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IDProjectCategoryView StatusDate SubmittedLast Update
0006545Dwarf FortressCreaturespublic2014-07-07 20:222014-08-11 06:19
Assigned ToToady One 
PlatformWindowsOSWindows 7 x64OS Version
Product Version0.40.01 
Target VersionFixed in Version0.40.05 
Summary0006545: Flying creatures stop flying, fall to the ground, and explode
DescriptionWhile on an embark containing flying creatures, I find that they sometimes spontaneously stop flying, plummeting to the ground and dying. In at least one of these instances, there were no other creatures on the screen, so it was not a result of combat or anything similar.

When this happens, I sometimes get job cancellations from nearby dwarves on the surface that say "Urist McDwarf has cancelled job X: Horrified"

I would be too, Urist.
Steps To ReproduceStart dwarf mode in an area containing flying creatures and wait. Because this only happens randomly, reproduction is difficult. That said, I am not the only person to report this, since it was also mentioned here: [^] .
TagsNo tags attached.
Attached Files

- Relationships
related to 0005421new Adventurer flight empairment 
related to 0006737confirmedToady One Flying animals (e.g. birds) stuck in mid air (prevents invasions?) 
has duplicate 0006626resolvedFootkerchief Flying creatures keep exploding into pieces and dying: Are they crashing into trees? 
has duplicate 0006628resolvedFootkerchief Birds (and other fliers) fall from the sky under trees 
has duplicate 0007286resolvedFootkerchief Buzzards sometimes suicidally dive-bomb into the ground, instantly killing themselves as a result; corpses not butchurable 
has duplicate 0007449resolvedFootkerchief Dwarf Mode: Ravens smash into cliffs 

-  Notes
AseaHeru (reporter)
2014-07-07 21:56

I have seen this occur to multiple kea. Havent seen the horrified bit yet though.
slwstctt (reporter)
2014-07-08 05:52

Update: The horrified message may have been due to the fact that the flying creature falling was a Wren Man. Do dwarves become horrified from wrenmen?

Also, this may be related to multi-tile trees. All instances so far have been in close proximity to trees. (Would a creature crashing into a tree show up in the combat log?)
Firehound (reporter)
2014-07-10 17:58

Not necessarily attached to trees. Had a mountain embark in 40.01 that had no native plantlife, and a raven exploded itself onto the ground, but some keas were able to land and steal things. About 6-7 died within a month, and then I saw no more go missing/dead. This isn't counting the few that landed but flew away(had a case where all my dwarves near my farms got horrified, but no obvious source in the same embark.)
musicmastermsh (reporter)
2014-07-17 11:27

40.03 - just had a great horned owl crash and die in a treeless area.
windy_skunk (reporter)
2014-07-23 22:17

While testing in the arena, I've noticed that it seems to be related to flying creatures being overwhelmed by emotion.
Tzalizkan (reporter)
2014-07-24 00:14

@windy_skunk That's even better.
Toady One (administrator)
2014-07-24 11:56
edited on: 2014-07-24 12:06

I know this happens, due to the number of reports and since I've seen it myself, but I'm not able to reproduce it with strong emotions or with exhaustion. Those creatures "ground" in the air, but they don't fall. It has nothing to do with flying into things because there's no such notion in the game (flight does not use projectile velocity at this point because of the associated pathfinding difficulties with momentum).

off-chance: Any webs on the maps in question? Especially from larger critters? If there are heavy webs up in the air near the multi-tile trees now, they could tangle up a flier and cause it to fall. I guess it wasn't always linked to trees, so that might not be it, but it's the only possibility I have in the absence of combat.

Talvieno (reporter)
2014-07-26 18:06

No webs in the trees, Toady, sorry. :\ Not in my maps, at least. Still running tests to try to figure everything out.
thewonderidiot (reporter)
2014-07-26 18:35
edited on: 2014-07-26 18:42

Just had a raven explode on a map with no trees, and barely any plants (tundra/mountain). There was a ball of four ravens stuck way up in the sky, with none of them moving at all, for over half a season. It would seem that one of them managed to escape, but promptly hit the ground and exploded about 10 tiles away. Maybe them getting stuck is the necessary precondition to them falling?

e: Here's the save: [^]

Toady One (administrator)
2014-07-26 18:38

Yeah, I just had one die without webs... maybe it is the lash-out code when animals are stacked for too long, but then the question is why there isn't a combat report before the impact...
Talvieno (reporter)
2014-07-26 18:46
edited on: 2014-07-26 18:54

This is probably all wrong, but I have an idea. Perhaps the game is somehow having them fall asleep - modded fliers in 34.11 were . I wouldn't be sure why, but it just seems possible, given that they're falling. It would be a pain to test, though. You'd have to wait for them to pass out and fall asleep, and that would take a while, even with a large number of creatures in the arena.

I really do feel like it has something to do with getting stuck, though. Possibly related to how the sky is "broken" in places.

Edit: Perhaps the best way to test would be to dump a large number of creatures at roof height in arena mode in debug mode, with a custom debug trigger that pauses the game when a creature hits a certain z-level (e.g. if creature.z = 5 then pause, basically (looping through the list, if doable))... and then you just wait. When the game pauses, you see if the creature is stunned, dizzy, asleep, etc.

thewonderidiot (reporter)
2014-07-26 19:35
edited on: 2014-07-26 19:41

Lash-out could be. I think I may have found something else accidentally, though:

I've been watching this ravenball for a couple of seasons. The one on the upper z-level flew down one, so for quite a while I've had two ravens occupying the same tile (with, of course, one prone in the air, heh).

That was pretty much the status quo for a long time. Then, traders entered the map very close to right below the ravens, and the ball split. Two of them started flying around normally, and one fell out of the sky and exploded.

I was able to reproduce this once by assigning a dwarf to a squad and stationing him right below the ball, but it's not totally consistent. Still messing around with it...

e: Just got it to reproduce a second time, same thing as above -- stationing a military dwarf just below the group of stuck ravens. It seems that they're getting spooked, and maybe if they're frightened enough they can fall from the sky? (although you said that strong emotions weren't causing it...)

Toady One (administrator)
2014-07-26 20:19

Was there anything like a tree or ramp around them before they fell? I've found one cause of this that reproduced and is fixed: jumping. When the birds are flying over trees or ramps/cliffs and are near their destination, they are deciding to push off and jump, and when there is a flock, there can be mid-air collisions that nullify their velocities, which makes them drop like a rock, because it isn't anticipating a flier being a projectile. The only case it wouldn't explain is treeless flat maps, or birds in the air away from any feature.

I'll try to scare a flock of ravens on a flat tundra map and see if something happens.
thewonderidiot (reporter)
2014-07-26 20:33
edited on: 2014-07-26 20:36

Hmmm... not sure about the ramp, I'll start messing with it.

I've spent the last 45 minutes or so attempting to create a prepared save that has a *bit* of repeatability. Here it is: [^]

There's a dwarf on his way to be stationed beneath the birdball. If you follow the first raven on the units list, it explodes itself about 33% of the time.

One time, in particular, was interesting... it seemed to gib itself against the top of the map, and all of its guts rained down the approximately 10 z-levels to the ground from where it exploded.

All of the others have more or less just been running into the mountain, which could possibly be explained by the ramp thing.

Toady One (administrator)
2014-07-26 20:47

Hopefully the last piece of the puzzle: AI birds didn't have any qualms about jumping when standing in the middle of the air (it isn't legal for flying adventurers). So they were possible springing out of the ball mid-air and crashing mid-air. That said, if you've seen one fall while other birds aren't very close, it's probably not the jumping. I herded around 20 ravens with one soldier without a dropping bird for a while, anyway.

I'll check the save and see what happens.
Talvieno (reporter)
2014-07-26 20:54

I've had lone great horned owls and eagles fall to the ground, so it might not be all of it.
thewonderidiot (reporter)
2014-07-26 21:02

Talvieno -- was there anything else on the map? Other kinds of birds or nearby creatures or something that they may have hit?

Toady -- I've been repeatedly spreading my flock in slow-mo to try to catch one that explodes without hitting another bird. No luck yet (haven't directly seen one hit another bird though). Success on the save might be a little more like 20% or so... I have noticed that I don't always get reports from the explosions. There will occasionally just be one less raven listed on the unit screen, and if I scour the mountainsides sometimes I'll be able to find the remains.
Toady One (administrator)
2014-07-26 21:05

I did 10 runs on the save with zero drops, so it seems like we've got progress anyway. I suppose we'll leave this open for 0.40.05 and see how high the drop rate still is, and for what kinds of critters and situations.
Talvieno (reporter)
2014-07-26 21:09
edited on: 2014-07-26 21:11

thewonderidiot - No, no other aboveground creatures. I had a very large number of trees on the map, though. I think the only other thing nearby would've been vermin, and as far as I know, the game doesn't check for collisions with vermin.

edit: They do seem to explode more often with dwarves nearby, though - kind of like your experiment with the random gibbing against the top of the map, but it's usually at tree level.

thewonderidiot (reporter)
2014-07-26 21:24

Zero out of ten is a good sign! I don't think I've had a streak that long without any drops at all yet. I'll repeat all of this tomorrow after 40.05 is out.
thewonderidiot (reporter)
2014-07-28 19:28

I just did two dozen runs of the save on 40.05 and didn't get any drops, so it definitely looks like you've fixed the main issue there, at least. I'll keep an eye out for any unusual avian deaths in my regular play, but I suspect this one is likely resolved.
Talvieno (reporter)
2014-07-28 19:50
edited on: 2014-07-28 19:51

Something else has cropped up in its place, though - frozen birds. I have keas frozen on my map that have been there for a few seasons, stuck while carrying a few masterwork gold goblets out of the fort. (but they got my artifact adamantine mug, lol) I suppose that's a topic for a different thread, though. I think this one is pretty much resolved, yeah.

lethosor (manager)
2014-07-28 20:11

Talvieno, that's a separate issue (0006737).
Talvieno (reporter)
2014-07-28 20:13

Lol, thanks. I didn't see it until just today.
4maskwolf (reporter)
2014-08-10 19:00

I haven't seen this in any of the recent versions, has anyone else experienced it?
lethosor (manager)
2014-08-10 19:26

I've seen some other reports of this being fixed as well, so I'll resolve this. If anyone can reproduce this, please send me a PM on the forums and I'll reopen this report. Thanks!

- Issue History
Date Modified Username Field Change
2014-07-07 20:22 slwstctt New Issue
2014-07-07 21:56 AseaHeru Note Added: 0024926
2014-07-08 05:52 slwstctt Note Added: 0025007
2014-07-08 06:51 Footkerchief Relationship added has duplicate 0006626
2014-07-08 06:52 Footkerchief Summary Suicidal flying creatures (Flying creatures stop flying at random?) => Flying creatures stop flying, fall to the ground, and explode
2014-07-08 07:07 Footkerchief Relationship added has duplicate 0006628
2014-07-08 07:07 Footkerchief Summary Flying creatures stop flying, fall to the ground, and explode => Flying creatures crash into trees, stop flying, fall to the ground, and explode
2014-07-10 17:58 Firehound Note Added: 0025636
2014-07-12 11:25 Dwarfu Relationship added related to 0005421
2014-07-14 13:17 Footkerchief Relationship added has duplicate 0007286
2014-07-17 11:27 musicmastermsh Note Added: 0026768
2014-07-18 07:23 Footkerchief Relationship added has duplicate 0007449
2014-07-23 22:17 windy_skunk Note Added: 0027383
2014-07-23 22:26 Footkerchief Summary Flying creatures crash into trees, stop flying, fall to the ground, and explode => Flying creatures stop flying, fall to the ground, and explode
2014-07-24 00:14 Tzalizkan Note Added: 0027388
2014-07-24 11:56 Toady One Note Added: 0027438
2014-07-24 11:57 Toady One Note Edited: 0027438 View Revisions
2014-07-24 12:02 Toady One Note Edited: 0027438 View Revisions
2014-07-24 12:06 Toady One Note Edited: 0027438 View Revisions
2014-07-26 15:22 Footkerchief Relationship added related to 0006737
2014-07-26 16:35 Footkerchief Assigned To => Footkerchief
2014-07-26 16:35 Footkerchief Status new => needs feedback
2014-07-26 18:06 Talvieno Note Added: 0027650
2014-07-26 18:29 Roomghost Note Added: 0027653
2014-07-26 18:30 Roomghost Note Deleted: 0027653
2014-07-26 18:35 thewonderidiot Note Added: 0027654
2014-07-26 18:38 Toady One Note Added: 0027655
2014-07-26 18:42 thewonderidiot Note Edited: 0027654 View Revisions
2014-07-26 18:46 Talvieno Note Added: 0027656
2014-07-26 18:49 Talvieno Note Edited: 0027656 View Revisions
2014-07-26 18:54 Talvieno Note Edited: 0027656 View Revisions
2014-07-26 19:35 thewonderidiot Note Added: 0027660
2014-07-26 19:41 thewonderidiot Note Edited: 0027660 View Revisions
2014-07-26 20:19 Toady One Note Added: 0027661
2014-07-26 20:33 thewonderidiot Note Added: 0027662
2014-07-26 20:36 thewonderidiot Note Edited: 0027662 View Revisions
2014-07-26 20:47 Toady One Note Added: 0027664
2014-07-26 20:54 Talvieno Note Added: 0027665
2014-07-26 21:02 thewonderidiot Note Added: 0027666
2014-07-26 21:05 Toady One Note Added: 0027667
2014-07-26 21:09 Talvieno Note Added: 0027668
2014-07-26 21:11 Talvieno Note Edited: 0027668 View Revisions
2014-07-26 21:24 thewonderidiot Note Added: 0027669
2014-07-28 19:28 thewonderidiot Note Added: 0027836
2014-07-28 19:50 Talvieno Note Added: 0027840
2014-07-28 19:51 Talvieno Note Edited: 0027840 View Revisions
2014-07-28 20:11 lethosor Note Added: 0027843
2014-07-28 20:12 lethosor Assigned To Footkerchief => lethosor
2014-07-28 20:12 lethosor Status needs feedback => acknowledged
2014-07-28 20:13 Talvieno Note Added: 0027844
2014-08-10 19:00 4maskwolf Note Added: 0028769
2014-08-10 19:00 4maskwolf Issue Monitored: 4maskwolf
2014-08-10 19:26 lethosor Note Added: 0028773
2014-08-10 19:26 lethosor Status acknowledged => resolved
2014-08-10 19:26 lethosor Fixed in Version => 0.40.05
2014-08-10 19:26 lethosor Resolution open => fixed
2014-08-10 19:26 lethosor Assigned To lethosor => Toady One
2014-08-11 06:19 4maskwolf Issue End Monitor: 4maskwolf

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