Function PlaceTreeGroupAroundTile

src/tree_cmd.cpp:422–461

* Place some trees in a radius around a tile. * The trees are placed in an quasi-normal distribution around the indicated tile, meaning that while * the radius does define a square, the distribution inside the square will be roughly circular. * @note This function the interactive RNG and must only be used in editor and map generation. * @param tile Tile to place trees around. * @param tr

 * @return Number of trees actually placed.
 */
uint PlaceTreeGroupAroundTile(TileIndex tile, TreeType treetype, uint radius, uint count, bool set_zone)
{
	assert(_game_mode == GM_EDITOR); // Due to InteractiveRandom being used in this function
	assert(treetype < TREE_TOYLAND + TREE_COUNT_TOYLAND);
	const bool allow_desert = treetype == TREE_CACTUS;
	uint planted = 0;

	for (; count > 0; count--) {
		/* Simple quasi-normal distribution with range [-radius; radius) */
		auto mkcoord = [&]() -> int32_t {
			const uint32_t rand = InteractiveRandom();
			const int32_t dist = GB<int32_t>(rand, 0, 8) + GB<int32_t>(rand, 8, 8) + GB<int32_t>(rand, 16, 8) + GB<int32_t>(rand, 24, 8);
			const int32_t scu = dist * radius / 512;
			return scu - radius;
		};
		const int32_t xofs = mkcoord();
		const int32_t yofs = mkcoord();
		const TileIndex tile_to_plant = TileAddWrap(tile, xofs, yofs);
		if (tile_to_plant != INVALID_TILE) {
			if (IsTileType(tile_to_plant, MP_TREES) && GetTreeCount(tile_to_plant) < 4) {
				AddTreeCount(tile_to_plant, 1);
				SetTreeGrowth(tile_to_plant, TreeGrowthStage::Growing1);
				MarkTileDirtyByTile(tile_to_plant, 0);
				planted++;
			} else if (CanPlantTreesOnTile(tile_to_plant, allow_desert)) {
				PlantTreesOnTile(tile_to_plant, treetype, 0, TreeGrowthStage::Grown);
				MarkTileDirtyByTile(tile_to_plant, 0);
				planted++;
			}
		}
	}

	if (set_zone && IsInsideMM(treetype, TREE_RAINFOREST, TREE_CACTUS)) {
		for (TileIndex t : TileArea(tile).Expand(radius)) {
			if (GetTileType(t) != MP_VOID && DistanceSquare(tile, t) < radius * radius) SetTropicZone(t, TROPICZONE_RAINFOREST);
		}
	}

	return planted;
}

/**
 * Place new trees.