Backwards compatibility: U3.5 asset bundle migration to U5.x

Unity Engine
1

I have a project that is being brought back to support iOS 64bit.
It uses asset bundles build in Unity 3.5.
We’d like to use Unity 5.5. I’ll take any version that supports 64bit.

The catch - we only have assetbundles and not the raw assets for some things.
And thus no way to rebuild the assetbundles.

We’re using 2d Toolkit if that matters.

Is there some way to save assetbundles in the new format?
Is there some way to read in the raw assets and save them?
Any other suggestions?

  1. The original unity project with these assets is lost
    I have the project that loads the assetbundles.

  2. I’ve found DisUnity that can extract some of the data.
    GitHub - ata4/disunity: An experimental toolset for Unity asset and asset bundle files.
    It doesn’t extract enough - no animationsClips, none of the GameObjects

  3. I’ve tried dragging the item created in the scene into the project - it generates an object with empty elements. And none of the required assets

  4. I’ve looked for scripts that will do something similar except in code.

  5. I’ve considered rebuilding the scene by stepping through the objects in U3.5 but when I do that, I get the following popup error dialog:

  • rebuilding index. scanning project folder
    That hangs the Editor.

Here’s a shortened list of the contents of one of the asset bundles.

PID CID Class name Offset Size Object name
1 142 AssetBundle 0x0 2096
2 21 Material 0x830 160 background
3 21 Material 0x8d0 76 atlas0 material
4 28 Texture2D 0x920 5592476 atlas0
5 28 Texture2D 0x555ec0 699216 back_tex
6 43 Mesh 0x600a10 8156 room_wall_mesh
7 48 Shader 0x6029f0 1740 BlendVertexColor
8 74 AnimationClip 0x6030c0 296 background_scroll
9 83 AudioClip 0x6031e8 749576 audio
10 115 MonoScript 0x6ba1f0 69 tk2dSprite
11 115 MonoScript 0x6ba238 93 tk2dSpriteCollectionData
12 1 GameObject 0x6ba298 63 spriteCollection
21 1 GameObject 0x6ba4d8 59 room
28 4 Transform 0x6ba6e0 60
29 4 Transform 0x6ba720 60
44 23 MeshRenderer 0x6bab50 64
45 23 MeshRenderer 0x6bab90 64
53 33 MeshFilter 0x6bad90 16
54 33 MeshFilter 0x6bada0 16
62 82 AudioSource 0x6bae20 164
63 108 Light 0x6baec8 104
64 108 Light 0x6baf30 104
65 108 Light 0x6baf98 104
66 111 Animation 0x6bb000 68

thanks.
Bob

2

The path I’m taking is dumping the object as a text file to disk as I’m creating it in Unity 3.5 after reading in from the assetbundle.
And then I’ll recreate it in Unity 5.5 (even if manually, getting the data was the blocker)

My scene dumper is based on this:
http://wiki.unity3d.com/index.php?title=SceneDumper

Just writing out useful info like transform position, rotation (if not Q.identity), scale (if not Vector3.one)

Comparing two scenes, I would have never guessed the light rigs were different. Well, I did guess they might be. The dump showed me there were and what I need to do to recreate them.

The one thing I really wanted to recover was the animations. This looks like it should work.

And indeed it does, I am saving the “lost” animations.

Next, I’m going to look at using the AssetDatabase to save the primary game object so I don’t have to recreate all the transform data in the tree.

+environment_one
Transform name: environment_one
Pos (0.0, 0.0, 0.0)
Rot (359.4, 180.0, 0.0)
AudioSource name: environment_one
Clip environment_one_audio
+background_static
Transform name: background_static
Pos (-12.0, -1.0, 15.7)
MeshFilter name: background_static
Mesh plane Instance
MeshRenderer name: background_static
tk2dSprite name: background_static
+LIGHT_RIG
Transform name: LIGHT_RIG
Pos (0.0, 12.0, 0.1)
Rot (359.4, 180.0, 0.0)
+back_light
Transform name: back_light
Pos (0.0, 0.0, 0.0)
Rot (55.0, 28.6, 203.2)
Light name: back_light
Color RGBA(0.872, 1.000, 0.459, 1.000) intensity 0.32
+key_light
Transform name: key_light
Pos (0.0, 0.0, 0.0)
Rot (27.2, 231.2, 34.0)
Light name: key_light
Color RGBA(0.846, 0.847, 0.578, 1.000) intensity 0.46
+back
Transform name: back
Pos (0.0, -3.4, 23.0)
Rot (359.4, 180.0, 0.0)
Scale (2.1, 2.1, 2.1)
MeshFilter name: back
Mesh room_wall_mesh
MeshRenderer name: back
Animation name: environment_one_back
Name environment_one_back
Saved as Assets/environment_one_back.anim