Dwarf Fortress Bug Tracker - Dwarf Fortress
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0011190Dwarf FortressPathfindingpublic2019-12-10 16:192019-12-29 19:02
normalminorhave not tried
resolvedno change required 
Windows10 Pro
0011190: Dwarves unable to path into/out of base despite 2 valid routes.
I recently dug a side path in my entrance to trap invaders but had not yet built the drawbridge that would toggle which path could be used. 3 dwarves on the outside of the base are unable to re enter and dwarves inside base are unable to leave despite both possible paths being usable.
Using squad move it is clear that the problem is on the down ramp from -1 to -2 z-level. These ramps have existed since I first dug into the base but I only recently added the zig-zag route on the -2 layer. The old route, which is unchanged, should still work and the new route should also grant access to the interior. By repeatedly telling the squad to station on the 1 by 5 tile landing between the ramp for z0 to z-1 and the ramp from z-1 to z-2 one dwarf managed to get across to the inside. Continuing this method another dwarf stepped on the z-1 to z-2 ramp and teleported through a wall onto a piece of floor that has no current ramp access. I then told the squad to station just outside the base on z0 and re paused after a couple seconds. When I switched my view back to z-1 the guy that was trapped on the piece of floor with no ramps was somehow properly inside the base. He had to have teleported off the platform he was on and given his specific location I think it also passed him back through the wall again. Have copied the save where I first realized the problem (alerted by a dehydration warning when I first loaded in) as well as a screen shot of the resulted location after the teleportation.
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Issue History
2019-12-10 16:190Uncertainty1New Issue
2019-12-11 02:22PatrikLundellNote Added: 0039608
2019-12-11 13:33LociNote Added: 0039611
2019-12-11 13:33LociAssigned To => Loci
2019-12-11 13:33LociStatusnew => needs feedback
2019-12-11 14:230Uncertainty1Note Added: 0039614
2019-12-11 14:230Uncertainty1Statusneeds feedback => assigned
2019-12-12 18:44LociNote Added: 0039615
2019-12-14 13:420Uncertainty1Note Added: 0039617
2019-12-29 19:02LociStatusassigned => resolved
2019-12-29 19:02LociResolutionopen => no change required

2019-12-11 02:22   
Bugged saves are uploaded to http://dffd.bay12games.com, [^] the bugged saves section.
The description indicates you've got unusable ramps blocking access, although they do not cause teleportation.

For a ramp to be usable, the lower level has to have a wall (up along which the ramp magically climbs), with a walkable surface above that wall, i.e. a dorf should be able to walk up the ramp and then continue straight ahead on the level above. Removing the wall (e.g. by digging it away, leaving the floor above intact) renders that side of the ramp unusable (it might still be usable in one or more of the other 3 perpendicular directions).
2019-12-11 13:33   
If a review of your ramps hasn't convinced you that they're unusable, please upload a save to DFFD.
2019-12-11 14:23   
http://dffd.bay12games.com/file.php?id=14637 [^]

Link to the save. The above explanation does explain why the pathing is behaving the way it is. That being said there still does seem to be some sort of bug going on since the dwarves outside should not be able to get in but I've been consistently able to get them across using the squad move to shuffle them around on the small area they have access to on that z level. Unless the dwarves are sometimes allowed to jump. I've not been able to recreate the teleporting incident but I do have a screen shot of where the dwarf ended up.
2019-12-12 18:44   
Yes, dwarves are allowed to jump and climb in some specific circumstances (including repathing when their previous path becomes blocked).
2019-12-14 13:42   
I'm going to assume there is something in the shuffling that sometimes triggers them to jump down to the ramp below allowing them to get inside. If that is the case then everything is functioning as intended.