[MC-12558] Light leaking through corners with Smooth Lighting on

The bug

With Smooth Lighting turned on (minimum or maximum doesn't matter) light will spill through the corner of a block if there is a light source either behind or beneath an adjacent block.

How to reproduce

/fill ~-1 ~-1 ~-1 ~3 ~3 ~3 sandstone hollow

```
/setblock ~3 ~2 ~2 glowstone
```
```
/setblock ~2 ~2 ~2 sandstone
```
Look at the corner with the light source behind
```
/teleport @s ~ ~ ~ -50 -10
```

Linked issues

is duplicated by 15

MC-135799 Lava light shining through block borders Resolved

MC-139513 Small bits of light appears to go through slabs Resolved

MC-140149 Found lighting bug still present with stairs Resolved

MC-148718 Weird diagonal lighting on sand block in closed environment Resolved

MC-149625 Light issue with lava and blocks next to it Resolved

10 more links

relates to 2

MC-197497 Smooth lighting transition from level 1 to 0 is not smooth Open

MC-93869 Blocks in front of extended pistons without blocks on the side darken the piston arm if smooth lighting is on Reopened

Attachments

crash-2013-03-21_16.08.45-client.txt

MC-12558.mp4

Comments 48

Carl Lystad 2013-03-21T23:25:11Z

Explanation on set 3:
(a) shows the glitch with the test setup. The two light patches point toward a hidden light source.
(b) shows the blocks behind the glitchy spot. Note the empty space above the glowstone.
(c) shows no glitch when the previously empty spot is filled with a solid block.

If the block removed between a and b is placed again after c, the result is no glitch on any of the blocks. So there seems to be some relation with the transparency of the blocks surrounding the light source in regards to whether the glitch appears or not.

Devon Collins-Wrenn 2013-03-21T23:55:54Z

when it's a corner like that, light will always pour in... just saying

Carl Lystad 2013-03-22T00:18:43Z

@Devon: Um, since when? And which picture are you referring to?

Daniel "Glampkoo" 2013-03-22T00:36:17Z

Confirmed.
http://i.imgur.com/SY83XWe.png
http://i.imgur.com/0rEZhz8.png

Carl Lystad 2013-04-18T20:16:17Z

Still present in 13w16a. Issue updated to reflect this.

38 more comments

Chris Koehler 2013-05-26T03:28:55Z

I am pretty sure this has happened since at least the update Maximum smooth lighting was added in.

Ezekiel 2014-01-14T17:41:21Z

Is this still a concern in the current Minecraft version 1.7.4 / Launcher version 1.3.8 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Chris Koehler 2014-01-14T20:28:42Z

@Ezekiel

This is still an issue with those versions, and in 14w02c it is even more of an issue. (I have not tested the other two snapshots)

Itouch2 2014-03-16T18:07:11Z

Confirmed for 1.7.5 and 14w11b

A Full Name 2014-04-05T22:48:53Z

I'm having a similar problem, but in a slightly different situation. If I'm inside a building with stone walls and a roof made of slabs, and no light sources inside, there is a little bit of light at the top of each wall. The slab roof covers the walls, so there is no "crack" for light to seep in through.
This only happens when the roof is made of slabs and only with Smooth Lighting turned on.
It still happens if I extend the walls upwards.
But it doesn't happen if I replace slabs near the edges with stone blocks.
Cross sectional view:
1234567 (roof)
#_____# (walls and empty space)
If blocks 2 and 6 are slabs, light leaks in. If they are stone blocks, light does not leak. The other numbered blocks don't matter; they can be either slabs or full blocks. Blocks 1 and 7 can even be air without changing the result.

fienxjox 2014-07-29T20:46:19Z

Is this still a concern in the current Minecraft version 14w30c or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

wobst.michael 2014-07-29T21:11:11Z

Still an issue in 14w30c. Could reproduce it.

marcono1234 2015-06-17T15:54:11Z

Confirmed for

1.8.7 Has also a strange effect on piston heads (see screenshot)

Example command

/summon MinecartCommandBlock ~ ~1 ~ {Command:/setblock ~ ~-4 ~ redstone_block,Riding:{id:MinecartCommandBlock,Command:"/execute @p ~ ~ ~ /setblock ~-1 ~3 ~1 air",Riding:{id:MinecartCommandBlock,Command:"/execute @p ~ ~ ~ /setblock ~-1 ~2 ~1 stone
",Riding:{id:MinecartCommandBlock,Command:"/execute @p ~ ~ ~ /setblock ~1 ~1 ~1 redstone_block
",Riding:{id:MinecartCommandBlock,Command:"/execute @p ~ ~ ~ /setblock ~1 ~2 ~1 piston 4
",Riding:{id:MinecartCommandBlock,Command:"/tp @p ~ ~ ~ 0 0
",Riding:{id:MinecartCommandBlock,Command:"/execute @p ~ ~ ~ /fill ~-2 ~-1 ~-2 ~2 ~3 ~2 stone 0 hollow
",Riding:{id:MinecartCommandBlock,Command:"/tp @p ~ ~15 ~
",Riding:{id:MinecartCommandBlock,Riding:{id:FallingSand,Time:1,Block:activator_rail,Riding:{id:FallingSand,Time:1,Block:redstone_block,Riding:{id:FallingSand,Time:1,Block:stone,Riding:{id:FallingSand,Time:1,Block:command_block,TileEntityData:{Command:/fill ~ ~-2 ~ ~ ~3 ~ air},Riding:{id:FallingSand,Time:1,Block:stone,Riding:{id:FallingSand,Time:1,Block:command_block,TileEntityData:{Command:/kill @e[type=MinecartCommandBlock,dy=6]}}}}}}}}}}}}}}}}

bob 2016-11-06T01:06:01Z

Is this still an issue in the latest snapshot 16w44a?

JUE13 2017-06-06T05:54:34Z

Confirmed for 1.12-pre7

Jackietheboy d 2018-06-07T18:31:22Z

May or may not be a different problem, but I've noticed light completely passing through corners of opaque blocks. The area I'm in in NotDark.png and NotDark2.png has no light sources, and the grass/dirt is right next to open daylight, so the daylight is bleeding in. On 1.13-pre1, macOS.

kumasasa 2018-06-08T10:45:24Z

@unknown, this is MC-129725