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Author Topic: Wierd scenario with water mechanics.  (Read 489 times)

thecrimsonbeard

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Wierd scenario with water mechanics.
« on: April 16, 2014, 12:40:00 pm »

I got tired of long drawn out goblin sieges (or ones where they invade at just the right wrong time during a temporary weakness) distracting me. As I'm still between moderate and noob at this game, I decided to create a long 2 Z-level hall as a flooding chamber with an elaborate (for me) series of floodgates as the only entrance to my fortress.  Well, wouldn't you know it, no gobbos, but I finally got my first necro siege, so I found I couldn't drown anyone but the necromancer.  The undead had to be pushed off the waterfall draining area.  Which didn't seem to work until I actually closed the floodgates that gave access from the river to the hall, which seems counter intuitive.  You would think constant streaming water after fully flooding the chamber and opening the exits would be more effective, but I perused the wiki and found this:

Spoiler (click to show/hide)

So is this a known bug or feature (for FPS reasons) that prevents full tiles of moving water to actually push objects, and my cutting off the source lets the tiles fall under 7/7 and switch from pressure to (non-teleporting) flow mechanics again?  Or does this only apply with vertical pressure mechanics?  The wiki seems to imply that pressure is mutually exclusive from flow and only affects elevation.

Here's some images of my setup, if that helps.  And yea, I could have used more than a single z-level drop for the flow, but I was only anticipating drownable hostiles from my sieges.  I take it that using a screw pump would be ineffective for the same reasons.

Spoiler (click to show/hide)
Spoiler (click to show/hide)

Again, when I close floodgate #2 is when things start to get pushed around.
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GavJ

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Re: Wierd scenario with water mechanics.
« Reply #1 on: April 16, 2014, 01:23:55 pm »

It's a technical feature -- it lets your computer not die when doing large fluid calculations. Water will teleport through already full tiles to somewhere on the other side, then start flowing, as a simpler simulation. It will teleport in all 3 dimensions.

Unfortunately this does have the side effect of making instajets of water not as cool as they would otherwise be.
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thecrimsonbeard

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Re: Wierd scenario with water mechanics.
« Reply #2 on: April 17, 2014, 09:10:00 am »

I was afraid of that. Is there a way to maximize the effects of flow?  Do it on a ramp and/or keep the water level around 5-6 to prevent teleporting?
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GavJ

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Re: Wierd scenario with water mechanics.
« Reply #3 on: April 17, 2014, 01:01:30 pm »

No not really. Just make sure that the channel doesn't fill entirely at any point. At some point though, even if you use a series of flows, you will usually have non flowing tiles, at least one, in between, requiring the critter to step off onto the next line themselves.

You might look into minecarts. I don't know anything about them, though.

And in your case, it looks like the end goal is to drop them.  Why not just dig your own 20 z level pit right at the beginning and not need flow? A single very skilled mining dwarf can just channel it all himself before dying of thirst, requiring no significant infrastructure to make sheer-walled pits.
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thecrimsonbeard

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Re: Wierd scenario with water mechanics.
« Reply #4 on: April 17, 2014, 07:02:31 pm »

My end goal was drowning before I realized I would be dealing with the undead.  The drop through the drainage shaft ended up being the best alternative, I could think of aside from basic traps.  I'm not sure what you mean by using a pit, unless you mean a retractable bridge.  Guess I could do that if I could get them into a more confined space. When I raised the drawbridges to trap the invaders, they were pretty spread out.  It would probably require a series of bridges.
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juxari

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Re: Wierd scenario with water mechanics.
« Reply #5 on: April 17, 2014, 09:59:41 pm »

My end goal was drowning before I realized I would be dealing with the undead.  The drop through the drainage shaft ended up being the best alternative, I could think of aside from basic traps.  I'm not sure what you mean by using a pit, unless you mean a retractable bridge.  Guess I could do that if I could get them into a more confined space. When I raised the drawbridges to trap the invaders, they were pretty spread out.  It would probably require a series of bridges.

A pressure plate connected to a few 1X10 or 2-3X10 sized bridges in front of the pressure plate and a 10+ z level drop under the bridges to a pit filled with erect spikes (bonus if the pit is also a little bit filled with magma).
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thecrimsonbeard

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Re: Wierd scenario with water mechanics.
« Reply #6 on: April 18, 2014, 02:04:43 pm »

A pressure plate connected to a few 1X10 or 2-3X10 sized bridges in front of the pressure plate and a 10+ z level drop under the bridges to a pit filled with erect spikes (bonus if the pit is also a little bit filled with magma).

Thanks, so pressure plates are instantaneous?  I've noticed a lag in levers which has led to at least one disater.  Guess I gotta go ahead and get into this weight business, which is always what stopped me from using them to begin with...didn't want trading caravans plummeting in my traps for goblins, but with the depot outside this time, that's no issue.
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Larix

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Re: Wierd scenario with water mechanics.
« Reply #7 on: April 19, 2014, 06:13:55 am »

Bridges have a reaction delay of 100 steps. Whether the signal comes from a pressure plate or lever doesn't matter for reaction time.

The pressure plate reacts to the presence of the "trigger condition", while a lever has to wait for a job performed by a dwarf. When you use machinery to trap goblins, the former tends to give better timing.

Friendly units never trigger pressure plates. The caravan will only fall into your pits if there are hostile/wild creatures nearby and trigger the pit while the caravan's coming in. It's still a good idea to keep trading path and invasion path separate, because ambushes and sieges _will_ attack traders if given the opportunity. (Oh, and pressure plates will block the path of wagons. They count as traps for that purpose.)
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Sadrice

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Re: Wierd scenario with water mechanics.
« Reply #8 on: April 19, 2014, 05:33:31 pm »

I was afraid of that. Is there a way to maximize the effects of flow?  Do it on a ramp and/or keep the water level around 5-6 to prevent teleporting?

In my experience, the easiest and best way to produce a limited flow of water for a pusher trap is using a diagonal pressure reducer, and you don't even need any fancy mechanics to maintain the water level.  The only moving part (aside from the water itself) is the on/off switch floodgates.  Pressure (water teleporting) only goes the six orthogonal directions (N, S, E, W, Up, Down).  Water will go through a diagonal path, but not by teleporting, just by moving individual units of water between adjacent tiles.

That means that if you provide a diagonal grating on an infinite water source, you get dependable limited flow, which as I recall is enough to provide pushing across a 3 wide path, like so:


It's been a while since I made one of those (too simple and effective, I've been trying to limit myself to either more elaborate traps or military), but that should work as drawn.  The fortifications could be done without, but then building destroyers could access the doors, although that shouldn't happen when water is flowing.  You could leave it turned off except in case of invasions, or use traffic designations to keep your dwarves out of it and leave it always on (though the constant flowing water will affect fps).

I drew it underground, but there's no reason why it couldn't be placed on a cliff, or the ramparts of your castle, or whatever (other than it being easier to get infinite water underground).

This style of pressure reducer is also useful for managing water levels in other situations, like if you have a cistern well below the water source, you could just have a pressure reducer at the end of the plumbing feeding the cistern, and then it will never fill above that Z level, no matter the pressure on the input plumbing.  No more massive floods coming out of your wells, drowning the meeting hall!

You can also put checkerboard columns across hallways or in your entrance hall (I like to put it around the depot, separating 'inside' from 'outside', with the depot being 'outside' but still underground.  Not only does that limit line of sight on invading marksmen, allowing your dwarves to ambush them behind the columns, but it also keeps water from flowing quickly through, so that in case of a major flood, you get muddy floor but water is not capable of quickly filling your fortress, so you can lock down the affected area while not limiting your dwarves movements.

Basically, I love diagonal gratings made of checkerboard columns.  They are functional, while providing easily visible symbolic boundaries between parts of the fortress, while also being totally dwarf permeable, and if you want to trap the boundary, it halves the required number of traps while also stopping arrow fire, reducing scared dwarf cancelations, and preventing disastrous flooding.
« Last Edit: April 19, 2014, 05:39:47 pm by Sadrice »
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