The bug
When the camera is below minimum world height (feet at about y = -65 by default), the bottom half of the sky suddenly goes dark.
How to reproduce
Generate a void superflat world, and fly down to the void. The lower portion of the skybox will abruptly flash to black.
Code analysis
Based on 1.11.2 decompiled using MCP 9.35 rc1
This happens when the player eye level is below net.minecraft.world.World.getHorizon() which might be done to not have a blue blackground when you are in caves. It would be good if this effect was achieved differently.
Linked issues
is duplicated by 16
MC-119908
Sunset and horizon looks weird below sea level
Resolved
MC-129349
Color of the void looks bad around Y=60
Resolved
MC-158782
Floating Islands below horizon
Resolved
MC-184704
Floating island annoying lighting bug
Resolved
MC-190190
Add smooth transition in the fog between layer 61 and 62 (overworld)
Resolved
MC-191034
The horizon turns black upon going below Y62.
Resolved
MC-214813
The sky is visible horizontally in unloaded chunks when in caves
Resolved
MC-215387
Fog color in underground caves is out of place, resembles sky color
Resolved
MC-217380
Fog is too bright in caves / Can see the sky - More obvious at lower render distances
Resolved
MC-219922
Skybox does not match with cave fog
Resolved
MC-221638
The Moon is visible in Caves
Resolved
MC-222178
Fog in the caves
Resolved
MC-222657
Low render distance caves
Resolved
MC-227530
The sky is visible above a certain height even when the player is below the surface, whilst on spectator mode
Resolved
MC-236722
Vanilla surface fog "bleeds through" when exploring large unlit caves.
Resolved
MC-239036
White fog in caves
Resolved
relates to 1
Attachments
Comments 30
Can confirm for MC 1.12.1.
Apparently happens at y=0 now, 20w07a.
Can still reproduce in 20w10a, but not on superflat worlds.
This also happens in buffet worlds and in the ocean.
1.16 pre3 in a superflat custom dimension
1.16 pre5 still has this problem
Is this a bug or a feature?
1.16 rc1
Cnfirmo que este bug pasa en mundos superplanos en la 1.16.1
This issue is especially annoying when using "Floating Islands" World Type. Perhaps add a setting where the user can adjust the horizon per world?
This is cave fog/underground fog.
I made a void data pack recently and realized the sky goes black due to this still... I wish this would fixed... Maybe link it to ocean height or have it as its own parameter in world gen.
Can confirm in 1.17.1 and 21w38a (very good decision to reopen this issue).
Can confirm in 21w39a.
Can confirm in 21w41a.
Can confirm in 21w42a.
Can confirm in 21w43a.
Can confirm in 21w43a.
Can confirm in 1.18 Pre-release 1.
Can confirm in 1.18 Pre-release 2.
Copying over my general fix suggestion from MC-214813 and MC-215387 as they were resolved into this, implying working on all three of these is planned:
It's probably a good idea to get rid of the "sky goes black" effect in its entirety. Instead, the lush caves and dripstone caves should specify their own sky and fog colors in the json files to get an equivalent effect. As for caves which are neither of these, a new generic "minecraft:caves" biome could be added, which defines fog and sky colors as well. This would also stop other biome effects from bleeding underground, as well as surface builders going down too deep.
This should make customization much easier since the black sky is no longer hardcoded.
I should also note that there's a similar sky darkening effect that can be seen below min_y, which is apparently a void fog leftover, so can also be removed for similar reasons.
I'm not sure if this approach may require some extrra biomes, however, such as a "mountain caves" biome for underground emerald generation handling, a "swamp/desert caves" biome for fossil generation as well as a "badlands caves" with extra gold.
Going into feature request territory at this point, but perhaps slime chunks could be replaced with a "slime caves" biome, allowing for their spawning to be configured like other biomes do rather than another hardcoded world thing. This is getting out of scope at this point, though.
Affects 22w03a.
[media]Another approach to maybe consider is to have the darkness slowly envelop the skybox as the player descends. At sea level the sky would begin to darken about 5 degrees below the horizon, fading into a dark gray at 20 degrees downwards. At min_y the transition begins at 30 degrees above the horizon and ends at 15 degrees above, while the color itself darkens into pitch black. Below that the angle increases rapidly, with darkness covering the entire sky at min_y - 32.
In tandem with this, fog color could use a gradient from light blue to dark gray, and this gradient would be evaluated at a point based on the percentage of the screen exposed to the open (i.e. blue/overcast/starry) sky. I don't know how tricky/expensive it would be to calculate this percentage, but if it's a heavy lift the number can be updated once every so often as opposed to every frame. This approach could lead to unexpected fog colors when chunks or parts of chunks don't render (i.e. the cave ceiling is high and the render distance is low), but I imagine the fittingness of the fog color would scale proportionally with hardware capabilities. This would also require a new setting to toggle fog fading in either the dimension or biome JSON files.
Affects 22w11a (edit: and 22w12a, 22w14a, 22w15a, 22w16b and 22w17a).
This is really jarring for any skyblock worlds.
Seems to be fixed as of 1.19.2. See screenshot 'fixed.png'.
Not really, when below the world, the color abruptly changes still; when in caves, it's the normal sky color (not darkened), etc.
There's more than 1 aspect to this bug.
Ah, I see. So the boundary is effectively at y=-64 now instead of y=+63, but the bug still exists? I'll update the report accordingly.
I will say that in earlier versions flying below minimum Y had its own darkening effect, which is the residual stuff from void fog. It's distinct from the black skybox of the void.
can confirm in 1.19.4 and 1.20-pre7
Confirmed in 1.21.4 prerelease 1.
@@unknown I changed the report a little bit, I hope you are fine with that.