[MC-8911] Able to get pulse through a comparator by right clicking Created: 01/Feb/13  Updated: 27/Oct/23

Status: Reopened
Project: Minecraft: Java Edition
Component/s: None
Affects Version/s: Snapshot 13w05b, Minecraft 1.8.8, Minecraft 15w42a, Minecraft 15w44b, Minecraft 15w47a, Minecraft 1.10.2, Minecraft 16w42a, Minecraft 1.12, Minecraft 1.12.2, Minecraft 18w20c, Minecraft 1.13-pre3, Minecraft 1.13-pre6, Minecraft 1.13-pre7, 1.16.5, 1.17 Pre-release 1, 1.17, 1.17.1, 1.19.3
Fix Version/s: None

Type: Bug
Reporter: George Gates Assignee: Unassigned
Resolution: Unresolved Votes: 9
Labels: redstone

Attachments: PNG File 2013-02-01_09.51.21.png     JPEG File screenshot-1.jpg     JPEG File screenshot-2.jpg    
Issue Links:
Relates
relates to MC-11611 Comparators don't activate in some ca... Reopened
CHK:
Confirmation Status: Confirmed
Category:
Redstone
Mojang Priority: Low
Area: Platform

 Description   

I had a one tick clock going and the comparators weren't allowing a pulse to go through (which could be a bug itself), but when I repeatedly right clicked the comparator, I was able to get the pulse through as you can see in the screenshot.


Code analysis by Schortan can be found in this comment.



 Comments   
Comment by Bombsan [ 06/Feb/23 ]

Can confirm for 1.19.3

Comment by [Mod] ampolive [ 08/Jul/21 ]

Can confirm in 1.17.1.

Comment by George Gates [ 01/Jun/21 ]

Still an issue in 1.17-pre2.

Comment by [Mod] violine1101 [ 28/May/21 ]

See also https://www.reddit.com/r/Mojira/comments/nmrthk/mc8911_is_still_an_issue_in_1165_and_117pre1/

Comment by George Gates [ 28/May/21 ]

Still an issue in both 1.16.15 and 1.17-pre1.

Comment by [Bot] Arisa [ 09/Feb/21 ]

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Comment by Oval [ 26/Oct/18 ]

Is this still an issue in 1.13.2 or the latest snapshot 18w43c?

Comment by [Mod] NeunEinser [ 23/Jun/18 ]

Can confirm for 1.13-pre3

Comment by [Mod] NeunEinser [ 06/Oct/17 ]

Please link this in the description.

This issue happens because in net.minecraft.block.BlockRedstoneComparator.onBlockActivated(World, BlockPos, IBlockState, EntityPlayer, EnumHand, EnumFacing, float, float, float) the method onStateChange which checks if the comparator should be powered is called right away. Since the redstone signal stays on for 2 game ticks, there is basically a 25% chance that the player happens to activate the comparator in the 1st game tick of the signal being turned on.
This can be prevented by adding a check if there is an update scheduled before executing onStateChange. That will ensure that the repeater will not let a signal through in between the ticks.

//...
if(!worldIn.isUpdateScheduled(pos, this))
	onStateChange(worldIn, pos, state);
Comment by [Mod] NeunEinser [ 23/Jul/17 ]

Can confirm for 1.12

Comment by Kumasasa [ 22/Oct/16 ]

Is this still an issue in the most recent versions (currently that is 1.10.2, or 16w42a) of Minecraft? If so, please update the affected versions and help us keeping this ticket updated from time to time.

Comment by Kumasasa [ 01/Nov/15 ]

rydian: Since you are the reporter of this ticket, you can update the affected versions by yourself.

Comment by George Gates [ 01/Nov/15 ]

Still happening in 15w44b.

Comment by [Mod] redstonehelper [ 14/Oct/15 ]

Reopened and gave the ticket to rydian.

Comment by George Gates [ 14/Oct/15 ]

Okay so it's still happening all the way in 15w42a, and here's a gfy of the setup and results.

http://gfycat.com/FrayedShadowyAustralianfurseal

Comment by George Gates [ 05/Mar/13 ]

This second screenshot shows the piston responding when I right-click the second comparator, though it usually takes a few clicks to get it to happen. It pulses really quickly so this is the best shot I got, but as you can see it did allow the signal through in 13w10a.

Comment by George Gates [ 05/Mar/13 ]

This is a shot of a test device, a very simple redstone clock using a comparator in subtract mode feeding itself.

Comment by Tails [ 04/Mar/13 ]

Unable to reproduce.

Comment by George Gates [ 15/Feb/13 ]

I was able to semi-confirm this on 13w07a, in that if a comparator is being fed a one-tick rapid pulse, it will not allow it through until it gets updated. Some designs update the comparator and so allow the signal through, while others do not and the comparator needs a block/redstone update to start letting the signal out.

Ones that worked had the comparator near other equipment that would update at the time, non-working designs (ones that needed an update) tended to have the comparator a few blocks away from the equipment sending the signal.

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