AnvilUpdateEvents don't fire if the middle slot is empty

[leod]

Line 149 in RepairContainer.java (in 1.15.2, I don't know about 1.16) checks whether the middle slot in the anvil GUI is empty, and only if it isn't the onAnvilChange ForgeHook is called, which makes is making it pretty impossible for me to implement anvil recipes that don't need an item in the center. I've had to resort to making a coremod to implement this, but I don't think it should be that way.

 

The relevant lines look like this:

if (!itemstack2.isEmpty()) {
    if (!ForgeHooks.onAnvilChange(this, itemstack, itemstack2, this.outputSlot, this.repairedItemName, j)) {
        return;
    }

I don't think much of anything would break if the ForgeHook was to be moved in front of the first line to allow events to be sent with empty center slots.

 

If you're wondering why I would want to do what I'm doing, it's a flavor thing for the mod I'm working on and also lets me make it cost XP to get the output item, to keep it out of the early game.

[DavidM]

I’m pretty sure that the anvil is supposed to work that way (with a center item, since the anvil combines the two).

If you want a crafting method that turns one item into another at the cost of experience, you should make a custom crafting block instead.

Edited July 5, 2020 by DavidM

[leod]

I don't think I should have to create a custom crafting block when the anvil fulfills exactly what I need and the restriction is purely a technical one. You can already rename Items in it without a center item present, so it's not like the anvil is hardcoded to never do anything at all without a center item.

[DavidM]

On 7/5/2020 at 10:21 PM, leod said:

I don't think I should have to create a custom crafting block when the anvil fulfills exactly what I need

It doesn't fulfill your need, since it doesn't update when the middle item changes.

 

I would say that since anvil is almost never used without a middle item (renaming is its own case), it would bring extra fuss (unnecessary event subscriber calls) to fire the event subscriber when the middle item changes. It can be made to do stuff without a center item, but it shouldn't design-wise IMO.

However you could propose a PR and see what others think.

Edited July 7, 2020 by DavidM