Junferno

Thanks for responding! The goal here is to be able to spawn a custom mob instead whenever a specific vanilla mob is spawned. When the LivingSpawnEvent.SpecialSpawn event is called, the spawning of that mob is cancelled and the custom mob is spawned instead. Just through trial and error, I found that the event can only be subscribed to on the client-side. In the bigger picture, I want to be able to have the attributes of MonsterEntitys to be controlled by some external program that changes the values of the mob every few seconds, which is why I am just spawning a subclass of the Entity that contains methods allowing me to change their values. I feel as if this may be a bit unsafe, but I wasn't sure how else to approach this. Here's an example: ModClientEvents#onEntitySpawn @SubscribeEvent public static void onEntitySpawn(LivingSpawnEvent.SpecialSpawn event) { if(!(event.getEntity() instanceof CreeperEntity) || event.getEntity() instanceof FearCreeperEntity || !event.isCancelable()) return; CreeperEntity creeper = (CreeperEntity) event.getEntity(); FearCreeperEntity fcreeper = FearCreeperEntity.createFromCreeper(creeper); PacketSpawnFearMod packet = new PacketSpawnFearMod(fcreeper, event.getSpawner(), event.getSpawnReason()); packetRegister.sendToServer(packet); FearMod.LOGGER.info("Packet sent"); event.setCanceled(true); }

My idea here is being able to spawn a MobEntity in the World that the player is in when a certain client-side Event is triggered. Specifically, I need to be able to encode the MobEntity Object (or at least the EntityType Object with the position coordinates) as well as the AbstractSpawner and SpawnReason Objects through a packet to be spawned server-side (I might also need to pass in a World object since I'm not sure if MobEntity.getEntityWorld() would work server-side). As of now, I am only able to send primitive data-types or serializable non-vanilla Objects. I know that encoding non-serializable Objects such as Entity and World is not secure (and it gets an error if I try it anyway), but I'm not sure what else I could do. Thanks in advance! PacketSpawnFearMod.java (running this would get a java.io.NotSerializableException when I attempt to convert the MobEntity, AbstractSpawner, and SpawnReason fields of the PacketSpawnFearMod Object to byte arrays) package com.junferno.fearmod.packets; import com.junferno.fearmod.FearMod; import net.minecraft.entity.MobEntity; import net.minecraft.entity.SpawnReason; import net.minecraft.network.PacketBuffer; import net.minecraft.world.spawner.AbstractSpawner; import net.minecraftforge.common.MinecraftForge; import net.minecraftforge.event.entity.living.LivingSpawnEvent; import net.minecraftforge.fml.network.NetworkEvent; import java.io.*; import java.util.function.Supplier; public class PacketSpawnFearMod implements Serializable { private MobEntity entity; private AbstractSpawner spawner; private SpawnReason spawnReason; public PacketSpawnFearMod(MobEntity entity, AbstractSpawner spawner, SpawnReason spawnReason) { this.entity = entity; this.spawner = spawner; this.spawnReason = spawnReason; } public static byte[] objToByte(PacketSpawnFearMod packet) throws IOException { ByteArrayOutputStream byteStream = new ByteArrayOutputStream(); ObjectOutputStream objStream = new ObjectOutputStream(byteStream); objStream.writeObject(packet); return byteStream.toByteArray(); } public static Object byteToObj(byte[] bytes) throws IOException, ClassNotFoundException { ByteArrayInputStream byteStream = new ByteArrayInputStream(bytes); ObjectInputStream objStream = new ObjectInputStream(byteStream); return objStream.readObject(); } public PacketSpawnFearMod(PacketBuffer buf) { try { PacketSpawnFearMod packet = (PacketSpawnFearMod) byteToObj(buf.readByteArray()); this.entity = packet.entity; this.spawner = packet.spawner; this.spawnReason = packet.spawnReason; } catch (IOException | ClassNotFoundException e) { FearMod.LOGGER.error("Failed to read packet"); FearMod.LOGGER.error(e.toString()); } } public static void encode(PacketSpawnFearMod packet, PacketBuffer buf) { try { buf.writeByteArray(objToByte(packet)); } catch (IOException e) { FearMod.LOGGER.error("Failed to encode packet"); // java.io.NotSerializableException FearMod.LOGGER.error(e.toString()); } } public static void handle(final PacketSpawnFearMod packet, Supplier<NetworkEvent.Context> context) { NetworkEvent.Context ctx = context.get(); ctx.enqueueWork(() -> { MinecraftForge.EVENT_BUS.post(new LivingSpawnEvent.SpecialSpawn( packet.entity, packet.entity.getEntityWorld(), packet.entity.getPosX(), packet.entity.getPosY(), packet.entity.getPosZ(), packet.spawner, packet.spawnReason )); }); ctx.setPacketHandled(true); } } I am using Forge 1.16.4 with Java 1.8.0, Gradle 4.10.3, and IntelliJ IDEA Community Edition 2020 on Windows 10