[MC-237621] Missing biome definitions in some peak grid cells causes unintended ocean placement

Background
In 1.18 the biomes are laid out in a 5d grid of noise values. Usually all grid cells are filed by one biome. However, if a grid cell is not filled, the world generation will pick the biome from the cell with the closest values.

The bug
For the combination of peak weirdness, coast continentalness, and erosions 0 to 3 there are no biomes defined. This causes the generation to sometimes pick ocean biomes (that are in the cells with lower continentalness) leading to them generating on land. These are the only grid cells that have no biome definitions.

Ingame effects
Here are some areas where oceans generate on land (sometimes very high up in the mountains) because of this bug. All of these positions are on seed 1 . (updated to 21w41a)

Ocean on land:

/execute in minecraft:overworld run tp @s -7100.73 103.11 63.60 20.70 49.80

[media]

Ocean on peak:

/execute in minecraft:overworld run tp @s 28441.72 153.99 -2198.79 -28.80 46.50

[media]

Linked issues

relates to 1

MCPE-149983 Seed parity: Bedrock cliff facades differ from the Java ones due to MC-237621 fix Resolved

Attachments

Minecraft 21w40a - Singleplayer 07_10_2021 23_30_24.png

Minecraft 21w40a - Singleplayer 07_10_2021 23_30_42.png

Minecraft 21w40a - Singleplayer 07_10_2021 23_31_31.png

Comments 9

syarumi 2021-09-25T06:46:22Z

Might be a duplicate of MC-237243, but this one has more info, so can confirm here.

Could this also be the cause of the weird generation of rivers (MC-236796)?

jacobsjo 2021-09-25T08:58:56Z

Oh, I must have missed MC-237243 during my search, sorry about that. At least some of the screenshots there are indeed caused by this (you can see in the F3 menu "Biome Builder PV: Peaks")

As for the rivers, they don't generate in the peaks, but the valleys - so MC-236796 should be unrelated.

ampolive 2021-10-08T23:45:35Z

Can confirm in 21w40a.

pbilk 2021-10-10T11:20:24Z

Sorry about the duplicate. However this one has a Weird and very technical title so I didn't find it in my search so here is my information in 21w40a.

"This one is funny one. I love it but it's clearly a bug. Haha! 😆

The Ocean is a chunk or two wide but since the generation is a little higher than normal the water did not generate."

ampolive 2021-10-13T19:54:11Z

Can confirm in 21w41a.

ampolive 2021-10-20T18:30:55Z

Can confirm in 21w42a.

dan hop 2021-11-06T12:51:15Z

not the only bug to do with biomes i found one were it does not respect the temp value or depth value

seems with out the depth value it works fine if you find a lush cave or dripstone it swaps to surface biome at around y 55

heres my bug report MC-240791 cave biomes jump to surface biomes - Jira (mojang.com)

this is for users to look up do not remove

SeaOfPixels 2021-11-16T18:15:34Z

Was not fixed in 1.18 Pre-release 1, still occurs a ton with all ocean biomes, as well as river biomes. Should be reopened, and additional info should note that this happens with rivers as well, and produces the same issues.

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jacobsjo 2021-11-16T18:46:53Z

@PotholedSea40 No, this was fixed in 1.18 Pre-release 1. What you are reporting is not caused by missing biome definitions (it is not at PV: Peak). What you are seeing is MC-237243 and MC-236796 - both resolved as WAI.