mapwright/module/lib/dungeon.mjs

/**
 * Dungeon generator — organic caves (no right angles).
 *
 * Wraps the organic core into a usable model: floor blob, smoothed contour
 * loops for rendering, simplified diagonal wall segments for Foundry, and a
 * handful of labelled feature points. Pure / Node-testable.
 */

import { Rng } from "./rng.mjs";
import {
  generateBlob, traceContours, loopToCells,
  simplifyClosed, chaikin, signedArea
} from "./organic.mjs";

const FEATURE_LABELS = [
  "Entrance", "Collapsed Tunnel", "Underground Pool", "Old Campsite",
  "Mushroom Grove", "Bone Pile", "Crystal Vein", "Narrow Squeeze",
  "Cave-in", "Stagnant Water", "Ancient Carving"
];

function clean(loop) {
  const out = [];
  for (const p of loop) {
    const last = out[out.length - 1];
    if (!last || last.x !== p.x || last.y !== p.y) out.push(p);
  }
  if (out.length > 1) {
    const a = out[0], b = out[out.length - 1];
    if (a.x === b.x && a.y === b.y) out.pop();
  }
  return out;
}

/**
 * @param {object} opts cols, rows, seed, subRes, fill, steps, simplifyTol, smooth, features
 * @returns {{ cols, rows, subRes, floor, loops, segments, features, floorCells }}
 */
export function generateCave(opts) {
  const blob = generateBlob({
    cols: opts.cols, rows: opts.rows, subRes: opts.subRes ?? 3,
    seed: opts.seed, fill: opts.fill ?? 0.46, steps: opts.steps ?? 5, margin: opts.margin ?? 1
  });

  const rawLoops = traceContours(blob.floor, blob.sw, blob.sh);
  const simplifyTol = opts.simplifyTol ?? 0.45;
  const smoothIter = opts.smooth ?? 2;
  const minLoopArea = opts.minLoopArea ?? 1.2;

  const loops = [];
  for (const raw of rawLoops) {
    const cells = clean(loopToCells(raw, blob.subRes));
    if (cells.length < 4) continue;
    const simp = simplifyClosed(cells, simplifyTol);
    if (simp.length < 3) continue;
    const area = signedArea(simp);
    if (Math.abs(area) < minLoopArea) continue;
    loops.push({ simp, smooth: chaikin(simp, smoothIter), area });
  }

  // Wall segments (diagonal, organic) for Foundry from the simplified loops.
  const segments = [];
  for (const lp of loops) {
    const p = lp.simp;
    for (let i = 0; i < p.length; i += 1) {
      const a = p[i], b = p[(i + 1) % p.length];
      segments.push({ x1: a.x, y1: a.y, x2: b.x, y2: b.y, kind: "wall" });
    }
  }

  const features = placeFeatures(blob, opts);

  return {
    cols: opts.cols, rows: opts.rows, subRes: blob.subRes,
    floor: blob.floor, loops, segments, features
  };
}

/** Scatter a few labelled feature points on floor cells, well spaced. */
function placeFeatures(blob, opts) {
  const rng = new Rng(`${opts.seed}::features`);
  const { floor, sw, sh, subRes } = blob;
  const floorPts = [];
  for (let y = 0; y < sh; y += 1) {
    for (let x = 0; x < sw; x += 1) {
      if (floor[y * sw + x] === 1) floorPts.push({ x, y });
    }
  }
  if (!floorPts.length) return [];

  const want = Math.min(opts.featureCount ?? Math.round((opts.cols * opts.rows) / 90) + 1, FEATURE_LABELS.length);
  const minSep = Math.max(3, Math.min(blob.cols, blob.rows) * 0.18) * subRes;
  const labels = rng.shuffle(FEATURE_LABELS.slice());
  const chosen = [];

  // Entrance: floor point closest to the grid edge.
  let entrance = floorPts[0];
  let bestEdge = Infinity;
  for (const p of floorPts) {
    const d = Math.min(p.x, p.y, sw - p.x, sh - p.y);
    if (d < bestEdge) { bestEdge = d; entrance = p; }
  }
  chosen.push({ x: entrance.x / subRes, y: entrance.y / subRes, label: "Entrance" });

  let guard = 0;
  while (chosen.length < want && guard++ < 2000) {
    const c = rng.pick(floorPts);
    const tooClose = chosen.some((o) => Math.hypot(o.x * subRes - c.x, o.y * subRes - c.y) < minSep);
    if (tooClose) continue;
    const label = labels[chosen.length % labels.length];
    if (label === "Entrance") continue;
    chosen.push({ x: c.x / subRes, y: c.y / subRes, label });
  }
  return chosen;
}