User Tools

Site Tools


tutorial:items

This is an old revision of the document!


Adding an Item

Introduction

Adding a basic item is one of the first steps in modding. You're going to need to create an Item object, register it, and give it a texture. To add additional behavior to the item you will need a custom Item class. In this tutorial and all future ones, the “tutorial” namespace is used as a placeholder. If you have a separate modid, feel free to use it instead.

Registering an Item

First, create an instance of Item. We'll store it at the top of our initializer class. The constructor takes in an Item.Settings (or a FabricItemSettings) object, which is used to set item properties such as the inventory category, durability, and stack count.

  1. public class ExampleMod implements ModInitializer {
  2.  
  3. // an instance of our new item
  4. public static final Item FABRIC_ITEM = new Item(new FabricItemSettings().group(ItemGroup.MISC));
  5. [...]
  6. }

You'll use the vanilla registry system for registering new content. The basic syntax is Registry#register(Registry Type, Identifier, Content). Registry types are stored as static fields in the Registry object, and the identifier is what labels your content. Content is an instance of whatever you're adding. This can be called anywhere as long as it occurs during initialization.

  1. public class ExampleMod implements ModInitializer {
  2.  
  3. // an instance of our new item
  4. public static final Item FABRIC_ITEM = new Item(new FabricItemSettings().group(ItemGroup.MISC));
  5.  
  6. @Override
  7. public void onInitialize() {
  8. Registry.register(Registry.ITEM, new Identifier("tutorial", "fabric_item"), FABRIC_ITEM);
  9. }
  10. }

Your new item has now been added to Minecraft. Run the runClient gradle task to see it in action.

Adding Item textures

Registering a texture for an item requires an item model .json file and a texture image. You're going to need to add these to your resource directory. The direct path of each is:

  Item model: .../resources/assets/tutorial/models/item/fabric_item.json
  Item texture: .../resources/assets/tutorial/textures/item/fabric_item.png

Our example texture can be found here.

If you registered your item properly in the first step, your game will complain about a missing texture file in a fashion similar to this:

  [Server-Worker-1/WARN]: Unable to load model: 'tutorial:fabric_item#inventory' referenced from: tutorial:fabric_item#inventory: java.io.FileNotFoundException: tutorial:models/item/fabric_item.json

It conveniently tells you exactly where it expects your asset[s] to be found– when in doubt, check the log.

A basic item model template is:

{
  "parent": "builtin/generated",
  "textures": {
    "layer0": "tutorial:item/fabric_item"
  }
}

The parent of your item changes how it's rendered in the hand and comes in useful for things like block items in the inventory. “item/handheld” is used for tools that are held from the bottom left of the texture. textures/layer0 is the location of your image file.

Final textured result:

Creating an Item class

To add additional behavior to the item you will need to create an Item class. The default constructor requires an Item.Settings object.

  1. public class FabricItem extends Item {
  2.  
  3. public FabricItem(Settings settings) {
  4. super(settings);
  5. }
  6. }

A practical use-case for a custom item class would be making the item play a sound when you right click with it:

  1. public class FabricItem extends Item {
  2.  
  3. public FabricItem(Settings settings) {
  4. super(settings);
  5. }
  6.  
  7. @Override
  8. public TypedActionResult<ItemStack> use(World world, PlayerEntity playerEntity, Hand hand) {
  9. playerEntity.playSound(SoundEvents.BLOCK_WOOL_BREAK, 1.0F, 1.0F);
  10. return TypedActionResult.success(playerEntity.getStackInHand(hand));
  11. }
  12. }

Replace the old Item object with an instance of your new item class:

  1. public class ExampleMod implements ModInitializer {
  2.  
  3. // an instance of our new item
  4. public static final FabricItem FABRIC_ITEM = new FabricItem(new FabricItemSettings().group(ItemGroup.MISC));
  5. [...]
  6. }

If you did everything correctly, using the item should now play a sound.

What if I want to change the stack size of my item?

For this you would use maxCount(int size) inside FabricItemSettings to specify the max stack size. Note that if your item is damageable you cannot specify a maximum stack size or the game will throw a RuntimeException.

  1. public class ExampleMod implements ModInitializer {
  2.  
  3. // an instance of our new item, where the maximum stack size is 16
  4. public static final FabricItem FABRIC_ITEM = new FabricItem(new FabricItemSettings().group(ItemGroup.MISC).maxCount(16));
  5. [...]
  6. }

Next Steps

tutorial/items.1604302332.txt.gz · Last modified: 2020/11/02 07:32 by leocth2