code: def _parse_obj(f, data_dir: str):
      """
      Load a mesh from a file-like object. See load_obj function for more details
      about the return values.
      """
      verts, normals, verts_uvs = [], [], []
      faces_verts_idx, faces_normals_idx, faces_textures_idx = (
          [],
          [],
          [],
      )
      faces_materials_idx = []
      material_names = []
      mtl_path = None
  
      lines = [line.strip() for line in f]
  
      # startswith expects each line to be a string. If the file is read in as
      # bytes then first decode to strings.
      if lines and isinstance(lines[0], bytes):
          lines = [el.decode("utf-8") for el in lines]
  
      materials_idx = -1
  
      for line in lines:
          tokens = line.strip().split()
          if line.startswith("mtllib"):
              if len(tokens) < 2:
                  raise ValueError(
                      "material file name is not specified"
                  )
              # NOTE: only allow one .mtl file per .obj.
              # Definitions for multiple materials can be included
              # in this one .mtl file.
              mtl_path = line[
                  len(tokens[0]) :
              ].strip()  # Take the remainder of the line
              mtl_path = os.path.join(data_dir, mtl_path)
          elif len(tokens) and tokens[0] == "usemtl":
              material_name = tokens[1]
              # materials are often repeated for different parts
              # of a mesh.
              if material_name not in material_names:
                  material_names.append(material_name)
                  materials_idx = len(material_names) - 1
              else:
                  materials_idx = material_names.index(material_name)
          elif line.startswith("v "):  # Line is a vertex.
              vert = [float(x) for x in tokens[1:4]]
              if len(vert) != 3:
                  msg = "Vertex %s does not have 3 values. Line: %s"
                  raise ValueError(msg % (str(vert), str(line)))
              verts.append(vert)
          elif line.startswith("vt "):  # Line is a texture.
              tx = [float(x) for x in tokens[1:3]]
              if len(tx) != 2:
                  raise ValueError(
                      "Texture %s does not have 2 values. Line: %s"
                      % (str(tx), str(line))
                  )
              verts_uvs.append(tx)
          elif line.startswith("vn "):  # Line is a normal.
              norm = [float(x) for x in tokens[1:4]]
              if len(norm) != 3:
                  msg = "Normal %s does not have 3 values. Line: %s"
                  raise ValueError(msg % (str(norm), str(line)))
              normals.append(norm)
          elif line.startswith("f "):  # Line is a face.
              # Update face properties info.
              _parse_face(
                  line,
                  tokens,
                  materials_idx,
                  faces_verts_idx,
                  faces_normals_idx,
                  faces_textures_idx,
                  faces_materials_idx,
              )
  
      return (
          verts,
          normals,
          verts_uvs,
          faces_verts_idx,
          faces_normals_idx,
          faces_textures_idx,
          faces_materials_idx,
          material_names,
          mtl_path,
      )
  
imports: import os
  import warnings
  from collections import namedtuple
  from pathlib import Path
  from typing import List, Optional
  import numpy
  import torch
  from iopath.common.file_io import PathManager
  from PIL import Image
  from pytorch3d.common.datatypes import Device
  from pytorch3d.io.mtl_io import load_mtl, make_mesh_texture_atlas
  from pytorch3d.io.utils import _check_faces_indices, _make_tensor, _open_file, PathOrStr
  from pytorch3d.renderer import TexturesAtlas, TexturesUV
  from pytorch3d.structures import join_meshes_as_batch, Meshes
  from .pluggable_formats import endswith, MeshFormatInterpreter
label_desc: Use image node_id 5 for calling a global function with example usage: _parse_obj(f, data_dir) and returns: verts,  normals,  verts_uvs,  faces_verts_idx,  faces_normals_idx,  faces_textures_idx,  faces_materials_idx,  material_names,  mtl_path