0007121: Cutting down mushroom trees leaves floating ramps of indeterminate material

(0026317)
Talvieno (reporter)
2014-07-14 07:19
edited on: 2014-07-14 07:20

Can confirm this. It's not limited to those that have caps against the cavern ceiling - I cut some down at the bottom of a deep pit and had the same thing occur.

(0028993)
MrC (reporter)
2014-08-13 15:31

Also confirming this glitch.

(0029233)
Talvieno (reporter)
2014-08-18 10:05
edited on: 2014-08-19 21:14

Can confirm that this still happens in 40.09.

Edit: Here's an interesting addition: if a tree grows back in its place, like a spore tree, fungiwood, or blood thorn, the ramps change color to match the color of the new tree, but the tiles aren't updated.

(0031116)
ptb_ptb (reporter)
2014-11-22 07:17
edited on: 2014-11-22 07:18

There is similar behavior where unusable down slopes and vermin colonies are left floating in the air after large cave-ins.

Save file (before cave in):
http://dffd.wimbli.com/file.php?id=10110 [^]

See 0008573 for how to cave in the left hand side of the map.

(0031118)
ptb_ptb (reporter)
2014-11-22 07:21

I think this is related to, or duplicate of
0001547

(0036433)
anewaname (reporter)
2017-04-19 16:22
edited on: 2017-04-19 16:22

I have observations and speculation to add to this. In the dffd save below, there is a dwarf busy chopping a tree, where the tree's ramp was part of the route up to the fortress. A few seconds after the tree fell, I did 'b''C 'W' and as shown in this image (http://imgur.com/a/wcOti [^]), the distance to the materials is a negative number. Whether the wall was placed or not, FPS dropped from the cap of 50 to 4, for ten or twenty minutes, and there was much eat/drink job cancel spam, then the FPS returned to 50.

In comparison, if you 'd' 'x' the tree and 'd' 'z' that staircase, there is no FPS hit or job cancellation spam. My speculation is that these half-ramps (and the half-ramps in issue 0001547, possibly from upon-embark cave-ins) might effect pathing of fortress invaders (FBs, booze-thieves, etc) and cause some of those sudden FPS drops that players run into.

The game is 43.05 x64 from linux with MayDay tileset and no mods or dfhack used.
http://dffd.bay12games.com/file.php?id=12847 [^]

(0036447)
Loci (manager)
2017-04-23 12:00

@anewaname: Thank you for the save. The negative distance bug is a continuation of 0004372, which I have split out to 0010208.

(0037125)
Dwarfu (manager)
2017-11-29 20:28

These mushrooms don't have ramps as of 44.01.

(0037145)
Loci (manager)
2017-11-30 14:15

Yes they do, and they're still buggy as described above. Here's a before/after screenshot in v0.44.02:

http://dwarffortresswiki.org/index.php/File:Ramp-remnants.png [^]

(0037147)
Dwarfu (manager)
2017-11-30 15:01

Was that generated in 44.02? My game is unmodified and I’m looking at those mushrooms and they don’t have ramps and they cut down cleanly.

(0037152)
mrmagolor (reporter)
2017-11-30 17:47

I had this happen to me in 0.44.01.

(0037155)
Loci (manager)
2017-11-30 22:17

@Dwarfu:

Yes. How tall are your caverns? Mushroom trees seem to require at least 3 z-levels to produce ramps, and 4 z-levels to produce the problematic down-ramp tiles.

(0037161)
Dwarfu (manager)
2017-12-01 07:33

That’s exactly what it is. After looking over the caverns to try and narrow it down (because I certainly had the bug in previous versions), I see that although the caverns meander through 4-5 z-levels, at no point within them is there more than 2 z-levels available growth space.

I didn’t see anything in this report related to their size, but at least we’ve recorded the distinction now.

(0041099)
Bumber (reporter)
2021-07-16 17:42
edited on: 2021-07-16 17:43

I was reverse engineering tree-cutting code and think I found the cause of this. When removing the tree's tiles, it iterates from the top down. If there's an up ramp below the tile to be removed, it puts a down ramp in the tile (replacing the tree's down ramp with another down ramp.) It then proceeds downwards and removes the up ramp tile (because it's part of the tree,) and so on until it reaches the ground.

The simple fix is to check if the up ramp below is part of the tree, and put empty space instead of a down ramp if it is.

Issue History
Date Modified	Username	Field	Change
2014-07-12 02:08	Kumquat	New Issue
2014-07-14 07:19	Talvieno	Note Added: 0026317
2014-07-14 07:20	Talvieno	Note Edited: 0026317	View Revisions
2014-08-13 15:31	MrC	Note Added: 0028993
2014-08-13 15:35	Footkerchief	Relationship added	related to 0001573
2014-08-13 15:35	Footkerchief	Assigned To	=> Footkerchief
2014-08-13 15:35	Footkerchief	Status	new => confirmed
2014-08-18 10:05	Talvieno	Note Added: 0029233
2014-08-19 21:14	Talvieno	Note Edited: 0029233	View Revisions
2014-08-20 04:55	lethosor	Relationship added	has duplicate 0008084
2014-11-22 07:17	ptb_ptb	Note Added: 0031116
2014-11-22 07:18	ptb_ptb	Note Edited: 0031116	View Revisions
2014-11-22 07:21	ptb_ptb	Note Added: 0031118
2014-11-24 07:04	Footkerchief	Relationship added	related to 0001547
2017-04-19 16:22	anewaname	Note Added: 0036433
2017-04-19 16:22	anewaname	Note Edited: 0036433	View Revisions
2017-04-23 12:00	Loci	Note Added: 0036447
2017-06-08 18:32	Huntthetroll	Issue Monitored: Huntthetroll
2017-11-29 20:28	Dwarfu	Note Added: 0037125
2017-11-29 20:28	Dwarfu	Status	confirmed => resolved
2017-11-29 20:28	Dwarfu	Fixed in Version	=> 0.44.01
2017-11-29 20:28	Dwarfu	Resolution	open => fixed
2017-11-29 20:28	Dwarfu	Assigned To	Footkerchief => Toady One
2017-11-30 14:15	Loci	Note Added: 0037145
2017-11-30 14:15	Loci	Assigned To	Toady One => Loci
2017-11-30 14:15	Loci	Status	resolved => confirmed
2017-11-30 14:15	Loci	Resolution	fixed => open
2017-11-30 14:15	Loci	Fixed in Version	0.44.01 =>
2017-11-30 14:15	Loci	Description Updated	View Revisions
2017-11-30 14:15	Loci	Steps to Reproduce Updated	View Revisions
2017-11-30 14:15	Loci	Additional Information Updated	View Revisions
2017-11-30 15:01	Dwarfu	Note Added: 0037147
2017-11-30 15:02	Dwarfu	Status	confirmed => needs feedback
2017-11-30 17:47	mrmagolor	Note Added: 0037152
2017-11-30 22:17	Loci	Note Added: 0037155
2017-11-30 22:17	Loci	Status	needs feedback => confirmed
2017-12-01 07:33	Dwarfu	Note Added: 0037161
2021-07-16 17:42	Bumber	Note Added: 0041099
2021-07-16 17:43	Bumber	Note Edited: 0041099	View Revisions

Notes
(0026317) Talvieno (reporter) 2014-07-14 07:19 edited on: 2014-07-14 07:20	Can confirm this. It's not limited to those that have caps against the cavern ceiling - I cut some down at the bottom of a deep pit and had the same thing occur.

(0028993) MrC (reporter) 2014-08-13 15:31	Also confirming this glitch.

(0029233) Talvieno (reporter) 2014-08-18 10:05 edited on: 2014-08-19 21:14	Can confirm that this still happens in 40.09. Edit: Here's an interesting addition: if a tree grows back in its place, like a spore tree, fungiwood, or blood thorn, the ramps change color to match the color of the new tree, but the tiles aren't updated.

(0031116) ptb_ptb (reporter) 2014-11-22 07:17 edited on: 2014-11-22 07:18	There is similar behavior where unusable down slopes and vermin colonies are left floating in the air after large cave-ins. Save file (before cave in): http://dffd.wimbli.com/file.php?id=10110 [^] See 0008573 for how to cave in the left hand side of the map.

(0031118) ptb_ptb (reporter) 2014-11-22 07:21	I think this is related to, or duplicate of 0001547

(0036433) anewaname (reporter) 2017-04-19 16:22 edited on: 2017-04-19 16:22	I have observations and speculation to add to this. In the dffd save below, there is a dwarf busy chopping a tree, where the tree's ramp was part of the route up to the fortress. A few seconds after the tree fell, I did 'b''C 'W' and as shown in this image (http://imgur.com/a/wcOti [^]), the distance to the materials is a negative number. Whether the wall was placed or not, FPS dropped from the cap of 50 to 4, for ten or twenty minutes, and there was much eat/drink job cancel spam, then the FPS returned to 50. In comparison, if you 'd' 'x' the tree and 'd' 'z' that staircase, there is no FPS hit or job cancellation spam. My speculation is that these half-ramps (and the half-ramps in issue 0001547, possibly from upon-embark cave-ins) might effect pathing of fortress invaders (FBs, booze-thieves, etc) and cause some of those sudden FPS drops that players run into. The game is 43.05 x64 from linux with MayDay tileset and no mods or dfhack used. http://dffd.bay12games.com/file.php?id=12847 [^]

(0036447) Loci (manager) 2017-04-23 12:00	@anewaname: Thank you for the save. The negative distance bug is a continuation of 0004372, which I have split out to 0010208.

(0037125) Dwarfu (manager) 2017-11-29 20:28	These mushrooms don't have ramps as of 44.01.

(0037145) Loci (manager) 2017-11-30 14:15	Yes they do, and they're still buggy as described above. Here's a before/after screenshot in v0.44.02: http://dwarffortresswiki.org/index.php/File:Ramp-remnants.png [^]

(0037147) Dwarfu (manager) 2017-11-30 15:01	Was that generated in 44.02? My game is unmodified and I’m looking at those mushrooms and they don’t have ramps and they cut down cleanly.

(0037152) mrmagolor (reporter) 2017-11-30 17:47	I had this happen to me in 0.44.01.

(0037155) Loci (manager) 2017-11-30 22:17	@Dwarfu: Yes. How tall are your caverns? Mushroom trees seem to require at least 3 z-levels to produce ramps, and 4 z-levels to produce the problematic down-ramp tiles.

(0037161) Dwarfu (manager) 2017-12-01 07:33	That’s exactly what it is. After looking over the caverns to try and narrow it down (because I certainly had the bug in previous versions), I see that although the caverns meander through 4-5 z-levels, at no point within them is there more than 2 z-levels available growth space. I didn’t see anything in this report related to their size, but at least we’ve recorded the distinction now.

(0041099) Bumber (reporter) 2021-07-16 17:42 edited on: 2021-07-16 17:43	I was reverse engineering tree-cutting code and think I found the cause of this. When removing the tree's tiles, it iterates from the top down. If there's an up ramp below the tile to be removed, it puts a down ramp in the tile (replacing the tree's down ramp with another down ramp.) It then proceeds downwards and removes the up ramp tile (because it's part of the tree,) and so on until it reaches the ground. The simple fix is to check if the up ramp below is part of the tree, and put empty space instead of a down ramp if it is.