Method TryBuildNewIndustry

src/industry_cmd.cpp:2677–2740

* Try to create a random industry, during gameplay */

 * Try to create a random industry, during gameplay
 */
void IndustryBuildData::TryBuildNewIndustry()
{
	this->SetupTargetCount();

	int missing = 0;       // Number of industries that need to be build.
	uint count = 0;        // Number of industry types eligible for build.
	uint32_t total_prob = 0; // Sum of probabilities.
	IndustryType forced_build = NUM_INDUSTRYTYPES; // Industry type that should be forcibly build.
	for (IndustryType it = 0; it < NUM_INDUSTRYTYPES; it++) {
		int difference = this->builddata[it].target_count - Industry::GetIndustryTypeCount(it);
		missing += difference;
		if (this->builddata[it].wait_count > 0) continue; // This type may not be built now.
		if (difference > 0) {
			if (Industry::GetIndustryTypeCount(it) == 0 && this->builddata[it].min_number > 0) {
				/* An industry that should exist at least once, is not available. Force it, trying the most needed one first. */
				if (forced_build == NUM_INDUSTRYTYPES ||
						difference > this->builddata[forced_build].target_count - Industry::GetIndustryTypeCount(forced_build)) {
					forced_build = it;
				}
			}
			total_prob += difference;
			count++;
		}
	}

	if (EconomyIsInRecession() || (forced_build == NUM_INDUSTRYTYPES && (missing <= 0 || total_prob == 0))) count = 0; // Skip creation of an industry.

	if (count >= 1) {
		/* If not forced, pick a weighted random industry to build.
		 * For the case that count == 1, there is no need to draw a random number. */
		IndustryType it;
		if (forced_build != NUM_INDUSTRYTYPES) {
			it = forced_build;
		} else {
			/* Non-forced, select an industry type to build (weighted random). */
			uint32_t r = 0; // Initialized to silence the compiler.
			if (count > 1) r = RandomRange(total_prob);
			for (it = 0; it < NUM_INDUSTRYTYPES; it++) {
				if (this->builddata[it].wait_count > 0) continue; // Type may not be built now.
				int difference = this->builddata[it].target_count - Industry::GetIndustryTypeCount(it);
				if (difference <= 0) continue; // Too many of this kind.
				if (count == 1) break;
				if (r < (uint)difference) break;
				r -= difference;
			}
			assert(it < NUM_INDUSTRYTYPES && this->builddata[it].target_count > Industry::GetIndustryTypeCount(it));
		}

		/* Try to create the industry. */
		const Industry *ind = PlaceIndustry(it, IACT_RANDOMCREATION, false);
		if (ind == nullptr) {
			this->builddata[it].wait_count = this->builddata[it].max_wait + 1; // Compensate for decrementing below.
			this->builddata[it].max_wait = std::min(1000, this->builddata[it].max_wait + 2);
		} else {
			AdvertiseIndustryOpening(ind);
			this->builddata[it].max_wait = std::max(this->builddata[it].max_wait / 2, 1); // Reduce waiting time of the industry type.
		}
	}