MC-133224Chunks marked for repop are recreated from scratch when upgrading from 1.12
When a 1.12 world is upgraded to 1.13, chunks marked for repopulation are deleted and regenerated from scratch, as far as I can tell.
Expected behaviour
Existing structures in the chunk marked for repopulation should be preserved, and population is added on top of it. For example, if you built a house with a grass roof then marked the chunk for repopulation, next time you enter the area you might expect to see grass + trees on the roof. This was especially useful for larger areas.
Actual behaviour
The chunk is deleted and regenerated from scratch. For example, if you built a house then marked the chunk for repopulation, next time you enter the area the house will be gone.
Steps to reproduce
- Load the test world (attached) in 1.12.
- The pretty building is still intact, and a chorus flower has grown on the roof
- Load the test world in 1.13.
- The pretty building has disappeared
- Note: you have to load two copies of the test world or the chunk will no longer be marked for population
Environment
Windows 10
Attachments1
Created Issue:
Chunks marked for repop are recreated from scratch when upgrading from 1.12
When a 1.12 world is upgraded to 1.13, chunks marked for repopulation are deleted and regenerated from scratch, as far as I can tell.
Expected behaviour
Existing structures in the chunk marked for repopulation should be preserved, and population is added on top of it. For example, if you built a house with a grass roof then marked the chunk for repopulation, next time you enter the area you might expect to see grass + trees on the roof. This was especially useful for larger areas.
Actual behaviour
The chunk is deleted and regenerated from scratch. For example, if you built a house then marked the chunk for repopulation, next time you enter the area the house will be gone.
Steps to reproduce
- Load up 1.12
- Build some structure in a chunk (bonus points for prettiness!)
- Close the game and open the world in mcedit
- Mark the chunks containing the structure for repopulation
- Close mcedit
- Open the world in 1.13
- Observe your beutiful structure is gone
Note: building the structure in 1.12 and using mcedit is only for ease of reproduction. If mcedit or some other tool were to work for 1.13 worlds this bug would also probably apply.
Note 2: I did testing in the End if you can't reproduce it in the overworld
Environment
Windows 10
When a 1.12 world is upgraded to 1.13, chunks marked for repopulation are deleted and regenerated from scratch, as far as I can tell.
Expected behaviour
Existing structures in the chunk marked for repopulation should be preserved, and population is added on top of it. For example, if you built a house with a grass roof then marked the chunk for repopulation, next time you enter the area you might expect to see grass + trees on the roof. This was especially useful for larger areas.
Actual behaviour
The chunk is deleted and regenerated from scratch. For example, if you built a house then marked the chunk for repopulation, next time you enter the area the house will be gone.
Steps to reproduce
- Load up 1.12
Build some structure in a chunk (bonus points for prettiness!)Close the game and open the world in mcedit- Mark the chunks containing the structure for repopulation
Close mcedit- Open the world in 1.13
- Observe your beutiful structure is gone
Note: building the structure in 1.12 and using mcedit is only for ease of reproduction. If mcedit or some other tool were to work for 1.13 worlds this bug would also probably apply.
Note 2: I did testing in the End if you can't reproduce it in the overworld
When a 1.12 world is upgraded to 1.13, chunks marked for repopulation are deleted and regenerated from scratch, as far as I can tell.
Expected behaviour
Existing structures in the chunk marked for repopulation should be preserved, and population is added on top of it. For example, if you built a house with a grass roof then marked the chunk for repopulation, next time you enter the area you might expect to see grass + trees on the roof. This was especially useful for larger areas.
Actual behaviour
The chunk is deleted and regenerated from scratch. For example, if you built a house then marked the chunk for repopulation, next time you enter the area the house will be gone.
Steps to reproduce
- Load the test world (attached) in 1.12.
- The pretty building is still intact, and a chorus flower has grown on the roof
- Load the test world in 1.13.
- The pretty building has disappeared
When a 1.12 world is upgraded to 1.13, chunks marked for repopulation are deleted and regenerated from scratch, as far as I can tell.
Expected behaviour
Existing structures in the chunk marked for repopulation should be preserved, and population is added on top of it. For example, if you built a house with a grass roof then marked the chunk for repopulation, next time you enter the area you might expect to see grass + trees on the roof. This was especially useful for larger areas.
Actual behaviour
The chunk is deleted and regenerated from scratch. For example, if you built a house then marked the chunk for repopulation, next time you enter the area the house will be gone.
Steps to reproduce
- Load the test world (attached) in 1.12.
- The pretty building is still intact, and a chorus flower has grown on the roof
- Load the test world in 1.13.
- The pretty building has disappeared
- Note: you have to load two copies of the test world or the chunk will no longer be marked for population
![[Mod] NeunEinser](../../../data/avatars/users/39263.png){kind=small}
When a 1.12 world is upgraded to 1.13, chunks marked for repopulation are deleted and regenerated from scratch, as far as I can tell.
Expected behaviour
Existing structures in the chunk marked for repopulation should be preserved, and population is added on top of it. For example, if you built a house with a grass roof then marked the chunk for repopulation, next time you enter the area you might expect to see grass + trees on the roof. This was especially useful for larger areas.
Actual behaviour
The chunk is deleted and regenerated from scratch. For example, if you built a house then marked the chunk for repopulation, next time you enter the area the house will be gone.
Steps to reproduce
- Load the test world (attached) in 1.12.
- The pretty building is still intact, and a chorus flower has grown on the roof
- Load the test world in 1.13.
- The pretty building has disappeared
- Note: you have to load two copies of the test world or the chunk will no longer be marked for population
ProfMobius (Thomas Guimbretiere)
Is that only an upgrade issue or would a chunk that was created in 1.13 and is marked for repopulation also be regenerated entirely?
How did you mark the chunk for repopulation ?
The current behavior is the right one due to changes in generation. In 1.12, without using external tools, only border chunks are marked for population. they are dropped when loaded in 1.13 since they don't contain full data to be converted.
When your world is opened directly in 1.13, the chunk is regenerated since it is marked as not finished. If I open the map first in 1.12 than 1.13, the house is there since the chunk was marked as fully decorated in 1.12.
You can certainly push blocks into unpopulated chunks using a flying machine.
I don't think there is a vanilla way to mark a chunk as unpopulated, but that might be wrong.
I assume the example with the house was just done for easier reproducability.
doesn't this bug affect structures like mob dungeon on edge of chunk? If it will extend to unpopulated chunk it would be cut there on updating MC version, right?
[Helper] Michał Structures are stored separetly and ported from 1.12. They will keep on generating properly in 1.13. They are also part of the decoration, so at this point, the chunk is already decorated and will not be dropped. Only pre-decoration chunks are dropped (ie : the initial noise map).
[Mod] NeunEinser You can fly a machine into an unpopulated chunk, but this is a very rare case and like the name indicate, the chunk isn't done generating. In 1.12, it was accessible in some cases, but the data in it is still not valid data for any gameplay purpose. The fact that you could act on those chunks to begin with is a bug all by itself (which has been partially fixed in 1.13 with the introduction of protochunks).
As far as I understand it, the reported bug is that modifying the map with an external tool doesn't work properly when the map is loaded directly in 1.13. When loaded first in 1.12, the map ports perfectly fine.
You can make a flying machine to go out to unpopulated chunks in 1.12, then upgrade to 1.12 and the flying machine will disappear. However, I doubt players (even technical players) will encounter that by accident. NeunEinser is correct, this example was just for ease of reproducibility.
Also, getting the world that I uploaded would have been possible (but difficult) without external tools because you can generate the chunks in a way such that the 2x2 of chunks is never simultaneously loaded, and place the blocks with commands.
I encountered this when I was trying to test if something that works in 1.12 would work in 1.13, and was surprised to see that some stuff had disappeared. But if what ProfMobius said is true then that thing is unlikely to work in 1.13 anyway.
Since this is very minor I wouldn't mind it being closed as WaI.
I am going to close it as WAI.
I can see how it is possible to actually reach this state via commands. In 1.13, those border chunks are not accessible to the engine anymore.