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[Mort Stroodle]

Here I propose a hypothetical mega-project idea, for your consideration. I posit that one could construct a massive fortress within a volcano, by dropping an enormous, ~120 Z-level tall plug, constructed above the lip of the volcano, into the caldera. The plug would need to be tall enough to  extend from the very bottom of the map, the semi-molten rock, up to (and probably exceeding) the surface of the lava. The plug would need to be completely solid, but could be built and collapsed in parts. If you wanted to you could probably mod the world gen settings to give you enough height to build it all at once, but in theory the plug could be dropped in a couple layers at a time. Here's the set-up:

Code: [Select]

....WWWWWWWW....
....WWWWWWWW....
....WWWWWWWW....
....WWWWWWWW....
....WWWWWWWW....
....WWWWWWWW....
....WWWWWWWW....
....WWWWWWWW....
.WWSWWWWWWWWSWW.
.W............W.
.W............W.
XXX~~~~~~~~~~XXX
XXX~~~~~~~~~~XXX
XXX~~~~~~~~~~XXX
XXX~~~~~~~~~~XXX
XXX~~~~~~~~~~XXX
XXX~~~~~~~~~~XXX
XXX~~~~~~~~~~XXX
XXX~~~~~~~~~~XXX
RRRRRRRRRRRRRRRR
X: Natural walls around the volcano
R: Semi-molten rock
S: Supports
W: Player-constructed walls
~: Lava
. : Air

After releasing supports:

Code: [Select]

................
................
................
................
................
................
................
................
.WW..........WW.
.W............W.
.W..WWWWWWWW..W.
XXX~WWWWWWWW~XXX
XXX~WWWWWWWW~XXX
XXX~WWWWWWWW~XXX
XXX~WWWWWWWW~XXX
XXX~WWWWWWWW~XXX
XXX~WWWWWWWW~XXX
XXX~WWWWWWWW~XXX
XXX~WWWWWWWW~XXX
RRRRRRRRRRRRRRRR
This is scaled down, the real version would be much taller, but recall that you can drop a few layers at a time if you don't want to/can't build it all at once.

Now, with an enormous block of stone spanning from SMR to the surface, you can dig out an entire fortress inside of it. Dropping the plug will displace a preposterous amount of lava, so it doubles as an incredibly powerful/apocolyptic weapon. Just make sure your dwarves hide away underground every time they drop some layers down. You don't actually need to have it reach all the way to the surface either. Just make the first dozen layers or so fill the entire diameter of the volcano, and you can dig out an underground access tunnel and dig out your fortress from below. Just make sure you drop enough layers for your access tunnel to be above the magma sea. Instead of making a towering 120-block high fort that extends to the surface, you could make a more modest structure that's only a few dozen layers. In theory you could also drop a few layers, dig out part of the fort, then used the dug-out blocks to drop the next few layers for more efficiency regardless of what height you want the end result to be.

Potential reason why this might not be possible:

Will the constructed blocks survive the fall? If too much of the plug is damaged while falling this project might not be possible, as lava could leak into any cracks.
Will new layers dropping destroy old already-dropped layers? This might not be a game-breaker if it only destroys one layer at a time; if you drop 4 layers and destroy one, you've still increased the height by a net 3 layers. The big problem would be if RNG is involved: if blocks are destroyed in unpredictable ways, cracks could easily form.
Will the hollowed-out sections of the block attempt to fill back up with lava? What is exactly the trigger for the volcano to start filling? Can a volcano fill into an area completely sealed from the lava? Is there any way to cheese it to make sure your fort doesn't get flooded?
Do collapsing structures survive contact with SMR, or do they just get deleted? If SMR destroys collapsing blocks, it's game over. The plan will not work.

Post your thoughts. Is there any chance this plan could work? Are any modifications to the plan needed?

[WillowLuman]

This is doomed for a number of reasons:

1) Constructed walls never remain intact when collapsing, they revert to the items that were used to construct them. You can cast "natural" walls by filling a reservoir with magma and pouring water over it, one layer at a time, but...
2) The "magma flow" floor tiles at the bottom of the magma sea destroy anything than falls onto them.

[Mort Stroodle]

This is doomed for a number of reasons:

1) Constructed walls never remain intact when collapsing, they revert to the items that were used to construct them. You can cast "natural" walls by filling a reservoir with magma and pouring water over it, one layer at a time, but...
2) The "magma flow" floor tiles at the bottom of the magma sea destroy anything than falls onto them.

Well that's a shame, doesn't sound like there's any way around that. Follow up question, if you drain out a section of the volcano into the caverns, build a fortress inside (completely sealed from the lava itself, with only an access point above the surface or off to the side through the volcano wall), will lava still be able to fill the fort when you allow the volcano to refill, or would you need to constantly drain out the volcano to keep the fort from getting toasted? I've heard that the volcano fills by raining lava from a few tiles above the current lava level down. Based on that I would assume your new fort would fill as the volcano does, unless the lava rain needs uninterrupted LOS from the intended spawn point to the lava in order to spawn in the first place. But if you your fort does fill with lava this way, if you allow the volcano to fully refill, and allow your new fort to fully fill with lava, could you wait until your fort is submerged then drain all the lava out of the side of the fort? I'm thinking something like this:

Code: [Select]

XX~~~~~~~~XX
XX~WWWWWW~XX
XX~W~~~~W~XX
XXWW~~~~W~XX
..D~~~~~W~XX
XXWWWWWWW~XX
XX~~~~~~~~XX

With D being a drawbridge. Open the drawbridge, and

Code: [Select]

XX~~~~~~~~XX
XX~WWWWWW~XX
XX~W....W~XX
XXWW....W~XX
........W~XX
XXWWWWWWW~XX
XX~~~~~~~~XX

My question is, would the game consider that volcano to be "filled" because there's a full layer of lava on the top level, or would it attempt to fill all of the open space within your fortress again?

[PatrikLundell]

Magma rain is spawned at the top level of the volcano/magma tube, but only provided there's an unobstructed access to the SMR below. If the access to the SMR is obstructed the rain is spawned on the highest unobstructed level. Thus, the floor of your fortress container would keep the interior safe from magma rain, so the only dangers are overseer ineptitude allowing magma to flow in through holes in the side or top as the magma level rises back to its natural level.

Note that I've only read the first post up to the "no, the SMR will eat it all" stage, and the latest point up to the question. I haven't looked at the diagrams.

[Mort Stroodle]

Awesome, thanks. Sounds like the only real trouble is figuring out how to drain the volcano efficiently enough.

[PatrikLundell]

Pumps and Deployable Drains.

Also, I think I've seen magma rain "flow" in the air to a tile to the side, thus ending up on a ledge it shouldn't be able to reach. Thus, you may lose some dorfs due to occasional stray rain.

[gchristopher]

If the goal is "build inside a volcano", I'm with PatrikLundell on using pumps to empty it and then build.


If you want to try dropping a plug for the sake of watching your FPS die, save yourself the pain leading up to it and use dfhack's liquids command to cheat and build the plug. You'll need to generate a world with enough z-levels above ground to build your plug, because there's an invisible barrier in the sky at the height determined during world generation.

Then build a floor or whatever for your plug, maybe build a quick scaffold of walls around it, then alternate dropping lava and water to cast obsidian for the plug. Deconstruct enough for the whole atrocity to fall and watch the carnage. Any constructed parts will vaporize, but the solid cast obsidian should survive. (You might have to cast a layer of obsidian above the magma flow to catch it at the bottom? I can't remember if SMR eats falling natural stone. That casting process could be a pain that involves draining the volcano, if so, and then it won't refill, so you might have to refill the volcano using a pump stack from another lava source?)

At that point, you can decide whether your PC will ever recover enough to keep playing, both from the flowing lava and from the gigantic FPS-draining empty sky space above your map.


Alternately, I like the idea of draining the volcano (however feels best), then casting the obsidian in place inside the volcano from the bottom up, then digging out your new fortress (including chanelling the outer layer to be refilled with lava) in the cast obsidian. I think the biggest problem is that all of the tiles will have been exposed to the surface from the beginning, so you won't have any "underground" tiles to work with. So that means surface crops only, which isn't too bad, because surface crops are better than underground crops in every way except dorfiness.

[Werdna]

I can't remember if SMR eats falling natural stone.

It will.  Important to avoid it when building a magma piston.

[PatrikLundell]

You don't need to cast all the obsidian you're going to drop (at locations other than the SMR), unless you're actually building a magma piston. You can add one (or a few) layers at a time, as "natural" stone fuses with the stone it hits. This is beside the point for this post, as there is SMR at the bottom of volcanoes.

[gchristopher]

True, I was reacting piecemeal to the OP's desire to see a 120 z-level magma piston happen. (Actually, I don't know if that teleports 120 z-levels of magma upward?) I always just build a pump stack or fling it ballistically if I want it to rain magma. And then I always regret it while the liquid flow, temperature calculations, and fire dynamics murder my PC.

[Merlota]

I've done something akin to the concept.  First I drained the volcano by draining into 10x20 rooms and atom smashing the magma.  Then I solidified down to the semi-molten rock by pumping in water forming a foundation.  On top of that I built a copper tube around 20 tiles in diameter to the top of the volcano while it refilled. 

Much of it remained hollow and without floors as then I got bored and formed another site.