Chunkgen
A Fabric mod that pre-generates the terrain around spawn while the world is loading, and shows a map of it while you wait.
Download Chunkgen ↓1.0.0 · Fabric · Minecraft 26.1, 26.1.1, 26.1.2, 26.2, 26.3
Features
When you create a world, set a radius in the Chunkgen tab. Everything inside it gets generated on the loading screen, so when you join the terrain is already there and there's no chunk lag when you start exploring.
- Radius up to 1,024 chunks
- Square or circle
- Center on spawn or any coordinates
- Map of the terrain on the loading screen
- Zoom and drag the map
- Block, biome and height under the cursor
- Save the map as a PNG
- Time and disk estimate before you start
- Play now: join early, the rest keeps generating
- Slows down in the background if your FPS drops
- Continues after a quit or crash
- Works on existing worlds (Edit World)
- Delete preloaded chunks nobody visited
- Voxy support for distant terrain
- Smaller Voxy cache option
- Sound and notification when it's done
- Works on dedicated servers
- Hardcore-safe: no teleports, cheats or time changes
Screenshots
The Chunkgen tab when creating a world
Hovering over the map
Edit World → Chunkgen
Performance
Tested on an i5-12400F with Voxy installed, Minecraft 26.3, square shape. Radius 100 and 150 are measured, the others are estimates.
| Radius | Chunks | Time | Disk |
|---|---|---|---|
| 32 | 4,225 | about 20 s | about 70 MB |
| 100 | 40,401 | 2 min 30 s | 660 MB |
| 150 | 90,601 | 5 min 40 s | about 1.5 GB |
| 250 | 251,001 | about 16 min | about 4 GB |
Vanilla generation does about 130–190 chunks per second on the same PC. Chunkgen does 260–300 because it comes with C2ME and a few other world generation mods. RAM use stays flat: a radius 150 run stayed under 4 GB.
Downloads and version history
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What's in 1.0.0
- First release, for Minecraft 26.1, 26.1.1, 26.1.2, 26.2 and 26.3.
- Comes with C2ME, Lithium, ScalableLux, FerriteCore, Fast Noise, Material Rule Compiler, Fast Surface (26.2 and up), ZConfig and Dynamic FPS.
- Each version was tested on a dedicated server and in singleplayer before release.
Put the jar in your mods folder next to Fabric API. If you have a newer version of one of the included mods in that folder, the game uses yours instead.
Included mods
| Mod | What it speeds up | License |
|---|---|---|
| C2ME | Generation on all CPU cores | MIT |
| Lithium | Game logic | LGPL-3.0 |
| ScalableLux | Lighting | LGPL-3.0 |
| FerriteCore | Memory use | MIT |
| Fast Noise + ZConfig | Terrain shape | MPL-2.0 |
| Material Rule Compiler, Fast Surface | Surface blocks | MPL-2.0 |
| Dynamic FPS | CPU use while the game is in the background | MIT |
Questions
Does it change the terrain?
No, you get the same world you'd get without it. C2ME places trees and ores on several threads, so around 0.2% of blocks can come out slightly different between two runs of the same seed.
Do I need Voxy?
No. Without it you still get the generated world and the map. With Voxy, all of that terrain also shows up in the distance.
What doesn't it work with?
Noisium, Moonrise, Starlight and AntiXray. They change the same code as the included mods. Sodium, Iris and Voxy are fine.
Can I remove it later?
Yes. The chunks it generates are normal chunks, so the world works the same without the mod.
How do I get the disk space back?
Edit World → Chunkgen → Delete preloaded terrain. It deletes chunks no player has been close to and keeps the rest.
How do I use it on a server?
Put a chunkgen.properties file in the world folder with a line like radius=100, then start the server. It preloads before anyone can join and continues after a restart.