gltfpack removes existing KHR_textures_basisu extension

[prollin]

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Running gltfpack on a file already using the KHR_textures_basisu extension removes all traces of the extension in the output file

[zeux]

This is not a bug and rather a current limitation - you can pass -tc to recompress source textures if they are present. If KHR_texture_basisu is a required extension, gltfpack currently will refuse to process the file, because it assumes the role of a tool that converts a "vanilla" glTF file (that doesn't use various compression extensions) to an optimized one (that might).

[prollin]

For context, our use case was to use gltf-transform (or custom tool) for compression since it gave us a bit more flexibility there and gltfpack for geometry.

[zeux]

Got it, thanks. Out of curiosity, what prevents you from using gltfpack to compress the textures as well?

[prollin]

gltf-transform offers more granularity and more options for texture processing; we want to be able to resize certain class of textures and also have a bit more control over compression parameters.