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This guide will walk you through creating your first worldgen modifier with Lithostitched. You’ll learn how to add custom features to biomes using data-driven JSON configuration.

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What You’ll Build

By the end of this guide, you’ll have:
  • A working datapack that uses Lithostitched modifiers
  • A custom biome feature addition that adds flowers to plains biomes
  • Understanding of the modifier system and JSON structure

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Prerequisites

  • Lithostitched installed (see Installation)
  • Basic understanding of Minecraft datapacks
  • A text editor (VS Code, IntelliJ IDEA, etc.)

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Project Setup

1

Create the datapack structure

Create a new datapack in your world’s datapacks folder:
datapacks/
└── my_worldgen_pack/
    ├── pack.mcmeta
    └── data/
        └── my_worldgen_pack/
            └── lithostitched/
                └── worldgen_modifier/
2

Create pack.mcmeta

Add the datapack metadata file:
pack.mcmeta
{
  "pack": {
    "pack_format": 41,
    "description": "My first Lithostitched worldgen modifications"
  }
}

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Creating Your First Modifier

Let’s create a modifier that adds poppy flowers to plains biomes.

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Step 1: Define the Modifier

Create data/my_worldgen_pack/lithostitched/worldgen_modifier/add_poppies.json:
add_poppies.json
{
  "type": "lithostitched:add_features",
  "priority": 1000,
  "biomes": "minecraft:plains",
  "features": "minecraft:flower_plain",
  "step": "vegetal_decoration"
}
The priority field determines the order in which modifiers are applied. Lower numbers = higher priority. Default is 1000.
Let’s break down the fields:
  • type - The modifier type. See Lithostitched.java:103-118 for all available types
  • priority - Execution order (optional, defaults to 1000)
  • biomes - Target biomes (can be a tag like #minecraft:is_overworld or single biome)
  • features - Features to add (can be a list or single feature)
  • step - Generation step (see Generation Steps)

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Step 2: Test the Modifier

1

Load the datapack

Launch Minecraft and create a new world, or reload an existing world:
/reload
2

Verify in logs

Check the game logs for Lithostitched modifier loading:
[lithostitched] Loading worldgen modifiers...
[lithostitched] Loaded modifier: my_worldgen_pack:add_poppies
3

Generate terrain

Travel to a plains biome and observe the increased flower density.

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Understanding Modifier Types

Lithostitched provides many modifier types. Here are the most commonly used:

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Biome Modifiers

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Add Features

Add placed features to biomes during specific generation steps: 
{
  "type": "lithostitched:add_features",
  "biomes": ["minecraft:forest", "minecraft:birch_forest"],
  "features": "#my_mod:custom_trees",
  "step": "vegetal_decoration"
}

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Remove Features

Remove existing features from biomes: 
{
  "type": "lithostitched:remove_features",
  "biomes": "#minecraft:is_ocean",
  "features": "minecraft:seagrass_simple",
  "step": "vegetal_decoration"
}

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Replace Biome Effects

Customize biome colors, particles, sounds, and music: 
{
  "type": "lithostitched:replace_effects",
  "biomes": "minecraft:plains",
  "effects": {
    "grass_color": 8439583,
    "foliage_color": 6726447,
    "sky_color": 7907327,
    "fog_color": 12638463
  }
}

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Structure Modifiers

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Add Surface Rules

Add custom terrain generation rules: 
{
  "type": "lithostitched:add_surface_rule",
  "levels": ["minecraft:overworld"],
  "surface_rule": {
    "type": "minecraft:condition",
    "if_true": {
      "type": "lithostitched:biome",
      "biomes": "minecraft:desert"
    },
    "then_run": {
      "type": "minecraft:block",
      "result_state": {
        "Name": "minecraft:red_sand"
      }
    }
  }
}

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Add Template Pool Elements

Add structure pieces to jigsaw pools: 
{
  "type": "lithostitched:add_template_pool_elements",
  "target": "minecraft:village/plains/houses",
  "elements": [
    {
      "element": {
        "location": "my_mod:village/plains/custom_house",
        "processors": "minecraft:empty",
        "projection": "rigid",
        "element_type": "minecraft:single_pool_element"
      },
      "weight": 1
    }
  ]
}

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Advanced Example: Bandlands Terrain

Create custom banded terrain similar to badlands:

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Step 1: Define the Bandlands

Create data/my_worldgen_pack/lithostitched/bandlands/custom_bands.json:
custom_bands.json
{
  "base": {
    "Name": "minecraft:terracotta"
  },
  "bands": [
    {
      "type": "lithostitched:base",
      "state": {
        "Name": "minecraft:red_terracotta"
      },
      "height": 3,
      "offset": 0
    },
    {
      "type": "lithostitched:base",
      "state": {
        "Name": "minecraft:orange_terracotta"
      },
      "height": 2,
      "offset": 3
    },
    {
      "type": "lithostitched:repeating",
      "states": [
        {
          "element": {
            "Name": "minecraft:yellow_terracotta"
          },
          "weight": 1
        },
        {
          "element": {
            "Name": "minecraft:white_terracotta"
          },
          "weight": 1
        }
      ],
      "height": 4,
      "offset": 5,
      "count": 10
    }
  ]
}

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Step 2: Apply with Surface Rule

Create a modifier that uses the bandlands:
use_bandlands.json
{
  "type": "lithostitched:add_surface_rule",
  "levels": ["minecraft:overworld"],
  "surface_rule": {
    "type": "minecraft:condition",
    "if_true": {
      "type": "lithostitched:biome",
      "biomes": "minecraft:desert"
    },
    "then_run": {
      "type": "lithostitched:bandlands",
      "options": "my_worldgen_pack:custom_bands"
    }
  }
}
This creates colorful banded terrain in desert biomes, with:
  • 3 blocks of red terracotta at the base
  • 2 blocks of orange terracotta above
  • Repeating pattern of yellow and white terracotta (4 blocks high, repeating 10 times)

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Generation Steps

When using feature modifiers, specify the correct generation step:
StepDescriptionExamples
raw_generationTerrain featuresLakes, springs
lakesLake generation-
local_modificationsLocal terrain editsAmethyst geodes, icebergs
underground_structuresUnderground featuresDungeons, monster rooms
surface_structuresSurface structuresVillages, temples
strongholdsStronghold generation-
underground_oresOre generationAll ores
underground_decorationUnderground decorationsPointed dripstone, roots
fluid_springsSpring featuresWater/lava springs
vegetal_decorationPlant featuresTrees, flowers, grass
top_layer_modificationFinal layer changesFreeze top layer

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Debugging Tips

Worldgen modifiers only affect newly generated chunks. Use /tp @s ~ ~ ~ to teleport to unexplored areas.

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Enable Debug Logging

Create config/lithostitched.json in your instance folder:
lithostitched.json
{
  "logDebugMessages": true
}
This enables detailed logging from Lithostitched.java:234-238.

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Common Issues

Modifier not loading:
  • Check JSON syntax with a validator
  • Verify file is in correct location: data/<namespace>/lithostitched/worldgen_modifier/
  • Check logs for parsing errors
Changes not visible:
  • Ensure you’re in a newly generated chunk
  • Verify biome selector matches target biomes
  • Check modifier priority doesn’t conflict with other mods
Invalid feature references:
  • Use /locate to verify features exist
  • Check feature namespaces are correct
  • Ensure referenced tags are defined

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Next Steps

Now that you’ve created your first modifier, explore more advanced features:

Modifier Reference

Complete list of all modifier types and their options

Surface Rules

Learn about custom terrain generation with surface rules

Structure System

Advanced structure customization and processors

Common Patterns

Real-world examples and use cases

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