Asset packs in Unity

This page describes how asset packs work in the context of a Unity Android application that uses Play Asset Delivery.

You can configure Unity to generate an Android App Bundle (AAB) that includes your application split into a base module and asset packs:

• Base module: Contains the executables (Java and native), plug-insA set of code created outside of Unity that creates functionality in Unity. There are two kinds of plug-ins you can use in Unity: Managed plug-ins (managed .NET assemblies created with tools like Visual Studio) and Native plug-ins (platform-specific native code libraries). More info
  See in Glossary, and assets in the first sceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
  See in Glossary. The first scene is the scene that has a build index of 0.
• Asset packs: Contains everything else, including the remaining scenes, resources, and Streaming Assets. For more information about the asset packs that Unity generates at build time, refer to Generated asset packs.

Alongside the asset packs that Unity generates automatically, you can also create your own custom asset packs. This helps you to control which assets an asset pack contains. Unity adds your custom asset packs to the final AAB. For more information, refer to Custom asset packs.

Generated asset packs

Asset packs have download size limits. To account for this, Unity changes how it generates asset packs depending on the size of your additional assets:

• If the additional assets take less than 1GB of storage, Unity packs everything into a single asset pack that uses the install-time delivery mode and is called UnityDataAssetPack. If you don’t create any custom asset packs, this means that the device downloads the asset pack as part of the application installation and, when the user first launches the application, all assets are available.
• If the additional assets take more than 1GB of storage, Unity adds Streaming Assets into one asset pack called UnityStreamingAssetPack and adds all other assets into the UnityDataAssetPack asset pack. Unity assigns the install-time delivery mode to the larger asset pack and assigns the fast-follow delivery mode to the smaller one.

Important: If either of these asset packs is larger than the size limit that the Google Play Store allows, Unity displays a warning but doesn’t fail the build. Also, Unity checks the sizes of asset packs individually and doesn’t perform size verification for custom asset packs. This means that, if Unity-generated asset packs fit within the Google Play Store limits but their combination with custom asset packs is too large for the Google Play Store, Unity doesn’t display a warning or error.

If you enable texture compression targeting, Unity generates an additional install-time asset pack called UnityTextureCompressionsAssetPack which includes common assets and the assets required by the first scene. Texture compressionA method of storing data that reduces the amount of storage space it requires. See Texture Compression, Animation Compression, Audio Compression, Build Compression.
See in Glossary targeting doesn’t affect Streaming Assets so if you use Steaming Assets and enable texture compression3D Graphics hardware requires Textures to be compressed in specialized formats which are optimized for fast Texture sampling. More info
See in Glossary targeting, Unity always packs Streaming Assets into a separate asset pack called UnityStreamingAssetPack. Unity does this regardless of whether your additional assets are over 1GB or not. Both UnityDataAssetPack and UnityStreamingAssetPack might end up as install-time or fast-follow asset packs depending on their size and the size of UnityTextureCompressionsAssetPack.

For asset packs that Unity automatically generates, Unity doesn’t support changing the delivery mode. If you want to change the delivery mode of an asset pack, create custom asset packs with your assets.

Custom asset packs

If you want to control which non-code resources are in a particular asset pack, you can create a custom asset pack. Unlike Unity-generated asset packs, you can set the delivery mode for custom asset packs. If you create a custom asset pack, be aware that the Google Play Store has size and quantity limits for asset packs. For information on the limits, refer to Download size limits.

To use custom asset packs with Addressables, you must extend the Addressables functionality. The Play Asset Delivery Addressables sample provides an example of how to do this. For more information, refer to the sample documentation.

Additional resources

• Set up Play Asset delivery
• Create a custom asset pack