PolarConverter is a Java command-line tool for converting vanilla Minecraft worlds (Anvil format) into Polar world format, compatible with Minestom-based servers using the Polar engine. It supports full-world conversion or conversion of a specific chunk radius.
- Converts Minecraft worlds from Anvil to Polar format.
- Supports optional chunk radius conversion for partial worlds.
- Validates world version against the Minestom server version before converting.
- Minimal dependencies: Minestom, Polar.
- Java 25+
- Minecraft world in Java Edition Anvil format
⚠️ Only worlds matching the Minestom server’s supported DataVersion can be converted.
java -jar PolarConverter.jar --world "path/to/world" --output "output_name" [--radius N]| Argument | Description |
|---|---|
--world "world folder" |
Path to the Minecraft world folder to convert. Must contain a region folder and level.dat. |
--output "world" |
Output file name for the converted Polar world (.polar extension will be added). |
--radius N |
Optional. Limits conversion to a radius of N chunks from 0,0. If omitted, the full world is converted. |
Convert an entire world:
java -jar PolarConverter.jar --world "MyMinecraftWorld" --output "MyPolarWorld"Convert only a 10-chunk radius around spawn:
java -jar PolarConverter.jar --world "MyMinecraftWorld" --output "MyPolarWorld" --radius 10-
Minestom Initialization
Starts a minimal offline Minestom server to provide block registries and NBT support. -
World Validation
- Checks that
level.datexists. - Verifies
DataVersionmatches the Minestom server version.
- Checks that
-
Conversion
- Uses
AnvilPolarto read Anvil chunks. - Converts blocks and metadata to Polar format.
- Writes the output to a
.polarfile usingPolarWriter.
- Uses
-
Optional Chunk Radius
Only processes chunks within the specified radius around(0,0).
- DataVersion Mismatch: If the world’s version does not match the Minestom server’s supported version, the converter will stop and display an error.
This project is licensed under the MIT License.