Assets Tools NET by nesrak1 - 1


Read and write unity assets/bundle files, based on

Unknown VersionMIT LicenseUpdated 24 days agoCreated on March 11th, 2018
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AssetsTools.NET v2

A .net library for reading and modifying unity assets and bundles based off of the AssetsTools library from UABE.

Jump to a tool:

AssetsTools AssetsView


Nuget Prereleases

Table of contents


Programs/Libraries (since they all have similar names)

  • UABE - The original UABE program by DerPopo
  • UABE.NET - UABE.NET is the program in this repo, otherwise, it’s the original
  • AssetsTools - The original AssetsTools library by DerPopo
  • AssetsTools.NET - This asset viewing/modifying library in this repo
  • AssetsView/AssetsView.NET - The asset viewer program in this repo

Files (both assetstools and unity)

  • cldb/Class Database - Stores info about how to deserialize assets
  • cltpk/tpk/Class Type Package - Stores multiple class databases
  • asset - Any data of an asset, not to be confused with “assets file”
  • .assets/assets file - Stores multiple assets and optionally a type tree
  • .unity3d/bundle file - Stores multiple .assets files
  • ggm/globalgamemanagers - Metadata for unity games
  • resources.assets - The file where assets built in the Resources folder go
  • level file - Gameobjects and components go here
  • sharedassets file - Gameobjects shared across scenes and other non-scene specific assets like materials go here

Basic usage of AssetsTools.NET

AssetsTools is separated into two parts, Standard and Extra. Standard classes come with UABE’s AssetsTools. Extra classes are unique to AssetsTools.NET. The two most important classes in Extra are AssetsManager and MonoClass. Other than that, the difference between AssetsTools and AssetsTools.NET is not much different.

It is recommended to use AssetsManager for most cases unless you only need to read/write one assets file and it’s a simple task.

Assets file reading

To load an assets file, you can use LoadAssetsFile(string assetPath, bool loadDependencies) to get an AssetsFileInstance:

var am = new AssetsManager(); 
var inst = am.LoadAssetsFile("resources.assets", true);

See the bottom for how to load asset bundles (usually .unity3d)

An AssetsFileInstance holds the AssetsFile and AssetsFileTable instances. The AssetsFile contains information about the version of the file, the TypeTree which may contain serialization data and other info on decoding assets, and the dependencies that the file needs (it may be easier to look in AssetsFileInstance.dependencies though). The AssetsFileTable is a table of information about assets like their path id, type id, and pointer in data.

To get the info of an asset, if you know the path id, you can use GetAssetInfo(long pathId) to get an AssetFileInfoEx:

var table = inst.table;
var inf = table.GetAssetInfo(1);

If you know the name you can use GetAssetInfo(string name[, uint typeId]):

//if you know there is only one asset by the name RocketShip, you don't need to search by type
var inf1 = table.GetAssetInfo("RocketShip");
//if there are multiple assets by the same name, you can use type to narrow it down
var inf2 = table.GetAssetInfo("RocketShip", 0x01); //0x01 - GameObject type id

Otherwise, if you just want to loop through all assets or all assets of a specific type, you can use assetFileInfo or the extension method GetAssetsOfType(int typeId):

foreach (var inf in table.assetFileInfo)
    Console.WriteLine(____ROOT____quot;{inf.index} {inf.absoluteFilePos}");
foreach (var inf in table.GetAssetsOfType(0x01))
    Console.WriteLine(____ROOT____quot;{inf.index} {inf.absoluteFilePos}");

Serialized data loading

Once you have the info for an asset, you can start to get the serialized data of it. For the library to understand how to deserialize the fields, it needs a class database or a type tree. Class databases and type trees are basically the same thing, so they convert their fields into shared format, AssetTypeTemplateFields.

Unity usually puts type trees in bundles, but for assets files in built games there isn’t a type tree, so a class database is needed. UABE has class databases (dat files) stored in the class package file (classdata.tpk). If you are targeting multiple unity versions, you can use AssetsManager's LoadClassDatabaseFromPackage:


Or if you know you’re using a specific version, you can use one specific class database instead.


You can find more info about how to get these from UABE at the bottom.

With a loaded class database, you can finally use GetTypeInstance(AssetsFile file, AssetFileInfoEx info[, fromTypeTree]) to read the values from the asset:

var inf = table.GetAssetInfo("Pineapple");
//AssetTypeInstance isn't too useful, so we go directly into the base field
var baseField = am.GetTypeInstance(inst.file, inf).GetBaseField();

The base field is the first field of a serialized asset. From there, you can use Get(string name), Get(int index), or [int index] to get child fields. You can use GetValue() to get the value of the field and AsXXX() to convert it to a .net type.

//example for a GameObject
var m_Name = baseField.Get("m_Name")
Console.WriteLine("gameobject's name is " + m_Name);

The AssetTypeInstance only has one basefield, the field we opened. To view the data of another asset referenced by this asset, you can use GetExtAsset(AssetsFileInstance relativeTo, AssetTypeValueField atvf[, bool onlyGetInfo])

//example for a GameObject
var componentArray = baseField.Get("m_Component").Get("Array");
//get first component in gameobject, which is always transform
var transformRef = componentArray[0].Get("component");
var transform = am.GetExtAsset(instance, transformRef);
var transformBf = transform.instance.GetBaseField();

Set onlyGetInfo if you only want the asset info without reading the serialized data. You may want to do this if you want to only read a specific type which is much faster than reading all of the types you don’t need to read.

MonoBehaviour loading

Reading MonoBehaviours are a little different because the information for deserialization is stored in assemblies in the Managed folder, rather than the class database file. (Bundles will usually have a type tree with MonoBehaviours)

//example for a GameObject
var componentArray = baseField.Get("m_Component").Get("Array");
var startMenuRef = componentArray[1].Get("component");
var startMenu = am.GetExtAsset(instance, transformRef);
var managedFolderPath = Path.Combine(Path.GetDirectoryName(inst.path), "Managed");
var startMenuBf = MonoDeserializer.GetMonoBaseField(am, inst,, managedFolderPath);

You can also use AssetsManager.GetMonoBaseFieldCached to cache types that take long to load, however, with the speed improvements MonoDeserializer has now, it may not be needed.

Assets file writing

To modify an assets file, edit the values with Set(object value), get the bytes with WriteToByteArray(), create an AssetsReplacer, and call Write(AssetsFileWriter writer, AssetsReplacer[] replacers) on the AssetsFile:

//example for a GameObject
var am = new AssetsManager();

var inst = am.LoadAssetsFile("resources.assets", true);

var inf = inst.table.GetAssetInfo("MyBoringAsset");
var baseField = am.GetTypeInstance(inst.file, inf).GetBaseField();
var newGoBytes = baseField.WriteToByteArray();
//AssetsReplacerFromMemory's monoScriptIndex should always be 0xFFFF unless it's a MonoBehaviour
var repl = new AssetsReplacerFromMemory(0, inf.index, (int)inf.curFileType, 0xFFFF, newGoBytes);
var writer = new AssetsFileWriter(File.OpenWrite("resources-modified.assets"));
inst.file.Write(writer, 0, new List<AssetsReplacer>() { repl }, 0);

Once you write changes to a file, you will need to reopen the file to see the changes.

Value building

(Not fully tested yet)

With the above example, you can change the value of existing fields, but you can’t add new fields (like to add to an array or create an asset from scratch.) To do that, you can use the ValueBuilder which let’s you create blank AssetTypeValueFields from AssetTypeTemplateFields.

Set array items

//example for a GameObject
var componentArray = baseField.Get("m_Component").Get("Array");
//create two blank pptr fields
var transform = ValueBuilder.DefaultValueFieldFromArrayTemplate(componentArray);
var rigidbody = ValueBuilder.DefaultValueFieldFromArrayTemplate(componentArray);
AssetTypeValueField[] newChildren = new AssetTypeValueField[] 
    transform, rigidbody
//... do replacer stuff

If you need to add items instead of set, you’ll have to use array concat (I know, a little annoying)


Create new asset from scratch

//example for TextAsset
var templateField = new AssetTypeTemplateField();
var cldbType = AssetHelper.FindAssetClassByName(am.classFile, "TextAsset");
templateField.FromClassDatabase(am.classFile, cldbType, 0);
var baseField = ValueBuilder.DefaultValueFieldFromTemplate(templateField);
baseField.Get("m_Script").GetValue().Set("I have some sick text");

//or you can just use table.assetFileInfoCount + 2 but that doesn't always work
var nextAssetId = table.assetFileInfo.Max(i => i.index) + 1;
replacers.Add(new AssetsReplacerFromMemory(0, nextAssetId, cldbType.classId, 0xffff, baseField.WriteToByteArray()));
//... do other replacer stuff

Currently, there is no way to get just a template field of a MonoBehaviour, so you won’t be able to create MonoBehaviours from scratch yet. (You can read an existing MonoBehaviour with MonoDeserializer and do .templateField on it, but that’s a bit of a hack.)

Loading bundle files

Bundles are files that can hold multiple assets files. Sometimes they only hold one, but usually the assets file inside has a real type tree rather than just the list of types most assets files have. Bundles can be read with the bundle loader in AssetsManager.

var am = new AssetsManager();
var bun = am.LoadBundleFile("bundle.unity3d");
var firstAssetsFile = BundleHelper.LoadAssetFromBundle(bun, 0); //or use name instead

If you need to load binary entries such as .resS files in bundles, you can use BundleHelper.LoadAssetDataFromBundle to get a byte array.

Loading textures

Texture2Ds can contain data in many different kinds of compression types. AssetsTools.NET is meant to be portable and doesn’t rely on any native libraries or use any unsafe code. As a result, the Texture2D decoder won’t be 100% as fast as the native versions, however, they are fast enough for most tasks (85%-95% of native speed, depending on compression method.) If you know how to, you can always hook up a native library for extra speed using the data from resS or the data byte array.

Supported formats:

  • R8
  • R16
  • RG16
  • RGB24
  • RGBA32
  • ARGB32
  • RGBA4444
  • ARGB4444
  • Alpha8
  • DXT1
  • DXT5
  • BC7
  • ETC1
  • ETC2

In the future I’ll be adding more formats but these should be good for most games.

The output of these are in BGRA which makes it easy to use Format32bppArgb with System.Drawing’s bitmaps. Here’s a quick and dirty way to implement that:

var atvf = am.GetTypeInstance(inst.file, texInf).GetBaseField();
var tf = TextureFile.ReadTextureFile(atvf);
var texDat = tf.GetTextureData(inst); //giving the instance will find .resS files in the same directory
                                      //you can change this to a path if the .resS is somewhere else
                                      //if you have the resS in memory instead, set the pictureData bytes
if (texDat != null && texDat.Length > 0)
    var canvas = new Bitmap(tf.m_Width, tf.m_Height, tf.m_Width * 4, PixelFormat.Format32bppArgb,
        Marshal.UnsafeAddrOfPinnedArrayElement(texDat, 0));

Note that the original AssetsTools uses RGBA output instead of BGRA output. In the future I’ll probably add a flag to support choosing which order the output is in.

If you’re parsing the texture manually or have the bytes some other way, you can use TextureFile.GetTextureDataFromBytes to decode a texture from bytes, a texture format, and size without having to create a TextureFile manually.

Extracting classdata.tpk and cldb.dat

The easiest way to get a decompressed classdata.tpk is to download it from the zip in the releases section.

To get the classdata.tpk from UABE yourself go to Options -> Edit Type Package in UABE’s main window, open the tpk in the same folder as UABE, uncheck Compress the file (LZMA), and click OK.

To get a cldb.dat, export a class database from the Edit Type Package dialog. Make sure you do not export from the uncompressed tpk, otherwise the output will be garbage. Once you’ve exported the database, go to Options -> Edit Type Database, uncheck Compress the file (LZMA), and click OK, and click OK again.

Hmms 🤔

Why does AssetsView.NET or my program with AssetsTools.NET crash when reading a specific type

Most likely a minor version update changed a field or two and broke the reader. You can check if that’s the issue by attempting to open the asset in UABE. If it shows up blank or shows an error message, that’s probably the issue. There’s not much you can do unless you can generate a new cldb somehow or reading the asset manually with the AssetsFileReader.

Does AssetsTools.NET work for versions below Unity 5.5

Unity versions 5.0-5.4 are in testing at the moment. If you have a problem with reading/writing drop an issue so we can fix it.

Does the library have a way to extract assets

Extracting assets into non-serialized formats (like objs, wavs, etc.) is not supported by the library. I have no plan to write any extractors for them as they are not part of the original library, and as mentioned, there are already other tools that can do that.

Do I need Mono.Cecil

Only if you’re using MonoDeserializer.

Some other issue or need help

Create a github issue and I will try to get back to you when I can.


AssetsView is a viewer for assets files. Rather than being targeted toward extracting assets, AssetsView can view the raw data of assets. It improves on UABE by being easier to navigate with gameobject tree views and much more.


Hmms 🤔

“Can’t display monobehaviour data until dependencies are loaded”?

Run File->Update Dependencies. This check is just there to make sure that the script that the MonoBehaviour needs can be loaded. Eventually, you would only need to load the file that has the script file. For bundles that have type trees (most likely), you can safely ignore this message for now.

Follow Reference button in GameObject Viewer?

For PPtrs, select either the m_FileID or m_PathID fields and click Follow Reference to go to that asset.

Red text in GameObject Viewer?

Disabled GameObject.

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