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[1.15.2] Doubts about how Forge handles the spawn of custom entities.


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Hi everyone, I'm a bit confused on how Forge handles the spawn of custom entities. I have created a test project to show what confuses me (GitHub repository).


In my test mod I have created an entity called TestEntity that only has one extra boolean parameter called shorty that controls if the entity is rendered as block or as a slab (TestEntityRenderer checks this flag and renders one of two models accordingly).  Here is the code for the Entity class, readAdditional is overridden to read shorty from the NBT.

package com.github.neutrinokillerino.entitytest.entity;

import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityType;
import net.minecraft.nbt.CompoundNBT;
import net.minecraft.network.IPacket;
import net.minecraft.world.World;
import net.minecraftforge.fml.network.NetworkHooks;

public class TestEntity extends Entity {
	public boolean shorty = false;
	public TestEntity(EntityType<?> entityTypeIn, World worldIn) {
		super(entityTypeIn, worldIn);
		// TODO Auto-generated constructor stub

	protected void registerData() {
		// TODO Auto-generated method stub

	protected void readAdditional(CompoundNBT compound) {
		// TODO Auto-generated method stub
		this.shorty = compound.getBoolean("shorty");

	protected void writeAdditional(CompoundNBT compound) {
		// TODO Auto-generated method stub

	public IPacket<?> createSpawnPacket() {
		// TODO Auto-generated method stub
		return NetworkHooks.getEntitySpawningPacket(this);



Here is what confuses me, when I spawn the entity using the summon command /summon entitytest:test_entity ~ ~ ~ {shorty:true} the following happens (inspected using breakpoints on eclipse):

  1.  Constructor is called.entityID = 4247
  2.  readAdditional is called. NBT contains information passed through command and shorty is set totrue. entityID = 4247
  3.  createSpawnPacket is called. shorty has valuetrue. entityID = 4247
  4. Constructor is called again. entityID = 4248
  5.  Renderer is called with an  entity with ID 4247,shorty is false.


Why is the constructor called twice and why is shorty set to false again?


Something weird also happens when I create an item that spawns the entity. The item is PlacerItem and it's class is:

package com.github.neutrinokillerino.entitytest.item;

import com.github.neutrinokillerino.entitytest.init.ModEntityTypes;

import net.minecraft.entity.SpawnReason;
import net.minecraft.item.Item;
import net.minecraft.item.ItemUseContext;
import net.minecraft.nbt.CompoundNBT;
import net.minecraft.util.ActionResultType;
import net.minecraft.util.Direction;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.World;

public class PlacerItem extends Item {

	public PlacerItem(Properties properties) {
	public ActionResultType onItemUse(ItemUseContext context) {
		BlockPos blockpos = context.getPos();
		Direction direction = context.getFace();
		BlockPos blockpos1 = blockpos.offset(direction);
		World world = context.getWorld();
		if (!world.isRemote()) {
			CompoundNBT compound = new CompoundNBT();
			compound.putBoolean("shorty", true);
			ModEntityTypes.TEST_ENTITY.get().spawn(world, compound, null, null, blockpos1, SpawnReason.SPAWN_EGG, false, false);
		return ActionResultType.SUCCESS;



When using the item, the following happens:

  1. Constructor is called. entityID = 4254
  2.  createSpawnPacket is called.entityID = 4254
  3. Constructor is called. entityID = 4255
  4. Renderer is called. entityID = 4254

In this case, readAdditional is not called and the constructor is  called two times.


I have also tried to create a bifunction as the constructor but then the calls  get very messy.

I'd be grateful if anyone could clarify how Forge calls everything and how the spawn packet is handled.



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