TagPrefixes and the power of .setIgnored()

What is a TagPrefix?

TagPrefixes are GTCEu Modern's way of streamlining applying item and block tags to Materials, along with some other functions. The TagPrefix class, available for use in startup and server scripts, contains a number of predefined TagPrefixes that associate potentially everything from drill heads to flawless gemstones with a material. A common and easy-to-understand example is TagPrefix.ingot, which associates with all Materials that have an IngotProperty and thus an associated ingot item, including custom ones defined via KubeJS. TagPrefixes provide localization, item and block tagging, and influence many crafting recipes, and are integral to the functioning of GTCEu's material definition system.

What TagPrefixes are there?

A list of all availabe TagPrefixes can be found in GTCEu Modern's GitHub or in the .JAR file, in the class TagPrefix.

What is .setIgnored()?

While trawling thorugh GTCEu Modern's codebase, or simply by playing Minecraft, you may have noticed that GTCEu Modern treats some vanilla materials differently. For example, iron ingots are a vanilla item, yet GTCEu Modern does not create a duplicate iron ingot, as its Material definition would suggest it is meant to do. Instead, the GTCEu Modern Material entry for iron treats the vanilla iron ingot as the material's ingot, and thus produces no duplicates. This functionality is governed by TagPrefixes, and can also be harnessed by packmakers for their own custom items, or when writing compatibility between GTCEu Modern and another mod.

Okay, but how do I use this?

This functionality can be leveraged in the material modification event, which is a startup event. The material modification event occurs in Minecraft's boot sequence after Material registration is finalized, but before the Material registry is closed; you won't be able to define any new Materials using it. The following calls are available for each TagPrefix: - .setIgnored() with one input parameter: Takes a Material as input and prevents GTCEu from associating that specific TagPrefix with that Material. - .setIgnored() with two input parameters: Takes a Material and an Item or Block (or any class that that implements the ItemLike interface) as input; causes GTCEu to treat the passed ItemLike as whatever item the TagPrefix would have originally generated for the Material. An ItemLike... varargs in the form of a JS array may also be passed to perform the action on multiple blocks and/or items at once. - .removeIgnored(): takes a Material as input and re-enables generation of the item associated with the TagPrefix for that material.

!!! caution "Beware of Item.of()!" The classic way to retrieve an Item in KubeJS, namely the Item.of() wrapper, doesn't work here. You will need to directly pass an ItemLike from a Java class for .setIgnored() to work correctly.

A more illustrative example, using some Applied Energistics 2 items:

setignored_usage_example.js

GTCEuStartupEvents.materialModification(event => { // (1)
    TagPrefix.gemChipped.setIgnored(GTMaterialRegistry.getMaterial("fluix_crystal")) // (2)
    TagPrefix.rock.setIgnored(GTMaterialRegistry.getMaterial("sky_stone"), AEBlocks.SKY_STONE_BLOCK) // (3)
    TagPrefix.ingot.removeIgnored(GTMaterials.Iron) // (4)
})

1. This event has no methods such as event.create(), as it is not intended to be used to create anything, only tweak pre-existing Material associations. In fact, this event has no accessible methods whatsoever. 2. This call prevents GTCEu Modern from creating a chipped gem variant of the custom 'fluix_crystal' Material. 3. This call makes GTCEu Modern associate AE2's Sky Stone block as a rock type (like vanilla stone is associated with the GTCEu Modern stone Material) with the custom 'sky_stone' Material. It may be necessary to manually load whatever data definition class contains the ItemLike you wish to associate with your Material, depending on how the mod's author has provided KubeJS access to the modn's classes. 4. This call makes GTCEu Modern de-associate vanilla iron ingots from GTCEu Modern's iron Material entry, causing it to generate a duplicate iron ingot.

The Material for which you are adjusting the TagPrefix must be registered in GTCEu Modern's material registry; if this material is custom, this is done using GTCEuStartupEvents.registry(), as depicted in these docs.