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Author Topic: Water Pressure Weirdness  (Read 1365 times)

Gus Smedstad

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Water Pressure Weirdness
« on: May 03, 2010, 10:11:25 pm »

I built a little water deathtrap.  It's a water-filled pit below a long, retracting bridge.  I thought I'd be slightly clever and put the water channel below the surface - the water pressure is at level 135, the water goes down a flight of stairs to 134, and then fills the pit from there.

Except, it doesn't.  It fills level 134 and stops.  135 remains dry.   This really surprises me, since I've had overflows with water when I didn't want them, but the one time I do it deliberately, nothing happens.  And no, I didn't put a diagonal flow in there anywhere.

 - Gus
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Max White

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Re: Water Pressure Weirdness
« Reply #1 on: May 03, 2010, 10:12:49 pm »

There are two reasons for this!
The first is that you most likely have water going along a diagonal at one point, and this depressurizes water.
The second is that the game is smart enough to know how to screw you over.

FunkyWaltDogg

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Re: Water Pressure Weirdness
« Reply #2 on: May 03, 2010, 10:16:21 pm »

If the water has to flow down before it flows back up, it will rise to at most one z-level lower than the source.
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Rotten

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Re: Water Pressure Weirdness
« Reply #3 on: May 03, 2010, 10:17:21 pm »

Not sure exactly what you're trying to describe, but water, due to physics engine limitations apparently, will only rise to the level under it's source. So if the source is 0, then you have a U-bend back up to 0, it will only rise to -1, in least in 40d (and AFAIK no physics were changed between versions)
Basically (side view):
Code: [Select]
##########
S77####.##
##7####7##
##7####7##
##777777##

S is source
# is wall
7 is water
. is no water


If that isn't the case, pumps also reset water pressure. Perhaps a blueprint of your design would help out?
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Gus Smedstad

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Re: Water Pressure Weirdness
« Reply #4 on: May 03, 2010, 10:29:15 pm »

Yeah, it's a u-bend, and it's only reaching 1 level below the source.  I guess I hadn't encountered this before because my prior involuntary floods involved sources that were 4-5 levels above the receiving tank.

Code: [Select]
top view

#############
####r.......#
777#r.......#
####r.......#
#############

side view

####.......#
777#r......#
##777777777#
############

r = ramp, used during construction of the pit, and used to allow the miners to get out.

 - Gus
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Reese

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Re: Water Pressure Weirdness
« Reply #5 on: May 04, 2010, 12:38:58 am »

This is based off of my understanding of 40d, but I don't believe the mechanic has changed at all, so...

water will rise up to one level below it's source if you have unpressurized water, such as water sitting in a reservoir.  Water will not flow by itself.

Water is 'pressurized' by a pump due to the nature of how a pump works.  If you have a pump, the water will raise up to the level of the pump past the U bend.  This is due to how pumps teleport water to the nearest tile with room for it that is connected by a path through water.

There was a great tutorial on water pressure somewhere around here, and it's probably still good.

http://df.magmawiki.com/index.php/Pressure
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