Creating items

The simplest way

groovy

content.createItem(String name).register()

Simple right? Let's break it up:

content is a global variable.
createItem(String name) creates an item and returns it. The name is the registry name and must only consist of lower case letters and _.
register() registers the item. Without this the item will not appear in game.

Registering an item

The example above creates a simple item for you, but you can also create items yourself (to create custom behaviour). Use the following methods to register custom items.

groovy

content.registerItem(String name, Item item)

Texture

Minecraft's items need a texture (or multiple) and a model file which describes how the textures are rendered. If groovy can't find a model file it will generate a default file at .minecraft/groovy/assets/[pack id]/models/item/[item name].json. It will point to a texture you will need to place at .minecraft/groovy/assets/[pack id]/textures/items/[item name].png.

Translating the items name

By default, the items name will show up as item.[pack id].[item name].name. To change that you need add an entry to the lang file. GroovyScript generates a default lang file at .minecraft/groovy/assets/[pack id]/lang/en_us.lang.

Example

First create an item

groovy

content.createItem('heart_of_the_universe')

Let's assume that the pack id is nomifactory so that the item id will be nomifactory:heart_of_the_universe. Insert this line into the lang file.

ini

item.nomifactory.heart_of_the_universe.name=Heart of the universe

(item.nomifactory.heart_of_the_universe.name is the default generated translation key. You can change to anything you want.)
Finally, put a texture at .minecraft/groovy/assets/nomifactory/textures/items/heart_of_the_universe.png