Water, Cobwebs, Magma, Leaves and other blocks save sunlight
This issue is about sunlight. For the related block light issue, see MC-102162.
The bug
Certain blocks "save" sunlight, emiting it even after the original source has been removed. This creates an annoying glowing spot and is very difficult to clean up given that the blocks are not obviously the source of the glowing (and that it can chain between multiple of them).
Affected blocks (may be incomplete)
- Water
- Leaves
- Cobweb
- Magma
- Lit redstone ore
- Lit furnace
- Powered redstone lamp
- Glowstone
- Sea lantern
- Jack-o-lantern
Reproduction
- Build a sealed room without any lights in it with a single layer between it and the sky.
- Place one of the effected blocks on the floor.
- Break the ceiling block above that block.
- Replace the ceiling block.
- Observe that the room remains lit, despite the lack of a light source.
Notes
In versions prior to 1.7.2ish, this also affected other blocks (for sure glowstone, lit redstone ore, lit furnaces, and jack 'o lanterns — mostly, blocks that exhibitthis issue returned for 1.11.2MC-102162but also similar blocks that emit full light). In 1.7.2 it was fixed for those blocks. Incidentally, 1.7.2 had a fix that removed an x-ray effect when inside of glowstone; it's possible that those are related.- Lava is not effected, despite also being a fluid.
- Water only finicky about being affected; if it's in a pit it doesn't get affected but if it's above the ground it is.
- This only happens when the block is in direct sunlight; if it's next to the sunlight but not exposed to the sun it doesn't seem to happen.
Demos
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b: https://youtu.be/bPUdssOvU78
Linked Issues
is duplicated by10
MC-13574Glowstone lighting issueDuplicateMC-22737When sky light is blocked it does not update below waterDuplicateMC-56362sunlight bug with some light emiting blocksDuplicateMC-77178Webs save light.DuplicateMC-110343Water saving sunlightDuplicateMC-111503Water blocks, under the right circumstances can create Sunlight.DuplicateMC-114780lighting errorDuplicateMC-120269Glowing Water 1.12.1DuplicateMC-124484Weird auto-lighting bugDuplicateMC-129147Sea Lanterns absorb natural sky light and retransmit it in certain casesDuplicaterelates to6
MC-102162Some light-emitting blocks (magma, lit furnace, lit redstone ore) 'save' block lightFixedMC-117067Trees/Leaves too bright under big platformFixedMC-13003Lighting Bug - I shut off light, the light shuts off, but there is still light. Check this picture.Awaiting ResponseMC-18526Light with no nearby light sources
NormalMC-77311Wrong light level through covered ice. FixedMC-119932Light-emitting solid blocks (lit furnaces, magma blocks, glowstone, lit redstone ore) let light (sunlight, block light) throughFixed- Fixed
Hinata![[Mojang] Georgii Gavrichev](../../../data/avatars/users/22428.png)
[Mojang] Georgii Gavrichev- 49
- 19
- Confirmed
- cobweb leaves light magma_block sky water
1.4.5 - 1.13.1
1.4.5 1.4.7 13w05b 1.5 13w11a 1.7.5 14w11b 14w21b 1.7.10 14w28a 14w28b 1.8 1.8.1-pre3 1.8.1 1.8.2-pre6 15w38b 15w47c 1.9-pre1 1.10 1.10.2 16w32a 16w32b 16w33a 16w35a 16w44a 1.11.2 17w06a 17w13a 17w13b 17w14a 17w15a 17w16a 17w17b 17w18a 17w18b 1.12-pre1 1.12-pre2 1.12-pre3 1.12-pre4 1.12-pre5 1.12-pre6 1.12-pre7 1.12 17w31a 1.12.1-pre1 1.12.1 1.12.2-pre1 1.12.2-pre2 1.12.2 17w43a 17w43b 17w45a 17w48a 17w50a 18w01a 18w03b 18w06a 18w09a 18w16a 1.13-pre1 1.13-pre3 1.13-pre10 1.13 18w30b 18w31a 1.13.1- 18w43a
Created Issue:
Cobweb 'saves' skylight
I was on Creative MP (Custom Map). I haven't fully tested this behavior, but when I place Cobweb and seal room, and seal celling located directly above Cobweb, Cobweb still remember 'light' value. It (apparently) removes when block update occurs.
Demonstration: http://youtu.be/8nTd1KbbrLA
Environment
OS: Windows XP Build 2600 Service Pack 3
- Unresolved
- Open
- Unconfirmed
- Creative
- Cobweb Light Sky
- 1.4.5
![[Mod] CubeTheThird](../../../data/assets/gravatar/cubethethird.jpeg){kind=small}
Cobweb 'saves' skylightGlowstone, Water, Cobweb 'save' skylight
is duplicated by
![[Mod] Torabi](../../../data/assets/gravatar/torabi.png){kind=small}
is duplicated by
Fixed in 14w31a
2014-08-02_12.08.56.png
is duplicated by
relates to
relates to
relates to
I was on Creative MP (Custom Map). I haven't fully tested this behavior, but when I place Cobweb and seal room, and seal celling located directly above Cobweb, Cobweb still remember 'light' value. It (apparently) removes when block update occurs.Demonstration: http://youtu.be/8nTd1KbbrLA
Make a room completely sealed off. Place a cobweb/glowstone/etc, and make a hole in the ceiling directly above the block. Seal the gap and the web is glowing with the skylight. Glowstones glow as usual, however, upon closer inspection using the debug key (F3), the glowstones hold/emit skylight, where they should only emit blocklight.
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b:
Make a room completely sealed off. Place a cobweb/glowstone/etc, and make a hole in the ceiling directly above the block. Seal the gap and the web is glowing with the skylight. Glowstones glow as usual, however, upon closer inspection using the debug key (F3), the glowstones hold/emit skylight, where they should only emit blocklight.
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b:
Make a room completely sealed off. Place a cobweb/glowstone/etc, and make a hole in the ceiling directly above the block. Seal the gap and the web is glowing with the skylight. Glowstones glow as usual, however, upon closer inspection using the debug key (F3), the glowstones hold/emit skylight, where they should only emit blocklight.
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b: https://youtu.be/bPUdssOvU78
relates to
Glowstone,Water, Cobweb 'save' skylight
is duplicated by
is duplicated by
![[Mod] Pokechu22](../../../data/avatars/users/92931.png){kind=small}
Make a room completely sealed off. Place a cobweb/glowstone/etc, and make a hole in the ceiling directly above the block. Seal the gap and the web is glowing with the skylight. Glowstones glow as usual, however, upon closer inspection using the debug key (F3), the glowstones hold/emit skylight, where they should only emit blocklight.
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b: https://youtu.be/bPUdssOvU78
NoteThis issue is about sunlight. For the related block light issue, see
MC-102162.The bug
Certain blocks "save" sunlight, emiting it even after the original source has been removed. This creates an annoying glowing spot and is very difficult to clean up given that the blocks are not obviously the source of the glowing (and that it can chain between multiple of them).
Affected blocks
The following blocks are effected. I did test all block IDs, so no other blocks should be effected, though it's possible that a subblock was missed.
- Water (minecraft:water)
- Leaves (minecraft:leaves and minecraft:leaves2)
- Cobweb (minecraft:web)
- Magma (minecraft:magma)
Reproduction
- Build a sealed room without any lights in it with a single layer between it and the sky.
- Place one of the effected blocks on the floor.
- Break the ceiling block above that block.
- Replace the ceiling block.
- Observe that the room remains lit, despite the lack of a light source.
Notes
- In versions prior to 1.7.2ish, this also affected other blocks (for sure glowstone, lit redstone ore, lit furnaces, and jack 'o lanterns — mostly, blocks that exhibit
MC-102162but also similar blocks that emit full light). In 1.7.2 it was fixed for those blocks. Incidentally, 1.7.2 had a fix that removed an x-ray effect when inside of glowstone; it's possible that those are related.- Lava is not effected, despite also being a fluid.
- Water only finicky about being affected; if it's in a pit it doesn't get affected but if it's above the ground it is.
- This only happens when the block is in direct sunlight; if it's next to the sunlight but not exposed to the sun it doesn't seem to happen.
Demos
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b: https://youtu.be/bPUdssOvU78
Water, Cobweb'save'skylightWater, Cobwebs, Magma blocks, and Leaves save sunlight
is duplicated by
NoteThis issue is about sunlight. For the related block light issue, see
MC-102162.The bug
Certain blocks "save" sunlight, emiting it even after the original source has been removed. This creates an annoying glowing spot and is very difficult to clean up given that the blocks are not obviously the source of the glowing (and that it can chain between multiple of them).
Affected blocks
The following blocks are effected. I did test all block IDs, so no other blocks should be effected, though it's possible that a subblock was missed.
Water(minecraft:water)- Leaves (minecraft:leaves and
minecraft:leaves2)Cobweb(minecraft:web)- Magma (minecraft:magma)
Reproduction
- Build a sealed room without any lights in it with a single layer between it and the sky.
- Place one of the effected blocks on the floor.
- Break the ceiling block above that block.
- Replace the ceiling block.
- Observe that the room remains lit, despite the lack of a light source.
Notes
- In versions prior to 1.7.2ish, this also affected other blocks (for sure glowstone, lit redstone ore, lit furnaces, and jack 'o lanterns — mostly, blocks that exhibit
MC-102162but also similar blocks that emit full light). In 1.7.2 it was fixed for those blocks. Incidentally, 1.7.2 had a fix that removed an x-ray effect when inside of glowstone; it's possible that those are related.- Lava is not effected, despite also being a fluid.
- Water only finicky about being affected; if it's in a pit it doesn't get affected but if it's above the ground it is.
- This only happens when the block is in direct sunlight; if it's next to the sunlight but not exposed to the sun it doesn't seem to happen.
Demos
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b: https://youtu.be/bPUdssOvU78
NoteThis issue is about sunlight. For the related block light issue, see
MC-102162.The bug
Certain blocks "save" sunlight, emiting it even after the original source has been removed. This creates an annoying glowing spot and is very difficult to clean up given that the blocks are not obviously the source of the glowing (and that it can chain between multiple of them).
Affected blocks (may be incomplete)
- Water
- Leaves (minecraft:leaves and minecraft:leaves2)
- Cobweb (minecraft:web)
- Magma
- Lit redstone ore (minecraft:lit_redstone_ore)
- Lit furnace (minecraft:lit_furnace)
- Powered redstone lamp (minecraft:lit_redstone_lamp)
- Glowstone
- Sea lantern
- Jack-o-lantern (minecraft:lit_pumpkin)
Reproduction
- Build a sealed room without any lights in it with a single layer between it and the sky.
- Place one of the effected blocks on the floor.
- Break the ceiling block above that block.
- Replace the ceiling block.
- Observe that the room remains lit, despite the lack of a light source.
Notes
In versions prior to 1.7.2ish, this also affected other blocks (for sure glowstone, lit redstone ore, lit furnaces, and jack 'o lanterns — mostly, blocks that exhibitthis issue returned for 1.11.2MC-102162but also similar blocks that emit full light). In 1.7.2 it was fixed for those blocks. Incidentally, 1.7.2 had a fix that removed an x-ray effect when inside of glowstone; it's possible that those are related.- Lava is not effected, despite also being a fluid.
- Water only finicky about being affected; if it's in a pit it doesn't get affected but if it's above the ground it is.
- This only happens when the block is in direct sunlight; if it's next to the sunlight but not exposed to the sun it doesn't seem to happen.
Demos
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b: https://youtu.be/bPUdssOvU78
Water, Cobwebs, Magmablocks, and Leaves save sunlightWater, Cobwebs, Magma, Leaves and other blocks save sunlight
relates to
![[Mod] Neko](../../../data/avatars/users/92901.png){kind=small}
is duplicated by
![[Mod] Michael Wobst](../../../data/avatars/users/37868.png){kind=small}
OS: Windows XP Build 2600 Service Pack 3
is duplicated by
Okay i think its not time to fix cuz glowstone is a half transparent block
NoteThis issue is about sunlight. For the related block light issue, see
MC-102162.The bug
Certain blocks "save" sunlight, emiting it even after the original source has been removed. This creates an annoying glowing spot and is very difficult to clean up given that the blocks are not obviously the source of the glowing (and that it can chain between multiple of them).
Affected blocks (may be incomplete)
- Water
- Leaves (minecraft:leaves and minecraft:leaves2)
- Cobweb (minecraft:web)
- Magma
- Lit redstone ore (minecraft:lit_redstone_ore)
- Lit furnace (minecraft:lit_furnace)
- Powered redstone lamp (minecraft:lit_redstone_lamp)
- Glowstone
- Sea lantern
- Jack-o-lantern (minecraft:lit_pumpkin)
Reproduction
- Build a sealed room without any lights in it with a single layer between it and the sky.
- Place one of the effected blocks on the floor.
- Break the ceiling block above that block.
- Replace the ceiling block.
- Observe that the room remains lit, despite the lack of a light source.
Notes
In versions prior to 1.7.2ish, this also affected other blocks (for sure glowstone, lit redstone ore, lit furnaces, and jack 'o lanterns — mostly, blocks that exhibitthis issue returned for 1.11.2MC-102162but also similar blocks that emit full light). In 1.7.2 it was fixed for those blocks. Incidentally, 1.7.2 had a fix that removed an x-ray effect when inside of glowstone; it's possible that those are related.- Lava is not effected, despite also being a fluid.
- Water only finicky about being affected; if it's in a pit it doesn't get affected but if it's above the ground it is.
- This only happens when the block is in direct sunlight; if it's next to the sunlight but not exposed to the sun it doesn't seem to happen.
Demos
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b: https://youtu.be/bPUdssOvU78
NoteThis issue is about sunlight. For the related block light issue, see
MC-102162.The bug
Certain blocks "save" sunlight, emiting it even after the original source has been removed. This creates an annoying glowing spot and is very difficult to clean up given that the blocks are not obviously the source of the glowing (and that it can chain between multiple of them).
Affected blocks (may be incomplete)
- Water
- Leaves
- Cobweb
- Magma
- Lit redstone ore
- Lit furnace
- Powered redstone lamp
- Glowstone
- Sea lantern
- Jack-o-lantern
Reproduction
- Build a sealed room without any lights in it with a single layer between it and the sky.
- Place one of the effected blocks on the floor.
- Break the ceiling block above that block.
- Replace the ceiling block.
- Observe that the room remains lit, despite the lack of a light source.
Notes
In versions prior to 1.7.2ish, this also affected other blocks (for sure glowstone, lit redstone ore, lit furnaces, and jack 'o lanterns — mostly, blocks that exhibitthis issue returned for 1.11.2MC-102162but also similar blocks that emit full light). In 1.7.2 it was fixed for those blocks. Incidentally, 1.7.2 had a fix that removed an x-ray effect when inside of glowstone; it's possible that those are related.- Lava is not effected, despite also being a fluid.
- Water only finicky about being affected; if it's in a pit it doesn't get affected but if it's above the ground it is.
- This only happens when the block is in direct sunlight; if it's next to the sunlight but not exposed to the sun it doesn't seem to happen.
Demos
Demonstration from the Minecraft version 1.4.5 : http://youtu.be/8nTd1KbbrLA
EDIT SEPT 19 2015: Demonstration from the Minecraft version 15w38b: https://youtu.be/bPUdssOvU78
![[Mod] tryashtar](../../../data/avatars/users/41963.png){kind=small}
is duplicated by
[Mojang] Georgii GavrichevDupe of/relates to MC-3961.
Dupe of/relates to MC-3961.
This issue is about block light. For the related sunlight issue, see MC-3961.
The bug
Certain blocks "save" block light, emiting it even after the original source has been removed.
Affected blocks
- Lit furnace
- Lit redstone ore
- Magma
Reproduction
- Build a sealed room without any lights in it with a single layer between it and the sky.
- Use /setblock to create one of the effected blocks.
- Measure the value of block light using.
- Put a glowstone block right next to the effected block.
- Break the glowstone.
- Observe that the lighting value (as seen in F3) has changed.
Notes
- All of the affected blocks are full cubes that emit less than 14 block light. (Non-full-cube blocks such as brown mushrooms (1 light) are not affected, and the effect isn't observable for bright blocks)
- The resultant light is 2 less than the light value of the block you placed next to it, which is 13 if glowstone is used. This is because the block receives (and thus emits) the light level - 1, and then another - 1 occurs due to going back to you.
- This behavior randomly decays
- This behavior when using magma blocks is fairly popular for builds (as it is nice for decorations). If removed, it may be beneficial to introduce a similar behavior within the block's state and use an upgrade path to store the current light.
Can confirm. I also wanted to add that, since this occurs with sky light as well, I wonder if it might be related to this old bug: MC-3961
Just to help point the devs on a possible bug-hunting path...
@Irritated Gamer Yes, the linked MC-3961: "Water, Cobweb 'save' skylight".
Thank you for your report!
However, this issue has been closed as a Duplicate of MC-3961.
It has been linked to this report. If you have additional information, please add it to that report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki
![[Mod] bemoty](../../../data/avatars/users/50554.png){kind=small}
Duplicate of MC-3961
The code-accurate description of the issue is that light-emitting blocks let light through, even if they're solid and their light level is much less than the light they're letting through.
MC-102162 is just a side-effect of the lighting update code not handling light-emitting blocks which emit less light than their in-world value. In other words, MC-102162 is caused by this issue.
Fixing MC-102162 doesn't fix this issue. On the other hand, fixing this issue would hide (but not technically fix) MC-102162.
The same applies to sunlight, as both sunlight and block light share most of the update code (NB: sunlight code also includes direct downwards propagation, which is the part that does not suffer from this issue - the solid blocks listed in this issue stop downwards propagation - however see MC-3961). The part that is shared uses a simple value to control which lightmap to access.
The relevant code lines that cause the issue are
IBlockState iblockstate1 = this.getBlockState(pos); int blockLight = iblockstate1.getBlock().getLightValue(iblockstate1, this, pos); int j2 = lightType == EnumSkyBlock.SKY ? 0 : blockLight; int k2 = iblockstate1.getBlock().getLightOpacity(iblockstate1, this, pos); if (k2 >= 15 && blockLight > 0) { k2 = 1; }
inside World.getRawLight(...). The opacity for solid light sources is set to 1 (for whatever reason...).
However, MC-3961 is mainly caused by an unrelated issue. See MC-117067 for a detailed description and solution.
Thank you for your report!
However, this issue has been closed as a Duplicate of MC-3961.
It has been linked to this report. If you have additional information, please add it to the duplicated report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki
Can confirm.
Confirmed
Is this still a concern in the latest Minecraft version 14w04b? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
can confirm for 14w21b
I can also confirm for 14w21b. Additionally powered redstone blocks act as transparent and exhibit this behavior. It seems that transparent blocks often do not update their light level, thus preserving previous sky light levels.
I've had this same problem with stained glass but am having trouble duplicating it.
this is still a problem in 1.7.10 and 14w28b
EDIT: wait no, I was wrong
Bug still confirmed in 15w38b. It's been 3 years, maybe it's time to fix it, Mojang?
Confirmed in 15w47c. It interferes with the operation of daylight sensors, which think the "saved" light from glowstone, etc. are daylight and emit a signal where there should be none. It's also difficult to fix once it occurs, because the "sky light" emitting from one block of glowstone will be "saved" as "sky light" in nearby blocks, so they must all be broken before you can replace them or else it'll still think there's skylight around.
Confirmed for 1.9-pre1, although glowstone doesn't seem to be affected anymore. It still occurs with water and cobwebs.
Please mark both videos (https://youtu.be/bPUdssOvU78 and http://youtu.be/8nTd1KbbrLA) as either public or hidden, if it's private, we can't watch them.
Confirmed for 1.10, glowstone not affected. You can see the result with cobweb on this video : https://youtu.be/fZa-kKz-K3E
What i think is that when the ceiling is sealed, all the air blocks's light level underneath are updated but they omit other blocks (for optimisation purpose) so cobweb is not updated except if you place the block just above it (for glass and other stuff it works though)
F3 confirms that the light is skylight, not block light
Confirmed for 1.12.1
Carson He, 1.12.1 has already been marked as affected.
Redstone ore is supposed to do this, according to Minecraft.net here. However, this may be wrong, because I doubt the author would know definitively what the desired behavior should be here.
No, it's a bug and the blog author was already notified.