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Custom structure types extend Minecraft’s structure generation system with additional functionality.

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Overview

The More RPG Library provides the ConditionalJigsawStructure type, which extends the standard jigsaw structure with mod dependency checking. This allows structures to only generate when specific mods are loaded.

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ConditionalJigsawStructure

Registry ID: more_rpg_classes:conditional_jigsaw
Source: net.more_rpg_classes.worldgen.structure.ConditionalJigsawStructure

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Description

A jigsaw-based structure that only generates when a specified mod is loaded. This is particularly useful for add-on mods that want to add structures that depend on specific mod content.

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Configuration

{
  "type": "more_rpg_classes:conditional_jigsaw",
  "mod_id": "example_mod",
  "start_pool": "example_mod:village/plains/town_centers",
  "start_jigsaw_name": "minecraft:bottom",
  "size": 7,
  "start_height": {
    "absolute": 0
  },
  "use_expansion_hack": false,
  "project_start_to_heightmap": "WORLD_SURFACE_WG",
  "max_distance_from_center": 80,
  "dimension_padding": {
    "bottom": 0,
    "top": 0
  },
  "liquid_settings": "APPLY_WATERLOGGING"
}

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Parameters

ParameterTypeRequiredDefaultDescription
typeStringYes-Must be "more_rpg_classes:conditional_jigsaw"
mod_idStringYes-Mod ID that must be loaded for structure to generate
start_poolStringYes-Registry ID of the starting structure pool
start_jigsaw_nameStringNo-Name of the jigsaw block to start from
sizeIntegerYes-Maximum depth of jigsaw generation (0-128)
start_heightHeightProviderYes-Height provider for structure placement
use_expansion_hackBooleanNofalseWhether to use the expansion hack for better terrain adaptation
project_start_to_heightmapStringNo-Heightmap type to project start position to (e.g., "WORLD_SURFACE_WG")
max_distance_from_centerIntegerYes-Maximum distance pieces can generate from center (1-128)
dimension_paddingObjectNoNONEPadding to prevent structures from generating near dimension boundaries
liquid_settingsStringNo"IGNORE_WATERLOGGING"How to handle water ("IGNORE_WATERLOGGING" or "APPLY_WATERLOGGING")

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How It Works

  1. Mod Check: When the structure attempts to generate, it checks if the specified mod_id is loaded using Fabric Loader
  2. Early Exit: If the mod is not loaded, returns Optional.empty(), preventing generation
  3. Standard Generation: If the mod is loaded, proceeds with standard jigsaw structure generation

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Height Providers

The start_height parameter accepts various height providers:

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Absolute Height

"start_height": {
  "absolute": 64
}

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Uniform Range

"start_height": {
  "type": "minecraft:uniform",
  "min_inclusive": {
    "absolute": 0
  },
  "max_inclusive": {
    "absolute": 64
  }
}

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Biased to Bottom

"start_height": {
  "type": "minecraft:biased_to_bottom",
  "min_inclusive": {
    "absolute": 0
  },
  "max_inclusive": {
    "absolute": 64
  },
  "inner": 16
}

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Heightmap Types

The project_start_to_heightmap parameter accepts these values:
TypeDescription
WORLD_SURFACE_WGWorld surface during world generation
WORLD_SURFACEWorld surface including structures
OCEAN_FLOOR_WGOcean floor during world generation
OCEAN_FLOOROcean floor including structures
MOTION_BLOCKINGBlocks that block motion or contain fluids
MOTION_BLOCKING_NO_LEAVESLike MOTION_BLOCKING but ignores leaves

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Dimension Padding

Prevents structures from generating too close to dimension boundaries: 
"dimension_padding": {
  "bottom": 8,
  "top": 8
}
Or use the shorthand for no padding: 
"dimension_padding": "NONE"

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Liquid Settings

Controls how water is handled:
  • "IGNORE_WATERLOGGING" - Does not waterlog blocks (default)
  • "APPLY_WATERLOGGING" - Waterlogs waterloggable blocks when placed in water

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Use Cases

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Add-on Mod Structures

The ConditionalJigsawStructure is specifically designed for add-on mods (like LNE Add-Ons) that want to add structures depending on whether the base mod is loaded: 
{
  "type": "more_rpg_classes:conditional_jigsaw",
  "mod_id": "lootandexplore",
  "start_pool": "lne_addon:dungeons/start_pool",
  "size": 5,
  "start_height": {
    "type": "minecraft:uniform",
    "min_inclusive": {"absolute": 0},
    "max_inclusive": {"absolute": 48}
  },
  "max_distance_from_center": 64
}
This structure will only generate if the “lootandexplore” mod is installed.

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Datapack Compatibility

For datapacks that add content depending on other mods: 
{
  "type": "more_rpg_classes:conditional_jigsaw",
  "mod_id": "wizards",
  "start_pool": "custom_pack:wizard_towers/centers",
  "size": 3,
  "start_height": {
    "type": "minecraft:uniform",
    "min_inclusive": {"absolute": 80},
    "max_inclusive": {"absolute": 120}
  },
  "project_start_to_heightmap": "WORLD_SURFACE_WG",
  "max_distance_from_center": 32
}

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Integration with Structure Processors

ConditionalJigsawStructure works seamlessly with the custom structure processors: 
{
  "type": "more_rpg_classes:conditional_jigsaw",
  "mod_id": "lootandexplore",
  "start_pool": "lne_addon:paths/start",
  "size": 7,
  "start_height": {"absolute": 0},
  "project_start_to_heightmap": "WORLD_SURFACE_WG",
  "max_distance_from_center": 96
}
Then in your structure pool templates, you can use the processors: 
{
  "processors": "lne_addon:path_processors"
}
Where path_processors.json contains: 
{
  "processors": [
    {
      "processor_type": "more_rpg_classes:path_adaptation",
      "filler_block": "minecraft:pink_concrete",
      "water_output": "minecraft:oak_planks",
      "terrain_mappings": [
        {"terrain": "#minecraft:sand", "output": "minecraft:smooth_sandstone"}
      ]
    },
    {
      "processor_type": "more_rpg_classes:water_pillar",
      "corner_block": "minecraft:yellow_concrete",
      "pillar_block": "minecraft:oak_log",
      "fence_block": "minecraft:oak_fence"
    },
    {
      "processor_type": "more_rpg_classes:terrain_blending",
      "blend_block": "minecraft:grass_block",
      "sample_radius": 2
    }
  ]
}

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Implementation Details

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Mod Loading Check

The structure uses Fabric Loader’s API to check for mod presence: 
@Override
public Optional<StructurePosition> getStructurePosition(Context context) {
    if (!FabricLoader.getInstance().isModLoaded(modId)) {
        return Optional.empty();
    }
    // Continue with standard jigsaw generation...
}

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CODEC Definition

The structure uses Mojang’s Codec system for serialization: 
public static final MapCodec<ConditionalJigsawStructure> CODEC = 
    RecordCodecBuilder.<ConditionalJigsawStructure>mapCodec(instance ->
        instance.group(
            configCodecBuilder(instance),
            Codec.STRING.fieldOf("mod_id").forGetter(s -> s.modId),
            StructurePool.REGISTRY_CODEC.fieldOf("start_pool").forGetter(s -> s.startPool),
            // ... other fields
        ).apply(instance, ConditionalJigsawStructure::new)
    );

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Registration

The structure type is registered in ModStructureTypes: 
public static final StructureType<ConditionalJigsawStructure> CONDITIONAL_JIGSAW = 
    () -> ConditionalJigsawStructure.CODEC;

public static void register() {
    Registry.register(
        Registries.STRUCTURE_TYPE,
        MRPGCMod.id("conditional_jigsaw"),
        CONDITIONAL_JIGSAW
    );
}

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Version History

  • v2.5.17 - Fixed some issues with ConditionalJigsawStructure and PathAdaptationProcessor
  • v2.5.16 - Added ConditionalJigsawStructure for LNE Add-On support