[MC-209558] Biome borders on client are inconsistent

When connecting to a server, the biome borders (in the overworld) are not constant across all y-levels, unlike in a client/singleplayer world. This is easiest to observe when using the Biome Border Viewer mod, but can also be observed using the F3 screen.

Tested by comparing a client world and a server world with the same seed, the client world's biome borders were constant across all y-levels, while the biome borders when connecting to the server varied with the y-level.

https://github.com/mrp-v2/BiomeBorderViewer/issues/2 is the source of this issue.

Attached Images (taken using the referenced mod above):

world seed: 7031511839578461877

location of camera: -258.5, 73, 0.0 (-145, -17.5)

observe the smooth borders on the client world, compared with the rough borders on the server world.

Images taken without mod:

The ones with the default skin are taken on a dedicated server, the other ones were taken on a client world. Notice that on the server, moving up/down by a block changes the biome, unlike on the client world.

Linked issues

is duplicated by 4

MC-221910 Server sends incorrect biome data to the client Resolved

MC-222816 Ocean biomes over mushroom island biomes Resolved

MC-240717 Hostile mobs spawning within a mushroom biome Resolved

MC-240850 Servers Reporting Wrong Y Axis Biome Resolved

relates to 2

MC-239446 Vertical biome smoothing causes surface biomes to appear 3D in some cases Open

MC-173878 Biome changes with height at some decimals Resolved

Attachments

Minecraft 20w51a - Multiplayer (LAN) 2020-12-31 17-21-59.mp4

Comments 15

Avoma 2020-12-26T10:34:03Z

This report is invalid as your game was modified when experiencing this issue. Just to inform you, the bug tracker only handles issues that occur in Vanilla Minecraft so if this issue persists without the use of modifications, feel free to create a new report.

Matthew Partington 2020-12-26T12:59:35Z

This issue was observed on a vanilla server and also verified using a vanilla client. I only used a modded client because it is easier to see the biome borders using modded than by using the F3 screen. However, I will add screenshots from vanilla in a bit to prove it.

Avoma 2020-12-27T12:07:47Z

Possible duplicate of MC-173878 in that case.

Matthew Partington 2020-12-27T17:59:34Z

MC-173878 may be related, but I don't think it is a duplicate issue. It describes an intended behavior that can be observed on both clients and servers. This issue, however, represents a discrepancy between server and client behavior.

violine1101 2020-12-31T16:23:54Z

Easy way to reproduce: Go to the border of a swamp biome as a guest in a LAN world and fall from world height to the ground while looking at the biome in F3. You'll see that it'll constantly change. Now place a pillar of oak leaves there. Notice that they all have the same color.

[media]

5 more comments

Matt H 2021-02-20T23:13:13Z

I came across the same issue, I thought it might be to do with the fact that I had joined a paper server, so I tried it again on another regular server and the same inconsistent biomes appeared, I don't know really what's causing it but as violine1101 pointed out, the leaves don't change even though the biomes on F3 do, I can only speculate but it's possible that the client is viewing these 3 dimensional biome borders while the server actually still sees the regular 2D borders that you would see on a single player world, I have only tried observing this issue in version 1.16.4, I have been looking around for answers for about an hour and have found nothing helpful, so this is all I have come up with. I believe someone mensioned in a similar thread that the biomes in the nether changed depending on the Y level, if you go to the nether in a single player world using a mod to visualise biome borders, the same inconsistent borders are visible and while they roughly outline the different biomes and how they are seperated, they are still blocky like the ones you get on the server, perhaps it is a bug confusing biome mechanics with the ones in the nether? I don't really know what is causing these problems but I would really like this to be fixed because some mob farms depend on specific biomes to be efficient and right now it is getting difficult to build them on my server.

Roscoe Patnode 2021-04-19T04:04:06Z

After testing this I found that at y=0 the borders match the client exactly, if you want I could provide screenshots using the borders mod.

Brevort 2021-05-05T13:02:51Z

Would this cause a single double tall grass to be two different colours on a server, but not in singleplayer?

Zuccy Succy 2021-11-18T22:27:07Z

can confirm this is the case on 1.17.1

Moesh 2022-03-02T08:08:24Z

Is this still an issue in 1.18.2 or newer?

SmashPortal 2022-03-02T18:30:20Z

Confirmed for 1.18.2

ampolive 2022-03-02T21:28:44Z

This seems related to MC-239446.

user-f2760 2022-03-02T23:43:36Z

It's the exact same root issue, actually.

Cries 2022-11-21T20:14:50Z

I've noticed monsters spawning on mushroom biomes and MiniHUD showed ocean biomes are often created above mushroom biomes, especially around the edges of the mooshroom island. I suspect this bug report is related.

[media]

ampolive 2022-11-21T20:57:37Z

@unknown That is MC-93271.