90 lines
3.9 KiB
Rust
90 lines
3.9 KiB
Rust
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// Shared helpers used by per-entity tessellation impls in `crate::entities`
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// and the dispatcher in `crate::scene::tessellate`.
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//
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// Anything cross-entity (colour resolution, arc sampling, chord tolerance)
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// lives here. Entity-specific helpers (dim format strings, mleader path
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// types, etc.) stay with their entity file.
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use acadrust::types::Color as AcadColor;
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use glam::Vec3;
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use crate::scene::wire_model::{SnapHint, TangentGeom, WireModel};
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/// Output of the legacy per-entity geometry path used by entities not
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/// (yet) covered by the truck topology pipeline (Viewport, Insert,
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/// Hatch outline, Ole2Frame, …). Tuple form preserved to avoid
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/// touching every callsite when the dispatcher wraps these into a
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/// WireModel.
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///
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/// Layout: `(points, snap_pts, tangent_geoms, key_vertices)`.
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pub type LegacyGeometry = (
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Vec<[f32; 3]>,
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Vec<(Vec3, SnapHint)>,
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Vec<TangentGeom>,
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Vec<[f32; 3]>,
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);
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// ── Arc tessellation helpers ─────────────────────────────────────────────
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/// Convert hatch-boundary arc `(start, end, ccw)` into a
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/// `(start, signed_span)` ready for the sampling loop. Matches the
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/// legacy `(TAU - sa, TAU - ea)` flip used here for years — direction
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/// semantics are preserved on real files. (Wrap-through-2π is a known
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/// edge case in that convention; do not "fix" it without a wider audit
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/// of how upstream writers emit CW boundary arcs.)
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pub fn arc_signed_span(start: f64, end: f64, ccw: bool) -> (f64, f64) {
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const TAU: f64 = std::f64::consts::TAU;
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let (sa, ea) = if ccw { (start, end) } else { (TAU - start, TAU - end) };
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(sa, ea - sa)
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}
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/// Segment count for an arc, targeting `chord_tol_world` chord-height
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/// error in world units. Floor 8, cap 512.
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///
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/// Two production callers:
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/// - hatch fill polygon (built at load / on edit) passes a radius-
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/// relative tol via [`fill_chord_tol`] — ~0.1% radius, zoom-free so
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/// the polygon stays sharp at extreme zoom-in without re-tessellation.
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/// - hatch wire outline (re-tessellated every frame inside the render
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/// scope) passes a zoom-adaptive tol via [`wire_chord_tol`] — pulls
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/// from the per-frame override set by `Scene::wires_for_block` so
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/// far-out arcs collapse to a handful of segments.
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pub fn arc_segments(radius: f64, span_abs: f64, chord_tol_world: f64) -> u32 {
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if span_abs < 1e-9 || radius < 1e-9 {
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return 1;
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}
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let tol = chord_tol_world.max(1e-9).min(radius * 0.99);
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// θ where r * (1 - cos(θ/2)) = tol → θ = 2 * acos(1 - tol/r).
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let max_step = (2.0 * (1.0 - tol / radius).acos()).max(1e-6);
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((span_abs / max_step).ceil() as u32).clamp(8, 512)
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}
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/// Chord tolerance for the load-time fill polygon: 0.1% of radius,
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/// floor 1 µm so degenerate radii still produce a workable count.
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pub fn fill_chord_tol(radius: f64) -> f64 {
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(radius * 0.001).max(1e-6)
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}
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/// Chord tolerance for the per-frame wire outline: pulls the active
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/// `truck_tess::set_curve_tol_override` value (Scene sets it to
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/// `world_per_pixel × 0.5` so curves stay at ~half-pixel chord error at
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/// the current zoom). When no override is active (snap / hit-test
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/// passes, load-time builds), falls back to [`fill_chord_tol`] so we
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/// never under-sample.
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pub fn wire_chord_tol(radius: f64) -> f64 {
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match crate::scene::truck_tess::active_curve_tol() {
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Some(t) => t.min(fill_chord_tol(radius)).max(1e-9),
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None => fill_chord_tol(radius),
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}
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}
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// ── Colour helper ──────────────────────────────────────────────────────────
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/// Convert an acadrust Color (ACI index or true-color) to a GPU RGBA value.
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pub fn aci_to_rgba(color: &AcadColor) -> [f32; 4] {
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if let Some((r, g, b)) = color.rgb() {
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[r as f32 / 255.0, g as f32 / 255.0, b as f32 / 255.0, 1.0]
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} else {
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WireModel::WHITE
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}
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}
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