Dwarf Fortress Bug Tracker - Dwarf Fortress
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0007585Dwarf FortressDwarf Mode -- Environmentpublic2014-07-23 06:042014-09-12 11:42
Toady One 
0007585: Trees channel light underground
Exactly what it says in the description - light passes vertically through trees. I suppose the idea is that you don't want there to be darkness under the branches, but it has the added effect of making areas light that are underground - if the tile in question is one tile below the central trunk.
Mine out an area one z-level below ground. Wait for a tree to grow above, or simply mine out the roots of existing trees. Press K and check the tile. It'll say it's light. This permits growing aboveground crops underground.
has duplicate 0007712resolved Knight Otu Light underground, through trees 
has duplicate 0008143resolved Knight Otu Above Ground tile underground directly beneath a tree 
related to 0007068resolved Toady One Tile dug under tree trunk growing on rock is considered inside/light/aboveground 
related to 0000087resolved Toady One If one tile of a farm plot is dry or has the wrong biome, it also prevents the succeeding tiles from getting planted 
Issue History
2014-07-23 06:04TalvienoNew Issue
2014-07-29 08:20Knight OtuRelationship addedhas duplicate 0007712
2014-07-30 10:15IjieroNote Added: 0027964
2014-07-30 10:20TalvienoNote Added: 0027965
2014-07-30 13:32IjieroIssue Monitored: Ijiero
2014-07-30 13:33IjieroIssue End Monitor: Ijiero
2014-07-31 22:23DrazinonondaNote Added: 0028071
2014-08-01 11:41TalvienoNote Added: 0028091
2014-08-01 11:51PeepsNote Added: 0028092
2014-08-03 19:36lethosorAssigned To => lethosor
2014-08-03 19:36lethosorStatusnew => acknowledged
2014-08-03 19:36lethosorTag Attached: 0.40.06
2014-08-03 19:37lethosorNote Added: 0028254
2014-08-06 10:34FootkerchiefRelationship addedrelated to 0007068
2014-08-18 09:37slinkNote Added: 0029223
2014-08-24 15:05Knight OtuRelationship addedhas duplicate 0008143
2014-08-29 08:26FootkerchiefStatusacknowledged => confirmed
2014-09-12 09:25FootkerchiefRelationship addedrelated to 0000087
2014-09-12 11:42Toady OneStatusconfirmed => resolved
2014-09-12 11:42Toady OneFixed in Version => Next Version
2014-09-12 11:42Toady OneResolutionopen => fixed
2014-09-12 11:42Toady OneAssigned Tolethosor => Toady One

2014-07-30 10:15   
I can confirm this bug. I just registered to report it myself.

Additionaly: upon removal of the tree, your underground lair will have an open ceiling where the tree used to be. I assume this is as intended...
2014-07-30 10:20   
I wouldn't think that's intended, no. I suppose it makes sense in a way, but I don't think it's intended.
2014-07-31 22:23   
As far as realism goes, it makes sense... if you dig out a room that has a tree for a ceiling, then remove the tree, you've removed the ceiling.

From a game mechanics standpoint, I assume that tree trunks work off the same base code as constructed walls, so that they block movement but leave full empty tiles (rather than a floor) when cut down. Otherwise trimming the branches off a tree would leave branch-shaped floors in the upper reaches, which wouldn't make sense.
2014-08-01 11:41   
That part makes sense. The weird part is that trees act like glass would in real life, and channel light downwards through them - or at least pass light downwards. The light remains there permanently.
2014-08-01 11:51   
Maybe there were holes between the roots that let light filter down or something.
As for the light staying after the hole was filled, DF has always been like that; try channeling out an area on the surface then covering it with a floor.
2014-08-03 19:37   
Fairly easy to reproduce in 0.40.06 with 0006749 fixed.
2014-08-18 09:37   
In 0.40.09, if you cut down the tree first then the roots vanish and there is no problem with light coming down when you dig where the roots used to be. I don't know yet what happens if a new tree grows over a room. Perhaps they don't grow there.