text: export function RemoveChild3DAt(parent, index) {
    const children = parent.children;
    let child;
    if (index >= 0 && index < children.length) {
      const removed = children.splice(index, 1);
      if (removed[0]) {
        child = removed[0];
        child.parent = null;
      }
    }
    return child;
  }
  