Project: stand-in ground, volumes and saved points

if (prof.ok && (a.pvis || []).length >= 2) z = Math.round((a.pvis.reduce((v, q) => v + q.z, 0) / a.pvis.length) * 100) / 100;
else { basis = 'zero'; z = 0; prof = buildProfile([{ sta: al.start, z: 0 }, { sta: al.end, z: 0 }]); }
// flat ground under the alignment, wide enough for its daylight (the profile's rise and fall at the flattest slope)
const pl = al.polyline(Math.max(al.length / 200, 1));
const zs = basis === 'profile' ? a.pvis.map((q) => q.z) : [0], dz = Math.max(...zs) - Math.min(...zs);
const pad = (m ? 60 : 200) + 6 * dz;
const x0 = Math.min(...pl.map((q) => q.x)) - pad, x1 = Math.max(...pl.map((q) => q.x)) + pad, y0 = Math.min(...pl.map((q) => q.y)) - pad, y1 = Math.max(...pl.map((q) => q.y)) + pad;
const pts = []; for (const x of [x0, (x0 + x1) / 2, x1]) for (const y of [y0, (y0 + y1) / 2, y1]) pts.push({ x, y, z });
const flat = buildSurface({ points: pts }).surface;

/** Cut and fill (grid method) inside every daylight line, in total and per item. */
volumes(cell) {
  const g = this.graded(), eg = this.eg().surface;
  if (!g.surface || !eg) return null;
  const regions = g.regions.filter(Boolean);
  if (!regions.length) return null;
  return this.memo('vol', this.surfaceDeps() + '|' + this.gradeDeps() + '|' + cell, () => {
    const total = gridVolume(eg, g.surface, { region: regions, cell });
    total.items = g.items.filter((it) => it.region).map((it) => ({ id: it.id, name: it.name, ...gridVolume(eg, g.surface, { region: it.region, cell: total.cell }) }));
    return total;
  });
}

points: this.points.map((p) => (p.blk ? [p.n, p.x, p.y, p.z, p.d, p.blk] : [p.n, p.x, p.y, p.z, p.d])),   // 0.5 WL.19: + the block it came from