Function TileLoopTreesAlps

src/tree_cmd.cpp:775–804

}

static void TileLoopTreesAlps(TileIndex tile)
{
	int k = GetTileZ(tile) - GetSnowLine() + 1;

	if (k < 0) {
		switch (GetTreeGround(tile)) {
			case TREE_GROUND_SNOW_DESERT: SetTreeGroundDensity(tile, TREE_GROUND_GRASS, 3); break;
			case TREE_GROUND_ROUGH_SNOW:  SetTreeGroundDensity(tile, TREE_GROUND_ROUGH, 3); break;
			default: return;
		}
	} else {
		uint density = std::min<uint>(k, 3);

		if (GetTreeGround(tile) != TREE_GROUND_SNOW_DESERT && GetTreeGround(tile) != TREE_GROUND_ROUGH_SNOW) {
			TreeGround tg = GetTreeGround(tile) == TREE_GROUND_ROUGH ? TREE_GROUND_ROUGH_SNOW : TREE_GROUND_SNOW_DESERT;
			SetTreeGroundDensity(tile, tg, density);
		} else if (GetTreeDensity(tile) != density) {
			SetTreeGroundDensity(tile, GetTreeGround(tile), density);
		} else {
			if (GetTreeDensity(tile) == 3) {
				uint32_t r = Random();
				if (Chance16I(1, 200, r) && _settings_client.sound.ambient) {
					SndPlayTileFx((r & 0x80000000) ? SND_39_ARCTIC_SNOW_2 : SND_34_ARCTIC_SNOW_1, tile);
				}
			}
			return;
		}
	}
	MarkTileDirtyByTile(tile);
}

/*
 * Check if trees on this tile are allowed to spread.