Generate archipelago ring

island/generators.ts

@@ -91,10 +91,17 @@ export const ERODED_LOBE: LobeGeneratorConstructor =
     return true;
   };
 
-export const BIG_ISLANDS = [BIG_BEACH, BIG_MOUNTAIN];
+/** form low-lying beach with eroded sections */
+export const NO_ISLAND: LobeGeneratorConstructor =
+  (islands: IslandGrid, basePos: number) => () => {
+    return true;
+  };
+
+export const BIG_ISLANDS = [BIG_MOUNTAIN, BIG_BEACH];
 export const ALL_ISLANDS = [
   BIG_MOUNTAIN,
   SMALL_BEACH,
+  BIG_BEACH,
   FOREST_LOBE,
   ERODED_LOBE,
 ];

island/grid.ts

@@ -1,6 +1,11 @@
 import { Prng, mulberry32 } from "../lib/prng";
 import { BEACH, ICECAP } from "./data";
-import { ALL_ISLANDS, BIG_ISLANDS, LobeGenerator } from "./generators";
+import {
+  ALL_ISLANDS,
+  BIG_ISLANDS,
+  LobeGenerator,
+  NO_ISLAND,
+} from "./generators";
 
 export class IslandGrid {
   data: number[];
@@ -14,25 +19,27 @@ export class IslandGrid {
     this.data = Array(width * height).fill(0);
     this.rng = mulberry32(seed);
 
-    this.generators.push(this.choose(BIG_ISLANDS)(this, this.data.length >> 1));
-    this.generators.push(
-      this.choose(ALL_ISLANDS)(
-        this,
-        this.xy(
-          (width >> 1) + (this.rng() % 48) - 24,
-          (height >> 1) + (this.rng() % 48) - 24
-        )
-      )
-    );
-    this.generators.push(
-      this.choose(ALL_ISLANDS)(
-        this,
-        this.xy(
-          (width >> 1) + (this.rng() % 48) - 24,
-          (height >> 1) + (this.rng() % 48) - 24
-        )
-      )
-    );
+    const islandBag = this.shuffle([
+      this.choose(BIG_ISLANDS),
+      this.choose(BIG_ISLANDS),
+      this.choose(ALL_ISLANDS),
+      this.choose(ALL_ISLANDS),
+      this.choose(ALL_ISLANDS),
+      this.choose(ALL_ISLANDS),
+      NO_ISLAND,
+      NO_ISLAND,
+    ]);
+
+    const islandCount = islandBag.length;
+    const spacing = (Math.PI * 2) / islandCount;
+    for (let i = 0; i < islandCount; i++) {
+      const y = height / 2 + (Math.sin(spacing * i) * height) / 4;
+      const x = width / 2 + (Math.cos(spacing * i) * width) / 4;
+
+      console.log("xy", x | 0, y | 0);
+
+      this.generators.push(islandBag[i](this, this.xy(x | 0, y | 0)));
+    }
   }
 
   public xy(x: number, y: number): number {
@@ -121,6 +128,15 @@ export class IslandGrid {
     return list[this.rng() % list.length];
   }
 
+  public shuffle<T>(list: T[]) {
+    const shuffled = list.slice();
+    for (let i = 0; i < shuffled.length - 1; i++) {
+      const swapIndex = (this.rng() % (shuffled.length - i)) + i;
+      [shuffled[i], shuffled[swapIndex]] = [shuffled[swapIndex], shuffled[i]];
+    }
+    return shuffled;
+  }
+
   public dropWithin(tiles: number[]) {
     if (tiles.length > 0) {
       this.drop(this.choose(tiles));

lib/prng.ts

@@ -1,5 +1,7 @@
 export type Prng = () => number;
 
+export const UINT_MAX = 0xffffffff;
+
 export function mulberry32(state: number) {
   return function () {
     let t = (state += 0x6d2b79f5);