MC-278399Falling block upon world generation might cause dark spot with client light 0
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Create a World with the Seed:
6974066552162750007
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/tp @s -170.26 65 -581.52 156 30
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LowCreated Issue:
Client Light 0 can be found through normal world generation in strange spot
Create a World with the Seed:
6974066552162750007
Type in
/tp @s -170.26 65 -581.52 156 30
Attachments1
Changed Summary:
Client Light 0 can be found through normal world generationin strange spotClient Light 0 can be found through normal world generation, which is inconsistent with other lighting
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Removed Category: (Unassigned)
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Added Affects Versions: 24w45a
Changed Summary:
Client Light 0 can be found through normal world generation, which is inconsistent withotherlightingFalling block upon world generation might cause dark spot with client light 0
Added Affects Versions: 1.21.4-pre1
Added Attachments:
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Added Mojang Priority: 
Important
ImportantAdded Assignee: ![[Mojang] Rebecca](../../../data/avatars/users/18936.svg)
[Mojang] Rebecca
[Mojang] RebeccaRemoved Assignee: [Mojang] Rebecca
[Mojang] RebeccaDeleted Comment:
We are unable to reproduce this on any version.
Could you give us more detailed reproduction steps?
Ex. Does this only occur on Windows? Are you using specific Video settings?
Added Assignee: [Mojang] Rebecca
[Mojang] RebeccaAdded Affects Versions: 24w44a
Removed Assignee: [Mojang] Rebecca
[Mojang] RebeccaAdded Affects Versions: 1.21.4-pre2
Added Attachments:
Deleted Comment:
In the newest Pre-Release 2, I don't encounter this issue anymore, was it fixed?
Added Assignee: [Mojang] Rebecca
[Mojang] Rebecca![[Mojang] Gegy](../../../data/avatars/users/10122.svg){kind=small}
Added Affects Versions: 1.21.3
Added Affects Versions: 1.21.4-pre3
Added Affects Versions: 1.18
Changed Description:
Create a World with the Seed:
6974066552162750007
Type in
/tp @s -170.26 65 -581.52 156 30
See comments
Create a World with the Seed:
6974066552162750007Type in
/tp @s -170.26 65 -581.52 156 30
Removed Assignee: [Mojang] Rebecca
[Mojang] Rebecca
Steps to reproduce
- Create a debug world in 1.21.3
- Upgrade it to 1.21.4 Pre1
Observed results
- Some blocks get 0 light level
Expected results this wouldn't happen
Possibly related: MC-278399
Can confirm.
After doing some testing, I found that this bug was introduced in 24w45a (at least at the specific location mentioned in the bug report).
I reproduced this issue in 24w45a but can't reproduce it in 24w46a.
Btw, there is gravel in the place of the block with zero lighting, which immediately falls when you teleport to this place. Maybe this was fixed as part of another fix, somehow related to falling blocks..?
I can reproduce this in 24w46a.
Found similar things in 1.16 (but not in 1.21.3)
Edit: Seems to only happen sometimes with Fancy + Smooth Lightning OFF
I did reproduce this with Fabulous and Smooth Lighting ON.
Nevermind still happens
Looks like there is a case where this doesn't happen. I wonder if it has to do with how the chunk loads.
I then clearly noticed and saw that there's a gravel block that falls off around that time, into the water. I wonder if it ever falls before the chunk loaded or something.
Do placed blocks even have a light level at the location they're placed at? Is there some async like behavior where the block was thought to be solid but at the same time the solid block started falling, so then it just got client light 0?