[TUTORIAL] The Elevator Trifecta

[Pianodan]

Wonderful tutorial, it definitely exposed me to more of the tools available at my disposal.

One of my map ideas is pretty much a vertical payload map, only the bomb is in fact an elevator. On my small test map, I've been playing around with triggers and such, and can't seem to find a way to make the platform move vertically past the first floor by simply having someone stand on it. What I'd like is for the platform to stop dead when the player gets off of it, and continue rising when he gets on.

The basic func_movelinear design hits a snag in that I cannot find a way for the trigger to increment the current position by 1 each time.. so my question is:

How would I set up an entity that only moves when a player touches it, and stands still otherwise?

I would think you could basically just set it up like a normal payload map, with a track that goes up. Use path_tracks and a func_tracktrain, with whatever model you want for the elevator instead of the standard bomb. Even if you want to do something slightly different, you can probably start with the pl tutorial and modify it from there.