[MC-12122] Rail "shape" not updated when pushed by a piston Created: 16/Mar/13  Updated: 18/Mar/13  Resolved: 18/Mar/13

Status: Resolved
Project: Minecraft: Java Edition
Component/s: None
Affects Version/s: Minecraft 1.5
Fix Version/s: None

Type: Bug
Reporter: Nicolas BARBOTIN Assignee: Unassigned
Resolution: Works As Intended Votes: 0
Labels: circuit, rail, redstone
Environment:

Windows 7 x64, Java 7 (1.7.0_03-b05) x64


Attachments: PNG File 2013-03-16_20.15.16.png     PNG File 2013-03-16_20.15.25.png     PNG File 2013-03-16_20.15.31.png    
Confirmation Status: Unconfirmed

 Description   

Let's name the movable rail that can be pushed by piston A, a second swithing rail B, a stationary rail C, and the "source" rail, where the Minecart should come from D, placed like this:

|
WD
ABC

Where | is the piston, aiming the wall W.

An activated redstone torch is under B to link the rail D to C. If the torch is off, the rail B links the rail D to A. This works. Now, if the piston | pushes the wall W which pushes the rail A (when the torch under B is off) the rail B is still linking D to the wall.

What I was expecting is that when I turn the torch on, the rail B links rail C again. Instead, whatever I do, it's still linking the rail D to the wall.

This can be fixed by recomputing the rail's shape when the neighbor block changes (I tested).
Thanks, Nicolas.



 Comments   
Comment by Tails [ 18/Mar/13 ]

Switch the rail before extending the piston - problem solved.

Comment by user-571ee (Inactive) [ 18/Mar/13 ]

Can't reproduce. If I push the rail back and it forms a T shape again I can switch the junction (with a redstone signal).

What you have is a timing issue. Switch the junction first (with a redstone signal). Then push the rail away. Then do the same the other way around.

Everything works as intended. Re-computing the rails with every block update will break a lot of constructions. No bug here.

Comment by Nicolas BARBOTIN [ 17/Mar/13 ]

In this world I simplified the system to make it easyier to understand, but on my survival vanilla server, the piston moves the rail to hide it, and make a "secret passage"; when the "secret passage" is closed, the minecart goes from rail D to C, else from the rail D to A.

I know that the rails must be in a T shape to make the switch working, but even if I push the rail in the original position, and all the 4 rails A, B, C and D are making a T shape again, the switch rail B does not move. I'm sorry, it's hard to explain: I'm french, and here everything is in english.

Comment by user-571ee (Inactive) [ 17/Mar/13 ]

What's the reason for having a piston there? Why not simply power the rail at B with redstone?

What you show in the last picture is intended. It's not possible to switch a curved rail if it does not have three other rails connected. It must be a T shape to work.

Summary: Everything works as intended.

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