gltf-clone.js

export default function(gltf, THREE) {
  const clone = {
    animations: gltf.animations,
    scene: gltf.scene.clone(true)
  }

  const skinnedMeshes = {}

  gltf.scene.traverse(node => {
    if (node.isSkinnedMesh) {
      skinnedMeshes[node.name] = node
    }
  })

  const cloneBones = {}
  const cloneSkinnedMeshes = {}

  clone.scene.traverse(node => {
    if (node.isBone) {
      cloneBones[node.name] = node
    }

    if (node.isSkinnedMesh) {
      cloneSkinnedMeshes[node.name] = node
    }
  })

  for (let name in skinnedMeshes) {
    const skinnedMesh = skinnedMeshes[name]
    const skeleton = skinnedMesh.skeleton
    const cloneSkinnedMesh = cloneSkinnedMeshes[name]

    const orderedCloneBones = []

    for (let i = 0; i < skeleton.bones.length; ++i) {
      const cloneBone = cloneBones[skeleton.bones[i].name]
      orderedCloneBones.push(cloneBone)
    }

    cloneSkinnedMesh.bind(new THREE.Skeleton(orderedCloneBones, skeleton.boneInverses), cloneSkinnedMesh.matrixWorld)
  }

  return clone
}