This section lists all the Tunnels in this map. Note that internally each Tunnel listed here is one cell wide and one way, meaning a typical three-cell wide two-way tunnel construct requires six entries in this section, three running one way and three going backwards. While you can give each one a different path, it is not recommended since it breaks the unit pathfinding.
(You don't need the Terrain Expansion to make use of tunnels in YR, they're still part of the engine, but it'll be necessary if you want it looking pretty.)
Tunnels don't exist.
Red Alert, Counterstrike, Aftermath
Tunnels don't exist.
Tiberian Sun, Firestorm, Red Alert 2, Yuri's Revenge
The [Tubes] section takes the following format:
|Index||This is an index into the list, not parsed, so any string without equals-signs will do. Note: The game was not designed to support more than 127 entries in this list (which is 127/6 = 21 typical tunnel constructs). Exceeding that limit will cause problems.|
|ENTER_X||The X coordinate of the entrance cell. Each tunnel should have a different entrance cell.|
|ENTER_Y||The Y coordinate of the entrance cell.|
|FACING||The numeric value of the facing the unit should assume before entering this tunnel. 0 - 7, with 0 standing for game North (NorthEast of the screen) and rotating clockwise.|
|EXIT_X||The X coordinate of the exit cell.|
|EXIT_Y||The Y coordinate of the exit cell.|
|DIRECTIONS||A comma-separated list of directions the unit should follow as it moves through the tunnel. Up to 100 directions can be specified in one tunnel, list should end with -1.|
Special care should be taken to ensure the entrance and exit cells are at the same height, or units will get stuck in them, see here (VXL and SHP units can and will get stuck; train units can get stuck too in RA2YR). Also, due to the fact that Tunnels were never a proper feature in RA2/YR, they don't cooperate well with new additions such as Battle Bunkers. It is advised to keep the edges of tunnel roofs unbuildable.
In the event a Tube doesn't actually reach the ending coordinate (because Tunnel Drawer only lets you move 100 cells so you have to force-end it) units will teleport to exit coordinates. You can abuse this to create portals. Note that it seems like InfantryTypes don't teleport to exit coordinates and instead simply "exit" the tunnel; VehicleTypes are teleported without trouble.
Note the game was not designed to support more than 127 entries in this list (which is 127/6 = 21 typical tunnel constructs). Exceeding that limit will cause problems.
Tunnel Drawer (requires Flash Player; scroll to last post on thread for mirror)