Draco: memory access out of bounds

[marwie]

Describe the bug
compressing the attached glb results in a RuntimeError: memory access out of bounds error

To Reproduce
Steps to reproduce the behavior:

1. run `gltf-transform draco "path/to/glb" "some/output/path"
2. observe error

Expected behavior
Mesh should be compressed, no errors

Versions:

• Version: 2.5.1 but seems to reproduce on 3.x
• Environment: node 18.15.0

Additional context
MyMesh.zip

                                                                                                                                                   
                                                                                                                                                   
g: memory access out of bounds                                                                                                                     
    at Se.run (C:\Users\...\AppData\Roaming\npm\node_modules\@gltf-transform\cli\node_modules\@caporal\core\dist\index.js:1:27764)               
    at async Te._run (C:\Users\...\AppData\Roaming\npm\node_modules\@gltf-transform\cli\node_modules\@caporal\core\dist\index.js:1:32257) {      
  meta: {                                                                                                                                          
    error: RuntimeError: memory access out of bounds                                                                                               
        at wasm://wasm/0017a2d6:wasm-function[344]:0x3e869                                                                                         
        at wasm://wasm/0017a2d6:wasm-function[200]:0x16f68                                                                                         
        at wasm://wasm/0017a2d6:wasm-function[588]:0x586dd                                                                                         
        at wasm://wasm/0017a2d6:wasm-function[390]:0x41f99                                                                                         
        at wasm://wasm/0017a2d6:wasm-function[599]:0x59f5f                                                                                         
        at wasm://wasm/0017a2d6:wasm-function[601]:0x5a028                                                                                         
        at wasm://wasm/0017a2d6:wasm-function[471]:0x47b02                                                                                         
        at wasm://wasm/0017a2d6:wasm-function[473]:0x48558                                                                                         
        at wasm://wasm/0017a2d6:wasm-function[297]:0x37760                                                                                         
        at wasm://wasm/0017a2d6:wasm-function[201]:0x22a01                                                                                         
  }                                                                                                                                                
}                                                                                                                                                  

[donmccurdy]

I'm AFK for a bit, but do you mind testing whether this works with glTF Pipeline? I've seen this issue in the past and think it might be a Draco library issue, if it fails in glTF Pipeline as well that's a good sign it's Draco.

[marwie]

Hi @donmccurdy it runs fine with gltf-pipeline

MyMesh-o.zip

[marwie]

I also tried with gltf-transform 3.2.1 again and get:

λ gltf-transform draco Downloads\MyMesh.glb Downloads\MyMesh-o2.glb
info: prune: No unused properties found.

error: memory access out of bounds

[donmccurdy]

On MacOS the error message doesn't mention memory, but reports a "bus error". 🤔

I'm also noticing validation errors that look important here. Is it possible this could be an error in the UnityGLTF exporter? I'd be curious what glTF Pipeline is doing to handle NaN, I'm not sure we'd want to scrub through vertex data looking for those.

code	message	severity	pointer
ACCESSOR_INVALID_FLOAT	Accessor element at index 107644 is NaN.	0	/accessors/2
ACCESSOR_INVALID_FLOAT	Accessor element at index 107645 is NaN.	0	/accessors/2
ACCESSOR_INVALID_FLOAT	Accessor element at index 107646 is NaN.	0	/accessors/2
ACCESSOR_INVALID_FLOAT	Accessor element at index 107648 is NaN.	0	/accessors/2
ACCESSOR_INVALID_FLOAT	Accessor element at index 107649 is NaN.	0	/accessors/2
ACCESSOR_INVALID_FLOAT	Accessor element at index 107650 is NaN.	0	/accessors/2
ACCESSOR_INVALID_FLOAT	Accessor element at index 107652 is NaN.	0	/accessors/2
ACCESSOR_INVALID_FLOAT	Accessor element at index 107653 is NaN.	0	/accessors/2
ACCESSOR_INVALID_FLOAT	Accessor element at index 107654 is NaN.	0	/accessors/2

[marwie]

Hello @donmccurdy I tried exporting the obj to glb using Blender and that works fine with draco then - so it's most likely a UnityGLTF bug as you said. I should have checked the validation errors error, sorry.

[donmccurdy]

Cool, no worries! Glad the validator catches this stuff, not sure how we'd have discovered a small handful of NaNs in there otherwise. 😅

[hybridherbst]

Just to close the loop, it's actually a Unity OBJ Importer bug 🥹, the importer produces a bunch of NaN tangents for that model. I've followed up with them and added some sanitization for exporting with UnityGltf. Thanks!