[Forge 4.0.0.204] Entity spawn not synced properly

[SirEntropy]

I'm writing a mod to add a new type of boat: the Dinghy and an ItemDinghy that spawns the dinghy in a similar way as a vanilla boat. However, when I spawn a dinghy in the world, strange things happens: Instead of the dinghy appearing right in front of the player, the dinghy appears at position 0,0,0, then quickly moves to the correct position. I printed the position of both the client-side and server-side dinghy entities. The client-side dinghy has the correct position from the beginning (right in front of the player). The server-side dinghy starts with position 0,0,0, then quickly moves to the correct position.

 

This problem does not happen with the vanilla boat when the mod is installed.

 

The code that registers the dinghy entity is:

 

protected void registerEntity(Class<? extends Entity> entityClass, String entityName,
		int trackingRange, int updateFrequency, boolean sendsVelocityUpdates) {
	int id = ModLoader.getUniqueEntityId();
	EntityRegistry.registerModEntity(entityClass, entityName, id, mod, trackingRange,
			updateFrequency, sendsVelocityUpdates);
	EntityRegistry.registerGlobalEntityID(entityClass, entityName, id);
}
...
registerEntity(Dinghy.class, "EntityDinghy", 80, 3, false);

 

The code of Dinghy entity

 

public class Dinghy extends EntityAnyBoat {

public Dinghy(World world, double x, double y, double z) {
	super(world, x, y, z, 1.5f, 0.5f);
}

public Dinghy(World world) {
	super(world);
}

@Override
protected double getSpeedFactor() {
	return 0.1;
}

@Override
protected int getMaxHP() {
	return 100;
}

}


public abstract class EntityAnyBoat extends EntityBoat {

public EntityAnyBoat(World world, double x, double y, double z, float width, float height) {
	super(world, x, y, z);
	setSize(width, height);
	this.yOffset = this.height / 2.0F;
}

public EntityAnyBoat(World world) {
	super(world);
}

protected abstract double getSpeedFactor();

protected abstract int getMaxHP();
}

 

And the code of the Item that creates the dinghy:

 

public abstract class ItemAnyBoat extends Item {

public ItemAnyBoat(int par1) {
	super(par1);
	this.maxStackSize = 1;
	this.setTabToDisplayOn(CreativeTabs.tabTransport);
}

@Override
public ItemStack onItemRightClick(ItemStack itemStack, World world, EntityPlayer player) {

	if (!world.isRemote) {
                        // findBoatPosition has the same code that ItemBoat uses to find the spawn position of the boat
		Vec3 pos = WorldUtil.findBoatPosition(itemStack, world, player);
		if (pos != null) {
			world.spawnEntityInWorld(createBoat(world, pos));
			if (!player.capabilities.isCreativeMode) {
				--itemStack.stackSize;
			}
		}
	}
	return itemStack;
}

public abstract EntityAnyBoat createBoat(World world, Vec3 pos);

@Override
public String getTextureFile() {
	return SABResourceRegistry.ITEMS;
}
}

public class ItemDinghy extends ItemAnyBoat {

public ItemDinghy(int par1) {
	super(par1);
	setMaxStackSize(1);
	setIconIndex(items.DINGHY);
}

@Override
public EntityAnyBoat createBoat(World world, Vec3 pos) {
	return new Dinghy(world, pos.xCoord, pos.yCoord, pos.zCoord);
}



}

 

Could you please tell me what I'm doing wrong?

[SanAndreaP]

Don't use the ModLoader.getUniqueEntityID() method!

 

Use the EntityRegistry.findGlobalUniqueEntityId() instead.

[Quintinity]

Those do the exact same thing. The code for the ModLoader method is

 

    public static int getUniqueEntityId()
    {
        return EntityRegistry.findGlobalUniqueEntityId();
    }

[SanAndreaP]

hm, okay then, but I would rather use the method from the EntitiyRegistry instead of the ModLoader equivalent, because you don't have troubles then when Forge will be updated and something has changed in the ModLoader compatibility layer of forge.

 

Anyway, try to use this as the constructor of your boat entity:

public Dinghy(World world, double x, double y, double z) {
	super(world, x, y, z, 1.5f, 0.5f);
	setPosition(x, y, z);
}

 

Sometimes my entities spawn at 0,0,0 client-side, too. Then the server will teleport the client-side entity to the right location. But I would say it occurs only in 1 out of 25 spawns for me.

[SirEntropy]

hm, okay then, but I would rather use the method from the EntitiyRegistry instead of the ModLoader equivalent, because you don't have troubles then when Forge will be updated and something has changed in the ModLoader compatibility layer of forge.

 

Anyway, try to use this as the constructor of your boat entity:

public Dinghy(World world, double x, double y, double z) {
	super(world, x, y, z, 1.5f, 0.5f);
	setPosition(x, y, z);
}

 

Sometimes my entities spawn at 0,0,0 client-side, too. Then the server will teleport the client-side entity to the right location. But I would say it occurs only in 1 out of 25 spawns for me.

 

I tried it and it doesn't work. My problem is entities spawning at 0,0,0 at the server side.

 

Any other ideas on how to fix this problem?

[SirEntropy]

Update: I found the problem. Actually, there were two:

 

- The entity with position 0,0,0 is at the client-side. My mistake

- The problem is with EntityBoat.setPositionAndRotation2. The last parameter of this method (par9) is used by the EntityBoat class to smoothly move the client-side boat from its current position to the latest position reported by the server. The problem is the number of steps in that movement, stored in the attribute boatPosRotationIncrements, is calculated in a very weird way. See this snippet of EntityBoat.setPositionAndRotation2:

 

if (this.field_70279_a)
        {
            this.boatPosRotationIncrements = par9 + 5;
        }
        else
        {
           ...

            this.boatPosRotationIncrements = 3;
        }

 

The solution is to completely rewrite EntityBoat.onUpdate and EntityBoat.setPositionAndRotation2 in my subclass.