Forge Event for EXP Orb Pickup

[charsmud]

Hello!  I am trying to do something when the player picks up an XP orb.  I am using the following Event code for detecting XP orbs:

 

@ForgeSubscribe
public void onPlayerEntityInteract(EntityItemPickupEvent event)
{
	System.out.println("");
	if(event.entity instanceof EntityXPOrb)
	{
		System.out.println(" :D");
		int xpAmt = ((EntityXPOrb)event.entity).getXpValue();
		int amtOfEnhance = 0;
		if(event.entityPlayer.inventory.hasItem(TimeTraveler.expEnhance.itemID))
		{
			ItemStack[] items = event.entityPlayer.inventory.mainInventory;
			for(int i = 0; i < 35; i++)
			{
				if(items[i].getItem() instanceof ItemExpEnhance)
				{
					amtOfEnhance++;
				}
			}
		}
		System.out.println(amtOfEnhance);
		int newXpAmt = (amtOfEnhance * 2) * (xpAmt);
		event.entityPlayer.experience = event.entityPlayer.experience + newXpAmt;
	}
}
}

 

however, " :D" never prints and amtOfEnhance does not print as well.  Any idea?

[Draco18s]

Do this:

		System.out.println(event.entity);
	if(event.entity instanceof EntityXPOrb)

 

That'll tell you what's going on.

[charsmud]

Nothing is printed when I pick up an XP orb. 

[EdgarAllen]

EntityXPOrb is not an EntityItem. I don't think there is an event that get fired off when you interact with xp orbs. See "onCollideWithPlayer" in both EntityXPOrb and EntityItem and you can see where that event is getting sent from, and the lack of any event in EntityXPOrb.

 

[charsmud]

I looked at those methods, and I didn't see anything that would help.  I need to essentially change the amount of xp an EntityXPOrb gives you based on certain conditions:  any ideas?

[coolAlias]

One way would be to intercept EntityXPOrb when they join the world and spawn a new xp orb in its place:

@ForgeSubscribe
public void onEntityJoin(EntityJoinWorldEvent event) {
if (event.entity instanceof EntityXPOrb) {
// first spawn a new xp orb entity with amount of xp you want
event.entity.setDead(); // kill the old xp orb
}
}

You don't even have to make a new class, just use the vanilla xp orb's constructor:

public EntityXPOrb(World world, double x, double y, double z, int xpAmount);

You can see from that how easy this should be to adjust the amount. It doesn't looked like it is capped at any max value other than the limits of Short values.

 

[Draco18s]

One way would be to intercept EntityXPOrb when they join the world and spawn a new xp orb in its place:

@ForgeSubscribe
public void onEntityJoin(EntityJoinWorldEvent event) {
if (event.entity instanceof EntityXPOrb) {
// first spawn a new xp orb entity with amount of xp you want
event.entity.setDead(); // kill the old xp orb
}
}

You don't even have to make a new class, just use the vanilla xp orb's constructor:

public EntityXPOrb(World world, double x, double y, double z, int xpAmount);

You can see from that how easy this should be to adjust the amount. It doesn't looked like it is capped at any max value other than the limits of Short values.

 

The new one would then throw its OWN EntityJoinWorldEvent, which would be bad.  You'd be better off modifying the properties of the one that joined the world.

[coolAlias]

Excellent point. I was just showing that it's possible. Anyway, as Draco said you should just use reflection API or some other method of changing the private xpValue field. If you don't want to do it that way, then your best bet would be what I showed, but use a custom entity that extends xp orb instead so you avoid the nasty recursion when the entity joins the world (unless you are familiar with ASM, then you can do as diesieben pointed out and make a core mod).

[GotoLink]

You can modify the values in xp orb without reflection. Just use the NBT methods:

 

NBTTagCompound nbt = new NBTTagCompound();
xpOrb.writeEntityToNBT(nbt);
nbt.setShort("Value", nbt.getShort("Value")*2);//beware out of Short range values 
xpOrb.readEntityFromNBT(nbt);

 

I'd recommend using the LivingUpdateEvent and perform collision detection for xp orb around the player. This way you can be player specific

[charsmud]

@GotoLink, that seems to be the thing I want to do:  However, I cannot seem to find a method or variable that I can use to check if the xp orb is colliding with the player or not. 

[Draco18s]

    public void onCollideWithPlayer(EntityPlayer par1EntityPlayer)
    {
        if (!this.worldObj.isRemote)
        {
            if (this.field_70532_c == 0 && par1EntityPlayer.xpCooldown == 0)
            {
                par1EntityPlayer.xpCooldown = 2;
                this.playSound("random.orb", 0.1F, 0.5F * ((this.rand.nextFloat() - this.rand.nextFloat()) * 0.7F + 1.8F));
                par1EntityPlayer.onItemPickup(this, 1);
                par1EntityPlayer.addExperience(this.xpValue);
                this.setDead();
            }
        }
    }

 

There's no hook there.  I don't think you'll be able to do what you want to be able to do.

[GotoLink]

With a player instance taken from LivingUpdateEvent:

            AxisAlignedBB aabb= null;
            if (player.ridingEntity != null && !player.ridingEntity.isDead)
            {
                aabb= player.boundingBox.func_111270_a(player.ridingEntity.boundingBox).expand(1.0D, 0.0D, 1.0D);
            }
            else
            {
                aabb= player.boundingBox.expand(1.0D, 0.5D, 1.0D);
            }

            List list = player.worldObj.getEntitiesWithinAABB(EntityXPOrb.class, aabb);

            if (list != null)
            {
                for (int i = 0; i < list.size(); ++i)
                {
                    EntityXPOrb xpOrb = (EntityXPOrb)list.get(i);

                    if (!xpOrb.isDead)
                    {
                        //We are sure the xp orb is colliding here
                    }
                }
            }

[EdgarAllen]

Would that actually work in LivingUpdateEvent? There is a lot of stuff that is updated between when your code runs and when the xpOrbs do their thing in onCollideWithPlayer. Depending on what is updated there might be a difference in what orbs you collide with and what orbs are actually picked up.

 

 

If you are targeting 1.7.2, I'd add a hook to onCollideWithPlayer that fires an XpOrbPickedUpEvent. If you get it pulled now, it'll be in when the recommended build is set. That way you'll be all set going forward, not to mention any other mods that may want to mess with xpOrb pickups.