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====== Adding Biomes [1.16.3] ======
> :!: **The tutorial applies for only old versions!** For versions 1.18 and beyond, biomes are made completely using JSON, see [[https://minecraft.wiki/Biome/JSON_format|Minecraft Wiki page]] for more information.

There are 3 steps that are required to add a biome to the world.
  * Creating a biome
  * Registering a biome
  * Adding a biome to a climate zone in the world

In this tutorial, we will add new biome called obsiland biome, whose surface is covered with obsidian.

Note that this tutorial depends on [[https://github.com/FabricMC/fabric/pull/1053|the Biome API in Fabric API]] which is marked as experimental.
If the API doesn't work, consider using [[start?rev=1602901100|the mixin version]].

==== Creating a Biome ====
To create a biome, use ''Biome.Builder'' and configure properties.
Missing one property will likely cause the game to crash.
It is recommended to look at vanilla biomes (created in ''DefaultBiomeCreator'') as examples.

<code java>
public class ExampleMod implements ModInitializer {
  // SurfaceBuilder defines how the surface of your biome looks.
  // We use custom surface builder for our biome to cover surface with obsidians.
  private static final ConfiguredSurfaceBuilder<TernarySurfaceConfig> OBSIDIAN_SURFACE_BUILDER = SurfaceBuilder.DEFAULT
    .withConfig(new TernarySurfaceConfig(
      Blocks.OBSIDIAN.getDefaultState(),
      Blocks.DIRT.getDefaultState(),
      Blocks.GRAVEL.getDefaultState()));

  private static final Biome OBSILAND = createObsiland();

  private static Biome createObsiland() {
    // We specify what entities spawn and what features generate in the biome.
    // Aside from some structures, trees, rocks, plants and
    //   custom entities, these are mostly the same for each biome.
    // Vanilla configured features for biomes are defined in DefaultBiomeFeatures.

    SpawnSettings.Builder spawnSettings = new SpawnSettings.Builder();
    DefaultBiomeFeatures.addFarmAnimals(spawnSettings);
    DefaultBiomeFeatures.addMonsters(spawnSettings, 95, 5, 100);

    GenerationSettings.Builder generationSettings = new GenerationSettings.Builder();
    generationSettings.surfaceBuilder(OBSIDIAN_SURFACE_BUILDER);
    DefaultBiomeFeatures.addDefaultUndergroundStructures(generationSettings);
    DefaultBiomeFeatures.addLandCarvers(generationSettings);
    DefaultBiomeFeatures.addDefaultLakes(generationSettings);
    DefaultBiomeFeatures.addDungeons(generationSettings);
    DefaultBiomeFeatures.addMineables(generationSettings);
    DefaultBiomeFeatures.addDefaultOres(generationSettings);
    DefaultBiomeFeatures.addDefaultDisks(generationSettings);
    DefaultBiomeFeatures.addSprings(generationSettings);
    DefaultBiomeFeatures.addFrozenTopLayer(generationSettings);

    return (new Biome.Builder())
      .precipitation(Biome.Precipitation.RAIN)
      .category(Biome.Category.NONE)
      .depth(0.125F)
      .scale(0.05F)
      .temperature(0.8F)
      .downfall(0.4F)
      .effects((new BiomeEffects.Builder())
        .waterColor(0x3f76e4)
        .waterFogColor(0x050533)
        .fogColor(0xc0d8ff)
        .skyColor(0x77adff)
        .build())
      .spawnSettings(spawnSettings.build())
      .generationSettings(generationSettings.build())
      .build();
  }
}
</code>

==== Registering Biomes ====
We register our biome at the entrypoint ''onInitialize''.
If you use your own surface builder, you will also have to register it.

<code java>
public class ExampleMod implements ModInitializer {
  public static final RegistryKey<Biome> OBSILAND_KEY = RegistryKey.of(Registry.BIOME_KEY, new Identifier("tutorial", "obsiland"));

  @Override
  public void onInitialize() {
    Registry.register(BuiltinRegistries.CONFIGURED_SURFACE_BUILDER, new Identifier("tutorial", "obsidian"), OBSIDIAN_SURFACE_BUILDER);
    Registry.register(BuiltinRegistries.BIOME, OBSILAND_KEY.getValue(), OBSILAND);
  }
}
</code>

You should also give your biome a language entry in your ''en_us.json'' file:

<code JavaScript src/main/resources/assets/modid/lang/en_us.json>
{
  "biome.tutorial.obsiland": "Obsiland"
}
</code>

==== Adding a biome to a climate zone in the world ====
We need to specify the climate to which the biome is added, the biome which we are adding, and the weight of the biome (a double value).
The weight is a measurement of the chance the biome has to spawn.
A higher weight corresponds to a higher chance for the biome to spawn, proportional to the weights of other biomes.
You may want to give your biome a higher weight during testing so you can find the biome more easily.
In this tutorial, we will add the custom biome to the TEMPERATE and COOL climates as an example.

<code java>
public class ExampleMod implements ModInitializer {
  @Override
  public void onInitialize() {
    [...]

    OverworldBiomes.addContinentalBiome(OBSILAND_KEY, OverworldClimate.TEMPERATE, 2D);
    OverworldBiomes.addContinentalBiome(OBSILAND_KEY, OverworldClimate.COOL, 2D);
  }
}
</code>

==== Result ====
**Congratulations!** Your biome should now be generating in the world!
You can use below command to find your biome in the world.

<code>
/locatebiome tutorial:obsiland
</code>

{{tutorial:obsiland.png}}