Function CheckIfCanLevelIndustryPlatform

src/industry_cmd.cpp:1620–1684

* This function tries to flatten out the land below an industry, without * damaging the surroundings too much. */

 *  damaging the surroundings too much.
 */
static bool CheckIfCanLevelIndustryPlatform(TileIndex tile, DoCommandFlags flags, const IndustryTileLayout &layout)
{
	int max_x = 0;
	int max_y = 0;

	/* Finds dimensions of largest variant of this industry */
	for (const IndustryTileLayoutTile &it : layout) {
		if (it.gfx == GFX_WATERTILE_SPECIALCHECK) continue; // watercheck tiles don't count for footprint size
		if (it.ti.x > max_x) max_x = it.ti.x;
		if (it.ti.y > max_y) max_y = it.ti.y;
	}

	/* Remember level height */
	uint h = TileHeight(tile);

	if (TileX(tile) <= _settings_game.construction.industry_platform + 1U || TileY(tile) <= _settings_game.construction.industry_platform + 1U) return false;
	/* Check that all tiles in area and surrounding are clear
	 * this determines that there are no obstructing items */

	/* TileArea::Expand is not used here as we need to abort
	 * instead of clamping if the bounds cannot expanded. */
	TileArea ta(tile + TileDiffXY(-_settings_game.construction.industry_platform, -_settings_game.construction.industry_platform),
			max_x + 2 + 2 * _settings_game.construction.industry_platform, max_y + 2 + 2 * _settings_game.construction.industry_platform);

	if (TileX(ta.tile) + ta.w >= Map::MaxX() || TileY(ta.tile) + ta.h >= Map::MaxY()) return false;

	/* _current_company is OWNER_NONE for randomly generated industries and in editor, or the company who funded or prospected the industry.
	 * Perform terraforming as OWNER_TOWN to disable autoslope and town ratings. */
	Backup<CompanyID> cur_company(_current_company, OWNER_TOWN);

	for (TileIndex tile_walk : ta) {
		uint curh = TileHeight(tile_walk);
		if (curh != h) {
			/* This tile needs terraforming. Check if we can do that without
			 *  damaging the surroundings too much. */
			if (!CheckCanTerraformSurroundingTiles(tile_walk, h, 0)) {
				cur_company.Restore();
				return false;
			}
			/* This is not 100% correct check, but the best we can do without modifying the map.
			 *  What is missing, is if the difference in height is more than 1.. */
			if (std::get<0>(Command<CMD_TERRAFORM_LAND>::Do(DoCommandFlags{flags}.Reset(DoCommandFlag::Execute), tile_walk, SLOPE_N, curh <= h)).Failed()) {
				cur_company.Restore();
				return false;
			}
		}
	}

	if (flags.Test(DoCommandFlag::Execute)) {
		/* Terraform the land under the industry */
		for (TileIndex tile_walk : ta) {
			uint curh = TileHeight(tile_walk);
			while (curh != h) {
				/* We give the terraforming for free here, because we can't calculate
				 *  exact cost in the test-round, and as we all know, that will cause
				 *  a nice assert if they don't match ;) */
				Command<CMD_TERRAFORM_LAND>::Do(flags, tile_walk, SLOPE_N, curh <= h);
				curh += (curh > h) ? -1 : 1;