World Generation (WorldGen) (Strongly not recommended on 1.20; data packs are recommended for 1.20)

Gu-meng note: This document references wudji's worldgen guide. It may be rewritten later.

• Event Declaration

WorldgenEvents is the event group for world-generation changes. It includes WorldgenEvents.add and WorldgenEvents.remove.

WorldgenEvents.add((event) => {})
WorldgenEvents.remove((event) => {})

• Event Methods

Method	Description
addLake(Consumer lake)	Add a lake in world generation
addOre(Consumer ore)	Add ore generation in worldgen
getAnchors()	Get height anchors (VerticalAnchor)
addSpawn(BiomeFilter biomeFilter, MobCategory spawnType, String mob)	Add mob spawns
addSpawn(MobCategory spawnType, String mob)	Add mob spawns
addSpawn(Consumer props)	Add mob spawns
addFeatureJson(BiomeFilter biomeFilter, JsonObject feature)	Add features/structures
addFeatureJson(BiomeFilter biomeFilter, ResourceLocation ID, JsonObject feature)	Add features/structures

WorldgenEvents.remove

Method	Description
removeSpawns(Consumer removeSpawn)	Remove mob spawns
removeAllFeatures(BiomeFilter biomeFilter)	Remove all matching features
printSpawns(MobCategory spawnType)	Print matching mob spawns
printFeatures(DecorationGenerationStep generationStep)	Print matching features
printSpawns()	Print all mob spawns
removeFeatureById(BiomeFilter biomeFilter, DecorationGenerationStep generationStep, ResourceLocation[] featureIDs)	Remove features by ID
printFiltered(DecorationGenerationStep generationStep)	Print filtered matching features
printFiltered(DecorationGenerationStep generationStep, BiomeFilter biomeFilter)	Print filtered matching features
printFeaturesForType(DecorationGenerationStep generationStep, BiomeFilter biomeFilter, Boolean afterRemoval)	Print features for specific type
removeAllFeatures()	Remove all features
removeAllFeatures(BiomeFilter biomeFilter, DecorationGenerationStep generationStep)	Remove all matching features
removeAllSpawns()	Remove all mob spawns
removeFeatureById(DecorationGenerationStep generationStep, ResourceLocation[] featureIDs)	Remove features by ID
removeOres(Consumer removeOre)	Remove matching ores
printFeatures()	Print all features
printFeatures(DecorationGenerationStep generationStep, BiomeFilter biomeFilter)	Print all matching features

• Common Components

  • Biome Filter

    You can use biome categories (Biome Categories) as biome filters. The ore example below demonstrates biome filter usage. Code source: wudji Example Code.

    WorldgenEvents.add((event) => {
    	// Get vertical anchors
    	const { anchors } = event
    
    	event.addOre((ore) => {
    		ore.id = 'kubejs:glowstone_test_lmao' // Set ID for this feature (optional, recommended)
    		ore.biomes = {
    			not: 'minecraft:savanna' // Biome filter (optional)
    		}
    
    		// Add target examples
    		ore.addTarget('#minecraft:stone_ore_replaceables', 'minecraft:glowstone') // Replace target blocks in #minecraft:stone_ore_replaceables with minecraft:glowstone
    		ore.addTarget('minecraft:deepslate', 'minecraft:nether_wart_block')       // Replace target (minecraft:deepslate) with minecraft:nether_wart_block
    		ore.addTarget([
    			'minecraft:gravel',
    			/minecraft:(.*)_dirt/
    		], 'minecraft:tnt')       // Replace targets (minecraft:gravel and all dirt variants) with minecraft:tnt
    
    		ore.count([15, 50])                      // Set vein size (random from 15 to 50). You can also use a single number for fixed count.
    			.squared()                       // Enable cross-chunk style placement distribution
    			.triangleHeight(				 // Height provider using triangular distribution
    				anchors.aboveBottom(32), // Lower anchor: 32 blocks above world bottom (Y=-64), i.e. Y=-32
    				anchors.absolute(96)	 // Upper anchor: fixed Y=96
    			)								 // Overall range is Y=-32 to Y=96, with peak probability around midpoint Y=32
    
    		// More optional params (shown with defaults)
    		ore.size = 9                            // Maximum vein size
    		ore.noSurface = 0.5                     // Probability of being exposed to air
    		ore.worldgenLayer = 'underground_ores'  // Worldgen generation step for this ore
    		ore.chance = 0							// If non-zero and ore.count is not set, ore has 1/n chance per chunk
    	})
    
    	// Add lake
    	// This feature is planned for deprecation in vanilla
    	event.addLake((lake) => {
    		lake.id = 'kubejs:funny_lake' // BlockStatePredicate
    		lake.chance = 4
    		lake.fluid = 'minecraft:lava'
    		lake.barrier = 'minecraft:diamond_block'
    	})
    })
    
    WorldgenEvents.remove(event => {
    	//console.debugEnabled = true;
    
    	// Print all features in a given biome filter
    	event.printFeatures('', 'minecraft:plains')
    
    	event.removeOres((props) => {
    		// Like adding ores, ore removal also supports worldgen layer
    		props.worldgenLayer = 'underground_ores'
    		// Use biome filters
    		props.biomes = [{
    			category: 'icy',
    		}, {
    			category: 'savanna',
    		}, {
    			category: 'mesa',
    		}];
    
    		// Remove iron ore and copper ore in the above biomes
    		// Note: tags cannot be used here
    		props.blocks = ['minecraft:iron_ore', 'minecraft:copper_ore']
    	})
    
    	// Remove features by ID (first parameter is generation step)
    	event.removeFeatureById('underground_ores', ['minecraft:ore_coal_upper', 'minecraft:ore_coal_lower'])
    })