GLTFExporter: Add support for signed data types.

[spearwolf]

Fixed #20474
Fixed #25310

Description

Within the GLTFExporter only the buffer attributes types float, uint, ushort and ubyte are supported.
All other types cancel the export with an error: An error happened during parsing Error: THREE.GLTFExporter: Unsupported bufferAttribute component type.

What is missing are the signed data types: byte, short and int. These are also valid data types according to the KHR_mesh_quantization extension.

With this fix the signed data types are now also supported in the GLTFExporter.

This will allow the export of meshes that have already been quantized (e.g. with tools like gltf-transform):

• try GLTFExporter: Add support for KHR_mesh_quantization. #20474 (comment)

[LeviPesin]

Related: #20762

[donmccurdy]

Thanks @spearwolf!

These are also valid data types according to the KHR_mesh_quantization extension.

I think we'll need to detect when these types are used, and add the KHR_mesh_quantization extension to the export. Do you mind including that change here as well?

[Mugen87]

Yeah, #20762 was closed since KHR_mesh_quantization wasn't added at that time and without the extensions the PR was incomplete.

[spearwolf]

ok, I added a simple check that adds the KHR_mesh_quantization extension to the required (and used) list when non-standard vertex attribute data types are used 🕵🏻

[donmccurdy]

A couple bits of feedback, but would love to get this merged in soon – thank you!

[spearwolf]

@donmccurdy so have your feeback implemented - hope it fits so

[donmccurdy]

Thank you!

Tested with #25354.