advanced-usage.md

Advanced Usage

Registry Event Listeners

Your mod may include data driven features, usually you would put these in your resources/data directory for your mod and Minecraft loads everything into it's dynamic registries just before the server boots.

These are registries that aren't listed in BuiltInRegistries, you can find all the registries that are like this in the RegistryDataLoader class.

If you prefer to programmatically add entries into these registries, you can do so by using the RegistryEventHandler, we provide the registry key for the registry we want to modify, and an event listener which will be invoked when that registry is loaded. This fires before the registry is frozen so you can register your entries.

It is important to note that you should register your event in your mod initializer. If you try to register your event too late, an exception will be thrown.

override fun onInitialize() {
    RegistryEventHandler.register(Registries.DIMENSION_TYPE) { (registry) ->
        Registry.register(registry, ResourceLocation.withDefaultNamespace("foo"), DimensionType(/* */))
    }
}

Injected Listener Providers

This allows us to dynamically add ListenerProviders depending on the specific event being broadcasted.

This may help performance instead, for example, instead of each minigame registering for a specific PlayerEvent then checking whether the player from that event belongs in a minigame. We can instead add an injected listener provider which gets the player's minigame then adds that minigame's listener provider.

Here's how this is used for minigame related events:

GlobalEventHandler.Server.addInjectedProvider { event, consumer ->
    if (event is ExtensionEvent) {
        return@addInjectedProvider
    }
    val minigames = ObjectOpenHashSet<Minigame>(3)
    if (event is PlayerEvent) {
        val minigame = event.player.getMinigame()
        if (minigame != null) {
            minigames.add(minigame)
        }
    }
    if (event is LocatedLevelEvent) {
        minigames.addAll(event.level.getMinigames(event.pos))
    } else if (event is LevelEvent) {
        minigames.addAll(event.level.getMinigames())
    }
    if (event is MinigameEvent) {
        minigames.add(event.minigame)
    }
    for (minigame in minigames) {
        consumer.accept(minigame.events.getInjectedProvider())
    }
}