3D view

/** A part's solid in its own frame (u, v, x) — the profile extruded along +z, copes cut by splitting the length. */
export function partGeometry(p) {
  const pr = p.profile, L = p.length;
  const copes = p.cuts.filter((c) => c.kind === 'cope');
  const cuts = new Set([0, L]);
  for (const c of copes) cuts.add(c.end === 'start' ? Math.min(c.length, L) : Math.max(L - c.length, 0));
  const xs = [...cuts].sort((a, b) => a - b);
  const geos = [];
  for (let i = 1; i < xs.length; i++) {
    const a = xs[i - 1], b = xs[i];
    if (b - a < 0.01) continue;
    const mid = (a + b) / 2;
    let loops = pr.loops;
    for (const c of copes) {
      const inCope = c.end === 'start' ? mid < c.length : mid > L - c.length;
      if (!inCope) continue;
      if (c.side === 'top') loops = loops.map((l, k) => (k === 0 ? clipLoopV(l, pr.depth / 2 - c.depth, true) : null)).filter((l) => l && l.length);
      else loops = loops.map((l, k) => (k === 0 ? clipLoopV(l, -pr.depth / 2 + c.depth, false) : null)).filter((l) => l && l.length);
    }
    if (!loops.length) continue;
    const shape = new THREE.Shape(loops[0].map(([u, v]) => new THREE.Vector2(u, v)));
    for (const h of loops.slice(1)) shape.holes.push(new THREE.Path(h.map(([u, v]) => new THREE.Vector2(u, v))));
    const g = new THREE.ExtrudeGeometry(shape, { depth: b - a, bevelEnabled: false, steps: 1, curveSegments: 1 });
    g.translate(0, 0, a);
    geos.push(g);
  }
  const g = geos.length === 1 ? geos[0] : mergeSimple(geos);
  if (p.endCuts) cutEnds(g, p);
  return g;
}

/** Plane-cut ends (mitres, 0.7.1 71.20): the end caps' vertices moved onto the cut faces, so the solid ends on the plane. */
function cutEnds(g, p) {
  const pos = g.attributes.position, L = p.length;
  for (let i = 0; i < pos.count; i++) {
    const z = pos.getZ(i);
    if (p.endCuts.start && Math.abs(z) < 1e-6) pos.setZ(i, endX(p, 'start', pos.getX(i), pos.getY(i)));
    else if (p.endCuts.end && Math.abs(z - L) < 1e-6) pos.setZ(i, endX(p, 'end', pos.getX(i), pos.getY(i)));
  }
  pos.needsUpdate = true;
  g.computeVertexNormals();
}

/** The part under a canvas point (CSS px) and where the ray meets it (mm), clipping respected. */
pickRef(l) {
  const ray = new THREE.Raycaster();
  ray.setFromCamera(new THREE.Vector2(l.x / l.w * 2 - 1, -(l.y / l.h) * 2 + 1), this.camera);
  const planes = this.clipPlanes;
  const hits = ray.intersectObjects(this.pickables, false).filter((h) => h.object.visible && planes.every((pl) => pl.distanceToPoint(h.point) >= 0));
  // solid steel before see-through concrete, and a reference picture (under everything) last
  const rank = (o) => (o.userData.mat === 'picture' ? 2 : o.userData.mat === 'concrete' ? 1 : 0);
  hits.sort((a, b) => rank(a.object) - rank(b.object) || a.distance - b.distance);
  const h = hits[0];
  if (!h) return { ref: null, point: null };
  let ref;
  if (h.object.userData.bolts) { const b = h.object.userData.bolts[h.instanceId]; ref = b && b.conn ? { kind: 'conn', id: b.conn } : null; }
  else ref = h.object.userData.ref;
  return { ref, point: [h.point.x / MM, h.point.y / MM, h.point.z / MM] };
}