0008383: Flying/swimming/climbing creatures can move vertically through diagonal gaps containing down-stairways

(0030475)
Quietust (reporter)
2014-10-01 13:30
edited on: 2014-10-01 13:35

A side view makes it a bit more clear what's going on here:

######## Z =  2

#..>#### Z =  1

####...# Z =  0

######## Z = -1

(0030476)
Loci (manager)
2014-10-01 14:01

Related to 0007130 and a duplicate of 0002820, though more accurately described.

(0030480)
Footkerchief (manager)
2014-10-01 15:58

Quietust, any differences from 0002820?

(0030481)
Quietust (reporter)
2014-10-01 17:05
edited on: 2014-10-01 17:06

0002820 looks to be describing the same issue (albeit being specific to HFS, and not including the case of Swimming creatures), though I would've been hard pressed to actually find it via Search given the way it was worded...

(0030484)
Footkerchief (manager)
2014-10-01 18:15

Yeah, I'll let 0002820 focus on the game not detecting the HFS breach, while this report focuses on the movement.

(0031796)
Catharsis (reporter)
2015-01-08 17:35

Hey Footkerchief, how can I upload this save?

(0031797)
Footkerchief (manager)
2015-01-08 18:03

Best way is to upload to http://dffd.wimbli.com/, [^] then post the link here. A save probably isn't strictly necessary for this bug, but it can't hurt.

(0031800)
Catharsis (reporter)
2015-01-08 20:05

Here you go: http://dffd.wimbli.com/file.php?id=10398 [^]
All you have to do is go down to the bottom, and you'll find the end of the 3x3 stairwell, with one block remaining to the southwest. Digging an upstair here let's the bug come into effect (I think building one work too), while digging a down stair causes the magma sea to be revealed.

(0035759)
Loci (manager)
2016-08-07 07:08

v0.43.03: a climbing dwarf moved vertically-diagonal into a stairway in a save posted by Leonidas in 0009644:

http://dffd.bay12games.com/file.php?id=12329 [^]

(0036693)
PatrikLundell (reporter)
2017-08-12 03:11

It's also possible for swimmers (magma crabs) to enter diagonally upwards from the magma sea through the absence of a floor. Obsidianizing the last magma sea level on top of the SMR involves a stair which leaves a security hole as per the below. Removing the stair after obsidianization also removes the floor, and magma crabs can enter through that hole, so it's not directly tied to stairs (delaying obsidianization until the stair above has been removed causes the obsidianization to produce a normal floor, plugging the hole).

I would suggest the issue is that there is a diagonal passage generated, and that passage can probably be passed through by climbing and flying. Since climbing isn't part of normal dwarf pathing, dwarves cannot pass though these holes normally, but climbers (such as crundles or troglodytes) can probably do so. I would guess the reason I see magma crabs exiting the magma sea is that exiting liquids probably involves a climbing step that's "normal" for liquid exiting (and I'd suggest dumping a swimming capable dwarf into water with a diagonal upwards hole being the only exit should see the dwarf exit through that hole).

(0036739)
syler19839 (reporter)
2017-09-15 00:07

Is it a bug? It's basically a diagonal moving (+ z-level moving).
It would be a bug if diagonal directions were forbidden.

(0036740)
PatrikLundell (reporter)
2017-09-15 00:51

Yes, it is a bug. It's a diagonal movement through a non existent crack, so you'd have to be infinitely thin to pass through.
You can, of course, say that horizontal diagonal movement has the same problem, but there you have visibility, and the fact that the passage is infinitely thin is a result of the world being made up of blocks, so you can rationalize it into the passage actually being wide enough to pass through.

(0036749)
syler19839 (reporter)
2017-09-17 21:25

Didn't know you can't see through z-level gaps like you can through horizontal one's. This makes me agree with Patrik Lundell.

(0036750)
PatrikLundell (reporter)
2017-09-18 00:49

One really annoying case of this is when you dig a probing up/down staircase that hits the SMR. This causes the work to be aborted without any notification. You can then get magma crabs that enter this staircase from the magma sea which still hasn't been discovered.

Issue History
Date Modified	Username	Field	Change
2014-10-01 13:20	Quietust	New Issue
2014-10-01 13:30	Quietust	Note Added: 0030475
2014-10-01 13:35	Quietust	Note Edited: 0030475	View Revisions
2014-10-01 14:01	Loci	Note Added: 0030476
2014-10-01 15:58	Footkerchief	Note Added: 0030480
2014-10-01 15:58	Footkerchief	Assigned To	=> Footkerchief
2014-10-01 15:58	Footkerchief	Status	new => needs feedback
2014-10-01 15:58	Footkerchief	Relationship added	duplicate of 0002820
2014-10-01 17:05	Quietust	Note Added: 0030481
2014-10-01 17:05	Quietust	Status	needs feedback => assigned
2014-10-01 17:06	Quietust	Note Edited: 0030481	View Revisions
2014-10-01 18:14	Footkerchief	Relationship replaced	related to 0002820
2014-10-01 18:15	Footkerchief	Note Added: 0030484
2014-10-01 18:15	Footkerchief	Status	assigned => confirmed
2014-10-01 18:15	Footkerchief	Relationship added	related to 0007130
2015-01-08 06:09	Footkerchief	Relationship added	has duplicate 0008707
2015-01-08 06:09	Footkerchief	Issue Monitored: Detros
2015-01-08 17:33	Catharsis	Issue Monitored: Catharsis
2015-01-08 17:35	Catharsis	Note Added: 0031796
2015-01-08 18:03	Footkerchief	Note Added: 0031797
2015-01-08 20:05	Catharsis	Note Added: 0031800
2015-01-11 08:14	Footkerchief	Relationship added	related to 0008322
2015-01-11 08:14	Footkerchief	Relationship added	related to 0008186
2016-08-07 07:08	Loci	Note Added: 0035759
2016-08-07 07:08	Loci	Summary	Flying/swimming creatures can move vertically through diagonal gaps containing down-stairways => Flying/swimming/climbing creatures can move vertically through diagonal gaps containing down-stairways
2017-08-12 03:11	PatrikLundell	Note Added: 0036693
2017-09-15 00:07	syler19839	Note Added: 0036739
2017-09-15 00:51	PatrikLundell	Note Added: 0036740
2017-09-17 21:25	syler19839	Note Added: 0036749
2017-09-18 00:49	PatrikLundell	Note Added: 0036750
2018-01-19 16:21	Toady One	Status	confirmed => resolved
2018-01-19 16:21	Toady One	Fixed in Version	=> Next Version
2018-01-19 16:21	Toady One	Resolution	open => fixed
2018-01-19 16:21	Toady One	Assigned To	Footkerchief => Toady One

Notes
(0030475) Quietust (reporter) 2014-10-01 13:30 edited on: 2014-10-01 13:35	A side view makes it a bit more clear what's going on here: `######## Z = 2 #..>#### Z = 1 ####...# Z = 0 ######## Z = -1`

(0030476) Loci (manager) 2014-10-01 14:01	Related to 0007130 and a duplicate of 0002820, though more accurately described.

(0030480) Footkerchief (manager) 2014-10-01 15:58	Quietust, any differences from 0002820?

(0030481) Quietust (reporter) 2014-10-01 17:05 edited on: 2014-10-01 17:06	0002820 looks to be describing the same issue (albeit being specific to HFS, and not including the case of Swimming creatures), though I would've been hard pressed to actually find it via Search given the way it was worded...

(0030484) Footkerchief (manager) 2014-10-01 18:15	Yeah, I'll let 0002820 focus on the game not detecting the HFS breach, while this report focuses on the movement.

(0031796) Catharsis (reporter) 2015-01-08 17:35	Hey Footkerchief, how can I upload this save?

(0031797) Footkerchief (manager) 2015-01-08 18:03	Best way is to upload to http://dffd.wimbli.com/, [^] then post the link here. A save probably isn't strictly necessary for this bug, but it can't hurt.

(0031800) Catharsis (reporter) 2015-01-08 20:05	Here you go: http://dffd.wimbli.com/file.php?id=10398 [^] All you have to do is go down to the bottom, and you'll find the end of the 3x3 stairwell, with one block remaining to the southwest. Digging an upstair here let's the bug come into effect (I think building one work too), while digging a down stair causes the magma sea to be revealed.

(0035759) Loci (manager) 2016-08-07 07:08	v0.43.03: a climbing dwarf moved vertically-diagonal into a stairway in a save posted by Leonidas in 0009644: http://dffd.bay12games.com/file.php?id=12329 [^]

(0036693) PatrikLundell (reporter) 2017-08-12 03:11	It's also possible for swimmers (magma crabs) to enter diagonally upwards from the magma sea through the absence of a floor. Obsidianizing the last magma sea level on top of the SMR involves a stair which leaves a security hole as per the below. Removing the stair after obsidianization also removes the floor, and magma crabs can enter through that hole, so it's not directly tied to stairs (delaying obsidianization until the stair above has been removed causes the obsidianization to produce a normal floor, plugging the hole). I would suggest the issue is that there is a diagonal passage generated, and that passage can probably be passed through by climbing and flying. Since climbing isn't part of normal dwarf pathing, dwarves cannot pass though these holes normally, but climbers (such as crundles or troglodytes) can probably do so. I would guess the reason I see magma crabs exiting the magma sea is that exiting liquids probably involves a climbing step that's "normal" for liquid exiting (and I'd suggest dumping a swimming capable dwarf into water with a diagonal upwards hole being the only exit should see the dwarf exit through that hole).

(0036739) syler19839 (reporter) 2017-09-15 00:07	Is it a bug? It's basically a diagonal moving (+ z-level moving). It would be a bug if diagonal directions were forbidden.

(0036740) PatrikLundell (reporter) 2017-09-15 00:51	Yes, it is a bug. It's a diagonal movement through a non existent crack, so you'd have to be infinitely thin to pass through. You can, of course, say that horizontal diagonal movement has the same problem, but there you have visibility, and the fact that the passage is infinitely thin is a result of the world being made up of blocks, so you can rationalize it into the passage actually being wide enough to pass through.

(0036749) syler19839 (reporter) 2017-09-17 21:25	Didn't know you can't see through z-level gaps like you can through horizontal one's. This makes me agree with Patrik Lundell.

(0036750) PatrikLundell (reporter) 2017-09-18 00:49	One really annoying case of this is when you dig a probing up/down staircase that hits the SMR. This causes the work to be aborted without any notification. You can then get magma crabs that enter this staircase from the magma sea which still hasn't been discovered.