definitions/feature_rules/ocean_surface_kelp_feature.json

{
  "format_version": "1.13.0",
  "minecraft:feature_rules": {
    "description": {
      "identifier": "minecraft:ocean_surface_kelp_feature",
      "places_feature": "minecraft:kelp_feature"
    },
    "conditions": {
      "placement_pass": "surface_pass",
      "minecraft:biome_filter": [
        // ocean && !(warm || (frozen && monster)) ->
        // ocean && !warm && !(frozen && monster)  ->
        // ocean && !warm && (!frozen || !monster)
        {
          "test": "has_biome_tag",
          "operator": "==",
          "value": "ocean"
        },
        {
          "test": "has_biome_tag",
          "operator": "!=",
          "value": "warm"
        },
        {
          // legacy_frozen_ocean should receive this kelp feature, but regular
          // frozen_ocean should not. The only distinguishing tag between the two
          // is "monster", which is not present on legacy_frozen_ocean
          "any_of": [
            {
              "test": "has_biome_tag",
              "operator": "!=",
              "value": "frozen"
            },
            {
              "test": "has_biome_tag",
              "operator": "!=",
              "value": "monster"
            }
          ]

        }
      ]
    },
    "distribution": {
      "iterations": 20,
      "scatter_chance": {
        "numerator": 1,
        "denominator": 18
      },
      "x": {
        "distribution": "uniform",
        "extent": [ 0, 35 ]
      },
      "y": 43,
      "z": {
        "distribution": "uniform",
        "extent": [ 0, 35 ]
      }
    }
  }
}