PREREQUISITES

Make sure you've completed the datagen setup and created your first item.

For each item model we want to generate, we must create two separate JSON files:

1. An item model, which defines the textures, rotation and overall look of the item. It goes in the generated/assets/example-mod/models/item directory.
2. A client item, which defines which model should be used based on various criteria, such as components, interactions and more. It goes in the generated/assets/example-mod/items directory.

Setup

First, we will need to create our model provider.

Create a class that extends FabricModelProvider, and implement both abstract methods: generateBlockStateModels and generateItemModels. Then, create a constructor matching super.

public class ExampleModModelProvider extends FabricModelProvider {
	public ExampleModModelProvider(FabricDataOutput output) {
		super(output);
	}

	@Override
	public void generateBlockStateModels(BlockModelGenerators blockStateModelGenerator) {
	}

	@Override
	public void generateItemModels(ItemModelGenerators itemModelGenerator) {
	}

	@Override
	public String getName() {
		return "ExampleModModelProvider";
	}
}

Register this class in your DataGeneratorEntrypoint within the onInitializeDataGenerator method.

Built-In Item Models

For item models, we will be using the generateItemModels method. Its parameter ItemModelGenerators itemModelGenerator is responsible for generating the item models and also contains methods for doing so.

Here's a reference of the most commonly used item model generator methods.

Simple

Simple item models are the default, and they're what most Minecraft items use. Their parent model is GENERATED. They use their 2D texture in the inventory, and are rendered in 3D in-game. An example would be boats, candles or dyes.

itemModelGenerator.generateFlatItem(ModItems.RUBY, ModelTemplates.FLAT_ITEM);

Handheld

Handheld item models are generally used by tools and weapons (axes, swords, trident). They are rotated and positioned a little differently from the simple models to look more natural in hand.

itemModelGenerator.generateFlatItem(ModItems.GUIDITE_AXE, ModelTemplates.FLAT_HANDHELD_ITEM);

Dyeable

The method for dyeable items generates a simple item model and a client item which specifies the tint color. This method requires a default decimal color value, which is used when the item is not dyed. The default value for leather is 0xFFA06540.

itemModelGenerator.generateDyedItem(ModItems.LEATHER_GLOVES, 0xFFA06540);

IMPORTANT

You have to add your item to the ItemTags.DYEABLE tag to be able to dye it in your inventory!

Conditional

Next, we'll look into generating item models that change their visual based when a specific condition, indicated by the second parameter BooleanProperty, is met. Here are some of them:

Property	Description
IsKeybindDown	True when a specified key is pressed.
IsUsingItem	True when the item is being used (e.g. when blocking with a shield).
Broken	True when the item has 0 durability (e.g. elytra changes texture when broken).
HasComponent	True when the item has a certain component.

The third and fourth parameters are the models to be used when the property is true or false, respectively.

itemModelGenerator.generateBooleanDispatch(
				ModItems.FLASHLIGHT,
				ItemModelUtils.isUsingItem(),
				ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.FLASHLIGHT, "_lit", ModelTemplates.FLAT_ITEM)),
				ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.FLASHLIGHT, ModelTemplates.FLAT_ITEM))
);

IMPORTANT

To obtain the ResourceLocation that is passed in ItemModelUtils.plainModel(), always use itemModelGenerator.createFlatItemModel(), otherwise only the client items will be generated, not the item models!

Composite

Composite item models are composed of one or more textures layered on top of each other. There aren't any vanilla methods for this; you have to use the itemModelGenerator's itemModelOutput field, and call accept() on it.

ItemModel.Unbaked hoe = ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.ENHANCED_HOE, ModelTemplates.FLAT_ITEM));
ItemModel.Unbaked hoePlus = ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.ENHANCED_HOE, "_plus", ModelTemplates.FLAT_ITEM));

itemModelGenerator.itemModelOutput.accept(
				ModItems.ENHANCED_HOE,
				ItemModelUtils.composite(hoe, hoePlus)
);

Select

Renders an item model based on the value of a specific property. These are some of them:

Property	Description
ContextDimension	Renders an item model based on the dimension in which the player is (Overworld, Nether, End).
MainHand	Renders an item model when the item is equipped in player's main hand.
DisplayContext	Renders an item model based on where the item is (ground, fixed, head, ...).
ContextEntityType	Renders an item model based on the entity holding the item.

In this example, the item changes texture when traveling between dimensions: it's green in the Overworld, red in the Nether, and black in the End.

ItemModel.Unbaked crystalOverworld = ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.DIMENSIONAL_CRYSTAL, "_overworld", ModelTemplates.FLAT_ITEM));
ItemModel.Unbaked crystalNether = ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.DIMENSIONAL_CRYSTAL, "_nether", ModelTemplates.FLAT_ITEM));
ItemModel.Unbaked crystalEnd = ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.DIMENSIONAL_CRYSTAL, "_end", ModelTemplates.FLAT_ITEM));

itemModelGenerator.itemModelOutput.accept(
				ModItems.DIMENSIONAL_CRYSTAL,
				ItemModelUtils.select(new ContextDimension(),
								ItemModelUtils.when(Level.OVERWORLD, crystalOverworld),
								ItemModelUtils.when(Level.NETHER, crystalNether),
								ItemModelUtils.when(Level.END, crystalEnd)
				)
);

Range Dispatch

Renders an item model based on the value of a numeric property. Takes in an item and list of variants, each paired with a value. Examples include the compass, the bow, and the brush.

There are quite a few supported properties, here are some examples:

Property	Description
Cooldown	Renders an item model based on the item's remaining cooldown.
Count	Renders an item model based on the stack size.
UseDuration	Renders an item model based on how long the item is being used.
Damage	Renders an item model based on attack damage (minecraft:damage component).

This example uses the Count, changing the texture from one knife up to three based on the stack size.

ItemModel.Unbaked knifeOne = ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.THROWING_KNIVES, "_one", ModelTemplates.FLAT_ITEM));
ItemModel.Unbaked knifeTwo = ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.THROWING_KNIVES, "_two", ModelTemplates.FLAT_ITEM));
ItemModel.Unbaked knifeThree = ItemModelUtils.plainModel(itemModelGenerator.createFlatItemModel(ModItems.THROWING_KNIVES, "_three", ModelTemplates.FLAT_ITEM));

itemModelGenerator.itemModelOutput.accept(
				ModItems.THROWING_KNIVES,
				ItemModelUtils.rangeSelect(
								new Count(false),
								List.of(
												ItemModelUtils.override(knifeOne, 1.0F),
												ItemModelUtils.override(knifeTwo, 2.0F),
												ItemModelUtils.override(knifeThree, 3.0F)
								)
				)
);

Custom Item Models

Generating item models doesn't have to be done with vanilla methods only; you can, of course, create your own. In this section, we will create a custom model for a balloon item.

All fields and methods for this part of the tutorial are declared in a static inner class called CustomItemModelGenerator.

Show CustomItemModelGenerator

public static class CustomItemModelGenerator {
	//:::custom-item-model:::
	public static final ModelTemplate SCALED2X = item("scaled2x", TextureSlot.LAYER0);
	//:::custom-item-model:::

	//:::custom-item-datagen-method
	public static void registerScaled2x(Item item, ItemModelGenerators generator) {
		ResourceLocation itemModel = SCALED2X.create(item, TextureMapping.singleSlot(TextureSlot.LAYER0, ModelLocationUtils.getModelLocation(item)), generator.modelOutput);
		generator.itemModelOutput.accept(item, ItemModelUtils.plainModel(itemModel));
	}

	//:::custom-item-datagen-method

	@SuppressWarnings("SameParameterValue")
	//:::custom-item-model:::

	private static ModelTemplate item(String parent, TextureSlot requiredTextureKeys) {
		return new ModelTemplate(Optional.of(ResourceLocation.fromNamespaceAndPath(ExampleMod.MOD_ID, "item/" + parent)), Optional.empty(), requiredTextureKeys);
	}

	//:::custom-item-model:::
}

Creating a Custom Parent

First, let's create a parent item model that defines how the item looks in-game. Let's say we want the balloon to look like simple item models, but scaled up.

To do this, we'll create resources/assets/example-mod/models/item/scaled2x.json, set the parent to be the item/generated model, and then override the scaling.

{
  "parent": "item/generated",
  "display": {
    "ground": {
      "rotation": [ 0, 0, 0 ],
      "translation": [ 0, 2, 0],
      "scale":[ 1, 1, 1 ]
    },
    "head": {
      "rotation": [ 0, 180, 0 ],
      "translation": [ 0, 13, 7],
      "scale":[ 2, 2, 2 ]
    },
    "thirdperson_righthand": {
      "rotation": [ 0, 0, 0 ],
      "translation": [ 0, 3, 1 ],
      "scale": [ 1.1, 1.1, 1.1 ]
    },
    "firstperson_righthand": {
      "rotation": [ 0, -90, 25 ],
      "translation": [ 1.13, 3.2, 1.13],
      "scale": [ 1.36, 1.36, 1.36 ]
    }
  }
}

This will make the model twice as big as the simple ones.

Creating the ModelTemplate

Next, we need to create an instance of the ModelTemplate class. It will represent the actual parent item model inside our mod.

public static final ModelTemplate SCALED2X = item("scaled2x", TextureSlot.LAYER0);

private static ModelTemplate item(String parent, TextureSlot requiredTextureKeys) {
	return new ModelTemplate(Optional.of(ResourceLocation.fromNamespaceAndPath(ExampleMod.MOD_ID, "item/" + parent)), Optional.empty(), requiredTextureKeys);
}

The item() method creates a new ModelTemplate instance, pointing to the scaled2x.json file we created earlier.

TextureSlot LAYER0 represents the #layer0 texture variable, which will then be replaced by an identifier pointing to a texture.

Adding a Custom Datagen Method

The last step is creating a custom method, which will be called in the generateItemModels() method and will be responsible for generating our item models.

public static void registerScaled2x(Item item, ItemModelGenerators generator) {
	ResourceLocation itemModel = SCALED2X.create(item, TextureMapping.singleSlot(TextureSlot.LAYER0, ModelLocationUtils.getModelLocation(item)), generator.modelOutput);
	generator.itemModelOutput.accept(item, ItemModelUtils.plainModel(itemModel));
}

Let's go over what the parameters are for:

1. Item item: The item, for which we are generating the models.
2. ItemModelGenerators generator: the same that get passed into the generateItemModels() method. Used for its fields.

First, we get the ResourceLocation of the item with SCALED2X.create(), passing in a TextureMapping and the modelOutput from our generator parameter.

Then, we'll use another of its fields, the itemModelOutput (which essentially works as a consumer), and use the accept() method, so that the models are actually generated.

Calling the Custom Method

Now, we only need to call our method in the generateItemModels() method.

CustomItemModelGenerator.registerScaled2x(ModItems.BALLOON, itemModelGenerator);

Don't forget to add a texture file!

Download Balloon Texture

Sources and Links

You can view the example tests in Fabric API, this documentation's Example Mod for more information.