refactor(modify): take plane geometry from cadkernel

TRIM, FILLET and EXPLODE each carried their own copy of the same plane
maths. The copies had already drifted apart: `ll` differed only in
parameter names between trim.rs and fillet.rs, `arc_pts` only in which
angle helper it called, and `norm` meant angle normalisation in trim.rs
and explode.rs while meaning vector normalisation in two other files.

The implementations now live in cadkernel's geom2d. A new local `geom`
module adapts the call shapes — the kernel takes `[f64; 2]` points and
returns `[f64; 3]`, while these commands pass loose scalars and feed
`WireModel::points`, which is `[f32; 3]`. Narrowing stays on this side
because only the caller knows whether it is a preview wire, which leaves
`points_low` empty and accepts the loss, or resident geometry, which
splits the f64 into a high/low pair instead.

Call sites are untouched: the kernel functions are imported under the old
local names, so the signatures they were written against still hold.

This also fixes ELLIPSE trim and extend previews. `ellipse_pts` wrote its
components as [x, z, y] while `arc_pts` — reached from the same match in
`entity_pts`, feeding the same `[f32; 3]` — wrote [x, y, z], and
`WireModel::points` is documented as world-space positions. Ellipse
previews were collapsing onto y = 0 and displacing along Z. The kernel's
`ellipse_arc` orders them correctly, so delegating corrects it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Cargo.lock

@@ -946,7 +946,7 @@ checksum = "fc652a48c352aef3ea3aed32080501cf3ef6ed5da78602a020c991775b0aff04"
 [[package]]
 name = "cadkernel"
 version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/cadkernel.git#53e15eccfb5c476a04c49cbea2809c5c4e13b691"
+source = "git+https://github.com/HakanSeven12/cadkernel.git#0e4b23845de75242e00f016feed9fc2341b4a85a"
 
 [[package]]
 name = "calloop"

src/modules/draw/modify/explode.rs

@@ -14,7 +14,7 @@
 //
 //   Unsupported entity types are skipped silently.
 
-use std::f64::consts::TAU;
+use super::geom::normalize_angle as norm_angle;
 
 use acadrust::entities::EntityCommon;
 use acadrust::entities::{
@@ -260,10 +260,6 @@ fn bulge_to_arc(
     Some(EntityType::Arc(arc))
 }
 
-fn norm_angle(a: f64) -> f64 {
-    ((a % TAU) + TAU) % TAU
-}
-
 fn explode_mline(ml: &MLine) -> Vec<EntityType> {
     let n = ml.vertices.len();
     if n < 2 {

src/modules/draw/modify/fillet.rs

@@ -10,6 +10,10 @@
 //   Finds intersection, backs off dist1 along line 1 and dist2 along line 2.
 
 use acadrust::entities::{Arc as ArcEnt, Line as LineEnt, LwPolyline};
+
+// Shared plane geometry, from cadkernel via the local adapters.
+use super::geom;
+use super::geom::{arc_points as arc_pts, line_line as ll, normalize_angle as norm_angle};
 use acadrust::types::Vector3;
 use acadrust::{EntityType, Handle};
 use glam::DVec3;
@@ -46,26 +50,6 @@ pub const DROPDOWN_ITEMS: &[(&str, &str, IconKind)] = &[
 // Geometry
 // ══════════════════════════════════════════════════════════════════════════
 
-/// Intersect two infinite lines. Returns (t on L1, u on L2).
-fn ll(
-    ax: f64,
-    ay: f64,
-    dx: f64,
-    dy: f64,
-    cx: f64,
-    cy: f64,
-    ex: f64,
-    ey: f64,
-) -> Option<(f64, f64)> {
-    let det = dx * ey - dy * ex;
-    if det.abs() < 1e-10 {
-        return None;
-    }
-    let t = ((cx - ax) * ey - (cy - ay) * ex) / det;
-    let u = ((cx - ax) * dy - (cy - ay) * dx) / det;
-    Some((t, u))
-}
-
 /// Extract coords and unit direction for a Line entity.
 fn line_geom(l: &LineEnt) -> ([f64; 2], [f64; 2], [f64; 2], f64) {
     let p1 = [l.start.x, l.start.y];
@@ -229,32 +213,10 @@ fn trim_to_xy(
 // ── Point-generation helpers ──────────────────────────────────────────────
 
 fn line_pts(l: &LineEnt) -> Vec<[f32; 3]> {
-    vec![
-        [l.start.x as f32, l.start.y as f32, l.start.z as f32],
-        [l.end.x as f32, l.end.y as f32, l.end.z as f32],
-    ]
-}
-
-fn arc_pts(cx: f64, cy: f64, r: f64, a0: f64, a1: f64, z: f64) -> Vec<[f32; 3]> {
-    let span = {
-        let s = norm_angle(a1) - norm_angle(a0);
-        if s <= 0.0 {
-            s + TAU
-        } else {
-            s
-        }
-    };
-    let steps = (span.abs() * 20.0).ceil().max(4.0) as usize;
-    (0..=steps)
-        .map(|i| {
-            let ang = norm_angle(a0) + span * (i as f64 / steps as f64);
-            [
-                (cx + r * ang.cos()) as f32,
-                (cy + r * ang.sin()) as f32,
-                z as f32,
-            ]
-        })
-        .collect()
+    geom::line_points(
+        [l.start.x, l.start.y, l.start.z],
+        [l.end.x, l.end.y, l.end.z],
+    )
 }
 
 fn entity_pts(e: &EntityType) -> Vec<[f32; 3]> {
@@ -286,11 +248,6 @@ fn arc_geom(a: &ArcEnt) -> ([f64; 2], f64, f64, f64, f64) {
     )
 }
 
-/// Normalize angle to [0, 2π).
-fn norm_angle(a: f64) -> f64 {
-    ((a % TAU) + TAU) % TAU
-}
-
 /// Return the CCW angular span from `start` to `end`.
 fn arc_span(start: f64, end: f64) -> f64 {
     let s = (end - start).rem_euclid(TAU);

src/modules/draw/modify/geom.rs

@@ -0,0 +1,128 @@
+//! Adapters between the editing commands and `cadkernel`'s plane geometry.
+//!
+//! The kernel takes points as `[f64; 2]` and hands tessellation back as
+//! `[f64; 3]`. The commands here grew up passing loose `x, y` scalars and
+//! feeding [`WireModel::points`](crate::scene::model::wire_model::WireModel),
+//! which is `[f32; 3]`. These wrappers absorb that difference in one place so
+//! the maths itself lives once, in the kernel.
+//!
+//! Narrowing to `f32` happens here rather than in the kernel deliberately:
+//! preview wires leave `points_low` empty, so they accept the loss, while the
+//! resident render path splits the `f64` into a high/low pair instead. Only a
+//! caller knows which of the two it is.
+
+use acadrust::kernel::geom2d::{self, Ellipse};
+
+/// Re-exported unchanged: these already speak in plain `f64`, so there is no
+/// call-shape difference for this module to absorb.
+pub use acadrust::kernel::geom2d::{angle_within_arc, arc_parameter, lerp, normalize_angle};
+
+/// Preview geometry keeps the density the commands have always used.
+const SEGMENTS_PER_RADIAN: f64 = geom2d::DEFAULT_SEGMENTS_PER_RADIAN;
+
+fn narrow(points: Vec<[f64; 3]>) -> Vec<[f32; 3]> {
+    points
+        .into_iter()
+        .map(|p| [p[0] as f32, p[1] as f32, p[2] as f32])
+        .collect()
+}
+
+/// Where two infinite lines cross, as `(t, u)`; `None` when parallel.
+///
+/// Both parameters are unbounded, so EXTEND can use a crossing that lies past
+/// the end of either line.
+#[allow(clippy::too_many_arguments)]
+pub fn line_line(
+    px: f64,
+    py: f64,
+    dx: f64,
+    dy: f64,
+    qx: f64,
+    qy: f64,
+    ex: f64,
+    ey: f64,
+) -> Option<(f64, f64)> {
+    geom2d::line_line([px, py], [dx, dy], [qx, qy], [ex, ey])
+}
+
+/// Line parameters where `p + t·d` meets a circle: none, one when tangent, or
+/// two ordered by increasing `t`.
+pub fn line_circle(px: f64, py: f64, dx: f64, dy: f64, cx: f64, cy: f64, r: f64) -> Vec<f64> {
+    geom2d::line_circle([px, py], [dx, dy], [cx, cy], r)
+}
+
+/// Angles **on the first circle** where two circles meet.
+pub fn circle_circle_angles(cx1: f64, cy1: f64, r1: f64, cx2: f64, cy2: f64, r2: f64) -> Vec<f64> {
+    geom2d::circle_circle_angles([cx1, cy1], r1, [cx2, cy2], r2)
+}
+
+/// `(s_on_line, t_on_ellipse)` pairs where a line meets an ellipse.
+///
+/// `nx, ny` is the unit major axis.
+#[allow(clippy::too_many_arguments)]
+pub fn line_ellipse(
+    px: f64,
+    py: f64,
+    dx: f64,
+    dy: f64,
+    cx: f64,
+    cy: f64,
+    a: f64,
+    b: f64,
+    nx: f64,
+    ny: f64,
+) -> Vec<(f64, f64)> {
+    geom2d::line_ellipse(
+        [px, py],
+        [dx, dy],
+        &Ellipse {
+            centre: [cx, cy],
+            major_radius: a,
+            minor_radius: b,
+            major_axis: [nx, ny],
+        },
+    )
+}
+
+/// The two endpoints of a straight segment, as render vertices.
+pub fn line_points(start: [f64; 3], end: [f64; 3]) -> Vec<[f32; 3]> {
+    narrow(vec![start, end])
+}
+
+/// A circular arc sampled counter-clockwise, as render vertices.
+pub fn arc_points(cx: f64, cy: f64, r: f64, a0: f64, a1: f64, z: f64) -> Vec<[f32; 3]> {
+    narrow(geom2d::arc([cx, cy], r, a0, a1, z, SEGMENTS_PER_RADIAN))
+}
+
+/// An elliptical arc sampled between two of the ellipse's own parameters, as
+/// render vertices.
+///
+/// Components come back as `[x, y, z]`. The hand-rolled version this replaces
+/// wrote them as `[x, z, y]`, which flattened ELLIPSE trim previews onto
+/// `y = 0` and displaced them along Z.
+#[allow(clippy::too_many_arguments)]
+pub fn ellipse_points(
+    cx: f64,
+    cy: f64,
+    a: f64,
+    b: f64,
+    nx: f64,
+    ny: f64,
+    t0: f64,
+    t1: f64,
+    z: f64,
+) -> Vec<[f32; 3]> {
+    let ellipse = Ellipse {
+        centre: [cx, cy],
+        major_radius: a,
+        minor_radius: b,
+        major_axis: [nx, ny],
+    };
+    narrow(geom2d::ellipse_arc(
+        &ellipse,
+        t0,
+        t1,
+        z,
+        SEGMENTS_PER_RADIAN,
+    ))
+}

src/modules/draw/modify/mod.rs

@@ -8,6 +8,7 @@ pub mod delete;
 mod entity_index;
 pub mod explode;
 pub mod fillet;
+pub mod geom;
 pub mod join;
 pub mod lengthen;
 pub mod mirror;

src/modules/draw/modify/trim.rs

@@ -10,6 +10,15 @@
 
 use std::f64::consts::TAU;
 
+// The plane geometry these commands run on lives in cadkernel; `geom` adapts
+// its call shapes to the loose scalars and f32 render vertices used here.
+use super::geom;
+use super::geom::{
+    angle_within_arc as in_arc, arc_parameter as arc_t, arc_points as arc_pts,
+    circle_circle_angles as cc_angles, ellipse_points as ellipse_pts, lerp as lerp2,
+    line_circle as lc, line_ellipse as le, line_line as ll, normalize_angle as norm,
+};
+
 use crate::modules::draw::fence::{crossing_box_preview, FencePick};
 
 use acadrust::entities::{
@@ -54,163 +63,6 @@ pub const DROPDOWN_ITEMS: &[(&str, &str, IconKind)] = &[
 // Geometry helpers
 // ══════════════════════════════════════════════════════════════════════════
 
-/// Normalize angle to [0, 2π).
-fn norm(a: f64) -> f64 {
-    ((a % TAU) + TAU) % TAU
-}
-
-/// Is angle `a` within the arc from `s` to `e` (CCW, radians)?
-fn in_arc(a: f64, s: f64, e: f64) -> bool {
-    let (a, s, e) = (norm(a), norm(s), norm(e));
-    if (e - s).abs() < 1e-9 || (e - s - TAU).abs() < 1e-9 {
-        return true;
-    }
-    if s <= e {
-        a >= s - 1e-9 && a <= e + 1e-9
-    } else {
-        a >= s - 1e-9 || a <= e + 1e-9
-    }
-}
-
-/// Parametric t ∈ [0,1] on arc (a0→a1 CCW) for angle `a`.
-fn arc_t(a: f64, a0: f64, a1: f64) -> f64 {
-    let span = {
-        let s = norm(a1) - norm(a0);
-        if s <= 0.0 {
-            s + TAU
-        } else {
-            s
-        }
-    };
-    let da = {
-        let d = norm(a) - norm(a0);
-        if d < 0.0 {
-            d + TAU
-        } else {
-            d
-        }
-    };
-    (da / span).clamp(0.0, 1.0)
-}
-
-/// Intersect infinite lines (p+t·d) and (q+u·e). Returns (t, u).
-fn ll(
-    px: f64,
-    py: f64,
-    dx: f64,
-    dy: f64,
-    qx: f64,
-    qy: f64,
-    ex: f64,
-    ey: f64,
-) -> Option<(f64, f64)> {
-    let det = dx * ey - dy * ex;
-    if det.abs() < 1e-10 {
-        return None;
-    }
-    let t = ((qx - px) * ey - (qy - py) * ex) / det;
-    let u = ((qx - px) * dy - (qy - py) * dx) / det;
-    Some((t, u))
-}
-
-/// Intersect infinite line (p+t·d) with circle (cx,cy,r). Returns t values.
-fn lc(px: f64, py: f64, dx: f64, dy: f64, cx: f64, cy: f64, r: f64) -> Vec<f64> {
-    let fx = px - cx;
-    let fy = py - cy;
-    let a = dx * dx + dy * dy;
-    let b = 2.0 * (fx * dx + fy * dy);
-    let c = fx * fx + fy * fy - r * r;
-    let disc = b * b - 4.0 * a * c;
-    if disc < 0.0 {
-        return vec![];
-    }
-    let sq = disc.sqrt();
-    if disc < 1e-14 {
-        vec![(-b) / (2.0 * a)]
-    } else {
-        vec![(-b - sq) / (2.0 * a), (-b + sq) / (2.0 * a)]
-    }
-}
-
-/// Circle-circle intersection: angles on circle 1 where they meet.
-fn cc_angles(cx1: f64, cy1: f64, r1: f64, cx2: f64, cy2: f64, r2: f64) -> Vec<f64> {
-    let d = ((cx2 - cx1).powi(2) + (cy2 - cy1).powi(2)).sqrt();
-    if d < 1e-9 || d > r1 + r2 + 1e-9 || d < (r1 - r2).abs() - 1e-9 {
-        return vec![];
-    }
-    let a = (r1 * r1 - r2 * r2 + d * d) / (2.0 * d);
-    let h2 = r1 * r1 - a * a;
-    if h2 < 0.0 {
-        return vec![];
-    }
-    let h = h2.sqrt();
-    let mx = cx1 + a * (cx2 - cx1) / d;
-    let my = cy1 + a * (cy2 - cy1) / d;
-    let px = h * (cy2 - cy1) / d;
-    let py = -h * (cx2 - cx1) / d;
-    let a1 = ((my + py) - cy1).atan2((mx + px) - cx1);
-    let a2 = ((my - py) - cy1).atan2((mx - px) - cx1);
-    if h < 1e-9 {
-        vec![a1]
-    } else {
-        vec![a1, a2]
-    }
-}
-
-/// Line (px+s·d) vs ellipse (cx,cy,a,b,nx,ny). Returns (s_on_line, t_on_ellipse) pairs.
-/// nx,ny: unit major-axis; perp = (-ny, nx).  Parametric ellipse: P(t) = center + a·cos(t)·n + b·sin(t)·v.
-fn le(
-    px: f64,
-    py: f64,
-    dpx: f64,
-    dpy: f64,
-    cx: f64,
-    cy: f64,
-    a: f64,
-    b: f64,
-    nx: f64,
-    ny: f64,
-) -> Vec<(f64, f64)> {
-    // Transform line origin to ellipse local frame
-    let rx = px - cx;
-    let ry = py - cy;
-    // Project onto major/minor axes
-    let xl0 = rx * nx + ry * ny;
-    let yl0 = -rx * ny + ry * nx;
-    let dxl = dpx * nx + dpy * ny;
-    let dyl = -dpx * ny + dpy * nx;
-    // Scale by 1/a, 1/b → circle equation
-    let xa = xl0 / a;
-    let xda = dxl / a;
-    let yb = yl0 / b;
-    let ydb = dyl / b;
-    let big_a = xda * xda + ydb * ydb;
-    if big_a < 1e-20 {
-        return vec![];
-    }
-    let big_b = 2.0 * (xa * xda + yb * ydb);
-    let big_c = xa * xa + yb * yb - 1.0;
-    let disc = big_b * big_b - 4.0 * big_a * big_c;
-    if disc < 0.0 {
-        return vec![];
-    }
-    let sq = disc.sqrt();
-    let s_vals: Vec<f64> = if disc < 1e-14 {
-        vec![(-big_b) / (2.0 * big_a)]
-    } else {
-        vec![(-big_b - sq) / (2.0 * big_a), (-big_b + sq) / (2.0 * big_a)]
-    };
-    s_vals
-        .into_iter()
-        .map(|s| {
-            let xl = xl0 + s * dxl;
-            let yl = yl0 + s * dyl;
-            let t = yl.atan2(xl); // ≡ atan2(yl/b, xl/a) but faster since sign is preserved
-            (s, t)
-        })
-        .collect()
-}
-
 // ── Boundary geometry ─────────────────────────────────────────────────────
 
 /// Virtual extent used to represent infinite ends of Ray / XLine.
@@ -1051,34 +903,6 @@ fn extend_ellipse(orig: &EllipseEnt, t_click: f64, geos: &[Geo]) -> Option<Entit
     Some(EntityType::Ellipse(e))
 }
 
-/// Generate preview points for an ellipse arc.
-fn ellipse_pts(
-    cx: f64,
-    cy: f64,
-    a: f64,
-    b: f64,
-    nx: f64,
-    ny: f64,
-    t0: f64,
-    t1: f64,
-    z: f64,
-) -> Vec<[f32; 3]> {
-    let span = t1 - t0;
-    let steps = (span.abs() * 20.0).ceil().max(4.0) as usize;
-    (0..=steps)
-        .map(|i| {
-            let t = t0 + span * (i as f64 / steps as f64);
-            let lx = a * t.cos();
-            let ly = b * t.sin();
-            [
-                (cx + lx * nx - ly * ny) as f32,
-                z as f32,
-                (cy + lx * ny + ly * nx) as f32,
-            ]
-        })
-        .collect()
-}
-
 // ── Spline trim / extend ──────────────────────────────────────────────────
 
 /// Find normalised t-params ∈ [0,1] where a Spline intersects boundary geos.
@@ -1221,10 +1045,6 @@ fn trim_intervals(ts: &[f64], t_click: f64) -> Vec<(f64, f64)> {
         .collect()
 }
 
-fn lerp2(p1: [f64; 2], p2: [f64; 2], t: f64) -> [f64; 2] {
-    [p1[0] + t * (p2[0] - p1[0]), p1[1] + t * (p2[1] - p1[1])]
-}
-
 /// Trim a Line entity. Returns the surviving line segments.
 fn trim_line(orig: &LineEnt, ts: &[f64], t_click: f64) -> Vec<EntityType> {
     let p1 = [orig.start.x, orig.start.y];
@@ -2004,32 +1824,10 @@ fn trim_xline(orig: &XLineEnt, ts: &[f64], t_click: f64) -> Vec<EntityType> {
 const DIM_RED: [f32; 4] = [1.0, 0.3, 0.3, 0.6];
 
 fn line_pts(l: &LineEnt) -> Vec<[f32; 3]> {
-    vec![
-        [l.start.x as f32, l.start.y as f32, l.start.z as f32],
-        [l.end.x as f32, l.end.y as f32, l.end.z as f32],
-    ]
-}
-
-fn arc_pts(cx: f64, cy: f64, r: f64, a0: f64, a1: f64, z: f64) -> Vec<[f32; 3]> {
-    let span = {
-        let s = norm(a1) - norm(a0);
-        if s <= 0.0 {
-            s + TAU
-        } else {
-            s
-        }
-    };
-    let steps = (span.abs() * 20.0).ceil().max(4.0) as usize;
-    (0..=steps)
-        .map(|i| {
-            let ang = norm(a0) + span * (i as f64 / steps as f64);
-            [
-                (cx + r * ang.cos()) as f32,
-                (cy + r * ang.sin()) as f32,
-                z as f32,
-            ]
-        })
-        .collect()
+    geom::line_points(
+        [l.start.x, l.start.y, l.start.z],
+        [l.end.x, l.end.y, l.end.z],
+    )
 }
 
 fn entity_pts(e: &EntityType) -> Vec<[f32; 3]> {