GLTFUtility - A simple glTF plugin

For far too long I've been annoyed by the lack of glTF 2.0 support in Unity, so I decided to make a plugin on my own.

A few months of loose development later I've checked most of the things I wanted off the list.

GLTFUtility supports meshes with submeshes, up to 8 uv channels, vertex colors, normals, tangents, embedded textures, materials, rigs and animations. And it's easy to set up. Just drop it anywhere in your project and you're ready to go.

Currently only edit-time import is supported, but export and runtime capabilities are on the roadmap as well.

The project is opensource and available on github.

Feedback, contributions and requests all welcome.

 

Just discovered rencently about GLTF and also found https://github.com/KhronosGroup/UnityGLTF from the Khronos Group itself, so was curious about what's GLTFUtility capable vs the UnityGLTF one. No hostilty, just asking.

 

The key differences lie in their complexity and features. While UnityGLTF boasts more features, it seems like an extremely messy project, and having to compile a DLL for it to work makes it inaccessible to most of the people who actually need it.

GLTFUtility is built with simplicity as the main focus, uses no external libraries, and is easy to navigate for potential contributors. It's plug and play.

 

Hi!

How would one go about actually configuring a model in Unity using the GLTFUtility?|
What I mean is, setting up all the animation clips like I would with a .blend or .fbx, setting up colliders, changing the rig to humanoid etc. Also extracting the embedded materials out of the file into the project so I can change to a custom shader etc.

All I get is a model I can drag into the scene with no configuration options.

When will you support BlendShapes/vertex animation?

The UnityGLTF seems like a HUGE mess, with a lot of stuff that is completely useless for an average user that just wants to import a model into Unity and set it up, with a ton of weird server stuff that I have absolutely no use for.

Cheers!

 

Hey,

Sorry for the lack of reply.
What you mentioned is on the roadmap, but this plugin is developed entirely out of personal interest, so there is no saying when certain features arrive.

 

Hi, I'm pretty sure I just emailed you also...Anyway, I'm wondering when (or if) runtime imports for GLTF will be added?

 

I think it might work already, actually. Try experimenting with something like this

Code (CSharp):

1. GLTFObject gltfObject = GLTFObject.Load(filepath);
2. GameObject[] roots = gltfObject.Create();

 

Thanks, I'll try it. So how do you use this in the Editor? I don't see any new menu's and the documentation is sparce.
The gltfObject.Load takes 2 arguments, not 1. Should this work?

gltfObject.Load("C:\\Users\\stephen\\AppData\\LocalLow\\BuilderWorldVR\\BuilderWorldVR\\unzip\\SkyCastle", "scene.gltf") ;

where scene.gltf is a file within the SkyCastle folder.

 

When I try the above, it's showing an error. It would be good to include a sample!

 

Please update GLTFUtility to latest version and try again.

 

Hmm, did you make a change? I just downloaded this a couple days ago, and GitHub says that last commit was 12 days ago. Unless I'm mistaken, I do have the latest version.

Hey could you try testing with the 2 attached GLTF files? Both of these are from Sketchfab (both are creative commons license, but I don't have the authors handy to give proper credit)

Both of these I can open using the "Sketchfab for Unity" asset and they work fine. Both fail with errors when I use UniGLTF-1.28. I was curious to see if they worked with your asset.

I need runtime GLTF loading, and I can't use "Sketchfab for Unity" because it seems coded so that when you load a GLTF file, it imports the file and creates a prefab. I'm pretty certain a prefab can only be created in the Editor, and not in a standalone application. But it's also really slow because if the GLTF has 100 pieces within it (meshes or whatever) then Unity takes its sweet time doing the import for all of these.

So "Sketchfab for Unity" seems to lack a simple method that lets you load a GLTF and return a Unity Game Object. That's what I need.

I'm not sure if UnityGLTF has this (the Khronos asset), but getting it working is a nightmare. As others have mentioned, it's a mess! I spent a whole day messing with it.

Regarding UniGLTF-1.28, when it works, it works quite well, and I'm pleased with how quickly it can create a GameObject. The only problem is that, as I pointed out above, I see errors with some of the files I have tried. I wanted to try out your asset to see if it works better than UniGLTF

 

Also, can you explain how to use your asset in the Editor? I was expecting a new menu that could be used to import files, but I don't see anything. thanks!

 

I made a few changes regarding runtime loading, yes. Loading only takes a single parameter now. If yours takes two parameters, you got the wrong version.

I can't test your files till next week

In the editor, the asset should do what it does automatically. Put the gltf/glb files in your assets folder and it will be imported as if it were an fbx or obj. This works for all of the official example files. If it doesn't work for yours, then I got some work to do

 

Does this project supports runtime loading of GLTF from remote url?

 

Not yet. It focuses on local files.

 

Great work on this so far! Is runtime import from a remote URL prioritized on your roadmap?

Our team is evaluating the various gltf runtime importers that are available right now that support animation. Our plan is to use the Sketchfab API to download models and then use GLTFUtility to import the gltf models.

Our team is working on a mobile AR app, and this is one of our most important features to implement. So if you're already working on it, we would rather work with GLTFUtiltiy since it's open-source and written well instead of the alternatives.

 

Remote import is definitely on the roadmap, but right now i'm working on switching the serialization out with Json.NET which will enable exports.

HOWEVER, if the sketchfab API allows .glb files, you could maybe feed that binary data directly into GLTFUtility without too much modification. Would this be an option for you?

 

Sketchfab only supports downloading models in the standard .gltf format in a .zip archive. It would be pretty awesome if there was also a .glb file for simple downloading and use at runtime, but that's not something they plan on supporting.

.glb support is also important though! We could instead download the .gltf on our web server and convert it to .glb format there, and then download the .glb formatted file during mobile runtime. That would basically do the same thing.

So yeah, downloading and using a .glb would also be a good way to go. Is this something you'll need to add to GLTFUtility or is it already possible?

As a side question, does GLTFUtility support animations for the .glb format?

 

It is not already possible, although it could probably be done with slight modifications. Loading .glb with raw data input will probably come before remote .gltf does.

And yeah, animations are supported for both formats already.

 

Thanks Siccity, looking forward to it!

Is this something you would be okay prioritizing after you've finished switching out the serialization to json.NET?

 

Yeah i can look into it. But no promises.

Can you send me a file using remote images to test on?

 

@Siccity I'm not sure what you mean by a test image, but if your asking for a test .glb file on a remote server, then sure, happy to oblige!

https://bxrtest.s3.amazonaws.com/AnimatedMorphCube.glb

Downloaded from the KhronosGroup's test files repo... https://github.com/KhronosGroup/glTF-Sample-Models

 

@Siccity I just realized AnimatedMorphCube.glb uses blend shapes, which you listed in the repo as not supported yet.

Here are BrainStem and Cesium, two animated characters you feature in your repo's readme. They should be using standard animations instead of any kind of blend shapes.

https://bxrtest.s3.amazonaws.com/BrainStem.glb
https://bxrtest.s3.amazonaws.com/CesiumMan.glb

 

Hi guys,

@Siccity I really like this plugin, it's much more lightweight than the other one. (KhronosGroup)
I want to import glb files (with animations and textures) in runtime. The static import without animations is working correctly, as you mentioned in a previous comment.

Code (CSharp):

1. GLTFObject gltfObject = new GLTFObject(pathToFile);
2. GameObject[] roots = gltfObject.Create();

But when I try to import with any kind of animation in runtime I got the non-legacy AnimationClip error.
(SetCurve will only work at runtime for legacy animation clips. For non-legacy AnimationClips it is an editor-only function. https://docs.unity3d.com/ScriptReference/AnimationClip.SetCurve.html)

I tried to change the clip to legacy but it doesn't solve my problem at all.

Any idea?

This is just not possible this way?

Thanks!

 

I will have to research if unity supports creating non-legacy animations in some way. If it is possible, GLTFUtility should definitely be able to do it.

 

@Siccity I've made progress importing .gltf models from the SketchFab API and loading them at runtime (save to local storage first, then load it into GLTFUtility). I won't be needing the .glb/.gltf runtime importer after all!

I have noticed a couple of things I want to give you feedback on...

1) In the readme, you should add that the GLTFUtility's Standard-Metallic and Standard-Specular shaders should be force-added to the project via the Project Settings -> Always Included Shaders section. That way GLTFMaterial.cs doesn't fail when making the Shader.Find() call outside of the Unity Editor.

2) In GLTFImage.cs, I ended up changing the OnLoad() function to use File.ReadAllBytes() to load the texture instead of Asset cache system, this allows GLTFUtility to load assets on mobile via the PersistentDataPath since the standard Assets folder doesn't exist at mobile runtime.

Code (CSharp):

1. if (!string.IsNullOrEmpty(uri) && File.Exists(glTFObject.directoryRoot + uri))
2.             {
3.                 //Debug.Log( "GLTFImage.cs OnLoad() Loaded texture at " + glTFObject.directoryRoot + uri );
4.  
5.                 byte[ ] fileData = File.ReadAllBytes( glTFObject.directoryRoot + uri );
6.                 cache = new Texture2D( 2, 2 );
7.                 cache.LoadImage( fileData );
8.  
9.                 imageIsAsset = true;
10.                 return true;
11.             }

3) In my current SketchFab .gltf test, I downloaded a Pac Man arcade cabinet model that has the animation clip "Take 001". This animation successfully plays when testing this on the SketchFab website viewer and via DonMcCurdy's "three-gltf-viewer".

Using GLTFUtility this model imports without animations. Or if it does, I have no idea where they are or how to play them. Any kind of documentation or pointing me in the right direction would be appreciated.

4) In the same Pac Man model there is also a texture/material/shader combination that seems to give GLTFUtility some problems (Check out the "scheibe") material that gets generated.

For comparison, I loaded this .gltf using DonMcCurdy's "three-gltf-viewer" and SketchFab's official Unity Editor importer. I believe GLTFUtility is failing to set up this material correctly because it's intended to be a Standard shader with transparency setup.

 

@DerrickBarra I'm glad that worked for you

1) I'm not a fan of post-installation setup, but if there really is no other way to keep the shaders in builds, I guess I'll have to. Thanks for bringing it up.

2) I think for best results we need to use both. The Asset cache system ensures we dont get dublicates in the editor.

3) There is some animation support in GLTFUtility, but it is likely that something in that particular model isn't supported yet. You can test an animation in unity by selecting it in the project window. It will show up in the preview window under the inspector.

4) Transparency is not yet supported in the shader. I might be adding support very soon.

 

GLTFUtility now supports different alpha modes on the new jsondotnet branch which will soon be merged into master

 

@Siccity dang that was quick! Awesome work!

 

Hi,


@Siccity Thanks for the updated version, it works well so far, but I have some questions with the animations ...

I updated to the latest GLTFUtility, (and using the JSON.net version) but I can't make the animation work with the legacy clips.

First of all, how should I access the animations? I use the GLTFUtility Importer class and the ImportGLB function.
It returns a GameObject but no animations in it. (I tried to access these with GetComponent<Animation>()).

If I add the animations inside the Importer (inside LoadInternal()), I got an animation component but it doesn't play anything when I call the anim.play().

Code (CSharp):

1. Animation anim = go.AddComponent<Animation>() as Animation;
2. foreach (GLTFAnimation.ImportResult animation in animations)
3. {
4.        anim.AddClip(animation.clip, animation.clip.name);
5. }

Am I doing something wrong?

Thanks in advance!

 

Importer.ImportGLB has an overload that takes 3 parameters.

Code (CSharp):

1. public static GameObject ImportGLB(string filepath, ImportSettings importSettings, out GLTFAnimation.ImportResult[] animations)

That last parameter returns the animations found by the importer. (animations[n].clip)

I don't think it returns legacy animations though. Try setting the 'legacy' bool manually

https://docs.unity3d.com/ScriptReference/AnimationClip-legacy.html

 

OMG, I don't know how I missed this parameter. Thanks!

I'll try it with the legacy (I already tried it in an earlier version, but I hope it will work now) and I'll tell you if it's working.

 

Yeah, it's definitely works with the legacy "hack".
Although I got some glitch effect with this modell while animating:

,
but I think it's because I exported the gltf to glb with blender and maybe I misconfigured something. ¯\_(ツ)_/¯

Now I tested with this:

)

and works perfectly.

 

@Siccity I modified your latest version of the GLTFImage.cs GetImage() to work with both the Unity editor and on mobile, you should place this modified function into your next release.

Code (CSharp):

1. public ImportResult GetImage(string directoryRoot, GLTFBufferView.ImportResult[] bufferViews) {
2.             ImportResult result = new ImportResult();
3.             result.isAsset = false;
4.  
5.             if (!string.IsNullOrEmpty(uri) && File.Exists(directoryRoot + uri)) {
6. #if UNITY_EDITOR
7.                 result.texture = UnityEditor.AssetDatabase.LoadAssetAtPath(directoryRoot + uri, typeof(Texture2D)) as Texture2D;
8.  
9.                 if( result.texture != null )
10.                 {
11.                     result.isAsset = true;
12.                     return result;
13.                 }
14.                 else
15.                 {
16.                     byte[ ] fileData = File.ReadAllBytes( directoryRoot + uri );
17.                     result.texture = new Texture2D( 2, 2 );
18.                     result.texture.LoadImage( fileData );
19.  
20.                     result.isAsset = true;
21.                     return result;
22.                 }
23. #else
24.                 byte[ ] fileData = File.ReadAllBytes( directoryRoot + uri );
25.                 result.texture = new Texture2D( 2, 2 );
26.                 result.texture.LoadImage( fileData );
27.  
28.                 result.isAsset = true;
29.                 return result;
30. #endif
31.                 Debug.Log("Couldn't load texture at " + directoryRoot + uri);
32.                 return null;
33.             } else if (bufferView.HasValue && !string.IsNullOrEmpty(mimeType)) {
34.                 byte[] bytes = bufferViews[bufferView.Value].bytes;
35.                 result.texture = new Texture2D(2, 2);
36.                 // If this fails, you may need to find "Image Conversion" package and enable it
37.                 if (result.texture.LoadImage(bytes)) {
38.                     return result;
39.                 } else {
40.                     Debug.Log("mimeType not supported: " + mimeType);
41.                     return null;
42.                 }
43.             } else {
44.                 Debug.Log("Couldn't find texture at " + directoryRoot + uri);
45.                 return null;
46.             }
47.         }

 

@Siccity Sorry to double post, I just finished testing out some GLTF models on mobile (Android) that contain animations. The Legacy clip loading works well in Editor. However, loading a model in mobile runtime causes the following errors...

Code (CSharp):

1. AndroidPlayer(ADB@127.0.0.1:34999)</i> Can't use AnimationClip::SetCurve at Runtime on non Legacy AnimationClips
2. UnityEngine.AnimationClip:SetCurve(String, Type, String, AnimationCurve)
3. Siccity.GLTFUtility.GLTFAnimation:Import(ImportResult[], ImportResult[]) (at D:\Unity Hub\Git Repos\BrandXR-Discovery\Assets\Plugins\Format Readers\GLTFUtility\Scripts\Spec\GLTFAnimation.cs:103)
4. Siccity.GLTFUtility.GLTFAnimationExtensions:Import(List`1, ImportResult[], ImportResult[]) (at D:\Unity Hub\Git Repos\BrandXR-Discovery\Assets\Plugins\Format Readers\GLTFUtility\Scripts\Spec\GLTFAnimation.cs:137)
5. Siccity.GLTFUtility.Importer:LoadInternal(GLTFObject, String, ImportSettings, ImportResult[]&) (at D:\Unity Hub\Git Repos\BrandXR-Discovery\Assets\Plugins\Format Readers\GLTFUtility\Scripts\Importer.cs:93)
6. Siccity.GLTFUtility.Importer:ImportGLTF(String, ImportSettings, ImportResult[]&) (at D:\Unity Hub\Git Repos\BrandXR-Discovery\Assets\Plugins\Format Readers\GLTFUtility\Scripts\Importer.cs:78)
7. BrandXR.SketchfabManager:LoadGLTFModel(String) (at D:\Unity Hub\Git Repos\BrandXR-Discovery\Assets\Scripts\Model Loading\SketchfabManager.cs:910)
8. BrandXR.<ModelInitialize>d__44:MoveNext() (at D:\Unity Hub\Git Repos\BrandXR-Discovery\Assets\Scripts\Model Loading\SketchfabManager.cs:514)
9. UnityEngine.SetupCoroutine:InvokeMoveNext(IEnumerator, IntPtr)
10.  
11. [/Users/builduser/buildslave/unity/build/Runtime/Animation/AnimationClip.cpp line 1296]
12. (Filename: D Line: 0)

To fix this is pretty simple, in GLTFAnimation.cs Import(), add the line result.clip.legacy = true; right after the clip is named! Voila, working animations on mobile.

 

Why are you setting result.isAsset to true for loaded images that aren't assets? I'm pretty sure that will cause issues in the editor.

 

No reason actually, I didn't dive too deeply into the code, I assumed result.isAsset was a flag used by a return function to determine if the asset was found. I've edited my code appropriately, thanks for the heads up!

 

Hi, I have a .glb file on s3 and i want to load it. Is there a possible way to load ?

 

What is s3? If it's a website you should download the file first, then load it.

 

Amazon s3 (AWS) online storage. My requirement is to load from url in runtime.

 

They probably have an API as well to download the file. Once you got it downloaded you can load it with Importer.LoadFromFile

 

@Siccity : Just wanted to give you props, so far we've been able to demo our Sketchfab loader and things are working well. I can't wait to implement the async/multithreading version once it's been completed!

 

@Siccity : I tried downloading the latest from the main branch (which includes multithreading). And there are a number of errors after importing. It looks like scripts in the Editor folder are trying to reference scripts outside of the editor folder so they can't be located (even though they are all in the same namespace).

 

There are two asmdef files in the project, one for runtime and one for editor. Try selecting the editor one, and in the inspector, under references, add the runtime one.

It seems to me that Unity changed the way that list is serialized, which destroys compatability.

 

@Siccity I narrowed those bugs down to an incorrect import on my end, so you're good!

I started using the new Importer.ImportGLTFAsync() function. But I noticed that the Action callback doesn't receive a reference to the generated 3D model or the animations. I didn't spot anywhere else these variables would be received either.

So I modified ImportGLTFAsync() and LoadAsync() accordingly to make it pass the generated model and animations to the Action callback. Feel free to add this functionality to the main branch on Github.

Code (CSharp):

1. public static void ImportGLTFAsync(string filepath, ImportSettings importSettings, Action<GameObject, GLTFAnimation.ImportResult[]> onFinished) {
2.             string json = File.ReadAllText(filepath);
3.  
4.             // Parse json
5.             LoadAsync(json, filepath, importSettings, onFinished).RunCoroutine();
6.         }

Code (CSharp):

1. private static IEnumerator LoadAsync(string json, string filepath, ImportSettings importSettings, Action<GameObject, GLTFAnimation.ImportResult[ ]> onFinished ) {
2.             // Threaded deserialization
3.             Task<GLTFObject> deserializeTask = new Task<GLTFObject>(() => JsonConvert.DeserializeObject<GLTFObject>(json));
4.             deserializeTask.Start();
5.             while (!deserializeTask.IsCompleted) yield return null;
6.             GLTFObject gltfObject = deserializeTask.Result;
7.  
8.             // directory root is sometimes used for loading buffers from containing file, or local images
9.             string directoryRoot = Directory.GetParent(filepath).ToString() + "/";
10.  
11.             importSettings.shaders.CacheDefaultShaders();
12.  
13.             // Setup import tasks
14.             List<ImportTask> importTasks = new List<ImportTask>();
15.  
16.             GLTFBuffer.ImportTask bufferTask = new GLTFBuffer.ImportTask(gltfObject.buffers, filepath);
17.             importTasks.Add(bufferTask);
18.             GLTFBufferView.ImportTask bufferViewTask = new GLTFBufferView.ImportTask(gltfObject.bufferViews, bufferTask);
19.             importTasks.Add(bufferViewTask);
20.             GLTFAccessor.ImportTask accessorTask = new GLTFAccessor.ImportTask(gltfObject.accessors, bufferViewTask);
21.             importTasks.Add(accessorTask);
22.             GLTFImage.ImportTask imageTask = new GLTFImage.ImportTask(gltfObject.images, directoryRoot, bufferViewTask);
23.             importTasks.Add(imageTask);
24.             GLTFTexture.ImportTask textureTask = new GLTFTexture.ImportTask(gltfObject.textures, imageTask);
25.             importTasks.Add(textureTask);
26.             GLTFMaterial.ImportTask materialTask = new GLTFMaterial.ImportTask(gltfObject.materials, textureTask, importSettings);
27.             importTasks.Add(materialTask);
28.             GLTFMesh.ImportTask meshTask = new GLTFMesh.ImportTask(gltfObject.meshes, accessorTask, materialTask, importSettings);
29.             importTasks.Add(meshTask);
30.             GLTFSkin.ImportTask skinTask = new GLTFSkin.ImportTask(gltfObject.skins, accessorTask);
31.             importTasks.Add(skinTask);
32.             GLTFNode.ImportTask nodeTask = new GLTFNode.ImportTask(gltfObject.nodes, meshTask, skinTask);
33.             importTasks.Add(nodeTask);
34.  
35.             // Ignite
36.             for (int i = 0; i < importTasks.Count; i++) {
37.                 TaskSupervisor(importTasks[i]).RunCoroutine();
38.             }
39.  
40.             // Fire onFinished when all tasks have completed
41.             if (onFinished != null) {
42.                 // Wait for all tasks to finish
43.                 while (!importTasks.All(x => x.IsCompleted)) yield return null;
44.  
45.                 GLTFAnimation.ImportResult[ ] animations = gltfObject.animations.Import( accessorTask.Result, nodeTask.Result );
46.  
47.                 onFinished( nodeTask.Result.GetRoot(), animations );
48.             }
49.         }

 

Added

Working on making room for a draco extension now

 

Hey @Siccity, here's a couple of notes, these are basically feature requests, let me know what you think...

1 - Progress Callback & Value : It would be beneficial to have a loading progress value and a callback on progress updates, so we can provide users with a loading bar during import progress.

2 - Cancel Import : In scenarios where the device gives us a Low Memory warning (which means a crash is about to happen), it would be very useful to have a command to Cancel the loading operation and free up the resources from the in-progress import (so we don't end up with a memory leak)

3 - Expected Import Size : Being able to query GLTFUtility to see the expected performance requirements for a model would prevent scenarios where imports are attempted on models + textures that bring the devices in use memory into Low Memory territory, prevent crashes during model import. This could be done by evaluating the models textures and import sizes to generate the number of bytes necessary to complete the import.

4 - Import Settings : Going along with the previous feature, being able to request that GLTFUtility import textures using optional settings ( max texture size, mipmap on/off, color depth ) would be beneficial in preventing low memory crashes during import.

 

Hi again @Siccity, I've been testing out GLTFUtility against a few different models from the web. In my testing, I'm expecting to see import results similar to the Sketchfab viewer.


I'm using a testing scene with a single directional light, nothing special here...

- This model loads in using the Metallic material, but the metallic values are between .9 and 1. Making the model come in incredibly dark.

---

- This R2-D2 model loads in using a specular material with a very high glossiness value for its materials (.7-1). Like before the model shows up incredibly dark. If we switch to the metallic shader for testing you'll see that it looks as expected.

---

- And just for reference, here's a similar R2-D2 that only uses the metallic shader, it imports as expected with all metallic materials.


I've mentioned before the project I'm working on loads in models from the Sketchfab API, so I have no control over them. But users will likely expect similar results to the Sketchfab viewer, any ideas what's causing these odd imports?

 

I see that you submitted an issue on GitHub with a solution. Did it solve this problem?