The bug
Loot tables ignore the skip_existing_chunks option within minecraft:exploration_map functions.
How to reproduce
Using a loot table such as:
{
"pools": [
{
"rolls": 1,
"entries": [
{
"type": "item",
"name": "minecraft:map",
"weight": 1,
"functions": [
{
"function": "minecraft:exploration_map",
"destination": "shipwreck",
"decoration": "red_x",
"zoom": 1,
"skip_existing_chunks": true
}
]
}
]
}
]
}→ Will result in maps leading to the same structure every time.
This is especially problematic for large servers, as this gave the ability to have naturally spawning explorer maps lead to unexplored chunks rather than always leading to treasure that is raided.
Comments 15
I will also mention that the maps that cartographers generate will always lead to the closest area, regardless of whether or not it leads to generated chunks. I don't know it the two relate to each other, but I thought I should mention it.
Have observed this happening with ocean explorer maps in 1.13-pre7
Actually, only Ocean Monument and Woodland Mansion maps from Cartographers utilized this function. Buried Treasure maps had it set to false, as if you already generated a chunk but didn't know that a buried chest was there and this property was set to true, you would possibly never know that it was ever there. But with the former structures, they're so large and not hidden that you know for sure if you've generated a chunk with them in it.
@Milo359: this has been mentioned, it references to being able to change loot tables in order to skip existing chunks. (Not just default functions).
@MukiTanuki What I'm saying is that you're incorrectly stating that Buried Treasure explorer maps have this function set to true, when they don't. The real problem in vanilla is that now that this function is removed, Ocean Monuments and Woodland Mansions are negatively affected. I would update your description to correct this error and accurately reflect this.
@Milo359 I never stated that they specifically included this function, but I've rewritten the description to be a bit less ambiguous.
@MukiTanuki ok, you never state it, but you kinda imply it by stating that this bug affects Buried Treasure maps, which is incorrect. This bug only affects explorer maps brought from Cartographers (assuming no data packs).
Affects 1.13-pre10.
19w13a affected
Can confirm for 1.14.4
Is this still the case in 1.15?
it is fixed somewhere between 1.14.4 and 20w06a.
We had skip_existing_chunks fail in 1.15.2 today, mapping to a structure that had already been explored, in this instance pointed to a village we were actively using as our home-base.
video of the event
https://youtu.be/PG91xhLCuAc?t=2588
That map was generated with this loot table portion:
{
"type": "minecraft:item",
"functions": [
{
"function": "minecraft:exploration_map",
"destination": "village",
"decoration": "target_point",
"zoom": 1,
"skip_existing_chunks": true
},
{
"function":"set_name",
"name":{"text":"Village Explorer Map"}
},
{
"function":"set_nbt",
"tag":"{display:{MapColor:14057086}}"
}
],
"name": "minecraft:map", "quality": 1, "weight": 1
}Skipping existing chunks is still not working in 1.16.4, at least for end cities.
Can confirm. This is very problematic, and should probably be fixed along with the other explorer map and /locate bugs.