Athelstan

Many servers have plugins that allow clients from multiple versions to access them. I do not know the inner mechanics behind this particular server, but it seems to me that they use these sorts of plugins as well, so even though the server is on 1.18.1, I can access it with a 1.17.1 client.

I took the snowy plains screenshot while playing on a 1.18.1 server with a 1.17.1 client. As the screenshot shows, the client displays snow on certain blocks and rain on other blocks, although it is snowing on all of these blocks according to the server.

Confirmed for 1.18.1.

Something I noticed about 1.18 is that, according to my experimentation, it fixes the root cause of MC-209558, since client biomes now seem to match server biomes. I believe this because in a newly generated chunk in a 1.18 server, I found a badlands hoodoo with stone in it. When I investigated, I found that the stone corresponded with a river biome while the terracotta corresponded with the badlands.

However, because of this vertical biome smoothing bug, the effect of MC-209558 (biomes changing by y-level) still persists, except that this is present both client-side and server-side.

If this bug is fixed in a future version and I upgrade a world from 1.18 to that future version, will the vertically changing biomes still be in the world? I'm thinking they won't be, since the biome blending is applied after loading, but I just want to make sure before starting any long-term 1.18 worlds.

This still occurs in 1.18-rc4.

Also, I believe the large biomes setting makes this bug more severe. I was playing in a large biomes world and noticed that between a taiga biome and a river biome, there was an 8-block wide zone and an 11-block wide zone in which going up or down switched the biome between taiga or river.

I haven't done much testing, so I don't know for certain that large biomes intensifies the bug, but I believe it does because I don't remember seeing such large transition zones in default worlds. In default worlds, these zones where moving vertically changes the biome seem to be only a few blocks wide, though it is possible they are wider and I just didn't notice.

Oh ok, thanks for clarifying!

Unrelated, but I can confirm that this issue still occurs in 1.18-rc3.

Dhranios thanks for the helpful info!

I am a bit confused, though. When I first found out about this bug, I tried to reproduce it in a 1.17.1 singleplayer world, but I was not able to. How rare was this bug pre-1.18?

Great visual analysis! It puts the issue into perspective very well.

This issue still occurs in 1.18 Pre-Release 8. The player can reliably reproduce it by going to a border between two biomes, opening the F3 screen, and flying up or digging down.

This issue still occurs in 1.18 Pre-Release 7. In the screenshot I attached to this report, I stacked two jungle leaf blocks on top of each other. The bottom block is in a beach biome and the top block is in a taiga biome.

I can confirm that this still occurs in 1.18 Pre-Release 5.

I believe this bug was resolved incorrectly. It was marked as "works as intended" on the basis that this behavior is intended for Nether biomes.

However, although the screenshots are from the Nether, the bug report itself does not specify the Nether and applies to all dimensions, which is supported by the fact that MC-209700 and MC-238804, both of which concern Overworld biomes, were marked as duplicates of this issue.

According to its patch notes, 21w40a removed non-cave biomes changing by height (the snapshot mostly resolved the issue, but biomes still change by height along their edges as of 1.18 Pre-Release 4). The fact that 21w40a tried to remove this implies that this is unintended for Overworld biomes and thus this feature does not work as intended.

No problem, I'm glad I could help! 🙂

Apologies for not responding to your questions. I had forgotten about this bug.

I feel that this bug may have been resolved incorrectly. I looked at MC-173878 and I noticed that the issue mainly pertains to Nether biomes. You clarified here that the bug applies to both the Overworld and the Nether, but since the issue uses pictures of Nether biomes, the moderator who marked it as "works as intended" probably assumed it was referring specifically to Nether biomes.

Additionally, while the Nether's biome behavior is not unique, the patch notes for 21w40a mentioning the removal of height-changing non-cave biomes leads me to believe that even with vertical biome blending, non-cave biomes are not supposed to change with height.

Just to clarify, this glitch happens in default worlds, too. I made this custom world so I could demonstrate it more easily.

This is intentional, since in wooded badlands, trees are only supposed to generate above a certain altitude.

I believe 21w40a fixed this. I tried to reproduce this bug with an old growth spruce taiga superflat and set the surface to stone so I would spawn on a grass block in a village. However, I didn't spawn in a village. When I repeated this but set the biome to taiga, I spawned in a village.