Multi-activation linedefs are linedefs that can activate different things each time they are crossed, so you can have a door that will only open the third time you pass near it, for example.
Implementation[]
The method as explained step by step in Bug's Revolutionary Techniques for Doom and Doom II v2.3 guide:
Steps:
- Trace a linedef which has the function lower sector with tag XXX to the lowest near.
- Create 2N - 1 adjacent sectors, where N is the number of times the linedef must be crossed before activation. I recommend to make them as thin as you can, put one after other, and use them to connect two rooms.
- Fix their floor height to be the same than the ceil.
- Give them the sector tag XXX.
- You might need to choose textures for the inner sectors.
Limitations[]
- This technique is limited to lower and raise sector heights.
- If a player cross again the linedef too soon, it may be required more than N activations. The lapse of time is a function of the height of the N sectors.
Example[]
LINEORD.WAD (file info) is an example of this trick. The player must fall five times to reach the exit. As the door is very tall, you must wait a little between activations.