Yo!
I'm trying to create a new custom biome, but I don't even know how to start.

I'm not trying to change blocks or ore generation from a vanilla biome, I want to change terraforming (and well, also blocks).

 

Here's the biome i want to reply: RockyBiome

You can make a biome using the datapack mechanism: https://minecraft.fandom.com/wiki/Biome/JSON_format

Your mod is automatically a datapack, you place the files in src/main/resources/data

 

Or you can create them in code using the DeferredRegister mechanism.

 

But having a biome won't do you much good unless you have dimension with a ChunkGenerator/BiomeSource that uses it.

e.g. your own custom dimension

Edited August 19, 20223 yr by warjort

If you just want to modify a biome, you can use: https://forge.gemwire.uk/wiki/Biome_Modifiers

26 minutes ago, warjort said:

But having a biome won't do you much good unless you have dimension with a ChunkGenerator/BiomeSource that uses it.

e.g. your own custom dimension

What do you mean with that?

Quote

What do you mean with that?

Exactly what I said, a biome is useless by itself, you need to have a dimension that uses it.

5 minutes ago, warjort said:

Exactly what I said, a biome is useless by itself, you need to have a dimension that uses it.

I can't add it to vanilla overworld?

Not to the vanilla overworld.

Things you can do include;

* override/replace the vanilla overworld using the datapack mechanism - not recommended for a mod to do by default

* use a WorldPreset to create a new "world type" that appears in the "create new world screen" and has a copy of the vanilla overworld with your biome included

* use an existing library mod like: https://www.curseforge.com/minecraft/mc-mods/terrablender

There are probably other options along similar lines.