chinko

mapTerrain.js

@@ -213,7 +213,7 @@ const TERRAIN_TYPES = [
     coastStyle: "inland_sea",
     mountainMode: "mixed",
     massifnessRange: [0.34, 0.62],
-    seaRatioRange: [0.20, 0.33],
+    seaRatioRange: [0.28, 0.43],
     twoSidedChance: 0.92,
     mountainOffsetRange: [0.22, 0.34],
     baseHeightRange: [0.46, 0.78],
@@ -226,7 +226,7 @@ const TERRAIN_TYPES = [
     lengthScale: 1.00,
     widthScale: 1.18,
     heightScale: 0.82,
-    coastStrength: 1.10,
+    coastStrength: 1.34,
     plainBiasRange: [0.26, 0.50],
     riverRichnessRange: [0.58, 0.96],
     bigRiverChanceRange: [0.18, 0.42],
@@ -580,10 +580,12 @@ function computeCoastLower(px, py, template, seed) {
   let pressure = 0;
 
   if (template.coastStyle === "inland_sea") {
-    // 瀬戸内型だけは中央を横切る浅い内海を許す。出現率は地形タイプ側で管理する。
-    const sideA = smoothstep((-axis + 0.25 + wave + bay) / 0.26);
-    const sideB = smoothstep((axis + 0.23 - wave + bay * 0.7) / 0.27);
-    const channel = smoothstep((0.060 - Math.abs(cross + wave * 0.65 + islandNoise)) / 0.090) * 0.82;
+    // 瀬戸内型は旧来の大きな内海＋両岸海岸線に戻す。
+    // 海面比率はテンプレート側で高めに保ち、微細な島ノイズではなく
+    // 連続した水道形状で海を増やす。
+    const sideA = smoothstep((-axis + 0.28 + wave + bay) / 0.28);
+    const sideB = smoothstep((axis + 0.26 - wave + bay * 0.7) / 0.29);
+    const channel = smoothstep((0.082 - Math.abs(cross + wave * 0.68 + islandNoise * 0.55)) / 0.112) * 0.98;
     pressure = Math.max(sideA, sideB, channel);
   } else if (template.coastStyle === "parallel_spine") {
     // 東北型: 左右端または上下端に海を置く。海岸線は脊梁山脈とおおよそ平行。
@@ -738,6 +740,81 @@ function computeFlowAccumulation(sea, flowTo, filled, flowAccum) {
   return area;
 }
 
+function buildWatershedId(sea, flowTo, flowAccum) {
+  const outletKey = new Int32Array(SIZE);
+  outletKey.fill(-1);
+  const ids = new Int32Array(SIZE);
+  ids.fill(-1);
+  const outletToId = new Map();
+  const quant = 12;
+
+  function keyForOutlet(i) {
+    if (i < 0) return -1;
+    const x = i % MAP_W;
+    const y = Math.floor(i / MAP_W);
+    const qx = Math.floor(x / quant);
+    const qy = Math.floor(y / quant);
+    return qy * 1000 + qx;
+  }
+
+  function resolve(start) {
+    if (start < 0 || sea[start]) return -1;
+    if (outletKey[start] >= 0) return outletKey[start];
+    const chain = [];
+    const seen = new Set();
+    let i = start;
+    let key = -1;
+    for (let guard = 0; guard < SIZE && i >= 0; guard++) {
+      if (sea[i]) { key = keyForOutlet(i); break; }
+      if (outletKey[i] >= 0) { key = outletKey[i]; break; }
+      if (seen.has(i)) { key = keyForOutlet(i); break; }
+      seen.add(i);
+      chain.push(i);
+      const to = flowTo[i];
+      if (to < 0 || to === i) { key = keyForOutlet(i); break; }
+      // Major channels should be a watershed's spine, not a sequence of tiny
+      // drainage labels. Continue to the coast/outlet even after hitting them.
+      i = to;
+    }
+    if (key < 0 && chain.length) key = keyForOutlet(chain[chain.length - 1]);
+    for (const ci of chain) outletKey[ci] = key;
+    return key;
+  }
+
+  for (let i = 0; i < SIZE; i++) {
+    if (sea[i]) continue;
+    const key = resolve(i);
+    if (key < 0) continue;
+    if (!outletToId.has(key)) outletToId.set(key, outletToId.size);
+    ids[i] = outletToId.get(key);
+  }
+
+  // Very small coastal outlet labels create noisy slivers. Merge them into the
+  // strongest neighbouring watershed so natural compartments remain basin-scale.
+  const counts = new Int32Array(outletToId.size || 1);
+  for (let i = 0; i < SIZE; i++) if (ids[i] >= 0) counts[ids[i]]++;
+  const minArea = 18;
+  for (let pass = 0; pass < 2; pass++) {
+    for (let y = 0; y < MAP_H; y++) {
+      for (let x = 0; x < MAP_W; x++) {
+        const i = indexOf(x, y);
+        const id = ids[i];
+        if (id < 0 || counts[id] >= minArea) continue;
+        const choices = new Map();
+        for (const [nx, ny] of [[x + 1, y], [x - 1, y], [x, y + 1], [x, y - 1]]) {
+          if (!inside(nx, ny)) continue;
+          const nid = ids[indexOf(nx, ny)];
+          if (nid >= 0 && nid !== id) choices.set(nid, (choices.get(nid) || 0) + 1 + (flowAccum[indexOf(nx, ny)] || 0));
+        }
+        let best = -1, bestScore = -1;
+        for (const [nid, score] of choices) if (score > bestScore) { bestScore = score; best = nid; }
+        if (best >= 0) { counts[id]--; counts[best]++; ids[i] = best; }
+      }
+    }
+  }
+  return ids;
+}
+
 function traceFlowPath(start, sea, flowTo, maxSteps = 900) {
   const path = [];
   const seen = new Set();
@@ -1129,6 +1206,9 @@ export function generateTerrainAndRivers(seed) {
         const lowHillNoise = clamp((fbm(x * 0.95 + 17, y * 0.95 - 23, seed + 571) - 0.38) * 2.9);
         const lowHillMask = clamp(0.34 + mountainMaskMax * 0.72 + lowHillNoise * 0.50 - coastPressure * 0.12);
         e += lowHillMask * 0.145;
+        // Do not add the previous fine speckle uplift here: it created too many
+        // tiny islets.  Sea amount is controlled by seaRatio/coast pressure.
+        e -= clamp((coastPressure - 0.42) * 1.35) * 0.026;
         const high = Math.max(0, e - 0.62);
         e -= high * 0.42;
       }
@@ -1150,6 +1230,7 @@ export function generateTerrainAndRivers(seed) {
   const filled = new Float32Array(SIZE);
   priorityFloodFlow(elevation, sea, flowTo, filled);
   computeFlowAccumulation(sea, flowTo, filled, flowAccum);
+  const watershedId = buildWatershedId(sea, flowTo, flowAccum);
   const { riverPaths, mainRivers, tributaryRivers, smallStreams } = buildRiverNetwork(seed, terrainTemplate, sea, lake, elevation, slope, flowTo, flowAccum, river, erosionField);
   enforceLandGradient(elevation, sea, seaLevel);
   deriveFields(seed, terrainTemplate, fields, seaLevel);
@@ -1162,7 +1243,7 @@ export function generateTerrainAndRivers(seed) {
   const natural = buildNaturalCompartments(
     landMask, sea, elevation, slope, river, ridgeField, valleyField, basinField, coastalLowland, flowAccum,
     null, plain, agriculture, zeroDensity, zeroLanduse,
-    { seed: seed + 17003, targetCompartmentCount: clamp(Math.round((SIZE - sea.reduce((sum, value) => sum + value, 0)) / 45), 70, 360) }
+    { seed: seed + 17003, watershedId, targetCompartmentCount: clamp(Math.round((SIZE - sea.reduce((sum, value) => sum + value, 0)) / 45), 70, 360) }
   );
   const sharedNaturalBarrierScore = natural.naturalBarrierScore || naturalBarrierScore;
   const prefectureBorder = extractMaskBorder(prefectureMask, sea);
@@ -1221,6 +1302,7 @@ export function generateTerrainAndRivers(seed) {
     basinField,
     coastalLowland,
     flowAccum,
+    watershedId,
     erosionField,
     depositionField,
     arcSpineField,