If we knew why you need it, we could tell you how.
There's no trigger who's purpose is for this, but there might be I/O commands that can interact with them under certain circumstances. A Boojum Snark will probably be the one to know 100% though.
mmk
im making a destroyable terrain (lag city/whatever/no gibs)
i want buildings to be place-able (so engies aren't useless)
although the obvious problem is that if the building is placed and the ground below is destroyed, we have a floating building
so.....
i want to check the place above the destroyable terrain for a building, and if there is a building:
set hp to 500000/whatever of the block it's on, do this every minute or so (or have a logic controller)
when building is destroyed set the terrains hp back to starting hp (i realize this causes the block to heal, not to big of a deal)
I don't know a super direct way, but you could do it by the follow: Whenver the terrain is destroyed, it enables a Nobuild for that area. When the terrain is set back up, it disables it. Not sure if that will work though.
does nobuild destroy buildings already there, though?
if not it doesnt matter....
as the terrain in which they could build on would be gone, rendering nobuild useless
i've thought of using this idea if another way didn't seem evident
The "payload" setup has a trigger_hurt on the front of the cart which affects engi buildings but not clients. So when the payload reaches a building it destroys it. Obviously the payload doesn't hurt players. You could look into implementing that. When the ground is destroyed it triggers the trigger_hurt and destroys all buildings within its volume.
You can use the filters there with a trigger_hurt to destroy the buildings. If I could remember how it was done I'd explain it, but I don't and I'm too lazy to download it and check it out.
Either the trigger or the buildings must be in motion for them to interact. You'll have to parent your trigger to a door or something that moves 3 units or so when you want the destruction to occur. (Also, make sure you have the Everything flag checked on the trigger)
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