Dwarf Fortress Bug Tracker - Dwarf Fortress
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0011708Dwarf FortressVegetationpublic2021-03-02 09:272021-03-02 23:49
normalminorhave not tried
64-bitWindows 7
0011708: Bugged grass is trampled immediately and grazers can't eat it
Here is a save on a lovely seashore where instead of the usual varied grasses, all the grass is plain "grass". The "grass" is apparently trampled instantly when any creature walks over it, and my grazing animals are starving despite being in a large pasture. Either they trample the thin layer of "grass" before they can eat it, or "grass" isn't actually edible.

This fort is the second in this world, and was created with the PyLNP 0.14a version of DF, including DFhack and TWBT. But opening the save in vanilla DF still shows "grass" and the grazers continue to go hungry.
Here is the save with bugged grass:

https://dffd.bay12games.com/file.php?id=15448 [^]
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Issue History
2021-03-02 09:27peanutsnraisinsNew Issue
2021-03-02 10:32peanutsnraisinsNote Added: 0040946
2021-03-02 23:49PatrikLundellNote Added: 0040947

2021-03-02 10:32   
Additional testing has shown that this only occurs in forts in the temperate conifer forest biome. Temperate savanna and temperate shrubland have the usual varied grasses (the world has limited biomes so I couldn't test them all).

Here's a save in the same world:

https://dffd.bay12games.com/file.php?id=15450 [^]

There are two pastures near the wagon. The one on the left with a water buffalo has only "grass" and is placed in a temperate conifer forest. The one of the right with a yak is placed in a temperate shrubland and has varied grasses (knotgrass, hair grass, etc).

So far I can't duplicate this bug in any newly-created world.
2021-03-02 23:49   
The reason is that the biome doesn't have any normal grass associated to it. It does have wormy tendrils and eyeballs, but as this area isn't evil those don't apply.

I would guess that the RNG happened to not select any of the available kinds of grass for this biome, something that's probably very uncommon.

Either DF accepts very rare freak cases like this or it includes a check to ensure at least one kind of grass is available in every biome. It could be that there is such a check, but that it's broken by the introduction of spreading evil, as evil used to be tied to regions, so a region was all evil or all non evil (or all good), so eyeballs alone would be sufficient to satisfy an "any grass?" check. If so, the logic would have to be extended to check that there's any neutral grass available in regions that are neutral natively.