Adding a Biome

A biome is a part of the world which has its own set of spawnable mobs, features, grass color, fog color, leaf color, precipitation etc.
Biomes are created using a BiomeBuilder during the BiomeRegisterEvent, this won’t make them appear by themselves, they then have to be added to a Biome Provider.

Creating the Biome

To create the Biome, make an event listener (described in Entrypoints & Events) for the BiomeRegisterEvent, something like this:

src/main/java/net/danygames2014/examplemod/event/BiomeListener.java

public class BiomeListener {  
    @EventListener  
    public void registerBiomes(BiomeRegisterEvent event){  
          
    }  
}

The biome creating process uses a Builder pattern so you will want to create a public static field for your biome to be able to reference it from anywhere in your mod and a local variable for our BiomeBuilder.

public class BiomeListener {  
    // Variables holding our biomes  
    public static Biome testBiome1;  
    public static Biome testBiome2;  
      
    @EventListener  
    public void registerBiomes(BiomeRegisterEvent event){  
        // A local biomebuilder instance that can be reused between biomes  
        BiomeBuilder biomeBuilder;  
          
        // Building Test Biome 1  
        biomeBuilder = BiomeBuilder.start("Test Biome 1");  
        testBiome1 = biomeBuilder.build();  
  
        // Building Test Biome 2  
        biomeBuilder = BiomeBuilder.start("Test Biome 2");  
        testBiome2 = biomeBuilder.build();  
    }  
}

You can see that the instance of the BiomeBuilder can be reused between the biomes since the actual biome is being passed to our holding variables in the .build() method.

 

We have now made 2 completely standard biomes with no distinct features to them. To modify the features and other factors of the biome, you need to call methods on the biomeBuilder after starting it and before building the biome, let’s change the foliage color and fog color

// Building Test Biome 1  
biomeBuilder = BiomeBuilder.start("Test Biome 1");  
biomeBuilder.fogColor(0xFF5CF4);  
biomeBuilder.leavesColor(0x00EAFF);  
biomeBuilder.grassColor(0x00EAFF);  
testBiome1 = biomeBuilder.build();

 

There are many more things you can call on the Biome Builder to customize your biomes

Method	Effect
grassColor	The color of grass
leavesColor	The color of leaves
grassAndLeavesColor	The color of both grass and leaves
fogColor	The color of fog
noDimensionFeatures	Disables the default features (ores, flowers etc.)
feature	Adds a feature to the biome
overworldOres	Adds overworld ores to the biome
overworldLakes	Adds overworld lakes to the biome
height	Sets the minimum and maximum height of the biome
precipitation	Enables or disables downfall (snow/rain)
snow	Use snow instead of rain
passiveEntity	Adds a passive entity to the biome spawnlist
hostileEntity	Adds a hostile entity to the biome spawnlist
waterEntity	Adds a water entity to the biome spawnlist
surfaceRule	Adds a surface rule to the biome. This will disable the default surface

Creating a Biome Provider

To have your biomes appear in game, you have to add them to a Biome Provider and register that provider to the dimension you want to add the biomes to.

There are 2 types of biomes providers:
Voronoi Provider (left) - creates a Voronoi diagram where to each of the cell a biome will be assigned.
Climate Provider (right) - generates a temperature and humidity Perlin Noise map, and you assign your biomes according to those values.

With Voronoi Provider, the temperature and humidity noise still exists, so it might be snowy in your biome

Let’s create a biome provider and add our Biomes to it. src/main/java/net/danygames2014/examplemod/event/BiomeListener.java

public class BiomeListener {       
    // Variables holding our biome providers  
    public static ClimateBiomeProvider climateBiomeProvider;  
    public static VoronoiBiomeProvider voronoiBiomeProvider;  
      
    @EventListener  
    public void registerBiomeProvider(BiomeProviderRegisterEvent event){  
        // Initialize the biome provider  
        climateBiomeProvider = new ClimateBiomeProvider();  
        // Add a biome in the temperature range of 0.7 - 1.0 and humidity of 0.4 - 1.0  
        climateBiomeProvider.addBiome(testBiome1, 1.0F, 0.7F, 1.0F, 0.4F);  
        // Add the biome provider to the overworld  
        BiomeAPI.addOverworldBiomeProvider(ExampleMod.NAMESPACE.id("climate_biome_provider"), climateBiomeProvider);  
          
        // Initialize the biome provider  
        voronoiBiomeProvider = new VoronoiBiomeProvider();  
        // Add a new biome to the provider  
        voronoiBiomeProvider.addBiome(testBiome2);  
        // Add the biome provider to the nether  
        BiomeAPI.addNetherBiomeProvider(ExampleMod.NAMESPACE.id("voronoi_biome_provider"), voronoiBiomeProvider);  
    }  
}

You can see that we have initialized the biome provider, added a biome to it and then called the BiomeAPI to add that provider to the respective dimension.

And these are our resulting biomes

 
The entire code for both Biomes and Biome Providers: src/main/java/net/danygames2014/examplemod/event/BiomeListener.java

public class BiomeListener {  
    // Variables holding our biomes  
    public static Biome testBiome1;  
    public static Biome testBiome2;  
      
    // Variables holding our biome providers  
    public static ClimateBiomeProvider climateBiomeProvider;  
    public static VoronoiBiomeProvider voronoiBiomeProvider;  
      
    @EventListener  
    public void registerBiomes(BiomeRegisterEvent event){  
        // A local biomebuilder instance that can be reused between biomes  
        BiomeBuilder biomeBuilder;  
          
        // Building Test Biome 1  
        biomeBuilder = BiomeBuilder.start("Test Biome 1");  
        biomeBuilder.fogColor(0xFF5CF4);  
        biomeBuilder.leavesColor(0x00EAFF);  
        biomeBuilder.grassColor(0x00EAFF);  
        testBiome1 = biomeBuilder.build();  
  
        // Building Test Biome 2  
        biomeBuilder = BiomeBuilder.start("Test Biome 2");  
        biomeBuilder.fogColor(0x00EAFF);  
        biomeBuilder.leavesColor(0xFF5CF4);  
        biomeBuilder.grassColor(0xFF5CF4);  
        biomeBuilder.surfaceRule(SurfaceBuilder.start(Block.GLOWSTONE).ground(1).replace(Block.NETHERRACK).build());  
        testBiome2 = biomeBuilder.build();  
    }  
      
    @EventListener  
    public void registerBiomeProvider(BiomeProviderRegisterEvent event){  
        // Initialize the biome provider  
        climateBiomeProvider = new ClimateBiomeProvider();  
        // Add a biome in the temperature range of 0.7 - 1.0 and humidity of 0.4 - 1.0  
        climateBiomeProvider.addBiome(testBiome1, 1.0F, 0.7F, 1.0F, 0.4F);  
        // Add the biome provider to the overworld  
        BiomeAPI.addOverworldBiomeProvider(ExampleMod.NAMESPACE.id("climate_biome_provider"), climateBiomeProvider);  
          
        // Initialize the biome provider  
        voronoiBiomeProvider = new VoronoiBiomeProvider();  
        // Add a new biome to the provider  
        voronoiBiomeProvider.addBiome(testBiome2);  
        // Add the biome provider to the nether  
        BiomeAPI.addNetherBiomeProvider(ExampleMod.NAMESPACE.id("voronoi_biome_provider"), voronoiBiomeProvider);  
    }

External Resources

StationAPI Test Mod Biome & Biome Provider
Spooky Squash Lands Biome & Biome Provider