Texture coordinate value is severely distorted after compression

[SunnyBily]

Hello,

I am trying to compress a GLTF file using my program with draco lib v1.5.3.

After compression, the texture coordinate value becomes the same coordinate value.

That's different with my source data. And it causes that the rendering result was completely black.

And before compression, the texture can be loaded properly like this:

The conversion parameters I used: position quantization: 16 tex_coord quantization: 10 normal quantization: 8 SpeedOption 3, 3 MESH_SEQUENTIAL_ENCODING

I use TriangleSoupMeshBuilder to build mesh, and SetAttributeValuesForFace interface to add texCoord to the mesh.

I've tested a lot of models this way and they're all fine except for this one.

Here is glTF model before compression I just mentioned. beforeCompression.zip

Here is glTF model after compression by my program. AfterCompression.zip

[ondys]

Is the model processed using draco_transcoder or some other way? The texture coordinate values look a bit suspicious. In most cases UVs are in range between 0-1, seeing -232.xx is rather unexpected

[ngcthuong]

Could you check whether these part of your mesh doesn't have UV? Draco tends to give dummy UV for part of the mesh without UV.

[donmccurdy]

Possibly related:

https://github.com/donmccurdy/glTF-Transform/issues/936#issuecomment-1536554093