Minecraft
  1. Minecraft
  2. MC-7809

Aiming at the very bottom of a side of an upper slab/stair places slabs/stairs right-side up in multiplayer

    Details

    • Type: Bug Bug
    • Status: Resolved
    • Resolution: Fixed
    • Affects Version/s: Minecraft 1.4.7, Snapshot 13w03a, Minecraft 1.5, Snapshot 13w11a, Minecraft 1.5.1, Minecraft 1.6.4, Minecraft 13w42b, Minecraft 13w43a, Minecraft 1.7.1, Minecraft 1.7.2, Minecraft 1.8.1, Minecraft 1.8.3, Minecraft 1.8.4, Minecraft 1.8.5, Minecraft 1.8.6, Minecraft 1.8.7, Minecraft 1.8.8, Minecraft 15w44b, Minecraft 1.8.9, Minecraft 1.9.2, Minecraft 1.9.4, Minecraft 16w20a, Minecraft 1.10.2
    • Security Level: Minecraft - Public (Viewable by everyone)
    • Labels:
    • Confirmation Status:
      Confirmed

      Description

      Just place a slab of any kind on the upper side of a block many times, and you'll sometime get one that converts to being on the bottom side of a block.


      Description from MC-89850

      When placing top- or bottom aligned blocks like slabs and stairs server and client disagree about the alignment of placed blocks

      Doesn't happen in single player (or isn't visible), but on dedicated server or Realms.

      Steps to reproduce:

      • Place a block with a well defined center (e.g. stone bricks) at ca. eye level
      • Take a stair or slab
      • Aim slightly above the center of the block
      • Place block

      The results:

      • Client places the block at the correct top alignment
      • Server overwrites the block a split second later at incorrect bottom alignment

      Screenshots show before and after placement (the in-between position is quite difficult to capture)


      Code analysis by Panda in this comment.

        Issue Links

          Activity

          Hide
          [Mod] Kumasasa added a comment -

          This happens only in Multiplayer but is not lag dependant.

          Show
          [Mod] Kumasasa added a comment - This happens only in Multiplayer but is not lag dependant.
          Hide
          Panda added a comment -

          I came across this issue when looking into MC-4 and found that it basically has the same cause.

          When you place a block the packet CPacketPlayerTryUseItemOnBlock is sent to the server. It encodes the facing into bytes to transmit them which causes this inaccuracy.
          The packet is just send when the player right clicks on a block holding an item, so it probably isn't an issue to just change the transmission of these values to floats.

          It would probably be good to add this to the description

          Show
          Panda added a comment - I came across this issue when looking into MC-4 and found that it basically has the same cause. When you place a block the packet CPacketPlayerTryUseItemOnBlock is sent to the server. It encodes the facing into bytes to transmit them which causes this inaccuracy. The packet is just send when the player right clicks on a block holding an item, so it probably isn't an issue to just change the transmission of these values to floats. It would probably be good to add this to the description
          Hide
          Nope. added a comment -

          Wrongly marked. This is a duplicate of MC-8

          Show
          Nope. added a comment - Wrongly marked. This is a duplicate of MC-8
          Hide
          [Mod] Mustek added a comment -

          It is not, this contains more details.

          Show
          [Mod] Mustek added a comment - It is not, this contains more details.
          Hide
          [Helper] Pokechu22 added a comment -

          @Nope. MC-8 can be a duplicate of this report because this one was created with more details, details that allowed the devs to actually fix the issue. Just because MC-8 was created first doesn't mean it's the best dupe-target for similar issues.

          In some cases the content from the newer report will be moved to the older report if the fact that there is an older issue that is the same thing is found, but (especially if there are a lot of linked issues on the newer one and the older one is basically abandoned for 3 years) it won't usually be changed. It doesn't matter, anyways - the issue number is insignificant for most purposes. If having the smallest issue ID mattered, then one could just constantly replace old dupes with other unrelated issues - not necessary and generally a waste of time.

          Show
          [Helper] Pokechu22 added a comment - @ Nope. MC-8 can be a duplicate of this report because this one was created with more details, details that allowed the devs to actually fix the issue. Just because MC-8 was created first doesn't mean it's the best dupe-target for similar issues. In some cases the content from the newer report will be moved to the older report if the fact that there is an older issue that is the same thing is found, but (especially if there are a lot of linked issues on the newer one and the older one is basically abandoned for 3 years) it won't usually be changed. It doesn't matter, anyways - the issue number is insignificant for most purposes. If having the smallest issue ID mattered, then one could just constantly replace old dupes with other unrelated issues - not necessary and generally a waste of time.

            People

            • Assignee:
              [Mojang] Grum (Erik Broes)
              Reporter:
              Halgdp Halgdp
            • Votes:
              36 Vote for this issue
              Watchers:
              21 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved:
                CHK: