BuildAssetBundleOptions.DeterministicAssetBundle

Description

Builds an asset bundle using a hash for the id of the object stored in the asset bundle.

This allows you to rebuild an asset bundle and reference assets in it directly. When rebuilding the asset bundle the objects in it are guaranteed to have the same id after rebuilding the asset bundle. Due to it being a 32 bit hash space, if you have a lot of objects in the asset bundle it will increase the potential for hash conflicts. Unity will give an error and not build the asset bundle in that case. The hash is based on the GUID of the asset and the local id of the object in the asset. DeterministicAssetBundle are also slower to load from than normal asset bundles, this is because the threaded background loading API usually expects objects to be ordered in a way that makes reading reduce seeking. With DeterministicAssetBundles that is not possible.

Note: This feature is always enabled.

//Create a folder (right click in the Assets folder and go to Create>Folder), and name it “Editor” if it doesn’t already exist
//Place this script in the Editor folder

//This script creates a new Menu named “Build Asset” and new options within the menu named “Normal” and “Deterministic Asset Bundle”. Click these menu items to build an AssetBundle into a folder with different build options.

using UnityEngine;
using UnityEditor;

public class Example : MonoBehaviour
{
    //Creates a new menu (Build Asset Bundles) and item (Normal) in the Editor
    [MenuItem("Build Asset Bundles/Normal")]
    static void BuildABsNone()
    {
        //Create a folder to put the Asset Bundle in.
        // This puts the bundles in your custom folder (this case it's "MyAssetBuilds") within the Assets folder.
        //Build AssetBundles with no special options
        BuildPipeline.BuildAssetBundles("Assets/MyAssetBuilds", BuildAssetBundleOptions.None, BuildTarget.StandaloneOSX);
    }

    //Creates a new item (Deterministic) in the new Build Asset Bundles menu
    [MenuItem("Build Asset Bundles/Deterministic ")]
    static void BuildABsDeterministic()
    {
        //Build the AssetBundles in this mode
        BuildPipeline.BuildAssetBundles("Assets/MyAssetBuilds", BuildAssetBundleOptions.DeterministicAssetBundle, BuildTarget.StandaloneOSX);
    }
}