feat(tess): use angular sampling

Route curve, hatch, sweep, loft, surface, edge, and isoline tessellation through the shared kernel policy.

src/scene/convert/tess_util.rs

@@ -1,9 +1,7 @@
 // Shared helpers used by per-entity tessellation impls in `crate::entities`
 // and the dispatcher in `crate::scene::convert::tessellate`.
 //
-// Anything cross-entity (colour resolution, arc sampling, chord tolerance)
-// lives here. Entity-specific helpers (dim format strings, mleader path
-// types, etc.) stay with their entity file.
+// Cross-entity rendering helpers live here.
 
 use acadrust::types::Color as AcadColor;
 use glam::Vec3;
@@ -28,81 +26,6 @@ pub type FallbackGeometry = (
     Vec<[f64; 3]>,
 );
 
-// ── Arc tessellation helpers ─────────────────────────────────────────────
-
-/// Convert hatch-boundary arc `(start, end, ccw)` into a
-/// `(start, signed_span)` ready for the sampling loop. Matches the
-/// legacy `(TAU - sa, TAU - ea)` flip used here for years — direction
-/// semantics are preserved on real files. (Wrap-through-2π is a known
-/// edge case in that convention; do not "fix" it without a wider audit
-/// of how upstream writers emit CW boundary arcs.)
-///
-/// VERIFIED against real AutoCAD output (KSR-039 DWG, CW arc edges with
-/// line neighbours): the stored angles of a `ccw = false` arc edge are
-/// MIRRORED — the true point is `center + r·(cos(TAU-θ), sin(TAU-θ))`.
-/// Sampling the mirrored parameter directly (this function's flip) gives
-/// exact endpoint continuity with the adjacent edges (Δ = 0.000000),
-/// while interpreting them as true angles lands tens of units away. Any
-/// code that *produces* CW boundary arcs (mirror transforms, explode)
-/// must therefore store mirrored angles, not geometric ones.
-pub fn arc_signed_span(start: f64, end: f64, ccw: bool) -> (f64, f64) {
-    const TAU: f64 = std::f64::consts::TAU;
-    let (sa, ea) = if ccw {
-        (start, end)
-    } else {
-        (TAU - start, TAU - end)
-    };
-    (sa, ea - sa)
-}
-
-/// Segment count for an arc, targeting `chord_tol_world` chord-height
-/// error in world units. Floor 8, cap 512.
-///
-/// Two production callers:
-/// - hatch fill polygon (built at load / on edit) passes a radius-
-///   relative tol via [`fill_chord_tol`] — ~0.1% radius, zoom-free so
-///   the polygon stays sharp at extreme zoom-in without re-tessellation.
-/// - hatch wire outline (re-tessellated every frame inside the render
-///   scope) passes a zoom-adaptive tol via [`wire_chord_tol`] — pulls
-///   from the per-frame override set by `Scene::wires_for_block` so
-///   far-out arcs collapse to a handful of segments.
-pub fn arc_segments(radius: f64, span_abs: f64, chord_tol_world: f64) -> u32 {
-    arc_segments_floored(radius, span_abs, chord_tol_world, 8)
-}
-
-/// Like [`arc_segments`] but with a caller-chosen segment floor. The 2-D wire
-/// wants floor 8 so a circle reads as round; a curved-surface grid patch or a
-/// short arc wants a lower floor so a small span isn't forced to 8 steps. Cap
-/// stays 512.
-pub fn arc_segments_floored(radius: f64, span_abs: f64, chord_tol_world: f64, floor: u32) -> u32 {
-    if span_abs < 1e-9 || radius < 1e-9 {
-        return floor.max(1);
-    }
-    let tol = chord_tol_world.max(1e-9).min(radius * 0.99);
-    // θ where r * (1 - cos(θ/2)) = tol  →  θ = 2 * acos(1 - tol/r).
-    let max_step = (2.0 * (1.0 - tol / radius).acos()).max(1e-6);
-    ((span_abs / max_step).ceil() as u32).clamp(floor, 512)
-}
-
-/// Chord tolerance for the load-time fill polygon: 0.1% of radius,
-/// floor 1 µm so degenerate radii still produce a workable count.
-pub fn fill_chord_tol(radius: f64) -> f64 {
-    (radius * 0.001).max(1e-6)
-}
-
-/// Chord tolerance for the per-frame wire outline: pulls the active
-/// `curve_tol::set_curve_tol_override` value (Scene sets it to
-/// `world_per_pixel × 0.5` so curves stay at ~half-pixel chord error at
-/// the current zoom). When no override is active (snap / hit-test
-/// passes, load-time builds), falls back to [`fill_chord_tol`] so we
-/// never under-sample.
-pub fn wire_chord_tol(radius: f64) -> f64 {
-    match crate::scene::convert::curve_tol::active_curve_tol() {
-        Some(t) => t.min(fill_chord_tol(radius)).max(1e-9),
-        None => fill_chord_tol(radius),
-    }
-}
-
 // ── Colour helper ──────────────────────────────────────────────────────────
 
 /// Convert an acadrust Color (ACI index or true-color) to a GPU RGBA value.