Custom Backpacks

Creating Backpacks is done through data-packs. We will have to create the recipe where we also define our backpacks traits, gift the player the recipe so it appears in the crafting book, make backpacks translatable, and finally texture them.

If you need help creating a data pack, read through the minecraft wiki's Tutorials/Creating a data pack or follow along with Copper Backpack Data. A Copper Backpack for crafting and a Netherite Backpack for smithing is what we will re-create though this tutorial.

If you are creating a backpack for a mod you should use that mod's file path for the data & resource packs. For example if I was adding mods for the aether, I would create my data pack folders with the path data/aether/recipes and resource pack folders with the path assets/aether/textures. Also I would change references to other files (not crafting types or backpack items) would look like aether:backpacks/copper_backpack. If you are unsure about this you may use beansbackpacks  

Defining Your Data & Recipe

Backpack recipe's are similar to vanilla with a few key differences. Create a .json file with the path data/beansbackpacks/recipes/backpacks. This can be named with characters a-z, 0-9, _, all lowercase, no spaces, and should be recognizable since we need it later. The mod will only register new backpacks inside the recipes/backpacks folder, so if there are multiple recipes placing the extra recipes outside of backpacks but still in recipes will not register new traits for the backpack_id.

Firstly, the recipe type can be either beansbackpacks:crafting or beansbackpacks:smithing to determine whether this backpack is created in the crafting or smithing table. a vanilla minecraft type cannot be used since we cannot add nbt data to our result normally. The recipe's pattern is written the same as vanilla, you can use TheDestruc7i0n's Crafting Generator to create the vanilla crafting/smithing recipe and copy pattern & key for crafting or template, base, & addition for smithing.

Note for smithing, the NBT of the base gets copied to the new backpack.

crafting (Copper Backpack)	smithing (Netherite Backpack)
"type": "beansbackpacks:crafting", "pattern": [ "iBi", "i i", "iBi" ], "key": { "i": { "item": "minecraft:copper_ingot" }, "P": { "item": "minecraft:phantom_membrane" } }	"template": { "item": "minecraft:netherite_upgrade_smithing_template" }, "base": { "item": "beansbackpacks:metal_backpack" }, "addition": { "item": "minecraft:netherite_ingot" }

This is where we deviate from the vanilla recipes. Define the backpack_id. This is the identifier used to collect a backpack's traits and textures. The backpack_id should be a-z, 0-9, _, all lowercase, no spaces. It should also be unique, yet defines the backpack in question. For example, the backpack id copper describes the material it's crafted with and if copper is used in another pack, your recipe will still create a copper backpack.

"backpack_id": "copper"

Then we'll describe the backpack's traits. So far there are 4 traits you can specify, if you do not include a value it will assume the Traits of an Iron Backpack (Default Value).

Trait	Definition	Default Value
max_stacks	Maximum number of stacks this backpack can hold	7
fire_resistant	Item will not burn and will float in lava	false
fallback_name	The name used if no translation is provided	"Iron Backpack"
button_material	gold, amethyst, diamond, netherite, or none	"diamond"

That's it! your data and recipe is completed and your backpack in now in the game (in a completely un usable state). Below is what your recipe's could look like once you're done. Keep reading to finish adding your backpack.

crafting (Copper Backpack)	smithing (Netherite Backpack)
{ "type": "beansbackpacks:crafting", "backpack_id": "copper", "pattern": [ "iBi", "i i", "iBi" ], "key": { "i": { "item": "minecraft:copper_ingot" }, "B": { "item": "minecraft:phantom_membrane" } }, "traits": { "fallback_name": "Copper Backpack" } }	{ "type": "beansbackpacks:smithing", "backpack_id": "netherite", "template": { "item": "minecraft:netherite_upgrade_smithing_template" }, "base": { "item": "beansbackpacks:metal_backpack" }, "addition": { "item": "minecraft:netherite_ingot" }, "traits": { "max_stacks": 11, "fire_resistant": true, "fallback_name": "Netherite Backpack", "button_material": "netherite" }

If your backpack has multiple recipes, place any additional outside of recipes/backpacks and inside of recipes to avoid registering a backpack's traits twice. If the recipe is outside of backpacks then traits from that file will not be registered and aren't needed to be written twice. Click this block of text for an example of a second Copper Backpack recipe.

{
  "type": "beansbackpacks:crafting",
  "backpack_id": "copper",
  "pattern": [
      "B",
      "i",
      "B"
  ],
  "key": {
      "B": {
          "item": "minecraft:phantom_membrane"
      },
      "i": {
          "item": "minecraft:copper_block"
      }
   }
}

Giving Players Recipes

Recipe's do not appear in the vanilla Crafting Book by default, they must be rewarded to the player through advancements. These advancements do not appear in any menus and do not have any notifications through sounds or popups. Use misode's Advancement Generator. The preset recipes/combat/iron_chestplate is a good place to start. That gives the player the recipe for an Iron Chestplate once a player picks up an Iron Ingot or Crafts an Iron Chestplate. It specifies the Iron Chestplate recipe with "rewards": {"recipes": ["minecraft:iron_chestplate"] }. We can specify our own by replacing minecraft:iron_chestplate with beansbackpacks:backpacks/ followed by the the name of the file we called our recipe.

Click to see the Copper Backpack recipe be rewarded by collecting a copper ingot, phantom membrane, any metal backpack, or by crafting the Copper Backpack.

{
  "parent": "minecraft:recipes/root",
  "criteria": {
    "has_backpack": {
      "trigger": "minecraft:inventory_changed",
      "conditions": {
        "items": [
          {
            "items": [
              "beansbackpacks:metal_backpack"
            ]
          }
        ]
      }
    },
    "has_gold": {
      "trigger": "minecraft:inventory_changed",
      "conditions": {
        "items": [
          {
            "items": [
              "minecraft:copper_ingot"
            ]
          }
        ]
      }
    },
    "has_membrane": {
      "trigger": "minecraft:inventory_changed",
      "conditions": {
        "items": [
          {
            "items": [
              "minecraft:phantom_membrane"
            ]
          }
        ]
      }
    },
    "has_the_recipe": {
      "trigger": "minecraft:recipe_unlocked",
      "conditions": {
        "recipe": "beansbackpacks:backpacks/copper_backpack"
      }
    }
  },
  "requirements": [
    [
      "has_backpack",
      "has_the_recipe",
      "has_gold",
      "has_membrane"
    ]
  ],
  "rewards": {
    "recipes": [
      "beansbackpacks:backpacks/copper_backpack"
    ]
  },
  "sends_telemetry_event": false
}

Setting Up Your Resources

The data-pack is now finished. To texture your backpack you will need to create a resource pack including the: item's model, item's texture, the entity's texture, and later the translation for the backpack. Let's setup your file structure so you have somewhere to put all this.

assets
└── beansbackpacks
    ├── lang
    │   └── en_us.json
    ├── models
    │   └── item
    │       └── backpack
    │           └── copper.json
    └── textures
        ├── entity
        │   └── backpack
        │       └── copper.png
        └── item
            └── copper_backpack.png

This is the file structure for a Copper Backpack. As you can see, under models/item/backpack & textures/entity/backpack the file names are the backpack_id we defined earlier. We'll get back to the other two files.

Item Model

The Item Model is written just like vanilla. It must be named the same as it's backpack_id and must be placed under models/item/backpack/ or the mod will not be able to find the model. Here is an example of the code inside copper.json

{
  "parent": "minecraft:item/generated",
  "textures": {
    "layer0": "beansbackpacks:item/copper_backpack"
  }
}

Item Texture

According to copper.json, this file should be named copper_backpack.png. If you're familiar with resource packs there's nothing special here.
You can use this template item texture as somewhere to start.

Entity Texture

Must be named the backpack_id of your backpack and placed in textures/entity/backpack/
You can use this template entity texture as somewhere to start.

Making Backpacks Translatable

The fallback_name provided above is incase there is no translation provided. In the case that you want to add your own, in the lang file of the given language create the translation tooltip.beansbackpacks.name. + the backpack_id of the backpack. For example, If I would want to add a translation for a copper backpack in United States English (en_us.json) I would write...

{
  "tooltip.beansbackpacks.name.copper": "Copper Backpack"
}

To find your country's translation, look it up on the Minecraft's Wiki Language page.