Transporter

Transporter
ZZT-OOP name	Transporter
Internal ID	30 (0x1E)
Character	#char 197 ┼ (0xC5)
Category	Terrain
Stats
X/Y-step	Direction
Default cycle	2
Other traits
Effect on movement	Transportation or Wall
Destructible?	No
Uses ZZT-OOP color names?	Yes

The transporter is device that moves the player or a pushable element to another location. Transporters can be used as a convenience (to shorten travel distance) or to create navigational puzzles.

Transporters have three different basic arrangements:

• One-Way: If it has nothing directly in front of it.
• Long-Distance: If there is a matching (opposite-faced) transporter in its line of sight.
• Unusable: If the transporter has something in front of it, and no matching transporter in its line of sight.

To be able to use a transporter in the first place, the element must enter it in the same direction (x/y-step) as it is pointed. Transporters then iteratively scan every tile in front of them to check for a valid destination. This scanning process only stops when the board edge element is encountered or a valid destination transporter is encountered.

The first tile in front of a transporter is a special case. The transporter assumes that it might be a valid destination, and attempts to push any blockages out of the way, and either the transportation happens (if the way is clear) or it begins its search in earnest for a matching transporter. The checking process from that point on is essentially the same: if there's a matching transporter, it tries to clear the way, and then either the transportation happens or it continues its search. Repeat until a board edge is encountered.

Transporters with non-standard x/y-steps can be used, but the player cannot just walk into them. Another object or pusher with the proper x/y-step must push them through it.

Note that because transporters use their x/y-step values as parameters, that they are especially prone to the diemove bug. This generally only happens with one-way transporter setups.

Draw Procedure

For standardly oriented transporters, the transporters cycle through the following frames of animation depending on their direction:

Animation frames

Frame	N	S	E	W
1	#char 94 ^ (0x5E)	#char 118 v (0x76)	#char 40 ( (0x28)	#char 41 ) (0x29)
2	#char 126 ~ (0x7E)	#char 95 _ (0x5F)	#char 60 < (0x3C)	#char 62 > (0x3E)
3	#char 94 ^ (0x5E)	#char 118 v (0x76)	#char 40 ( (0x28)	#char 41 ) (0x29)
4	#char 45 - (0x2D)	#char 45 - (0x2D)	#char 179 │ (0xB3)	#char 179 │ (0xB3)

The animation rate is controlled by the code (CurrentTick div Cycle) mod 4. Be aware that a cycle 0 transporter will crash the game due to a division-by-zero error if the transporter is drawn on-screen. This can be used as a particularly cruel form of anti-cheat in dark rooms if you can guarantee the transporter is always outside the torch-viewable area.

When using non-standard x/y-step values, transporters may use characters outside of the array bounds.