[MC-1836] Mobs glitch through half slabs and unsync between server and client Created: 02/Nov/12  Updated: 01/Jun/17  Resolved: 21/Nov/12

Status: Resolved
Project: Minecraft: Java Edition
Component/s: None
Affects Version/s: Minecraft 1.4.2, Minecraft 1.4.3
Fix Version/s: None

Type: Bug
Reporter: Fabio Oliveira Schmidt Capela Assignee: Unassigned
Resolution: Duplicate Votes: 1
Labels: None
Environment:

Windows 7, Java 1.7.0_05


Attachments: File Half Slab Mob Glitch.7z    
Issue Links:
Duplicate
duplicates MC-119 Mobs visually sinking through solid b... Resolved
Relates
relates to MC-73302 Block collision box issues (mobs glit... Resolved
CHK:
Confirmation Status: Unconfirmed
Game Mode: Survival

 Description   

Mobs sometimes glitch when walking across a floor made of half slabs without anything under it. I've directly seen two results, and believe there is a third one:

  • More commonly, a "ghost" of the mob drops through the half slab floor; it can't be attacked or interacted with in any way. It sometimes makes yo-yo movements and after a time jumps to where he fell from. Appears to happen when the mob glitches only on the client.
  • Less commonly, the mob really drops through the floor.
  • I believe sometimes the glitch happens only server-side; I've been hounded by invisible skeletons under my mob grinder completely made of half-slabs. Not sure, though, because I obviously can't see the invisible skeletons falling through the floor.

Saw all the above problems in Survival, in a heavily modded game, when I made a mob grinder almost entirely out of half slabs in a Skyblock-like map in order to save materials; reproduced the ghost mobs issue on Creative, in both Vanilla 1.4.2 and the 1.4.3 pre-release. The other issues are way rarer.

The attached file is a creative world with a copy of my mob grinder entirely made of half slabs; I typically see a few ghost mobs in less than a minute after loading that world.



 Comments   
Comment by Tails [ 19/Nov/12 ]

Duplicate of MC-119

Comment by Joël Fivat [ 02/Nov/12 ]

Confirmed, I saw a pigman into my nether base that was actually on the roof (half slabs).

Comment by Rickard Åberg [ 02/Nov/12 ]

Confirmed, I've seen this too.
Spiders tend to drop under the halfslabs making them hard to kill.

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