Refactor: migrate ice (#1308)

* refactor: migrate ice module

* chore: lint

* refactor: enhance rand function documentation for clarity on argument usage

* refactor: reorganize imports in probabilityUtils test file for clarity

src/modules/ice.ts

@@ -0,0 +1,175 @@
+import Alea from "alea";
+import { min } from "d3";
+import {
+  clipPoly,
+  getGridPolygon,
+  getIsolines,
+  lerp,
+  minmax,
+  normalize,
+  P,
+  ra,
+  rand,
+  rn,
+} from "../utils";
+import type { Point } from "./voronoi";
+
+declare global {
+  var Ice: IceModule;
+}
+
+class IceModule {
+  // Find next available id for new ice element idealy filling gaps
+  private getNextId() {
+    if (pack.ice.length === 0) return 0;
+    // find gaps in existing ids
+    const existingIds = pack.ice.map((e) => e.i).sort((a, b) => a - b);
+    for (let id = 0; id < existingIds[existingIds.length - 1]; id++) {
+      if (!existingIds.includes(id)) return id;
+    }
+    return existingIds[existingIds.length - 1] + 1;
+  }
+
+  // Clear all ice
+  private clear() {
+    pack.ice = [];
+  }
+
+  // Generate glaciers and icebergs based on temperature and height
+  public generate() {
+    this.clear();
+    const { cells, features } = grid;
+    const { temp, h } = cells;
+    Math.random = Alea(seed);
+
+    const ICEBERG_MAX_TEMP = 0;
+    const GLACIER_MAX_TEMP = -8;
+    const minMaxTemp = min<number>(temp)!;
+
+    // Generate glaciers on cold land
+    {
+      const type = "iceShield";
+      const getType = (cellId: number) =>
+        h[cellId] >= 20 && temp[cellId] <= GLACIER_MAX_TEMP ? type : null;
+      const isolines = getIsolines(grid, getType, { polygons: true });
+
+      if (isolines[type]?.polygons) {
+        isolines[type].polygons.forEach((points: Point[]) => {
+          const clipped = clipPoly(points, graphWidth, graphHeight);
+          pack.ice.push({
+            i: this.getNextId(),
+            points: clipped,
+            type: "glacier",
+          });
+        });
+      }
+    }
+
+    // Generate icebergs on cold water
+    for (const cellId of grid.cells.i) {
+      const t = temp[cellId];
+      if (h[cellId] >= 20) continue; // no icebergs on land
+      if (t > ICEBERG_MAX_TEMP) continue; // too warm: no icebergs
+      if (features[cells.f[cellId]].type === "lake") continue; // no icebergs on lakes
+      if (P(0.8)) continue; // skip most of eligible cells
+
+      const randomFactor = 0.8 + rand() * 0.4; // random size factor
+      let baseSize = (1 - normalize(t, minMaxTemp, 1)) * 0.8; // size: 0 = zero, 1 = full
+      if (cells.t[cellId] === -1) baseSize /= 1.3; // coastline: smaller icebergs
+      const size = minmax(rn(baseSize * randomFactor, 2), 0.1, 1);
+
+      const [cx, cy] = grid.points[cellId];
+      const points = getGridPolygon(cellId, grid).map(([x, y]: Point) => [
+        rn(lerp(cx, x, size), 2),
+        rn(lerp(cy, y, size), 2),
+      ]);
+
+      pack.ice.push({
+        i: this.getNextId(),
+        points,
+        type: "iceberg",
+        cellId,
+        size,
+      });
+    }
+  }
+
+  addIceberg(cellId: number, size: number) {
+    const [cx, cy] = grid.points[cellId];
+    const points = getGridPolygon(cellId, grid).map(([x, y]: Point) => [
+      rn(lerp(cx, x, size), 2),
+      rn(lerp(cy, y, size), 2),
+    ]);
+    const id = this.getNextId();
+    pack.ice.push({
+      i: id,
+      points,
+      type: "iceberg",
+      cellId,
+      size,
+    });
+    redrawIceberg(id);
+  }
+
+  removeIce(id: number) {
+    const index = pack.ice.findIndex((element) => element.i === id);
+    if (index !== -1) {
+      const type = pack.ice.find((element) => element.i === id).type;
+      pack.ice.splice(index, 1);
+      if (type === "glacier") {
+        redrawGlacier(id);
+      } else {
+        redrawIceberg(id);
+      }
+    }
+  }
+
+  randomizeIcebergShape(id: number) {
+    const iceberg = pack.ice.find((element) => element.i === id);
+    if (!iceberg) return;
+
+    const cellId = iceberg.cellId;
+    const size = iceberg.size;
+    const [cx, cy] = grid.points[cellId];
+
+    // Get a different random cell for the polygon template
+    const i = ra(grid.cells.i);
+    const cn = grid.points[i];
+    const poly = getGridPolygon(i, grid).map((p: Point) => [
+      p[0] - cn[0],
+      p[1] - cn[1],
+    ]);
+    const points = poly.map((p: Point) => [
+      rn(cx + p[0] * size, 2),
+      rn(cy + p[1] * size, 2),
+    ]);
+
+    iceberg.points = points;
+  }
+
+  changeIcebergSize(id: number, newSize: number) {
+    const iceberg = pack.ice.find((element) => element.i === id);
+    if (!iceberg) return;
+
+    const cellId = iceberg.cellId;
+    const [cx, cy] = grid.points[cellId];
+    const oldSize = iceberg.size;
+
+    const flat = iceberg.points.flat();
+    const pairs = [];
+    while (flat.length) pairs.push(flat.splice(0, 2));
+    const poly = pairs.map((p) => [
+      (p[0] - cx) / oldSize,
+      (p[1] - cy) / oldSize,
+    ]);
+    const points = poly.map((p) => [
+      rn(cx + p[0] * newSize, 2),
+      rn(cy + p[1] * newSize, 2),
+    ]);
+
+    iceberg.points = points;
+    iceberg.size = newSize;
+  }
+}
+
+window.Ice = new IceModule();

src/modules/index.ts

@@ -13,3 +13,4 @@ import "./states-generator";
 import "./zones-generator";
 import "./religions-generator";
 import "./provinces-generator";
+import "./ice";