How to Make Custom Ore Distributions with JER's DIY World-Gen Config

JER lets pack makers define their own ore spawn distributions instead of relying on defaults. This is the DIY world-gen workflow.

Setting Up the Config

In JER's config folder, create or edit a file named world-gen.json. This file describes the ore distributions you want the mod to display and use. Once the file exists, toggle the DIY setting in-game so JER reads your custom definitions instead of the automatic ones. From that point, the world-gen graphs in JEI reflect your file.

Defining Distributions

Each entry maps an ore to its spawn behavior across Y-levels. You describe where the ore appears and how it's weighted at each height, matching the shape you want the graph to show. Because the exact schema is version-specific, open an existing generated file or a scan output as a template rather than writing from scratch.

Combining With a Scan

Run /profile on a world you like to produce a world-gen-scan.json, then use those measured values as the basis for your world-gen.json. This gives you real distributions to copy or tweak instead of inventing numbers.

Practical Notes

• DIY mode is intended for pack makers and experienced players.
• Always keep a backup of your config before editing.
• If graphs stop updating, check that DIY is toggled and the JSON is valid.