ktx2 and meshopt support

[arpu]

Hey,

any plan to support ktx2 textures and mesh_OPT KHR_mesh_quantization

model viewer should support this

[arpu]

EXT_meshopt_compression
KHR_mesh_quantization
KHR_texture_basisu
KHR_texture_transform

Example File:
coffeemat.zip

[Mikko Haapoja]

These would need to be added to https://github.com/google/model-viewer