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Author Topic: Question on Volcano-erupting-on-unretire bug/feature  (Read 741 times)

nasobema

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Question on Volcano-erupting-on-unretire bug/feature
« on: October 07, 2018, 08:36:02 am »

Due to a corrupted save I recently had to go back to a copy I made to check my dwarfs out in Legends Viewer.
In the copy my fortress had been retired (in order to use Legends mode) and upon unretiring I learned the hard way about the bug (or feature, depending on your point of view) causing volcanos to sort of erupt after unretiring.
The bug is described here: http://www.bay12games.com/dwarves/mantisbt/view.php?id=8183

Well, it certainly is a lot of fun to have an erupting volcano. Only it apparently wouldn't stop and floods the lower levels until it reaches the border of the map.
This causes a lot of pressure on the FPS, which is obviously bad for my future plans to create the greatest volcano fortress in this world.

Does someone have an idea how to deal with this somehow?
The bug seems to be unresolved and I don't know if the magma will ever stop rising. It might be a miscalculation of the magma level but how would I know how high it will rise? Any idea apart from building a sky-high artificial magma tube?
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PatrikLundell

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Re: Question on Volcano-erupting-on-unretire bug/feature
« Reply #1 on: October 07, 2018, 11:35:44 am »

Obsidianization tends to stop magma progress by turning it into obsidian.

If this flooding follows the normal rules for magma pipes, magma should spawn in the air and rain down, which should allow you to determine its maximum level.

Obsidianizing the top would obviously stop its progress there and create a plug.

Also, magma isn't pressurized (unlike water) unless you use a screw pump, so it will not rise to a level higher than the one it flows in on (if that level is open above, the flow can start on that level when filling up, but pressing through a door won't cause it to reach a higher level than that of the door.

Now, the above is assuming the normal magma pipe rules are obeyed somewhat. Magma pipes cause rain in the whole 16*16 tile it's in, assuming there's a free line of sght to the SMR below, but not in adjacent 16*16 tiles.
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nasobema

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Re: Question on Volcano-erupting-on-unretire bug/feature
« Reply #2 on: October 07, 2018, 02:50:57 pm »

Hmm, there is no visible magma rain and I really don't think that it works this way.
I've built a bridge over the volcano that stayed safe until the magma level rose to the level of the bridge and just flooded it. There was no magma coming on the bridge from above (although there seem to be occasional splashes creating 1/7 magma on the next level).

So far, I built a wall two levels higher than the crater, which is now completely filled with magma. I also dug a tunnel below the magma level, which empties into a trench leading the magma off-map via fortifications. This works but the magma seems to rise faster than I can drain it with the trench. The idea was to drop the magma level, seal the volcano on top and close the tunnel with preinstalled basalt-bridges. No success though.

The last chance now seems to be the obsidian idea but with no river on the map, I need to pump water all the way from the first cavern level...

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PatrikLundell

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Re: Question on Volcano-erupting-on-unretire bug/feature
« Reply #3 on: October 07, 2018, 05:00:52 pm »

I usually obsidianize using a bucket brigade, unless I'm obsidianizing large amounts (which you are).

Again, I don't actually know how this bug behaves, only the normal behavior. It should be noted that building a bridge blocks line of sight to the SMR, so no magma should spawn above it to fall onto it (although I think I've seen cases where magma has "flown" sideways before falling, landing on a ledge that was actually outside of the magma pool tile 16*16 tile.

There is a DFHack command set I think is called "liquids" and "liquids-here" or something similar that can spawn water, magma and obsidian. That might be something to consider if things get desperate.

I would otherwise consider building a higher artificial crater and then a floor on top of it, as it might be faster than obsidianization (although I still think rain might be a danger). I'd have multiple drains (that can be closed) from that rim to protect the work while it's underway, i.e. more of what you've already done.
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