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Author Topic: Clarification on magma pistons...  (Read 1638 times)

Eater of Vermin

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Clarification on magma pistons...
« on: May 20, 2017, 12:06:15 am »

Having never experimented with magma pistons I'm not sure of all the details of how they work.  I get the concept, but there's one thing that niggles at me...

In the smaller controlled collapses I have used in times past, the dropped section always seems to break up into a cloud of dust and debris.  Which is pretty much why I used them: fortress defense.  But this was in DF versions long relegated to the archives.

So, with a magma piston, when the plug drops are the lower layers destroyed?   Or is it actually now feasible to build a self-contained fort in a plug and drop it into the sea of magma?   :o

Ghu, I hope so...   ;D
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Bumber

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Re: Clarification on magma pistons...
« Reply #1 on: May 20, 2017, 02:20:09 am »

AFAIK, nothing is destroyed. However, any hollow room you drop is going to have its roof caved-in to the floor. It needs to be hollowed-out after the fact.
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PatrikLundell

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Re: Clarification on magma pistons...
« Reply #2 on: May 20, 2017, 03:03:35 am »

I've never used a magma piston either, so my comments are theoretical...

Constructed walls/floors are destroyed when you cave them in. "Natural" rock/soil fuses onto the surface it lands on (assuming it doesn't smash through a roof) (and soil can transmute into something else in the process, but that's a different issue). Thus, the piston falls and fuses with the floor, you dig it out, cause it to collapse (onto magma), dig it out...
The piston functions because the magma displaced by the falling piston teleports up to the top of the piston, where you're supposed to lead most of the magma off for usage, while obsidianizing a small bit to extend the piston to make up for the part dug away at the bottom.
Also note that you can't do this in the magma sea, because "magma flow" covered by magma annihilates anything falling onto it (except, I think, [un]living creatures), so the whole piston would just disappear the first time you dropped it. You work around that issue by dropping the piston into a room which takes magma from the sea.

I've seen mixed results from trying to cave-in a mixture of "natural" rock and constructions, so I'm unsure how it would work. If your self contained fortress was completely dug (i.e. no constructions), and you'd dropped it onto rock (which can be in the sea) your structure should fuse with the rock. However, I expect any creatures inside that fortress to suffer the effects of being dropped.

* The term "natural" is used to cover player made obsidian.
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Bumber

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Re: Clarification on magma pistons...
« Reply #3 on: May 27, 2017, 07:44:21 am »

If your self contained fortress was completely dug (i.e. no constructions), and you'd dropped it onto rock (which can be in the sea) your structure should fuse with the rock. However, I expect any creatures inside that fortress to suffer the effects of being dropped.
I think the falling blocks ignore sideways support until they come to rest. The ceiling blocks will continue falling as individual columns until they fuse with the floor blocks, with predictable results for anything caught between.

I hope the moving fort sections feature will finally allow dwarven submersibles.
« Last Edit: May 27, 2017, 07:48:28 am by Bumber »
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PatrikLundell

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Re: Clarification on magma pistons...
« Reply #4 on: May 27, 2017, 11:21:36 am »

If your self contained fortress was completely dug (i.e. no constructions), and you'd dropped it onto rock (which can be in the sea) your structure should fuse with the rock. However, I expect any creatures inside that fortress to suffer the effects of being dropped.
I think the falling blocks ignore sideways support until they come to rest. The ceiling blocks will continue falling as individual columns until they fuse with the floor blocks, with predictable results for anything caught between.

I hope the moving fort sections feature will finally allow dwarven submersibles.
I'm not sure that's correct based on my experience with cave-ins to try to close off cavern lakes. In some of the early attempts the whole section fell only until a part of it was stopped by landing on a cavern tree, and the rest of it, outside of the radius of the tree stayed suspended, and I believe I've ended up with holes beneath some walls when I've miscalculated the shape of the section to drop. On the other hand, trying to use support based logic with the magma sea failed miserably, as everything above the SMR just vanished (I realize this contradicts what I said before, and I blame my poor memory for that case, so yes, the dropped fortress should definitely disappear without a trace in the part that fell into the sea above SMR).

Edit:
I tested the falling situation, and Bumber is correct.
From a previous test, I had an embark with a 4*4 hole in the ground with a 2*2 soil plug caved in in the middle, poking up a number of tiles from the bottom.
Using the DFHack tool pair liquids and liquids here I spawned a 4*4 layer of obsidian on top of a support over the hole, a pillar in each corner on top of that, plus one pillar on one of the 4 center tiles. Another 4*4 layer was placed on the top. After pulling the lever I ended up with a 2 Z level high obsidian ring at the bottom of the hole (around the center plug), with a pillar jutting up one tile at each corner. On top of the plug I ended up with a two Z level high cap, with an additional level pillar on top of that where I'd placed my "center" pillar.
Thus, once the cave-in started, structural support did not apply to any falling tile: everything just flattened down to the lowest possible level before fusing with the surrounding rock/soil when the fall had stopped. All interior spaces were thus crushed by the level above.
« Last Edit: May 28, 2017, 05:25:08 am by PatrikLundell »
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Eater of Vermin

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Re: Clarification on magma pistons...
« Reply #5 on: June 11, 2017, 09:20:56 pm »

Yeah, that makes sense. 

Thx for taking the time to try it, btw.
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