ForceBlend

Prepare existing chunks for Minecraft's built-in terrain blending.

ForceBlend is a Singleplayer Fabric, proof of concept mod, that change existing Overworld chunks so vanilla terrain blending feature is trigged when new chunks are generated next to them. The mod doesn't generate terrain, move chunks, or replace Minecraft's blending algorithm. It simply prepares existing chunks so vanilla blending can do its job.

It is useful after:

• Changing a world's seed
• Changing the terrain generator with datapacks/mods
• Importing chunks from another world ~!

Always keep a backup of important worlds! ForceBlend edits Anvil region files directly.

Compatibility

• Works with Sodium
• Fabric Loader 0.12.12+
• No Fabric API required or library required
• Java version must match your Minecraft version (Java 17 for Minecraft 1.18–1.20.4, Java 21 for Minecraft 1.20.5–1.21.x, Java 25 for Minecraft 26.x)

Only Minecraft 1.18.2 and 26.2 have been personally tested in-game. Other supported versions use the same processing core and have been mapping-audited but should be considered community-tested compatibility.

What ForceBlend changes

For eligible chunks, ForceBlend:

• Adds the correct blending_data marker
• Removes only the derived Heightmaps and isLightOn caches when necessary
• Preserves blocks, entities, structures, POI data, chunk status, and DataVersion
• Verifies the world has not changed since analysis before writing
• Safely rebuilds modified region files using temporary files and atomic replacement

Project Important Infos

ForceBlend version 1.0.0 is the first stable public release, about future new updates, features, mod support, and compatibility with new Minecraft versions are not guaranteed, that's why is marked as archived.

Issues and pull requests are welcome, but responses and reviews may be delayed or may not be possible. If you want to continue, adapt, or expand the project, forks are forced encouraged.

You are welcome to include ForceBlend in any modpack without requesting permission. If you redistribute the mod, please preserve the license and attribution under the MIT License.

Third-party libraries remain subject to their own licenses. Their license notices and full license texts are included in both the source tree and the published release JAR.

Limitations

~! If both sides of a terrain border have already been generated, delete the unwanted side, and than run ForceBlend.

Not tested with C2ME and other mods that change chunks loading.

Terrain blending is not retroactive.