Cubiomes parity notes

Seed Discovery Algorithms

How Minecraft seeds collapse from impossible search spaces into testable RNG states, biome maps, Bedrock parity rendering, and structure filters.

Current verificationLocal fixtures cover structure placement, Bedrock rendering, and seed metadata; Java Cubiomes GT passes when the external ground-truth matrix is present.

Bedrock scopeBedrock uses edition-specific seed normalization, a cubiomes-bedrock JS port, and optional BDS /locate verification for survivor seeds.

Pipeline

From seed to biome

Seed input

64-bit world seed, 48-bit Java RNG state, and chunk coordinates.

Legacy layers

Ocean, land, climate, rivers, shores, and biome zooms from Beta 1.8 through 1.17.

Beta climate

Beta 1.7 samples climate and sea-level noise directly instead of using the layer stack.

Modern noise

1.18+ resolves biomes from temperature, humidity, continentalness, erosion, weirdness, and depth.

Structure RNG

Many structures use region seeds and salts, so lower-bit searches can prune huge seed spaces.

RNG core

Java Random is reversible

Java Edition structure and decoration checks often begin with the same 48-bit linear congruential generator. Once enough outputs or placements are known, hunters can work backward instead of testing every world seed.

java.util.Random state step

next = (state * 0x5DEECE66D + 0xB) & ((1L << 48) - 1)

⚡ STRUCTURE SEED SEARCHER ⚡

Java Edition only. Results are structure candidates: placement and biome checks can pass before terrain/start or official 26.x fixture verification.

TargetGoalVersionRadiusSeeds to scanStart seed

Waiting for target coordinates...

Rare events

Some searches are probability filters

A fully lit End portal has twelve independent 10 percent checks, so a single portal lands at 10^-12. Good searchers stack cheap filters first: structure position, biome validity, then the expensive decoration or terrain condition.

12-eye portalP = (1/10)^12One in one trillion per portal.

Version behavior

Why the implementation has separate paths

Beta 1.7Climate table + interpolated sea-level noiseBlock and scale-4 parity

Beta 1.8Early layer stack with Beta land rulesScale-4 parity

1.0 - 1.17Layer stack, rivers, shores, hills, oceansScale-4 parity

1.18+Multi-noise biome sourceCubiomes GT fixture coverage for sampled biomes

Java 26.xMapped to the 1.21+ worldgen familySupported as current-family; 26.x-specific worldgen changes still need fixtures

Bedrockcubiomes-bedrock JS port + optional BDS /locate verifierCandidate model unless BDS confirms the survivor seed

Structures

Shadow seeds narrow the search

Many structure placements use a region coordinate, a salt, and only part of the world seed. That means different world seeds can share the same structure layout, letting tools search the lower bits first and resolve biome or terrain validity later. The visualizer treats rendered structure hits as candidates: Java can have verified placement math while still needing terrain/start checks. Bedrock now uses cubiomes-bedrock-style placement candidates and can call Bedrock Dedicated Server for /locate confirmation when the local verifier is configured.

Region placement sketch

structSeed = worldSeed & 0xFFFFFFFFFFFFL
regionSeed = regionX * A + regionZ * B + structSeed + salt
candidate = randomChunkInRegion(regionSeed)

Accuracy scope

What is verified, and what is still candidate-only

The app should not claim universal 100% accuracy for every edition and version yet. Java B1.8+ sampled biomes and Java structure placement have Cubiomes GT coverage, but Minecraft worldgen is a stack: seed parsing, version mapping, biome source, structure region placement, biome viability, terrain height, structure start, decoration RNG, and edition-specific behavior can each fail independently.

Java structure placementGround-truthed for region/chunk positions against local Cubiomes fixtures.Strong for placement math, but still a candidate until biome, terrain, and generated-world checks all agree.

Java B1.8 through 1.21 biomesCovered by the Cubiomes ground-truth matrix when ../cubiomes-original/ground_truth.txt is present.Beta 1.7 is intentionally excluded from the strict pass because its sea-level/noise path still needs separate work.

Java 26.xSelectable and mapped to the modern 1.21+ family.Minecraft 26.x is a new release line; any subtle worldgen change needs explicit fixtures before a 100% claim.

Bedrock biomesRendered through the cubiomes-bedrock JS port for supported modern profiles and covered by local golden fixtures.Patch versions without exact cubiomes-bedrock profiles map to the nearest known profile and stay candidate-labeled.

Bedrock structuresDedicated cubiomes-bedrock-style candidates for villages, temples, monuments, mansions, outposts, shipwrecks, ocean ruins, buried treasure, ruined portals, ancient cities, trail ruins, and trial chambers.Still candidate-only until checked against Bedrock Dedicated Server or in-game /locate fixtures.

Catalog categories and rare decorationsSeeds such as end portal eyes, cacti, fossils, spawners, or community discoveries can be stored and searched.Unless a category has a dedicated validator, it is catalog evidence or heuristic data, not generated proof.

Research

Built on public seed hunting work

The page summarizes ideas from the wider seed-hunting community, speedrunning seed filters, SeedCracker-style tools, and cubiomes-compatible verification suites, and Bedrock structure-placement research.

Cubiomes reference cubiomes-bedrock reference