[MC-241566] Mossy cobblestone boulders generate in a grid pattern in old-growth spruce taigas

The bug

Mossy cobblestone boulders in old-growth-spruce-taige biome appear to generate in a grid-like pattern.

To reproduce

Option #1
Seed used:

8100499608039829553

Coordinates:

/tp 999763 ~ -1998077

Option #2

Create a single-biome world and select "Old Growth Spruce Taiga" as the biome.

/give @p minecraft:repeating_command_block

Place the command block and set it to "Always Active".

Put the following command into the command block:

/execute at @p run fill ~-15 ~-18 ~-15 ~15 ~15 ~15 air replace minecraft:spruce_leaves

Fly around and look at the boulders. (The command will remove leaves for you so you can see more easily.)

Expected behavior

The boulders should be placed randomly.

Observed behavior

The boulders are in a grid.

Linked issues

is duplicated by 1

MC-241667 forest_rock is always generated as a grid Resolved

Attachments

Comments 2

pine1needle 2021-11-17T17:36:07Z

I also tested this in 1.17.1 using a "Giant Spruce Taiga" single-biome world. In 1.17.1, the boulders are placed randomly, so this bug is new to the 1.18 snapshots.

Misode 2021-11-17T17:47:21Z

This is caused because the forest_rock placed feature does not include an in_square placement modifier

{
  "feature": "minecraft:forest_rock",
  "placement": [
    {
      "count": 2,
      "type": "minecraft:count"
    },
    {
      "heightmap": "MOTION_BLOCKING",
      "type": "minecraft:heightmap"
    },
    {
      "type": "minecraft:biome"
    }
  ]
}