Function MakeRiverAndModifyDesertZoneAround

src/water_cmd.cpp:472–481

* Make a river tile and remove desert directly around it. * @param tile The tile to change into river and create non-desert around */

 * @param tile The tile to change into river and create non-desert around
 */
void MakeRiverAndModifyDesertZoneAround(TileIndex tile)
{
	MakeRiver(tile, Random());
	MarkTileDirtyByTile(tile);

	/* Remove desert directly around the river tile. */
	for (auto t : SpiralTileSequence(tile, RIVER_OFFSET_DESERT_DISTANCE)) {
		if (GetTropicZone(t) == TROPICZONE_DESERT) SetTropicZone(t, TROPICZONE_NORMAL);
	}
}

/**
 * Build a piece of canal.