[Minecraft - Forge 1.16] Make explosion from client.

#minecraft #forge #kotlin

I built Explosion Mod in following sequence.

Receive PlayerInteractEvent.LeftClickEmpty in client side.
Send ExplosionMessage to server side.
Make explosion in server side.

Code is written in Kotlin.

First, make ExplosionMessage class.

class ExplosionMessage(
    val x: Double,
    val y: Double,
    val z: Double
) {

    companion object {
        fun encode(message: ExplosionMessage, buf: PacketBuffer) {
            buf.writeDouble(message.x)
            buf.writeDouble(message.y)
            buf.writeDouble(message.z)
        }

        fun from(buf: PacketBuffer): ExplosionMessage {
            return ExplosionMessage(
                buf.readDouble(),
                buf.readDouble(),
                buf.readDouble()
            )
        }
    }
}

Prepare SimpleChannel.

class ExampleMod {

    private val channel: SimpleChannel = NetworkRegistry.newSimpleChannel(
        ResourceLocation(MOD_ID, "main"),
        { PROTOCOL_VERSION },
        PROTOCOL_VERSION::equals,
        PROTOCOL_VERSION::equals
    )

    init {
        channel.registerMessage(
            0,
            ExplosionMessage::class.java,
            ExplosionMessage::encode,
            ExplosionMessage::from,
            this::handle
        )

        MinecraftForge.EVENT_BUS.register(this)
    }

    ...

Receive PlayerInteractEvent.LeftClickEmpty.
This event is occurred in client side only.

    @SubscribeEvent
    fun on(event: PlayerInteractEvent.LeftClickEmpty) {
        val loc = Minecraft.getInstance().hitResult?.location
        if (loc == null) {
            return
        }

        logger.info("ExplosionMessage send: ${loc?.x} ${loc?.y} ${loc?.z} ")
        channel.sendToServer(ExplosionMessage(loc.x, loc.y, loc.z))
    }

Handle ExplosionMessage.

    fun handle(message: ExplosionMessage, context: Supplier<NetworkEvent.Context>) {
        logger.info("ExplosionMessage received: ${message.x} ${message.y}  ${message.z} ")

        ServerLifecycleHooks.getCurrentServer().overworld().explode(
            null,
            message.x,
            message.y,
            message.z,
            4.0F,
            Explosion.Mode.BREAK
        )
    }