gltfpack: mesh.primitives merged unexpectly

[scarletsky]

I am using this build of gltfpack.

The origin model is here monkey.glb.zip

No matter what flags (-kn -km -ke -vpf -noq) I pass, gltfpack will merge the primitives unexpectly.

[zeux]

This is by design - the point of gltfpack is that it reorganizes and reprocesses the scene to make it more efficient. The options you quoted affect various aspects of transformations that have an impact on application access - eg without kn, an application that uses named node access may not get access to the node or meshes attached to it. However, primitives are an internal detail of glTF file encoding and as such they don't get a special option to block merging.

[scarletsky]

The original glb above is output by my own gltf exporter, it omitted all materials fields.

And I've output another glb by blender. At this time the mesh.primitives had material field:

I use the same gltfpack -kn -km -ke -vpf command, and the mesh.primitives are not merged.

So if I want to keep the original primitives, I need to assign different material to them, right ?

[zeux]

Yes, if two primitives have different materials, gltfpack won't merge them.