🎉 initial commit

src/utils/noise.ts

@@ -0,0 +1,77 @@
+import { createNoise2D } from 'simplex-noise'
+import { WORLD_TILES } from '../config'
+import { TileType } from '../types'
+
+/** Simple seeded PRNG (mulberry32) */
+function mulberry32(seed: number): () => number {
+  return () => {
+    seed |= 0
+    seed = (seed + 0x6D2B79F5) | 0
+    let t = Math.imul(seed ^ (seed >>> 15), 1 | seed)
+    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t
+    return ((t ^ (t >>> 14)) >>> 0) / 4294967296
+  }
+}
+
+function classify(e: number, m: number): TileType {
+  if (e < 0.22) return TileType.DEEP_WATER
+  if (e < 0.30) return TileType.SHALLOW_WATER
+  if (e < 0.38) return TileType.SAND
+  if (e > 0.82) return TileType.ROCK
+  // land – split by moisture
+  if (m > 0.62 && e > 0.48) return TileType.FOREST
+  if (m > 0.38) return TileType.DARK_GRASS
+  return TileType.GRASS
+}
+
+export function generateTerrain(seed: number): number[] {
+  const prng1 = mulberry32(seed)
+  const prng2 = mulberry32(seed ^ 0xDEADBEEF)
+
+  const elevNoise = createNoise2D(prng1)
+  const moistNoise = createNoise2D(prng2)
+
+  const size = WORLD_TILES
+  const tiles = new Array<number>(size * size)
+
+  for (let y = 0; y < size; y++) {
+    for (let x = 0; x < size; x++) {
+      // Multi-octave elevation
+      const nx = x / size
+      const ny = y / size
+      const e =
+        (elevNoise(nx * 4,  ny * 4)  * 1.0 +
+         elevNoise(nx * 8,  ny * 8)  * 0.5 +
+         elevNoise(nx * 16, ny * 16) * 0.25) / 1.75
+      const eNorm = (e + 1) / 2   // -1..1 → 0..1
+
+      const m = moistNoise(nx * 6 + 10, ny * 6 + 10)
+      const mNorm = (m + 1) / 2
+
+      tiles[y * size + x] = classify(eNorm, mNorm)
+    }
+  }
+
+  return tiles
+}
+
+/** Find a walkable spawn tile near the world center */
+export function findSpawn(tiles: number[]): { tileX: number; tileY: number } {
+  const center = Math.floor(WORLD_TILES / 2)
+  const walkable = new Set([TileType.GRASS, TileType.DARK_GRASS, TileType.SAND])
+
+  for (let r = 0; r < center; r++) {
+    for (let dy = -r; dy <= r; dy++) {
+      for (let dx = -r; dx <= r; dx++) {
+        if (Math.abs(dx) !== r && Math.abs(dy) !== r) continue
+        const tx = center + dx
+        const ty = center + dy
+        if (tx < 0 || ty < 0 || tx >= WORLD_TILES || ty >= WORLD_TILES) continue
+        if (walkable.has(tiles[ty * WORLD_TILES + tx])) {
+          return { tileX: tx, tileY: ty }
+        }
+      }
+    }
+  }
+  return { tileX: center, tileY: center }
+}