def _parse_obj()

in pytorch3d/io/obj_io.py [0:0]

• 64 lines of code
• 23 McCabe index (conditional complexity)

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,
    )