Instances

What is an instance

Instances are what replace "worlds" from Minecraft vanilla, those are lightweight and should offer similar properties. There are multiple instances implementation, currently InstanceContainer and SharedInstance (both are explained below)

All instances can be accessed by using the InstanceManager or by getting an entity instance

InstanceManager instanceManager = MinecraftServer.getInstanceManager()
// Or
Entity#getInstance

Internally, the default Instance class have its own sets to store the entities in it, but all chunk based methods are abstract and meant to be implemented by a subclass

InstanceContainer

"Container" here means that this is an instance that can store chunks. And as every instance, have its own sets of entities

You can create an InstanceContainer by calling:

InstanceContainer instanceContainer = instanceManager.createInstanceContainer();

In order to have a valid world generation, you need to specify which ChunkGenerator the instance should use, without it no chunk can be generated. (check here to make your own)

instance.setChunkGenerator(YOUR_GENERATOR);

SharedInstance

A SharedInstance needs to have an InstanceContainer linked to it. The "Shared" means that this is an instance that takes all of its chunks from its parent instance container

What does it mean? That if you break or place a block to the instance container, the shared instance will also reflect the change (same if you place a block using the shared instance methods, changes will be reflected in the instance container and all of its shared instances)

You can create a SharedInstance using:

SharedInstance sharedInstance = instanceManager.createSharedInstance(instanceContainer);

Create your own Instance type

You are able to create your own class extending Instance and add entities to it.

In this case, the only thing you need to be aware of is that all instances need to be registered manually in the instance manager.

instanceManager.registerInstance(YOUR_CUSTOM_INSTANCE);

This method is ONLY required if you instantiate your instance object manually, InstanceManager#createInstanceContainer and InstanceManager#createSharedInstance already register the instance internally.