21 @@ fn bounded_curve(g: &CurveGeo, extent: &[mt::Point3]) -> R<mt::Curve> {
             mt::Curve::Line(mt::Line(*p + *d * lo, *p + *d * hi))
         }
         CurveGeo::Conic { f, a, b } => mt::Curve::NurbsCurve(conic_arc(f, *a, *b, 0.0, TAU)),
+        CurveGeo::Hyperbola { f, .. } | CurveGeo::Parabola { f, .. } => {
+            // Bounded by the face's points (their parameters along the curve), with a margin.
+            let along = |q: &mt::Point3| match g {
+                CurveGeo::Hyperbola { b, .. } => ((q - f.o).dot(f.y) / b).asinh(),
+                CurveGeo::Parabola { focal, .. } => (q - f.o).dot(f.y) / (2.0 * focal),
+                _ => 0.0,
+            };
+            let (mut lo, mut hi) = (f64::INFINITY, f64::NEG_INFINITY);
+            for t in extent.iter().map(along).filter(|t| t.is_finite()) {
+                lo = lo.min(t);
+                hi = hi.max(t);
+            }
+            let (lo, hi) = if lo < hi { (lo - (hi - lo) * 0.25 - 1e-3, hi + (hi - lo) * 0.25 + 1e-3) } else { (-1.0, 1.0) };
+            open_conic_curve(g, lo, hi)?
+        }
         CurveGeo::BSpline(c) => mt::Curve::BSplineCurve(c.clone()),
         CurveGeo::Nurbs(c) => mt::Curve::NurbsCurve(c.clone()),
     })

crates/kernel/src/step_in/mod.rs

@@ -1268,5 +1268,7 @@ impl StepReading {
     }
 }
 
+#[cfg(test)]
+mod conic_tests;
 #[cfg(test)]
 mod tests;

crates/kernel/src/step_out.rs

@@ -532,7 +532,7 @@ fn analytic_revolution(ex: &p21::Exchange, e: &p21::Entity) -> Option<Analytic>
                 [q.x, q.y, q.z]
             })
         }
-        CurveGeo::Conic { .. } => return None,
+        CurveGeo::Conic { .. } | CurveGeo::Hyperbola { .. } | CurveGeo::Parabola { .. } => return None,
     };
     // A sample point off the axis, its revolution normal (∂S/∂angle × ∂S/∂profile).
     let sample =
@@ -798,7 +798,9 @@ fn edge_points(ex: &p21::Exchange, edge: u64, n: usize) -> Option<Vec<V3>> {
         crate::step_in::geom::CurveGeo::Line { .. } => Some(ends.to_vec()),
         crate::step_in::geom::CurveGeo::BSpline(c) => Some(sample(&|t| c.subs(t), c.range_tuple())),
         crate::step_in::geom::CurveGeo::Nurbs(c) => Some(sample(&|t| c.subs(t), c.range_tuple())),
-        crate::step_in::geom::CurveGeo::Conic { .. } => None,
+        crate::step_in::geom::CurveGeo::Conic { .. }
+        | crate::step_in::geom::CurveGeo::Hyperbola { .. }
+        | crate::step_in::geom::CurveGeo::Parabola { .. } => None,
     }
 }
 
@@ -862,7 +864,9 @@ fn collapse_short_edges(ex: &mut p21::Exchange) {
                 crate::step_in::geom::CurveGeo::Line { .. } => return Some(true),
                 crate::step_in::geom::CurveGeo::BSpline(c) => c.subs((c.range_tuple().0 + c.range_tuple().1) / 2.0),
                 crate::step_in::geom::CurveGeo::Nurbs(c) => c.subs((c.range_tuple().0 + c.range_tuple().1) / 2.0),
-                crate::step_in::geom::CurveGeo::Conic { .. } => return Some(false),
+                crate::step_in::geom::CurveGeo::Conic { .. }
+                | crate::step_in::geom::CurveGeo::Hyperbola { .. }
+                | crate::step_in::geom::CurveGeo::Parabola { .. } => return Some(false),
             };
             Some(norm(sub([mid.x, mid.y, mid.z], pa)) <= 1e-6 * (1.0 + norm(pa)))
         });

docs/step-import.md

@@ -34,7 +34,7 @@ The contents of an imported assembly are **rigid by default**: rigid joints (a r
 
 Designs saved before imports made components keep their Import where it is (no component is made for it) and rebuild as they did.
 
-Read: manifold solid breps (with voids), faceted breps, shell-based surface models; planes, cylinders, cones, spheres, tori, B-spline and rational B-spline surfaces (with knots, Bézier, uniform, quasi-uniform), surfaces of revolution and linear extrusion, trimmed surfaces; lines, circles, ellipses, B-spline curves, polylines, trimmed/surface/seam curves; length and angle units (SI prefixes, conversion-based units such as inches); product names (body names come from the solid's name, else the product's; `names` below chooses); surface colours; assemblies (next-assembly-usage occurrences placed by item-defined transformations, and mapped items) — the product tree is kept in the feature and becomes the import's components (above). Files are untrusted: sizes, entity counts and nesting are capped and every kernel call is guarded. What cannot be read becomes a warning on the feature (a face left out gives an open body); not read yet: offset surfaces, pcurve-only edges.
+Read: manifold solid breps (with voids), faceted breps, shell-based surface models; planes, cylinders, cones, spheres, tori, B-spline and rational B-spline surfaces (with knots, Bézier, uniform, quasi-uniform), surfaces of revolution and linear extrusion, trimmed surfaces; lines, circles, ellipses, hyperbolas and parabolas (as exact rational curves, which export writes back as exact rational B-splines), B-spline curves, polylines, trimmed/surface/seam curves; length and angle units (SI prefixes, conversion-based units such as inches); product names (body names come from the solid's name, else the product's; `names` below chooses); surface colours; assemblies (next-assembly-usage occurrences placed by item-defined transformations, and mapped items) — the product tree is kept in the feature and becomes the import's components (above). Files are untrusted: sizes, entity counts and nesting are capped and every kernel call is guarded. What cannot be read becomes a warning on the feature (a face left out gives an open body); not read yet: offset surfaces, pcurve-only edges.
 
 ## Files from other CAD systems