BREP_kernel 0.15.0

//! Operand seam re-seat (lane X row 11b, `BREP_SEAM_RESEAT`).
//!
//! A cylinder grazing a planar wall of the other operand from inside touches
//! it along one generatrix, and the boolean cuts the cylinder's wall there.
//! When that generatrix is the wall's own seam (`tangent_on_seam_y10`), the
//! cut costs nothing. Anywhere else (`box_minus_tangent_cylinder`) the wall
//! comes out in two pieces that touch only across the old seam, 9F/21E/12V.
//! Moving the operand's seam onto the tangent generatrix BEFORE imprint gives
//! the first body at the first cost.
//!
//! The contact is closed form on the cached analytic carriers: a plane
//! parallel to a cylinder's axis at the radius from it. The re-seat is exact
//! by construction: the wall carrier, both rim circles and the caps' rim
//! pcurves each rotate by whole spans at a knot of multiplicity `degree`
//! (no basis function crosses it, and a closed curve's clamped ends join at
//! the same multiplicity), the seam edge becomes the carrier's new u = start
//! iso line, and the two seam vertices move onto the tangent points. Every id
//! and name is kept; the wall's own pcurves (its chart rectangle) are
//! unchanged.
//!
//! It moves a named edge and two vertices geometrically, so it runs only when
//! the caller says what follows: `BooleanOptions::seam_reseat_later_references`
//! lists the later features' references (their `inputParams` text), and any
//! of them naming the wall, a rim, the seam or a cap declines it. `None`
//! (every internal boolean, the raw API) declines.
//!
//! Scope: a primitive-shaped wall (one loop of rim, seam, rim, seam; closed
//! rims each shared with a one-coedge cap) whose contact sits on a
//! full-multiplicity knot, against exactly one tangent plane. Anything else
//! declines and the operand passes through unchanged.
use crate::topology::{BrepSolid, FaceRecord};
use crate::{NurbsCurve, NurbsSurface, Vec3, Vec4};
use rustc_hash::FxHashMap as HashMap;
use std::borrow::Cow;

/// The re-seat is on by default; `BREP_SEAM_RESEAT=0` (or `off`) disables it.
/// Promoted on the 239-document census (0 documents differ) and the tangent
/// bore's paired timing (8.05 -> 7.67 ms, 9F/21E/12V -> 8F/18E/10V).
pub(super) fn seam_reseat_enabled() -> bool {
    switch!("BREP_SEAM_RESEAT", true)
}


/// Both operands, each with every tangent cylinder wall the gate admits
/// re-seated on its contact line; an operand nothing applies to is borrowed.
pub(super) fn reseat_tangent_seams<'a>(
    first: &'a BrepSolid,
    second: &'a BrepSolid,
    later: &[String],
    tolerance: f64,
) -> (Cow<'a, BrepSolid>, Cow<'a, BrepSolid>) {
    let weld = crate::tolerance::assembler_weld(tolerance);
    let before = TOPOLOGY_WORK.with(|work| work.get());
    let result = (
        reseat_operand(first, second, later, weld).map_or(Cow::Borrowed(first), Cow::Owned),
        reseat_operand(second, first, later, weld).map_or(Cow::Borrowed(second), Cow::Owned),
    );
    if crate::profile::profile_enabled() {
        let after = TOPOLOGY_WORK.with(|work| work.get());
        profile_line!("boolean.seam_topology censuses={} coedges={}", after.0 - before.0, after.1 - before.1);
    }
    result
}

fn referenced(later: &[String], name: Option<&String>) -> bool {
    match name {
        Some(name) => later.iter().any(|text| text.contains(name.as_str())),
        // An unnamed record can only be referenced by id, which a non-empty
        // reference list cannot rule out.
        None => !later.is_empty(),
    }
}

/// A closed periodic curve or row list rotated to start at knot `c` (an
/// interior knot of multiplicity `degree`): `None` unless every moved knot
/// round-trips bit for bit.
fn rotate_closed<T: Clone>(knots: &[f64], degree: usize, items: &[T], c: f64) -> Option<(Vec<f64>, Vec<T>)> {
    let (k0, k1) = (*knots.first()?, *knots.last()?);
    if knots.len() != items.len() + degree + 1 || knots.iter().filter(|&&knot| knot == c).count() != degree {
        return None;
    }
    let first = knots.iter().position(|&knot| knot == c)?;
    let (to_high, to_low) = (c - k0, k1 - c);
    let moved = |value: f64, shift: f64, sign: f64| {
        let out = value - sign * shift;
        (out + sign * shift == value).then_some(out)
    };
    let mut rotated = vec![k0; degree + 1];
    for &knot in &knots[first + degree..knots.len() - degree - 1] {
        rotated.push(moved(knot, to_high, 1.0)?);
    }
    let joint = moved(k1, to_high, 1.0)?;
    rotated.extend(std::iter::repeat(joint).take(degree));
    for &knot in &knots[degree + 1..first] {
        rotated.push(moved(knot, to_low, -1.0)?);
    }
    rotated.extend(std::iter::repeat(k1).take(degree + 1));
    if rotated.len() != knots.len() || rotated.windows(2).any(|pair| pair[0] > pair[1]) {
        return None;
    }
    let row = first - 1;
    Some((rotated, items[row..].iter().chain(&items[1..=row]).cloned().collect()))
}

/// The interior knots of multiplicity `degree`.
fn full_knots(knots: &[f64], degree: usize) -> Vec<(f64, usize)> {
    let mut found: Vec<(f64, usize)> = Vec::new();
    for (index, &knot) in knots.iter().enumerate().skip(degree + 1).take(knots.len().saturating_sub(2 * degree + 2)) {
        if found.last().is_some_and(|&(last, _)| last == knot) {
            continue;
        }
        if knots.iter().filter(|&&other| other == knot).count() == degree {
            found.push((knot, index - 1));
        }
    }
    found
}

/// `curve` (closed) rotated to start where it passes through `point`, at a
/// full-multiplicity knot whose control point maps (through `chart`) within
/// `weld` of it.
fn rotate_curve_to(curve: &NurbsCurve, point: Vec3, chart: impl Fn(Vec4) -> Option<Vec3>, weld: f64) -> Option<NurbsCurve> {
    let (first, last) = (curve.control_points.first()?, curve.control_points.last()?);
    if chart(*first)?.sub(chart(*last)?).length() > weld {
        return None;
    }
    let hits: Vec<f64> = full_knots(&curve.knots, curve.degree)
        .into_iter()
        .filter(|&(_, row)| chart(curve.control_points[row]).is_some_and(|at| at.sub(point).length() <= weld))
        .map(|(knot, _)| knot)
        .collect();
    let [c] = hits.as_slice() else { return None };
    let (knots, controls) = rotate_closed(&curve.knots, curve.degree, &curve.control_points, *c)?;
    NurbsCurve::new(curve.degree, knots, controls).ok()
}

struct Contact {
    /// The tangent generatrix: a point and the axis direction.
    point: Vec3,
    axis: Vec3,
}

/// The one planar face of `other` tangent to the cylinder `wall` along a
/// generatrix inside both faces' extents, or `None` (no plane, or two).
fn tangent_contact(wall: &FaceRecord, other: &BrepSolid, weld: f64) -> Option<Contact> {
    let Some(crate::AnalyticSurface::RuledRevolution { frame, rho0, rho1, height }) = wall.surface.analytic() else {
        return None;
    };
    if rho0 != rho1 {
        return None;
    }
    let (radius, axis, height) = (*rho0, frame.axis, *height);
    let mut contacts = Vec::new();
    for face in other.shells.iter().flat_map(|shell| &shell.faces) {
        let Some(crate::AnalyticSurface::Plane { origin, u_dir, v_dir, .. }) = face.surface.analytic() else {
            continue;
        };
        let Ok(normal) = u_dir.cross(*v_dir).normalized() else { continue };
        if normal.dot(axis).abs() > weld / height.max(1.0) {
            continue;
        }
        let offset = frame.origin.sub(*origin).dot(normal);
        if (offset.abs() - radius).abs() > weld {
            continue;
        }
        let toward = normal.scale(-offset.signum());
        let point = frame.origin.add(toward.scale(radius));
        // The generatrix must cross the planar face's extent, read from its
        // boundary vertices' bounding box (padded by the weld).
        let points: Vec<Vec3> = face
            .loops
            .iter()
            .flat_map(|loop_record| &loop_record.coedges)
            .filter_map(|coedge| other.edges.iter().find(|edge| edge.id == coedge.edge_id))
            .flat_map(|edge| [edge.start_vertex_id, edge.end_vertex_id])
            .filter_map(|id| other.vertices.iter().find(|vertex| vertex.id == id).map(|vertex| vertex.point))
            .collect();
        if points.is_empty() {
            continue;
        }
        let lo = points.iter().fold(Vec3::new(f64::INFINITY, f64::INFINITY, f64::INFINITY), |a, p| Vec3::new(a.x.min(p.x), a.y.min(p.y), a.z.min(p.z)));
        let hi = points.iter().fold(Vec3::new(f64::NEG_INFINITY, f64::NEG_INFINITY, f64::NEG_INFINITY), |a, p| Vec3::new(a.x.max(p.x), a.y.max(p.y), a.z.max(p.z)));
        let inside = |p: Vec3| {
            p.x >= lo.x - weld && p.x <= hi.x + weld && p.y >= lo.y - weld && p.y <= hi.y + weld && p.z >= lo.z - weld && p.z <= hi.z + weld
        };
        let samples = (0..=4).map(|index| point.add(axis.scale(height * index as f64 / 4.0)));
        if samples.filter(|&p| inside(p)).count() < 2 {
            continue;
        }
        contacts.push(Contact { point, axis });
    }
    match contacts.len() {
        1 => contacts.pop(),
        _ => None,
    }
}

// Re-seating changes carrier/curve/pcurve coordinates, never record order,
// ids or coedge incidence. These readings therefore remain valid across all
// admitted walls of one operand. Keep the first slot for duplicate face ids,
// matching the old linear `find` even on malformed input.
struct ReseatTopology {
    face_slots: HashMap<u64, (usize, usize)>,
    uses: HashMap<u64, usize>,
}

thread_local! {
    static TOPOLOGY_WORK: std::cell::Cell<(u64, u64)> = const { std::cell::Cell::new((0, 0)) };
}

fn edge_uses(solid: &BrepSolid) -> HashMap<u64, usize> {
    let mut uses = HashMap::default();
    let mut visits = 0;
    for coedge in solid.shells.iter().flat_map(|s| &s.faces).flat_map(|f| &f.loops).flat_map(|l| &l.coedges) {
        *uses.entry(coedge.edge_id).or_default() += 1;
        visits += 1;
    }
    TOPOLOGY_WORK.with(|work| { let (calls, reads) = work.get(); work.set((calls + 1, reads + visits)); });
    uses
}

impl ReseatTopology {
    fn new(solid: &BrepSolid) -> Self {
        let mut face_slots = HashMap::default();
        for (shell, record) in solid.shells.iter().enumerate() {
            for (face, record) in record.faces.iter().enumerate() {
                face_slots.entry(record.id).or_insert((shell, face));
            }
        }
        Self { face_slots, uses: edge_uses(solid) }
    }
}

fn topology_memo_enabled() -> bool {
    switch!("BREP_RESEAT_TOPOLOGY_MEMO", true)
}

fn reseat_operand(solid: &BrepSolid, other: &BrepSolid, later: &[String], weld: f64) -> Option<BrepSolid> {
    reseat_operand_indexed(solid, other, later, weld, topology_memo_enabled())
}

fn reseat_operand_indexed(solid: &BrepSolid, other: &BrepSolid, later: &[String], weld: f64, indexed: bool) -> Option<BrepSolid> {
    let topology = indexed.then(|| ReseatTopology::new(solid));
    let mut result: Option<BrepSolid> = None;
    let faces: Vec<u64> = solid.shells.iter().flat_map(|shell| &shell.faces).map(|face| face.id).collect();
    for face_id in faces {
        let current = result.as_ref().unwrap_or(solid);
        if let Some(reseated) = reseat_wall(current, face_id, other, later, weld, topology.as_ref()) {
            result = Some(reseated);
        }
    }
    result
}

fn reseat_wall(solid: &BrepSolid, face_id: u64, other: &BrepSolid, later: &[String], weld: f64, topology: Option<&ReseatTopology>) -> Option<BrepSolid> {
    // The diagnostic hatch retains the original collect/find and census work.
    let faces: Option<Vec<&FaceRecord>> = topology.is_none().then(|| solid.shells.iter().flat_map(|shell| &shell.faces).collect());
    let wall = if let Some(topology) = topology {
        let &(shell, face) = topology.face_slots.get(&face_id)?;
        &solid.shells[shell].faces[face]
    } else { *faces.as_ref()?.iter().find(|face| face.id == face_id)? };
    // Structure: one loop of rim, seam, rim, seam (either order), the seam
    // edge used only here, each rim closed and shared with one cap whose
    // single loop is that rim alone.
    let [only] = wall.loops.as_slice() else { return None };
    if only.coedges.len() != 4 {
        return None;
    }
    let uncached_uses = topology.is_none().then(|| edge_uses(solid));
    let uses = topology.map(|t| &t.uses).or(uncached_uses.as_ref())?;
    let edge = |id: u64| solid.edges.iter().find(|edge| edge.id == id);
    let ids: Vec<u64> = only.coedges.iter().map(|coedge| coedge.edge_id).collect();
    let seam = *ids.iter().find(|id| ids.iter().filter(|other| other == id).count() == 2)?;
    let rims: Vec<u64> = ids.iter().copied().filter(|id| *id != seam).collect();
    let [rim0, rim1] = rims.as_slice() else { return None };
    if rim0 == rim1 || uses.get(&seam) != Some(&2) {
        return None;
    }
    let seam_edge = edge(seam)?;
    let mut caps = Vec::new();
    for &rim in [rim0, rim1] {
        let record = edge(rim)?;
        if uses.get(&rim) != Some(&2) || record.start_vertex_id != record.end_vertex_id || record.degenerate {
            return None;
        }
        let cap = solid.shells.iter().flat_map(|shell| &shell.faces).find(|face| {
            face.id != wall.id && face.loops.iter().flat_map(|loop_record| &loop_record.coedges).any(|coedge| coedge.edge_id == rim)
        })?;
        if cap.loops.len() != 1 || cap.loops[0].coedges.len() != 1 {
            return None;
        }
        caps.push(cap);
    }
    let seam_vertices = [seam_edge.start_vertex_id, seam_edge.end_vertex_id];
    let rim_vertices = [edge(*rim0)?.start_vertex_id, edge(*rim1)?.start_vertex_id];
    if !(seam_vertices == rim_vertices || seam_vertices == [rim_vertices[1], rim_vertices[0]]) {
        return None;
    }
    // References: the wall, its caps, its rims and seam, by name.
    if referenced(later, wall.name.as_ref())
        || caps.iter().any(|cap| referenced(later, cap.name.as_ref()))
        || [seam, *rim0, *rim1].iter().any(|&id| edge(id).is_some_and(|record| record.name.is_some() && referenced(later, record.name.as_ref())))
    {
        return None;
    }
    let contact = tangent_contact(wall, other, weld)?;
    // The carrier's full-multiplicity u knot whose control row lies on the
    // contact line at both ends; the one re-seat that is exact.
    let surface = &wall.surface;
    let on_line = |point: Vec3| {
        let delta = point.sub(contact.point);
        delta.sub(contact.axis.scale(delta.dot(contact.axis))).length() <= weld
    };
    let hits: Vec<f64> = full_knots(&surface.knots_u, surface.degree_u)
        .into_iter()
        .filter(|&(_, row)| {
            let column = &surface.control_points[row];
            [column.first(), column.last()].iter().all(|control| control.and_then(|c| c.point().ok()).is_some_and(on_line))
        })
        .map(|(knot, _)| knot)
        .collect();
    let [c] = hits.as_slice() else { return None };
    let (knots_u, rows) = rotate_closed(&surface.knots_u, surface.degree_u, &surface.control_points, *c)?;
    let rotated = NurbsSurface::new(surface.degree_u, surface.degree_v, knots_u, surface.knots_v.clone(), rows).ok()?;
    let [k0, _] = rotated.domain_u().ok()?;
    let seam_curve = rotated.iso_curve_u(k0).ok()?;
    let mut out = solid.clone();
    // The two seam vertices onto the tangent points, the seam's ends in order.
    let new_points = [seam_curve.evaluate(seam_curve.domain().ok()?[0]).ok()?, seam_curve.evaluate(seam_curve.domain().ok()?[1]).ok()?];
    for vertex in &mut out.vertices {
        if vertex.id == seam_edge.start_vertex_id {
            vertex.point = new_points[0];
        } else if vertex.id == seam_edge.end_vertex_id {
            vertex.point = new_points[1];
        }
    }
    let point_of = |id: u64| out.vertices.iter().find(|vertex| vertex.id == id).map(|vertex| vertex.point);
    let rim_points: Vec<Vec3> = [rim0, rim1].iter().map(|&&rim| point_of(edge(rim).unwrap().start_vertex_id)).collect::<Option<_>>()?;
    // Rims and caps, each rotated to start at its new vertex.
    let mut rim_curves = HashMap::<u64, NurbsCurve>::default();
    for (&rim, &point) in [rim0, rim1].iter().zip(&rim_points) {
        let record = edge(*rim)?;
        let [t0, t1] = record.curve.domain().ok()?;
        if record.t0 != t0 || record.t1 != t1 {
            return None;
        }
        rim_curves.insert(*rim, rotate_curve_to(&record.curve, point, |control| control.point().ok(), weld)?);
    }
    for record in &mut out.edges {
        if record.id == seam {
            let [t0, t1] = seam_curve.domain().ok()?;
            record.curve = seam_curve.clone();
            record.t0 = t0;
            record.t1 = t1;
        } else if let Some(curve) = rim_curves.get(&record.id) {
            let [t0, t1] = curve.domain().ok()?;
            record.curve = curve.clone();
            record.t0 = t0;
            record.t1 = t1;
        }
    }
    for shell in &mut out.shells {
        for face in &mut shell.faces {
            if face.id == wall.id {
                face.surface = rotated.clone();
            } else if let Some(position) = caps.iter().position(|cap| cap.id == face.id) {
                let point = rim_points[position];
                let cap_surface = face.surface.clone();
                let coedge = &mut face.loops[0].coedges[0];
                let chart = |control: Vec4| -> Option<Vec3> {
                    if control.w.abs() <= f64::EPSILON {
                        return None;
                    }
                    cap_surface.evaluate(control.x / control.w, control.y / control.w).ok()
                };
                coedge.pcurve = rotate_curve_to(&coedge.pcurve, point, chart, weld)?;
            }
        }
    }
    out.validate().is_empty().then_some(out)
}