add meshopt decompression to copy cli

[arpu]

the cli copy command decompress draco compressed Assets automatic at the moment but not mesh_opt

what i read gltf-transform use the inbuild transform() https://github.com/donmccurdy/glTF-Transform/blob/main/packages/cli/src/cli.ts#L142

is there a example script to do this with meshopt registered extention?

[donmccurdy]

Hmm it's definitely supposed to, and seems to work for me:

glTF-Transform/packages/cli/src/session.ts

Lines 24 to 34 in 6671e0c

	// Warn and remove lossy compression, to avoid increasing loss on round trip.
	for (const extensionName of ['KHR_draco_mesh_compression', 'EXT_meshopt_compression']) {
	const extension = doc
	.getRoot()
	.listExtensionsUsed()
	.find((extension) => extension.extensionName === extensionName);
	if (extension) {
	extension.dispose();
	this._logger.warn(`Decoded ${extensionName}. Further compression will be lossy.`);
	}
	}

Do you have an example model that doesn't decompress as expected?

[arpu]

you are right, not sure why this not worked on the server need some more investigation

[arpu]

ok, the problem comes from the basisu compressed images, would it be possible to unpack x.basis to PNG on the copy command?

[donmccurdy]

The copy command only removes Draco compression because it's necessary when unpacking the file to an in-memory Document. Decompressing .ktx2 textures isn't required, and so I wouldn't want the unnecessary loss from unpacking .ktx2 files by default — they'll lose quality if recompressed.

I do think a separate command (decompress?) would be a good feature request. I would probably want to wait to implement that myself until the Khronos lightweight transcoders support ETC1S -> RGBA transcoding first.