[MC-9523] Powered pistons require block update to extend if ability to extend becomes available Created: 10/Feb/13  Updated: 18/Dec/20  Resolved: 10/Feb/13

Status: Resolved
Project: Minecraft: Java Edition
Component/s: None
Affects Version/s: Snapshot 13w06a
Fix Version/s: None

Type: Bug
Reporter: Ian Assignee: Unassigned
Resolution: Works As Intended Votes: 0
Labels: block, piston, redstone
Environment:

Windows 7 64 bit, java 6


Attachments: File 13w06aPistonBug.rar     PNG File 2013-02-09_19.23.25.png    
Issue Links:
Duplicate
is duplicated by MC-11732 Pistons don't push if given a signal ... Resolved
is duplicated by MC-11856 Redstone block and piston issues Resolved
is duplicated by MC-69855 Pistons don't extend when they should Resolved
is duplicated by MC-146523 Powered pistons will not recognize an... Resolved
is duplicated by MC-163680 Pistons don't extend when a block is ... Resolved
is duplicated by MC-197920 Piston does not respond after destroy... Resolved
CHK:
Confirmation Status: Confirmed

 Description   

Pistons that are powered and cannot push forward (because of the amount of blocks in front of the piston or because another piston is pushing the opposite direction) do not extend when they gain the ability to push forward (when the number of blocks is less than the maximum allowed or the opposing piston attracts). These bugged pistons will then extend if any block update is made (placing/removing blocks, extension of an adjacent piston, etc.).

See the attached world file. In the example, there are two sets of pistons: one with two pistons pushing against each other in opposite directions with 1 space between them, and one with 3 blocks between them. If you remove the power from the extended piston in the first set, the powered piston on the other side will extend (because the retraction of the first piston updates the second piston).
In the next example, where there are blocks between the two pistons, the first piston's retraction does not update the second piston and thus the second piston does not retract regardless of it being powered.



 Comments   
Comment by Matthew Wiltzius [ 14/Mar/13 ]

Quite. Not only that, but if checking for updates was really the problem, then it would have lagged back when it worked - which it has since the piston was introduced.

Comment by Ian [ 14/Mar/13 ]

Agreed with Joris. I used to use that timer, and then had to modify it to make it work correctly (the old timer didn't make it lag any more than it does now, so I believe it is bug-related rather than technicality-related).

Comment by Joris Molnar [ 14/Mar/13 ]

But that does not really make sense. In this (http://youtu.be/bYwzd62cLSw) video by Etho, he shows a hopper timer build in one of the first 1.5 Snapshots. If you build it now in the 1.5 Release, it doesn't work anymore because of this bug.

Comment by Anon Ymus [ 10/Feb/13 ]

This is for technical reasons. If pistons had to constantly check (when they had power) if they could extend, there would be an enormous amount of lag. This is the reason for the block update system. If a block's updates had were carried by adjacent blocks, every removal or placement of block would update the entire world, causing the same lag issues.

Comment by Anon Ymus [ 10/Feb/13 ]

Confirmed.

Generated at Sun Jan 12 12:21:20 UTC 2025 using Jira 9.12.2#9120002-sha1:301bf498dd45d800842af0b84230f1bb58606c13.