When standing on a bottom slab (i.e. not a full block) the light level on the F3 screen will be 0 (0 sky, 0 block) even when standing next to a block. This also applies to the bottom step of the stairs.
As far as I know only slabs and stairs have this problem. Daylight sensors, chests, repeaters don't seem to be affected, but I haven't tested this extensively.
Related issues
is duplicated by
MC-4257
Half fireworks bug
MC-47275
Block light is zero on any slab
MC-50102
Light Levels on Half Blocks
MC-53450
Stairs give light level 0
MC-54719
Light level 0 in stairs and slabs
MC-59558
Light levels are not showing properly
MC-60399
0 Block Light on All Step Block Cut Out Portion
MC-62489
When standing on a half slab, the light level always shows "0"
MC-67268
Light Level is always 0 when on Soul Sand
MC-69102
Light level on lower-half slab is 0
MC-75132
No light level at Half Slab
MC-82132
Light problem
MC-89596
Light level reported as 0, but torches are close by.
MC-97032
0 light level on bottom level slabs
MC-97804
Stairs lighting issue
MC-98820
Light level displays 0 when on path block
MC-100818
Stair, Slab, Soulsand, and Path Block F3 Lighting Glitch
MC-102486
Dirt Path | Light Level 0
MC-102652
Light level on half-blocks (Slabs)
MC-105542
Once you till dirt, the light level goes to 0.
MC-105639
The F3 debug info problem about light
MC-105677
Light level of 0 on farmland
MC-106245
Light level 0 if on a half slab that is on the lower half of the block
MC-108537
Farmland and Dirt Pathway Light Levels are 0.
MC-108621
Lighting Issues With Grass Path
MC-109040
Light level
MC-114746
Farmland not showing light value in F3 overlay
MC-118769
Light level on slabs
MC-119037
No light on farm [Vanilla 1.12]
MC-120199
debug screen reports light level as (0 sky, 0 block)
MC-120203
Torches do not increase light level for tilled dirt blocks
MC-127992
Light level 0 on slabs
MC-129005
Can't see light level for plowed blocks
MC-133040
Light 0 on paths, farmlands, slab and stairs
MC-133578
Jack o lanterns not always registering as light
MC-133865
Light 0 on farmland
MC-134579
The light value is 0 when on top of a stair block
MC-136005
Light in F3 on half slabs (bottom) always 0
MC-137002
Light level shows as 0 when on path
MC-138629
no light levals when on a path block
MCL-4257
In F3, light level shows 0 while on slabs/stairs.
relates to
Attachments
Comments
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kumasasa
Confirmed.
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14w11b still has this issue, if I can, I'll attach my screenshot. I'm even standing next to a glowstone block!
Edit: Screenshot added.
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Still an issue in 14w28b
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Still an issue 14w30b
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still in 14w30c
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Also in 1.8-pre1
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Confirmed for 1.8,
Attatched screenshot.
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And 1.8.1
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Also in 1.8.3
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This bug appears to apply to the lower step of stair blocks as well.
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Can anyone confirm whether this affects mob spawns?
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Mobs do not spawn on half slabs or stairs.
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Bottom stair/bottom slab light of 0 confirmed for 1.8.7.
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Can also confirm for 1.8.7....
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Affects 15w31a
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Confirmed in Minecraft 1.8.8
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Also affects path blocks
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I'm closing this as working as intended: When you are standing on stairs/slabs like this, you are inside the 1x1x1 block boundary. Light level inside blocks is 0, so it should display 0.
Krimsar
What about the aforementioned path blocks though? Also, the light level on carpet, snow or a bed is just fine. Beds, slabs and carpets all behave the same when you place another block on top of them. Is there a significant difference other than the (visual) height?
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The blocks you listed do not block light. Path blocks are solid, but not full height.
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This also happens on farmland, which is actually a problem, because light level affects how crops grow.
kumasasa
There is no problem for farmland. This ticket is about the displayed light level on the debug screen (which is in fact zero when the player is inside blocks) but the actual light level internally used by the game for crops, spawning mobs etc. is correct.
migrated
Yes, I understand the mechanics of what's going on. The farmland is slightly shorter than a full block, putting the bottom of the player's feet in the farmland block, so the debug screen is showing the light level of the farmland block (an opaque block at light level zero), and not the light level of the crop block.
While this effect is rather benign for grass paths, light levels when walking on farmland is not. Light level affects crop growth, and not being able to read that from the debug screen poses a game play problem.
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The debug screen is not meant to be used for gameplay.
muzikbike
This bug has been fixed in 18w46a.
pokechu22
Fixed for everything other than soulsand; I've created MC-139631 for that since soulsand is a bit of a weird case.