Fantasy-Map-Generator/src/modules/biomes.ts

import { mean, range } from "d3";
import { rn } from "../utils";

declare global {
  var Biomes: BiomesModule;
}

class BiomesModule {
  private MIN_LAND_HEIGHT = 20;

  getDefault() {
    const name: string[] = [
      "Marine",
      "Hot desert",
      "Cold desert",
      "Savanna",
      "Grassland",
      "Tropical seasonal forest",
      "Temperate deciduous forest",
      "Tropical rainforest",
      "Temperate rainforest",
      "Taiga",
      "Tundra",
      "Glacier",
      "Wetland",
    ];

    const color: string[] = [
      "#466eab",
      "#fbe79f",
      "#b5b887",
      "#d2d082",
      "#c8d68f",
      "#b6d95d",
      "#29bc56",
      "#7dcb35",
      "#409c43",
      "#4b6b32",
      "#96784b",
      "#d5e7eb",
      "#0b9131",
    ];
    const habitability: number[] = [
      0, 4, 10, 22, 30, 50, 100, 80, 90, 12, 4, 0, 12,
    ];
    const iconsDensity: number[] = [
      0, 3, 2, 120, 120, 120, 120, 150, 150, 100, 5, 0, 250,
    ];
    const icons: Array<{ [key: string]: number }> = [
      {},
      { dune: 3, cactus: 6, deadTree: 1 },
      { dune: 9, deadTree: 1 },
      { acacia: 1, grass: 9 },
      { grass: 1 },
      { acacia: 8, palm: 1 },
      { deciduous: 1 },
      { acacia: 5, palm: 3, deciduous: 1, swamp: 1 },
      { deciduous: 6, swamp: 1 },
      { conifer: 1 },
      { grass: 1 },
      {},
      { swamp: 1 },
    ];
    const cost: number[] = [
      10, 200, 150, 60, 50, 70, 70, 80, 90, 200, 1000, 5000, 150,
    ]; // biome movement cost
    const biomesMatrix: Uint8Array[] = [
      // hot ↔ cold [>19°C; <-4°C]; dry ↕ wet
      new Uint8Array([
        1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
        2, 10,
      ]),
      new Uint8Array([
        3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 9, 9, 9, 9, 10,
        10, 10,
      ]),
      new Uint8Array([
        5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 9, 9, 9, 9, 9, 10,
        10, 10,
      ]),
      new Uint8Array([
        5, 6, 6, 6, 6, 6, 6, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10,
        10, 10,
      ]),
      new Uint8Array([
        7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9,
        10, 10,
      ]),
    ];

    // parse icons weighted array into a simple array
    const parsedIcons: string[][] = [];
    for (let i = 0; i < icons.length; i++) {
      const parsed: string[] = [];
      for (const icon in icons[i]) {
        for (let j = 0; j < icons[i][icon]; j++) {
          parsed.push(icon);
        }
      }
      parsedIcons[i] = parsed;
    }

    return {
      i: range(0, name.length),
      name,
      color,
      biomesMatrix,
      habitability,
      iconsDensity,
      icons: parsedIcons,
      cost,
    };
  }

  define() {
    TIME && console.time("defineBiomes");

    const {
      fl: flux,
      r: riverIds,
      h: heights,
      c: neighbors,
      g: gridReference,
    } = pack.cells;
    const { temp, prec } = grid.cells;
    pack.cells.biome = new Uint8Array(pack.cells.i.length); // biomes array

    const calculateMoisture = (cellId: number) => {
      let moisture = prec[gridReference[cellId]];
      if (riverIds[cellId]) moisture += Math.max(flux[cellId] / 10, 2);

      const moistAround = neighbors[cellId]
        .filter(
          (neibCellId: number) => heights[neibCellId] >= this.MIN_LAND_HEIGHT,
        )
        .map((c: number) => prec[gridReference[c]])
        .concat([moisture]);
      return rn(4 + (mean(moistAround) as number));
    };

    for (let cellId = 0; cellId < heights.length; cellId++) {
      const height = heights[cellId];
      const moisture =
        height < this.MIN_LAND_HEIGHT ? 0 : calculateMoisture(cellId);
      const temperature = temp[gridReference[cellId]];
      pack.cells.biome[cellId] = this.getId(
        moisture,
        temperature,
        height,
        Boolean(riverIds[cellId]),
      );
    }

    TIME && console.timeEnd("defineBiomes");
  }

  getId(
    moisture: number,
    temperature: number,
    height: number,
    hasRiver: boolean,
  ) {
    if (height < 20) return 0; // all water cells: marine biome
    if (temperature < -5) return 11; // too cold: permafrost biome
    if (temperature >= 25 && !hasRiver && moisture < 8) return 1; // too hot and dry: hot desert biome
    if (this.isWetland(moisture, temperature, height)) return 12; // too wet: wetland biome

    // in other cases use biome matrix
    const moistureBand = Math.min((moisture / 5) | 0, 4); // [0-4]
    const temperatureBand = Math.min(Math.max(20 - temperature, 0), 25); // [0-25]
    return biomesData.biomesMatrix[moistureBand][temperatureBand];
  }

  private isWetland(moisture: number, temperature: number, height: number) {
    if (temperature <= -2) return false; // too cold
    if (moisture > 40 && height < 25) return true; // near coast
    if (moisture > 24 && height > 24 && height < 60) return true; // off coast
    return false;
  }
}

window.Biomes = new BiomesModule();