Function GenerateIndustries

src/industry_cmd.cpp:2488–2542

* This function will create random industries during game creation. * It will scale the amount of industries by mapsize and difficulty level. */

 * It will scale the amount of industries by mapsize and difficulty level.
 */
void GenerateIndustries()
{
	if (_game_mode != GM_EDITOR && _settings_game.difficulty.industry_density == ID_FUND_ONLY) return; // No industries in the game.

	/* Get the probabilities for all industries. This is done first as we need the total of
	 * both land and water for scaling later. */
	IndustryGenerationProbabilities lprob = GetScaledProbabilities(false);
	IndustryGenerationProbabilities wprob = GetScaledProbabilities(true);

	/* Run generation twice, for land and water industries in turn. */
	for (bool water = false;; water = true) {
		auto &p = water ? wprob : lprob;

		/* Total number of industries scaled by land/water proportion. */
		uint total_amount = 0;
		if (lprob.total + wprob.total > 0) total_amount = p.total * GetNumberOfIndustries() / (lprob.total + wprob.total);

		/* Scale land-based industries to the land proportion, unless the player has set a custom industry count. */
		if (!water && _settings_game.difficulty.industry_density != ID_CUSTOM) total_amount = Map::ScaleByLandProportion(total_amount);

		/* Ensure that forced industries are generated even if the scaled amounts are too low. */
		if (p.total == 0 || total_amount < p.num_forced) {
			/* Only place the forced ones */
			total_amount = p.num_forced;
		}

		SetGeneratingWorldProgress(water ? GWP_WATER_INDUSTRY : GWP_LAND_INDUSTRY, total_amount);

		/* Try to build one industry per type independent of any probabilities */
		for (IndustryType it = 0; it < NUM_INDUSTRYTYPES; it++) {
			if (p.force_one[it]) {
				assert(total_amount > 0);
				total_amount--;
				PlaceInitialIndustry(it, water, true);
			}
		}

		/* Add the remaining industries according to their probabilities */
		for (uint i = 0; i < total_amount; i++) {
			uint32_t r = RandomRange(p.total);
			IndustryType it = 0;
			while (r >= p.probs[it]) {
				r -= p.probs[it];
				it++;
				assert(it < NUM_INDUSTRYTYPES);
			}
			assert(p.probs[it] > 0);
			PlaceInitialIndustry(it, water, false);
		}

		if (water) break;
	}

	_industry_builder.Reset();
}

template <>
Industry::ProducedHistory SumHistory(std::span<const Industry::ProducedHistory> history)