Terrain Patcher is a Subnautica and Below Zero library mod that allows anyone to modify the game's terrain.
This mod requires BepInEx and Nautilus. The Nautilus dependency is optional but recommended.
You can download Terrain Patcher from the releases page, below the changelog.
To install Terrain Patcher, just extract the zip file and place the TerrainPatcher folder into
your BepInEx/plugins folder.
To install a .optoctreepatch file manually, place it in the TerrainPatcher/patches folder. You
can also place a terrain patch anywhere in the BepInEx/plugins folder or any subfolder and it will
still be loaded.
You can specify a custom load order for .optoctreepatch files by writing the file names (without
the extensions) into the load-order.txt file.
Loading patch files can be enabled/disabled from the in-game config menu if Nautilus is installed.
Some mods, such as Sea To Sea, may require using the legacy QModManager version of Terrain Patcher instead of the current BepInEx version. The legacy version can be downloaded from the releases page, below the changelog. Installation and usage instructions for the legacy version can be found in an older version of the repository. Please do not submit issues for bugs encountered on an old version of Terrain Patcher.
Current versions of Terrain Patcher provide all the features that Terrain Extender provided and satisfy other mods' dependencies on Terrain Extender. Terrain Extender is deprecated and you should uninstall Terrain Extender if you have it installed.
The following is for modders who want to use Terrain Patcher in your mod. Keep in mind that if your mod uses Terrain Patcher, anyone using your mod needs to have Terrain Patcher installed to see your terrain changes.
To load a terrain patch, just distribute your .optoctreepatch file alongside your mod. Terrain
Patcher will find and load all .optoctreepatch files placed anywhere in the BepInEx/plugins
folder or any subfolder, so you don't need to do anything else to make sure your terrain patch
gets loaded.
Terrain Patcher also currently supports loading patches via the
TerrainPatcher.TerrainRegistry.PatchTerrain method, but this method is deprecated and may be
removed in a future release of Terrain Patcher.
If your mod contains terrain patches, you should add Terrain Patcher as a dependency of your mod.
If your mod requires Terrain Patcher to function, add the
[BepInDependency("Esper89.TerrainPatcher")] attribute to your mod's entry point (below the
BepInPlugin attribute), as shown here:
[BepInPlugin("YourName.ExampleMod", "Example Mod", "0.0.0")]
[BepInDependency("Esper89.TerrainPatcher")]
internal class Mod : BaseUnityPlugin { /* ... */ }If your mod does not require Terrain Patcher but still uses it, add the
[BepInDependency("Esper89.TerrainPatcher", BepInDependency.DependencyFlags.SoftDependency)]
attribute to your mod's entry point (below the BepInPlugin attribute), as shown here:
[BepInPlugin("YourName.ExampleMod", "Example Mod", "0.0.0")]
[BepInDependency("Esper89.TerrainPatcher", BepInDependency.DependencyFlags.SoftDependency)]
internal class Mod : BaseUnityPlugin { /* ... */ }Terrain Patcher is licensed under the GNU AGPL, which says that derivative works must also be
licensed under the GNU AGPL. If your mod directly interacts with Terrain Patcher (e.g. by
referencing TerrainPatcher.dll), it might be considered a derivative work. To avoid any possible
copyright issues, if your mod isn't licensed under the GNU AGPL, you should avoid referencing
TerrainPatcher.dll or otherwise interacting with Terrain Patcher directly. Terrain patches are
loaded without referencing Terrain Patcher by distributing them alongside your mod as separate
.optoctreepatch files.
The Subnautica Terrain Patch Format (the optoctreepatch format) is documented in Subnautica Terrain Patch Format.pdf. The format
is designed to be as similar to the game's native terrain format as possible, while still allowing
for proper patching of terrain. The patch format also allows as much data as necessary to be stored
in one file, for easier distribution.
An example optoctreepatch file is included at
example.optoctreepatch. Patches that demonstrate all valid
materials in-game can be found for Subnautica and Below Zero at
material-preview-sn.optoctreepatch and
material-preview-bz.optoctreepatch.
Patch files can be created using Reef Editor. Any files conforming to the specification will work.
Terrain Patcher places patched batches in CompiledOctreesCache/patches, using the same naming
system as the game. These patched batches can be loaded by external tools or other mods, if they
wish to support terrain patches. Anything using this feature should make it optional, as those files
aren't removed when Terrain Patcher is disabled or uninstalled.
-
Modifying the game's terrain in a modular way.
-
Replacing some parts of a batch without replacing the whole batch.
-
As many world modifications as necessary can fit in one patch file.
-
No actual changes to game files.
-
Support for both Subnautica and Below Zero.
-
Easily load patches without making a mod.
-
Custom load order.
-
Enabling and disabling patch loading in-game.
-
Extending the current edge of the world to allow for more terrain.
-
Extending the edge of the world where entities can spawn and save.
-
Patching the in-game seaglide and scanner room maps.
-
Patching biomes and entities.
Contributions of any kind—issues, pull requests, feature requests—are all welcome. You can submit suggestions and bug reports as an issue, or code contributions as a pull request.
To build Terrain Patcher, run dotnet build in the project's root directory. This will build in
debug mode, and the output will be placed in target/Debug. If you create a file in the project
root called game-dirs.txt and input the paths to your Subnautica and/or Below Zero installations
(one per line), the output of debug builds will be automatically installed into those game
directories for easier testing.
To build Terrain Patcher in release mode, run dotnet build --configuration Release. This will
also create a dist.zip file in target for easy distribution.
Copyright © 2021, 2023–2025 Esper Thomson
This program is free software: you can redistribute it and/or modify it under the terms of version 3 of the GNU Affero General Public License as published by the Free Software Foundation.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License along with this program. If not, see https://www.gnu.org/licenses.
Additional permission under GNU AGPL version 3 section 7
If you modify this Program, or any covered work, by linking or combining it with Subnautica (or a modified version of that program), containing parts covered by the terms of its license, the licensors of this Program grant you additional permission to convey the resulting work.