[MC-3667] Light-emitting blocks don't emit light while being moved by a piston, causing flickering

The bug

Upon pushing or pulling a light-emitting block (see below for affected blocks), the light flickers off while it is moving. This can cause performance issues due to excessive lighting updates, as well as just be undesirable in general.

How to reproduce

Construct the contraption shown in this video if testing redstone lamps, or the simple contraption shown in this screenshot if testing Shroomlights or any other blocks
Notice how the redstone lamp flickers every time it is pushed by the piston
Replace the redstone lamp with any other light-emitting block from the list below and notice how this same behaviour is present

Affected blocks

Redstone Lamp (lit)
Shroomlight
Sea Lantern
Glowstone
Redstone Ore (lit)
Magma Block

Original description

Using the setup in the screenshot, the lamp will flicker when the lever is pulled.

Glowstone sometimes exhibits this behavior.

Linked issues

duplicates 1

MC-123217 Moving blocks don't inherit behaviors of the block they hold Open

Attachments

Comments 18

CubeTheThird 2012-11-22T04:55:43Z

Can you post said screenshot?

FireHunterX 2012-11-22T05:18:55Z

Delivered.

Don't know what exactly happened, I uploaded it already.

Pixelgraph 2012-11-22T06:01:03Z

Also happens with glowstone.

FireHunterX 2012-11-22T14:23:37Z

Updated.

Anon Ymus 2012-11-22T15:01:00Z

Confirmed. The glowstone and the lamp don't appear to flicker, but you can see that the light flickers if you set the time to midnight.

8 more comments

Chalmes (Jon) 2012-11-22T20:27:08Z

Flickers on the way back down again right?

Anon Ymus 2012-11-22T20:41:04Z

Glowstone flickers both ways, redstone lamps flicker only down.

Chalmes (Jon) 2012-11-22T20:56:42Z

I can't get the glowstone lamp to flicker going up. I can see the bottom redstone lamp going on a few ticks before the glowstone lamp turns on, which makes it look a little inconsistent, but the glowstone lamp only flickers for me when coming back down.

FireHunterX 2012-12-03T13:24:25Z

Yes, it only works when being PULLED by a piston, not pushed.

shufboyardee 2013-02-14T16:20:32Z

In 13w07a, both these blocks flicker, and both when being pushed and pulled.

shufboyardee 2013-03-07T15:26:39Z

also in 1.5.

galaxy_2alex 2014-10-30T16:48:41Z

Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases. If this has been done, we can reopen the issue.

Keep in mind that the "Resolved"-Status on this ticket just means "Answered", and that we are waiting for further information on whether this issue still exists or not. We will reopen it as soon as the requested information has been deliviered.

Aaron Rhodes 2015-02-24T05:44:57Z

Happens in 1.8.3 and affects sea lanterns as well as glowstone and redstone lamps. It seems that it does not matter whether the piston pushes or pulls these blocks, the flicker happens either way. I tested this using each set up in the screen shot separately. Hopefully I'm not misunderstanding this issue.

michael 2015-03-17T10:58:02Z

While being moved by pistons, blocks do not emit light.

[Mod] markderickson 2020-09-16T12:57:03Z

Hi! I'd like to request ownership of this report.

SunCat 2020-09-16T13:03:43Z

The ticket is yours now

[Mod] markderickson 2020-09-16T13:06:16Z

Thanks!

SunCat 2020-09-30T19:35:53Z

merged with MC-123217