[1.12.1] A problem with "toggle" functionality in entity processInteract() event

[jabelar]

So I'm updating my 1.7.10 mods to 1.12.1 and having a funny problem with the fact that now there are two hands to check during entity interactions.

 

In my mod I replicate (mostly) the EntityWolf sitting behavior. Basically it "toggles" -- if player interacts with nothing in the players hand(s) and if the entity is sitting it should stop sitting and if not sitting it should start sitting. However, for me the sitting wasn't working and I traced it down to the fact that processInteract() fires twice -- once for each hand -- and so it was toggling twice and basically cancelling itself. 

 

Now I know how to fix this -- I can check both hands. But the interesting thing is that I basically copied EntityWolf and so I wanted to see how they handled it and why my entity acts differently. The weird thing is that as far as I can see the EntityWolf code would have the same problem -- it fires twice and only checks one hand at a time. Here is the code from EntityWolf:

  public boolean processInteract(EntityPlayer player, EnumHand hand)
    {
        ItemStack itemstack = player.getHeldItem(hand);

        if (this.isTamed())
        {
            if (!itemstack.isEmpty())
            {
                if (itemstack.getItem() instanceof ItemFood)
                {
                    ItemFood itemfood = (ItemFood)itemstack.getItem();

                    if (itemfood.isWolfsFavoriteMeat() && ((Float)this.dataManager.get(DATA_HEALTH_ID)).floatValue() < 20.0F)
                    {
                        if (!player.capabilities.isCreativeMode)
                        {
                            itemstack.shrink(1);
                        }

                        this.heal((float)itemfood.getHealAmount(itemstack));
                        return true;
                    }
                }
                else if (itemstack.getItem() == Items.DYE)
                {
                    EnumDyeColor enumdyecolor = EnumDyeColor.byDyeDamage(itemstack.getMetadata());

                    if (enumdyecolor != this.getCollarColor())
                    {
                        this.setCollarColor(enumdyecolor);

                        if (!player.capabilities.isCreativeMode)
                        {
                            itemstack.shrink(1);
                        }

                        return true;
                    }
                }
            }

            if (this.isOwner(player) && !this.world.isRemote && !this.isBreedingItem(itemstack))
            {
                this.aiSit.setSitting(!this.isSitting());
                this.isJumping = false;
                this.navigator.clearPathEntity();
                this.setAttackTarget((EntityLivingBase)null);
            }
        }

 

You can see that the whole code will only check the hand passed in and if the wolf is tamed and there is nothing in that hand it will toggle the sitting. And the setSitting() method called is a simple setter that doesn't do any additional check to prevent toggling.

 

How the heck is that working? I actually think it doesn't really work but that the aiSit code is somehow correcting it elsewhere. The difference in my entity is that I keep track of sitting within my class, not the AI class, so probaly it has to do with that. However, still seems mysterious to me. What am I missing?

 

I can easily fix it in my code but am extremely curious about how it can possibly work in the vanilla code...

Edited September 10, 2017 by jabelar

[Draco18s]

The function is called twice: once for each hand. If both hands are empty, the "dog" will get toggled twice in a row.

You make no discrimination about which hand is being used (you do identify if the hand is holding food/dye/etc items, but the "dog" only sits when the hand is empty, and if both are empty, you process that interaction twice: sit, then unsit).

[jabelar]

21 minutes ago, Draco18s said:

The function is called twice: once for each hand. If both hands are empty, the "dog" will get toggled twice in a row.

You make no discrimination about which hand is being used (you do identify if the hand is holding food/dye/etc items, but the "dog" only sits when the hand is empty, and if both are empty, you process that interaction twice: sit, then unsit).

I know but that isn't my code -- that is the vanilla code! It works but it shouldn't. I think it should do what you said -- it will toggle twice and cancel, but it doesn't.

 

In my own entity I fixed it just like you said -- I only toggle if both hands are empty.

 

But why is the vanilla code working?

[Draco18s]

I don't know, but you can easily fix this by making it do nothing if the hand is the off-hand.

[jabelar]

1 minute ago, Draco18s said:

I don't know, but you can easily fix this by making it do nothing if the hand is the off-hand.

Actually not quite because I also didn't want it to toggle if only the main hand is empty. Like if the player has a breeding item in the off hand I didn't want sit to toggle. So basically when it fires I check that both hands are empty and then further do nothing if the hand is the off hand.

 

I got it working well, just the fact that the vanilla code should not work is driving me crazy!

[Draco18s]

It's called twice. All you have to do is check "is hand == mainhand" in that last if-block. That prevents an empty off-hand from making the "dog" sit.