Battle-for-Tismo/shared/game_state/world.js

// World generation and settlement placement: laying out capitals and cities,
// spawning their starting units, seeding population and budgets, and the small
// terrain predicates the rest of the model leans on.

import { ECONOMY } from "../data/economy.js";
import { Random } from "../rng.js";
import { key, parseKey } from "../hex.js";

export const worldMethods = {
  _placeSettlements() {
    const capitals = this._placeCapitals(this.civilisations.length);
    for (const site of this._placeCities(capitals)) this._spawnCity(site);
    this._rebuildCityIndex();
    for (let i = 0; i < Math.min(this.civilisations.length, capitals.length); i++) {
      this._spawnUnit(capitals[i], i, this.protoUnits[0]);
    }
    this._recomputeTerritory();
    this._generatePopulation();
    this._initBudgets();
    this._balanceStartingEconomy();
  },

  _placeCapitals(count) {
    const rng = new Random(this.seed);
    return this._generator.pickCapitals(count, rng);
  },

  _placeCities(capitals) {
    return this._generator.pickCities(capitals, this.mapConfig.citiesPerCiv, this.mapConfig.citySpacing);
  },

  _spawnCity(site) {
    const civIndex = site.civIndex;
    if (civIndex < 0 || civIndex >= this.civilisations.length) return;
    const civ = this.civilisations[civIndex];
    const coords = site.coords;
    const isCapital = site.isCapital;
    const name = this._nextCityName(civ, civIndex);
    const population = 500000 +
      (Math.abs((coords.x * 92837111) ^ (coords.y * 689287499)) % 3500000);
    const city = {
      id: this._nextCityId,
      civ: civIndex,
      coords,
      name,
      isCapital,
      population,
      improvements: [],
      buildings: {},
      statuses: [],
    };
    this.cities.push(city);
    this._cityById.set(this._nextCityId, city);
    this._nextCityId += 1;
  },

  _rebuildCityIndex() {
    this._cityByCoords = new Map();
    this._cityAdjacent = new Map();
    for (const city of this.cities) {
      this._cityByCoords.set(key(city.coords.x, city.coords.y), city);
      const owner = city.civ;
      if (!this._cityAdjacent.has(owner)) this._cityAdjacent.set(owner, new Set());
      const adjacent = this._cityAdjacent.get(owner);
      for (const neighbour of this._neighbours(city.coords)) {
        adjacent.add(key(neighbour.x, neighbour.y));
      }
    }
  },

  // Picks the civilisation's next city name, skipping any a city elsewhere has
  // already taken, and falls back to a numbered name so the whole world never
  // has two cities called the same thing.
  _nextCityName(civ, index) {
    const start = this._cityNamesUsed.get(index) || 0;
    for (let i = start; i < civ.cityNames.length; i++) {
      const candidate = civ.cityNames[i];
      if (this._usedCityNames.has(candidate)) continue;
      this._cityNamesUsed.set(index, i + 1);
      this._usedCityNames.add(candidate);
      return candidate;
    }
    let suffix = Math.max(start, civ.cityNames.length) + 1;
    let candidate = `${civ.name} ${suffix}`;
    while (this._usedCityNames.has(candidate)) {
      suffix += 1;
      candidate = `${civ.name} ${suffix}`;
    }
    this._cityNamesUsed.set(index, suffix);
    this._usedCityNames.add(candidate);
    return candidate;
  },

  _spawnUnit(center, civIndex, proto) {
    let index = this.protoUnits.indexOf(proto);
    if (index < 0) {
      this.protoUnits.push(proto);
      index = this.protoUnits.length - 1;
    }
    const unit = {
      id: this._nextUnitId,
      civ: civIndex,
      proto: index,
      coords: center,
      hp: proto.maxHp,
      maxHp: proto.maxHp,
      path: [],
      pathIndex: 0,
      progressHours: 0,
      moveSpeed: null,
      waypoints: [],
      invader: false,
      statuses: [],
    };
    this.units.push(unit);
    this._unitById.set(this._nextUnitId, unit);
    this._nextUnitId += 1;
    return unit;
  },

  _generatePopulation() {
    this.tilePopulation = new Map();
    for (const k in this.tiles) {
      if (this._isLand(parseKey(k))) this.tilePopulation.set(k, this._basePopulation(parseKey(k)));
    }
    for (const city of this.cities) {
      this.tilePopulation.set(key(city.coords.x, city.coords.y), city.population);
    }
  },

  _basePopulation(coords) {
    return Math.round(ECONOMY.basePopulation * this.terrainStats.populationMultiplier(coords));
  },

  _initBudgets() {
    for (let i = 0; i < this.civilisations.length; i++) {
      this.budgets.set(i, ECONOMY.startingBudget);
    }
  },

  // Map generation should not hand one civilisation a richer start than
  // another. Terrain makes the raw territories unequal, so after the world is
  // populated we scale each civ's population to the common mean and then its
  // GDP per capita to the mean of the raw per-capita figures. Total population
  // and total GDP are preserved; from here on the factors are constants and
  // terrain, buildings, technology and war move the numbers normally.
  _balanceStartingEconomy() {
    const count = this.civilisations.length;
    this._populationBalance = new Map();
    this._perCapitaBalance = new Map();
    if (count <= 1) return;
    const bases = [];
    let totalPopulation = 0;
    let totalGdp = 0;
    for (let i = 0; i < count; i++) {
      const base = this._basePlayerAggregates(i);
      bases.push(base);
      totalPopulation += base.population;
      totalGdp += base.gdp;
    }
    if (totalPopulation <= 0) return;
    const targetPopulation = totalPopulation / count;
    const targetPerCapita = totalGdp / totalPopulation;
    for (let i = 0; i < count; i++) {
      const base = bases[i];
      if (base.population <= 0) continue;
      const perCapita = base.gdp / base.population;
      this._populationBalance.set(i, targetPopulation / base.population);
      this._perCapitaBalance.set(i, perCapita > 0 ? targetPerCapita / perCapita : 1);
    }
  },

  _isLand(coords) {
    const tile = this.tiles[key(coords.x, coords.y)];
    return !!tile && tile.terrainClass === "Land";
  },

  _isNextToCity(coords, owner) {
    const adjacent = this._cityAdjacent.get(owner);
    return adjacent ? adjacent.has(key(coords.x, coords.y)) : false;
  },
};