Table of Contents
Добавление BlockEntity
Введение
BlockEntity в основном используется для хранения данных внутри блоков. Прежде чем создать его, вам понадобится Блок. В этом руководстве будет рассказано о создании вашего класса BlockEntity и его регистрации.
Создание BlockEntity
Простейший BlockEntity просто расширяет BlockEntity
и использует конструктор по умолчанию. Это вполне допустимо, но не предоставит вашему блоку никаких специальных функций.
public class DemoBlockEntity extends BlockEntity { public DemoBlockEntity(BlockPos pos, BlockState state) { super(ExampleMod.DEMO_BLOCK_ENTITY, pos, state); } }
Ниже будет показано, как создать поле ExampleMod.DEMO_BLOCK_ENTITY
.
Вы можете просто добавить переменные в этот скелет класса или реализовать такие интерфейсы, как Tickable
и Inventory
, чтобы добавить больше функциональности. Tickable
предоставляет один метод tick()
, который вызывается один раз за тик для каждого загруженного экземпляра вашего блока в мире, в то время как Inventory
позволяет вашему BlockEntity взаимодействовать с автоматизацией, такой как воронки - вероятно, позже будет отдельный туториал, полностью посвященный этому интерфейсу.
Регистрация вашего BlockEntity
Как только вы создадите класс BlockEntity
, вам нужно будет зарегистрировать его, чтобы он начал функционировать. Первым шагом этого процесса является создание BlockEntityType
, который связывает ваши Block
и BlockEntity
вместе. Предполагая, что ваш Block
был создан и сохранен в локальной переменной DEMO_BLOCK
, вы должны создать соответствующий BlockEntityType
со строкой ниже. В этом руководстве идентификатор BlockEntity - tutorial:demo_block_entity
.
BlockEntityType
должен быть зарегистрирован в вашем методе onInitialize
, это необходимо для того, чтобы он был зарегистрирован в нужное время.
public static BlockEntityType<DemoBlockEntity> DEMO_BLOCK_ENTITY; @Override public void onInitialize() { DEMO_BLOCK_ENTITY = Registry.register(Registry.BLOCK_ENTITY_TYPE, "tutorial:demo_block_entity", FabricBlockEntityTypeBuilder.create(DemoBlockEntity::new, DEMO_BLOCK).build(null)); }
Connecting a Block Entity to a Block
Once your BlockEntityType
has been created and registered, you'll need a block that is associated with it. You can do this by implementing BlockEntityProvider
and overriding createBlockEntity
. Each time your block is placed, your Block Entity will spawn alongside it.
public class DemoBlock extends Block implements BlockEntityProvider { [...] @Override public BlockEntity createBlockEntity(BlockPos pos, BlockState state) { return new DemoBlockEntity(pos, state); } }
Serializing Data
If you want to store any data in your BlockEntity
, you will need to save and load it, or it will only be held while the BlockEntity
is loaded, and the data will reset whenever you come back to it. Luckily, saving and loading is quite simple - you only need to override writeNbt()
and readNbt()
.
writeNbt()
returns a NBTCompound
, which should contain all of the data in your BlockEntity
. This data is saved to the disk and also send through packets if you need to sync your BlockEntity
data with clients. It is very important to call the default implementation of writeNbt
, as it saves “Identifying Data” (position and ID) to the tag. Without this, any further data you try and save will be lost as it is not associated with a position and BlockEntityType
. Knowing this, the example below demonstrates saving an integer from your BlockEntity
to the tag. In the example, the integer is saved under the key “number”
- you can replace this with any string, but you can only have one entry for each key in your tag, and you will need to remember the key in order to retrieve the data later.
public class DemoBlockEntity extends BlockEntity { // Store the current value of the number private int number = 7; public DemoBlockEntity(BlockPos pos, BlockState state) { super(ExampleMod.DEMO_BLOCK_ENTITY, pos, state); } // Serialize the BlockEntity @Override public void writeNbt(NbtCompound tag) { // Save the current value of the number to the tag tag.putInt("number", number); super.writeNbt(tag); } }
In order to retrieve the data later, you will also need to override readNbt
. This method is the opposite of writeNbt
- instead of saving your data to a NBTCompound
, you are given the tag which you saved earlier, enabling you to retrieve any data that you need. As with writeNbt
, it is essential that you call super.readNbt
, and you will need to use the same keys to retrieve data that you saved. To retrieve, the number we saved earlier, see the example below.
// Deserialize the BlockEntity @Override public void readNbt(NbtCompound tag) { super.readNbt(tag); number = tag.getInt("number"); }
Once you have implemented the writeNbt
and readNbt
methods, you simply need to ensure that they are called at the right time. Whenever your BlockEntity
data changes and needs to be saved, call markDirty()
. This will force the writeNbt
method to be called when the world is next saved by marking the chunk which your block is in as dirty. As a general rule of thumb, simply call markDirty()
whenever you change any custom variable in your BlockEntity
class.
Sync data from server to client
The data is read in the server world usually. Sometimes you may have to sync all or some of the data to the client, for example, for renderering.
For version 1.17.1 and below, implement BlockEntityClientSerializable
from the Fabric API. This class provides the fromClientTag
and toClientTag
methods, which work much the same as the previously discussed readNbt
and writeNbt
methods, except that they are used specifically for sending to and receiving data on the client. You may simply call readNbt
and writeNbt
in the fromClientTag
and toClientTag
methods.
For version 1.18 and above, override toUpdatePacket
and toInitialChunkDataNbt
:
@Nullable @Override public Packet<ClientPlayPacketListener> toUpdatePacket() { return BlockEntityUpdateS2CPacket.create(this); } @Override public NbtCompound toInitialChunkDataNbt() { return createNbt(); }
Block Entity Ticking
1.17 has added static ticking, where before you'd implement the Tickable
interface. For your block to tick, you would normally use getTicker
in Block
, linking back to a Block Entity
. See below for the common implementation of ticking.
In your Block
class:
public class DemoBlock extends BlockWithEntity { [...] @Override public BlockRenderType getRenderType(BlockState state) { // With inheriting from BlockWithEntity this defaults to INVISIBLE, so we need to change that! return BlockRenderType.MODEL; } @Override public <T extends BlockEntity> BlockEntityTicker<T> getTicker(World world, BlockState state, BlockEntityType<T> type) { return checkType(type, ExampleMod.DEMO_BLOCK_ENTITY, (world1, pos, state1, be) -> DemoBlockEntity.tick(world1, pos, state1, be)); }
And in your Block Entity
:
public class DemoBlockEntity extends BlockEntity { public DemoBlockEntity(BlockPos pos, BlockState state) { super(ExampleMod.DEMO_BLOCK_ENTITY, pos, state); } public static void tick(World world, BlockPos pos, BlockState state, DemoBlockEntity be) { [...] } }
Overview
You should now have your very own BlockEntity
, which you can expand in various ways to suit your needs. You registered a BlockEntityType
, and used it to connect your Block
and BlockEntity
classes together. Then, you implemented BlockEntityProvider
in your Block
class, and used the interface to provide an instance of your new BlockEntity
. You also learned how to save data to your BlockEntity
, how to retrieve for use later, and finally, you learned how to add ticking to it.