Sliding doors in Boom?

In axiom.wad there are these sliding doors:

I also looked at the involved triggers in the editor, but still I don't understand how the effect is actually done. Does someone knows the explanation?

Do you *see* them slide? Because I assume there's triggers to lower the original door sectors and raise new ones, so it looked like it slides to the side.

I haven't looked at the wad, but this is my guess: It uses a Boom-specific linedef action that scrolls a tagged wall when a tagged sector moves up or down. The tagged sector = the door, and the tagged wall = a 2-sided linedef with a middle texture covering the door. Additionally, a "fake ceiling/floor" linedef action may be used to hide the actual door (upper textures) and only keep the middle texture visible.

Linguica said:

Do you *see* them slide?

Yes, that's more accurate.

scifista42 said:

I haven't looked at the wad, but this is my guess: It uses a Boom-specific linedef action that scrolls a tagged wall when a tagged sector moves up or down. The tagged sector = the door, and the tagged wall = a 2-sided linedef with a middle texture covering the door. Additionally, a "fake ceiling/floor" linedef action may be used to hide the actual door (upper textures) and only keep the middle texture visible.

Wow that's pretty much correct. The only difference is that it's used a dummy sector to make the tagged walls to scroll in the right directions.
Thanks everyone for the help!

Whilst looking for some other test maps I found this - the setup described by scifista42 using the ZWOLF textures.

I think the open bars/gate texture pictured above is a better fit for this setup as you can shoot through a seemingly solid door at certain points in the opening process - whereas being able to shoot but not pass through a gate doesn't give the setup away so much.

https://dl.dropboxusercontent.com/u/56320770/td-wolfdoor1.zip