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Author Topic: Automatically resetting ice trap  (Read 5922 times)

Scraggletag

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Automatically resetting ice trap
« on: August 07, 2010, 04:15:19 am »

I've been lurking on these boards for a long time, but this is the first time I've posted. Why? Well, I finally built something I'm proud of.

Ladies and Gentledwarves, I submit to you, the Automatically Resetting Ice Trap: http://mkv25.net/dfma/movie-2239-automaticresettingicetrap

The idea was simple. I wanted to build a trap which froze enemies in a block of ice, then used magma to melt the ice and reset the trap. The execution of that idea was not.

The first problem was coming up with a design for The Device (it still needs a decent name). After sketching a few plans out on paper, I found one which I thought should work. I did a little experimentation in a junk fort, couldn't find any obvious flaws and decided to build the real thing.

The second hurdle was trying to find an appropriate site. Obviously, it had to be in a freezing biome. I knew I would need a lot of pumps (my rough design called for 4 pumps for each tile that freezes). I knew I would need power to run those pumps. I knew I would need magma, underground water and materials to make the pumps out of. From those criteria, I decided a 40d fortress with an underground river, magma vent and sand would suite my needs (Glass is mostly magma proof in 40d, and I wasn't sure about being able to generate enough power in a 0.31.XX fort from windmills, nor did I want to pump magma up a bunch of levels). I also *wanted* flux and a sedimentary layer for bauxite but finding such a perfect site in 40d was too much. In time, I found a suitable but not ideal location and set out to build The Device, bringing along lots of lumber and some bauxite. There was no sedimentary layer, but it had everything I needed plus marble and some Fun Stuff. Honestly, finding the right place to build was the hardest part of this adventure. In retrospect, maybe I should have used 0.31.XX

The video above is fun to watch but there is a lot going on behind the scenes. I'll be using screenshots of The Device while it was still under construction for the long boring explanation to explain how it works. These are all from on of my seasonal backup saves, just before I filled The Device with water and magma.

Here is a shot of the main hallway, where all the action takes place. Note that at this point in the construction, The Device hasn't been opened up to the outside world yet. Latter on I dug a set of stairs at the eastern end of the hallway to allow enemies to enter.
Spoiler (click to show/hide)
When an enemy steps on the pressure plate near the left end of the hallway, it opens the hatch covers you see to the north of the pumps (all of these pumps take water from the north side and push it south). Once the hatches are open, the pumps push water through the fortifications into the main hallway. The floors above the hallway have been channeled out so any water which enters this area freezes instantly, killing the enemy.

Note the second pressure plate at the east end of the hallway. This one is set to trigger where there is depth 3 or greater water on it's tile. There is only a diagonal connection to the fortification south west of the second pressure plate, so water only trickles onto it. The second pressure plate is linked to a whooping 20 hatch covers and two retracting bridges.


On the layer 1 z-level above the hallway is a second set of pumps facing the opposite direction but directly above the set which pump water into the hallway.
Spoiler (click to show/hide)
The second pressure plate opens the hatch covers blocking the input tile of these pumps. As soon as they open, they start sucking water out of the fortifications adjacent to the killing hallway on the layer below. The bridge north of these pumps is also triggered by the second pressure plate, but the bridge has a 100 tick delay before it opens. When this bridge opens, it dumps the water back down to the layer below, ready to be used again for the next wave.


On the z-level below the killing hallway is (surprise surprise) another retracting bridge, a set of pumps and their input-tile-blocking hatch covers.
Spoiler (click to show/hide)
These pumps take magma from beneath the southern hatch covers and push to out onto the green glass bridge on the north side. The green glass bridge is located directly beneath the freeze zone of the layer above and once the magma is on the bridge, it melts the ice on the layer above. These hatches and the green glass bridge are also triggered by the second pressure plate. Again, the hatch covers open instantly, putting magma on the bridge in just a couple ticks, but the bridge won't retract until 100 ticks after the second pressure plate was initially triggered.

The layer beneath that is just a set of magma return pumps, fed from the north and going to the south.
Spoiler (click to show/hide)
When the green glass bridge above them retracts, it conveniently dumps the magma directly into the input space of these pumps, ready to be used for the next wave.

The real key to this whole contraption is the fact that pressure plates send an ON signal when they are first triggered and an OFF signal after they've been untriggered for 100 ticks. It is hugely important that all these bridges and hatch covers close.

Unfortunately, after all this work, I ran into a bit of a snag. While you can recover the bodies and possessions of creatures that get frozen in ice, you can only do so by mining it out. The goblins (and all their precious goblinite) disappear from the world when the ice is melted instead of mined.

...

...

Oh well. It was a good idea at least.
Spoiler (click to show/hide)





For anybody who is interested, here is current map, world gen info and the embark location:
http://mkv25.net/dfma/map-9326-twinklespit
Spoiler (click to show/hide)
Spoiler (click to show/hide)

Inspired by the Degrinchinator http://mkv25.net/dfma/movie-231-degrinchinator

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Shinziril

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Re: Automatically resetting ice trap
« Reply #1 on: August 07, 2010, 04:29:54 am »

Wow.  That resets really fast.  I was expecting something with noticeable delays from my previous work with fluid mechanics.

If it was possible to manually disable the automatic reset, you could re-freeze the area *after* the siege had left, and then mine the ice out.  From what I've heard, that causes everything freezesmashed into the Phantom Zone in that particular tile to come spilling back into reality (and often causes hilarious lag in the process, but you can't argue with goblinite).  However, I'm not sure if this is possible with the way you have it set up, and also uncertain if there's a way to modify it to work. 

This requires more research.

For Science!

EDIT:  Eureka!

Okay, so first you need to be able to trigger the watery half of the trap without having a goblin on the pressure plate.  You can just do this manually by linking the hatches of the main level to a lever somewhere inside the fortress.  Second, you have to disable the automatic melting portion of the trap.  This one is simple- have a *second* lever, linked to the gear assembly that provides power to the magma pumps, thus disabling them when pulled.  Pull this lever first.  Once you have done so, toggle the second lever on, wait a bit, then toggle it off.  You may then commence mining out the lovely goblinite ore.

As for a name, I recommend Have A (n)Ice Death, since there is no such thing as bad puns where weaponized architecture is concerned.
« Last Edit: August 07, 2010, 04:49:40 am by Shinziril »
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Scraggletag

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Re: Automatically resetting ice trap
« Reply #2 on: August 07, 2010, 04:39:03 am »

Yeah, I knew its possible to recover the goblinite by manually digging out the area. I tried it using a bucket brigade by making a pond zone and dumping water from the layer above. But that takes a while and you have to reactivate/deactivate the pond zone each time.


Tomorrow I'm going to see if I can work out a level-controlled non-melting system to recover the loot after The Device breaks the siege. But its late and I'm going to bed.
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CinnibarMan

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Re: Automatically resetting ice trap
« Reply #3 on: August 07, 2010, 04:45:46 am »

Goblin dishwasher?
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The Yellow Peril

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Re: Automatically resetting ice trap
« Reply #4 on: August 07, 2010, 06:59:19 am »

Wow, really impressive feat of dwarfyness. It's just so annoying that that 31.xx this isn't nearly as viable, like you say, with magma being either 100 z-levels down or on top of a huge mountain, and no underground rivers at all.
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Talion

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Re: Automatically resetting ice trap
« Reply #5 on: August 07, 2010, 07:27:43 am »

That is indeed an awesome improvement on the Degrinchinator. Any thoughts on extending the width of the trap above 2 squares?
It would obviously require a change to the present design. It seems that if you could pump out the excess water fast enough, you could create a 3/7 pool of unfrozen water for the goblins to walk through. Then you would just need to be able to remove and replace the magma with enough speed to maintain the destructiveness of the present trap.
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Scraggletag

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Re: Automatically resetting ice trap
« Reply #6 on: August 07, 2010, 12:47:16 pm »

Well, I've modified the design a bit to include a manual Goblinite Recovery System. I had to move the entry stairs, rebuild a few walls and reroute power to the magma pumps. Its an ugly kludge, but it works.
Spoiler (click to show/hide)

The new southern drawbridge is controlled by a lever inside the fort. By having water enter the kill hall from the south side, it freezes before it can reach the second pressure plate, and doesn't trigger the melting sequence. All I have to do is pull the lever to lower the drawbridge, wait till the hall fills with ice, pull the lever again to raise the drawbridge (which also atom-smashes some extra water) and mine out the hall.

I'll post another video with the Goblinite Recovery System in place as soon as I get another siege.

As far as names go, I've been thinking "Ice Scream Machine".
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