In the YooAsset asset management framework, Package and Bundle are two core concepts representing different levels of asset management. Below are their definitions, differences, and typical application scenarios:

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1. Package (Asset Package)

Definition

A Package is a logical unit of asset collection, typically corresponding to a complete module or functional feature (e.g., “Login Module,” “Battle Module”). A Package can contain multiple Bundles and supports independent versioning, updating, and management.

Key Features

• Modular Management: Assets are divided by function or scene, enabling on-demand loading and unloading.
• Version Control: Supports updating a specific Package individually without needing to update the entire project’s assets.
• Dependency Isolation: Asset dependencies between different Packages can be isolated to avoid redundant loading.
• Hot-Update Friendly: Ideal for dynamically downloading and replacing module assets, reducing the initial download size for players.

Typical Scenarios

• Splitting a game into a “Core Package + Sub-module Packages.” Players download the core package first and get other modules as needed.
• Updating a specific feature (like a seasonal event) without re-packaging all game assets.

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2. Bundle (Asset Bundle)

Definition

A Bundle is a physical unit of asset files, which are binary files generated by the build tool (e.g., YooAsset), similar to Unity’s AssetBundle. A Bundle contains several asset files (textures, prefabs, scenes, etc.) and is the smallest unit of loading at runtime.

Key Features

• Asset Compression: Supports LZMA, LZ4, and other compression algorithms to reduce file size.
• Dependency Management: Automatically analyzes dependencies between assets to ensure integrity during loading.
• Incremental Updates: Only updates changed Bundles by comparing file hash values.
• Loading Optimization: Supports asynchronous loading and caching strategies to prevent frame drops.

Typical Scenarios

• Packaging high-frequency assets (e.g., UI Atlases) into independent Bundles to improve loading efficiency.
• Separating shared resources (e.g., Shaders, common scripts) into a “Common Bundle” to reduce duplication.

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3. Relationship Between Package and Bundle

Dimension	Package	Bundle
Level	Logical Layer (Module Level)	Physical Layer (File Level)
Function	Manages versions, updates, and dependencies	Manages file loading, compression, and storage
Update Granularity	By module (e.g., updating an “Event”)	By file (e.g., updating a texture or scene)
Dependencies	Isolates module-level dependencies	Handles internal resource cross-referencing
Typical Size	Large (may contain multiple Bundles)	Small (single or few assets)

Example

Suppose a game has two modules: Core Gameplay and Spring Event.

• Package:
  • CorePackage: Contains character, scene, and basic UI Bundles.
  • SpringEventPackage: Contains event scenes and limited-edition skin Bundles.
• Bundle:
  • characters.bundle (Character models and animations)
  • ui_atlas.bundle (UI textures)
  • spring_scene.bundle (Spring event specific scene)

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4. Actual Workflow

Asset Division

1. Logical: Divide assets into different Packages based on functionality (e.g., PackageA = Battle, PackageB = Story).
2. Physical: Within each Package, divide assets into Bundles based on type or frequency of use (e.g., effects.bundle = VFX assets).

Packaging and Distribution

• During the build, YooAsset generates an independent manifest and Bundle files for each Package.
• The core Package is distributed with the installation apk/ipa, while other Packages are downloaded via hot updates.

Runtime Loading

1. Initialize the Package:
   var package = YooAssets.GetPackage("CorePackage"); package.InitializeAsync();
2. Load Assets from the Package:
   var handle = package.LoadAssetAsync<GameObject("Assets/Characters/Player.prefab"); yield return handle;
GameObject player = handle.AssetObject as GameObject;

Hot Updates

When an update is detected for a specific Package, only the corresponding changed Bundle files are downloaded to replace the old versions.

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5. Summary

• Package is the macro-level management unit used for modularization, version control, and distribution.
• Bundle is the micro-level loading unit used to optimize storage, loading performance, and file dependencies.
• Collaboration: A Package organizes multiple Bundles to implement flexible distribution strategies, while Bundles ensure high efficiency during runtime through fine-grained control.