Dwarf Fortress Bug Tracker - Dwarf Fortress
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IDProjectCategoryView StatusDate SubmittedLast Update
0010466Dwarf FortressDwarf Mode -- Buildings, Generalpublic2017-12-22 11:232017-12-23 13:33
ReporterAgent Wowza 
Assigned ToLoci 
PriorityhighSeveritymajorReproducibilitysometimes
StatusresolvedResolutionno change required 
PlatformLaptopOSWindowsOS Version10
Product Version0.44.02 
Target VersionFixed in Version 
Summary0010466: Magma-safe raised bridges deconstructing
DescriptionRaised bridges made of orthoclase blocks, including mechanisms, used as walls of a magma cistern deconstruct shortly after opening. They also deconstruct if they are immediately closed after opening. No magma slag observed, so nothing seems to have melted.
Steps To Reproduce- Create a room 21x15 with orthoclase bridges for walls and normal constructed walls for corners. Link bridges to lever with orthoclase mechanisms.
- Fill with 7/7 magma from above. Fill the area in the layer above it with 7/7 magma.
- Open bridges.
- (Optional) close bridges immediately after opening.
Additional InformationOccurred to only 3 out of the 9 bridges used as walls. Bridges also contained non-magma safe mechanisms from previous lever linkage. Also observed to happen immediately after 1/7 magma comes into contact with mica floor hatches. Does not appear to be the case with mica doors.

Problematic layer (z):
Image before deconstruction: https://imgur.com/y9r6G8D [^]
Image after deconstruction: https://imgur.com/LNLfqIR [^]
Image after deconstruction (raised): https://imgur.com/MM5OdhF [^]

For reference:
Layer above problematic layer (z+1): https://imgur.com/duMuMBw [^]
Uppermost layer (z+2): https://imgur.com/OqZMkLe [^]
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Issue History
Date ModifiedUsernameFieldChange
2017-12-22 11:23Agent WowzaNew Issue
2017-12-22 18:22QuietustNote Added: 0037382
2017-12-22 18:23QuietustNote Edited: 0037382bug_revision_view_page.php?bugnote_id=0037382#r15086
2017-12-22 23:50Agent WowzaIssue Monitored: Agent Wowza
2017-12-22 23:50Agent WowzaIssue End Monitor: Agent Wowza
2017-12-22 23:55Agent WowzaNote Added: 0037383
2017-12-23 00:06Agent WowzaNote Edited: 0037383bug_revision_view_page.php?bugnote_id=0037383#r15088
2017-12-23 06:23QuietustNote Added: 0037384
2017-12-23 06:26QuietustNote Edited: 0037384bug_revision_view_page.php?bugnote_id=0037384#r15090
2017-12-23 13:33LociNote Added: 0037389
2017-12-23 13:33LociStatusnew => resolved
2017-12-23 13:33LociResolutionopen => no change required
2017-12-23 13:33LociAssigned To => Loci

Notes
(0037382)
Quietust   
2017-12-22 18:22   
(edited on: 2017-12-22 18:23)
If the bridges contained non-magma-safe mechanisms, then what happened is normal - if any component of a building melts, then the entire building deconstructs.

A save file upload would help confirm that this is what actually happened here.
(0037383)
Agent Wowza   
2017-12-22 23:55   
(edited on: 2017-12-23 00:06)
However, out of the nine bridges, only ones which contained mechanisms made of materials which have a melting point lower than or equal to 11500 U deconstructed, such as those containing granite or microline mechanisms. The other bridges contained hornblende and diorite mechanisms but did not deconstruct.

Also, none of the bridges deconstructed for about a year when the remained closed. Does this mean the mechanism is only exposed to magma when the bridge is lowered?

Link to zipped save file: https://drive.google.com/open?id=1F0hGbvsBIh_1ZhuEVPDY-Gc7pCtwQVBi [^]
(0037384)
Quietust   
2017-12-23 06:23   
(edited on: 2017-12-23 06:26)
Looking at your save, all of the behavior you described is 100% expected - if the bridge contains even one non-magma-safe mechanism, then that mechanism will melt when the bridge opens and cause the whole building to deconstruct.

I lowered all 28 bridges (on both Z-levels), and after several minutes (running at only 5-6 FPS) nearly all of them melted (in order of increasing melting temperature), except for the 9 which didn't have magma-unsafe mechanisms.

The reason it only deconstructs when the bridge is lowered is because the mechanisms are logically located at the center tile of the bridge - if you used an actual drawbridge, you could also see the bridge melt while raised if it was blocking the magma from the inside rather than from the outside.

For the record, this is all documented on the wiki: http://dwarffortresswiki.org/index.php/DF2014:Magma-safe [^]
(0037389)
Loci   
2017-12-23 13:33   
Indeed. The wiki is a good reference for expected behavior, as are previous bug reports (0008216, 0005983, 0003444).