Question WebGL build with Streamed Asset Bundle containing external package

I have been stumped by this issue for a while now.

My project (Unity 2022.2.13) consists of a script that makes a UnityWebRequest to an asset bundle stored at localhost on my computer. The asset bundle contains a scene and its associated assets, including a Cinemachine Camera Dolly. The asset bundle is unpacked, then the scene is loaded by the script. This process works flawlessly through the Unity Editor and through a Windows build of Unity but fails on WebGL. Upon loading the scene, the editor throws many warnings/errors, most declaring that "The referenced script x on this behaviour is missing!"



On previous builds without assets containing Cinemachine scripts, there were no such warnings. Therefore, there has to be some conflict between the assets in the scene containing Cinemachine and the Unity WebGL builder. Any ideas on how this can be resolved? Thanks.

 

Code (CSharp):

1. // Loads in the scene from the asset bundle and sends out events to other GameObjects once loaded
2.     IEnumerator LoadAssetBundle(string bundleURL)
3.     {
4.         print("Making request...");
5.         UnityWebRequest request = UnityWebRequest.Get(bundleURL);
6.         yield return request.SendWebRequest();
7.  
8.         if (request.result == UnityWebRequest.Result.Success)
9.         {
10.             print("Downloading...");
11.             byte[] bundleData = request.downloadHandler.data;
12.             AssetBundle assetBundle = AssetBundle.LoadFromMemory(bundleData);
13.             print("Success! Loading scene...");
14.  
15.             // Load the scene from the AssetBundle
16.            
17.             string[] scenePaths = assetBundle.GetAllScenePaths();
18.             AsyncOperation loadOperation = SceneManager.LoadSceneAsync(scenePaths[0], LoadSceneMode.Single);
19.             yield return loadOperation;
20.  
21.             startingSound.Play(); // play beginning sound as start of game to create excitement
22.             assetBundle.Unload(false);
23.             SceneLoaded?.Invoke();
24.            
25.  
26.             // only invoke scene loaded event once camera has come to a stop
27.             yield return new WaitForSeconds(3);
28.             Camera camera = GameObject.FindWithTag("MainCamera").GetComponent<Camera>();
29.             Vector3 prev = camera.velocity;
30.             yield return new WaitForSeconds(0.2f);
31.             while (camera.velocity != prev)
32.             {
33.                 prev = camera.velocity;
34.                 yield return new WaitForSeconds(0.2f);
35.             }
36.             GameStart?.Invoke();
37.  
38.         }
39.         else
40.         {
41.             Debug.LogError("Failed to load AssetBundle: " + request.error);
42.         }
43.     }

 

I set the asset bundle manifest path, but it unfortunately did not solve the problem. That being said, I'm not entirely sure if I am using it correctly. Is this implementation correct?

Code (CSharp):

1. using UnityEditor.Build.Reporting;
2. using UnityEditor;
3. using UnityEngine;
4.  
5. public class BuildWebGL : MonoBehaviour
6. {
7.     [MenuItem("Build/Build WebGL")]
8.     public static void MyBuild()
9.     {
10.         BuildPlayerOptions buildPlayerOptions = new BuildPlayerOptions();
11.         buildPlayerOptions.scenes = new[] { "Assets/Scenes/SampleScene.unity"};
12.         buildPlayerOptions.locationPathName = "C:\\Users\\gilre\\Documents\\Unity\\export\\Passport proof-of-concept";
13.         buildPlayerOptions.target = BuildTarget.WebGL;
14.         buildPlayerOptions.options = BuildOptions.None;
15.         buildPlayerOptions.assetBundleManifestPath = "C:\\Users\\gilre\\Documents\\Unity\\Passport-Proof-of-Concept\\loadables\\scene.manifest";
16.  
17.         BuildReport report = BuildPipeline.BuildPlayer(buildPlayerOptions);
18.         BuildSummary summary = report.summary;
19.  
20.         if (summary.result == BuildResult.Succeeded)
21.         {
22.             Debug.Log("Build succeeded: " + summary.totalSize + " bytes");
23.         }
24.  
25.         if (summary.result == BuildResult.Failed)
26.         {
27.             Debug.Log("Build failed");
28.         }
29.     }
30. }
31.  

Regarding code stripping, I have already disabled it due to causing numerous "could not produce class with ID x" errors.

 

That is what I did, but even with the manifest file pointed to in assetBundleManifestPath the scene is not imported properly in WebGL. What else can I try?

 

Just realized there was another .manifest file in the AssetBundle output. Unfortunately, this one did not work either, same error.

Interestingly enough, I opened up both .manifest files only to discover that neither one listed any dependencies. Should I manually add them in myself?

 

In that case, I need to figure out why my asset bundle manifest files are being generated incorrectly, then. Could it be because I'm using the Unity Asset Bundle Browser for builds, which is no longer supported?

 

I'm pretty lost right now. Is this what the .manifest file (the one listed as the output folder) is supposed to look like for an Asset Bundle using an external package like Cinemachine? Shouldn't the external package be listed here under dependencies?

ManifestFileVersion: 0

CRC: 1144967610

AssetBundleManifest:

  AssetBundleInfos:

    Info_0:

      Name: demo1

      Dependencies: {}

If I can determine the validity of this file, I might be able to narrow down the culprit of the problem.

 

Ok, I figured it out. In short, when I generated my Asset Bundle, I would generate them in another Unity project, and then move the files over to a streamed assets folder for the game project. However, I would only end up moving one of the manifest files, resulting in errors. Once I moved over every file generated in the Asset Bundle's output, and built the project with the BuildPlayerOptions.assetBundleManifestPath option enabled, the project ran perfectly.

 

New question: since the .manifest file has to be specified at compile time, that effectively limits what asset bundle(s) can be loaded in at runtime, correct? Since under this method, if I were to load in a separate scene, that would create errors since I would be using the wrong manifest file. Is there a way around this, such that any scene can be loaded in without rebuilding the project?

 

I'm stumped on how I can get around this. I was hoping for this project to dynamically load in scenes with external packages without rebuilding. Is there a way around this problem without using BuildPlayerOptions.assetBundleManifestPath, such as loading in a .manifest file during runtime or loading in only the external packages I want at buildtime?

 

Issue resolved - using this thread, I was able to create a link.xml file that forces the program to preserve the Cinemachine library at buildtime. Now, the program runs in WebGL with Cinemachine regardless of scene. Thanks for the help!