So, in my mod I have an object Lifeforce that has values "strength" and "purity". I want each chunk to have a Lifeforce. I figured I could accomplish this through NBT data, but a chunk doesn't seem to have an NBTTagCompound until it is saved. My question is how do I get and set data to a chunk. For example I'm subscribing ChunkGeneratorEvent.ReplaceBiomeBlocks and I want to assign the lifeforce when a chunk is created. How can I accomplish this, as a chunk doesn't have NBT?

You could use Capabilities or World Saved Data to store a per-

World

Map<ChunkPos, Lifeforce>

that contains the

Lifeforce

for each chunk.

 

Edit: Fixed incorrect closing tag.

TL;DR:

 

Chunk data needs to exist in its own native class object during runtime.  You only need to save to NBT when the chunk is saved (and then read it when its loaded again).

 

You'll need these events:

https://github.com/Draco18s/ReasonableRealism/blob/master/src/main/java/com/draco18s/flowers/FlowerEventHandler.java#L74

(CogOreGenEvent is just a deferred chunk generation event that I must use; you can use the vanilla chunk generation events)

 

And this is what I do with them:

https://github.com/Draco18s/ReasonableRealism/blob/master/src/main/java/com/draco18s/flowers/util/OreDataHooks.java

 

There's a lot going on for me (because my data is complex) but the basics is that when the chunk is generated I create some data that gets stored.  There's a "get" method for retrieving the stored value as well.  Then during ChunkSave the data is added to the chunk's nbt, and on ChunkLoad it's read.  At ChunkUnload the data is removed from the runtime storage (so memory isn't leaked by a player flying through the world).