[Bug] GLTF texture issues

[finetjul]

Bug description

There are issues with the textures (and the normals?) in the GLTF example.

Steps to reproduce

Open the GLTF example and zoom on the King in the ABeautifulGame model.

Detailed Behavior

No response

Expected Behavior

Correct textures

Environment

• vtk.js version: master
• Browsers: Chrome
• OS: Windows

[daker]

This is not a bug, PBR is not supported in the webgl implementation so i am just using addTexture in webgl which works in some cases. If you switch to WebGPU you will see the correct rendering.

https://github.com/Kitware/vtk-js/blob/master/Sources%2FIO%2FGeometry%2FGLTFImporter%2FReader.js#L247-L253

[finetjul]

Could it be that coordinate textures are not the same between WebGL and WebGPU ? It's odd that the same texture renders fine in WebGPU but not in WebGL. There must be a discrepancy somewhere hence it is a bug...

[daker]

Since the PBR is implemented for WebGPU only the diffuse texture is applied here with addTexture (workaround) the others are not applied (Normal, Roughness, Emission and Occlusion textures) because the code is using the PBR property methods

A working example with one texture https://kitware.github.io/vtk-js/examples/GLTFImporter/index.html?model=BoxTextured&viewAPI=WebGL

[finetjul]

It may works in trivial case, but with the chessmate dataset, it seems that there is issues with coordinate textures:

[daker]

I will try to see if there is something wrong or missing in the code