Overwriting Assets

Add-on Layering ​

The add-on system is built layer by layer, where each pack is added on top of the ones before it. Even if you only have a single pack added, there is an implicit vanilla pack which is always added. When you add custom content, this content will have full access to all vanilla files.

Accessing Vanilla Files ​

This layered structure is very useful, because it allows us to access the files inside of vanilla, without copy/pasting them into our add-on. For example you can access blocks/stone.png without moving it into your add-on! Just set it as the texture for your custom entity - it will work out of the box. This is particularly useful for things like models, or render controllers, or sounds.

If the vanilla assets change, for example if JAPPA updates the stone texture, your add-on will also receive the update, since you are relying on the actual dynamic, vanilla resources.

You should try to use this system of layering as often as you can. If you don't need to copy/paste something into your add-on, don't.

Overwriting Assets ​

Pack Layering also allows us to overwrite vanilla assets, by overwriting them with a file that shares the same path, or the same identifier. Our new file will replace the one being used in vanilla, allowing us to change textures, sounds, entity behavior, etc.

Overwriting by Path ​

Assets that are referenced by path, and do not have an identifier can be overwritten by simply placing a new asset into the same path. The following can be overwritten in this way:

• Functions
• Loot tables
• Textures
• Sounds
• Trade Tables

When you overwrite these files, the overwriting is absolute: The new asset will fully replace the old asset.

Overwriting by Identifier ​

Many assets are defined not by their name, but by their identifier! To overwrite these assets, simply create a new file that shares the same identifier, regardless of file-path. The following can be overwritten in this way:

• BP Entities
• RP Entities
• Animations
• Models
• Animation Controllers
• Spawn Rules
• Recipes
• Particles
• Render Controllers

When you overwrite these files, the overwriting is absolute: The new asset will fully replace the old asset.

Overwriting via Reference File ​

Many assets can also be registered into some kind of "registration system" file. These files are interesting, because unlike the other asset types, they are merged together instead of overwritten. This means that when you define these files, you do not need to copy from the vanilla resources. You can simply start with a blank file, and then overwrite the specific definitions you want.

The following files work in this way:

• All UI files
• All language files
• item_textures.json
• flipbook_textures.json
• terrain_textures.json
• sounds.json
• music_definitions.json
• sound_definitions.json

{
	"resource_pack_name": "vanilla",
	"texture_data": {
		"sugar": {
			"textures": "textures/path/to/my/sugar"
		}
	}
}

Overwriting Dangers ​

Since add-ons mostly overwrite each other rather than merge, it can be very difficult to get two incompatible add-ons to work together. For example, if you try to combine two add-ons that overwrite the creeper behavior (for example, one makes them very fast, and one makes them very large) the add-on you have applied second will overwrite the first.

This is mostly a problem with player.json (in either the RP or the BP), since this file is often used for gameplay purposes.

Things that Cannot be Overwritten ​

Not everything can be overwritten, the following is a list of things that cannot be overwritten using any of the described methods:

• Vanilla items (Not all)
• Vanilla blocks
• Vanilla fogs (create a fog with another namespace and change it everywhere it is used)