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from typing import *
from itertools import chain, repeat
from pathlib import Path
import os
import numpy as np
from numpy import ndarray
__all__ = [
'read_obj',
'write_obj',
]
class WavefrontOBJDict(TypedDict):
"Typing for wavefront .obj file content"
mtllib: List[str]
"Material library filenames"
v: ndarray
"Vertex coordinates"
vt: ndarray
"Vertex texture coordinates"
vn: ndarray
"Vertex normals"
f: Union[ndarray, Tuple[ndarray, ndarray]]
"Vertex indices of faces. NOTE: 0-based indexing"
ft: Union[ndarray, Tuple[ndarray, ndarray]]
"Vertex texture coordinate indices of faces. NOTE: 0-based indexing"
fn: Union[ndarray, Tuple[ndarray, ndarray]]
"Vertex normal indices of faces. NOTE: 0-based indexing"
l: Union[ndarray, Tuple[ndarray, ndarray]]
"Vertex indices of lines. NOTE: 0-based indexing"
lt: Union[ndarray, Tuple[ndarray, ndarray]]
"Vertex texture coordinate indices of lines. NOTE: 0-based indexing"
p: ndarray
"Vertex indices of points. NOTE: 0-based indexing"
pt: ndarray
"Vertex texture coordinate indices of points. NOTE: 0-based indexing"
o: Dict[str, Dict[Literal['f', 'l', 'p'], slice]]
"Object names and corresponding slices of faces/lines/points"
g: Dict[str, Dict[Literal['f', 'l', 'p'], slice]]
"Group names and corresponding slices of faces/lines/points"
usemtl: Dict[str, Dict[Literal['f', 'l', 'p'], slice]]
"Material names and corresponding slices of faces/lines/points"
def read_obj(
file : Union[str, Path, TextIOWrapper],
encoding: Union[str, None] = None,
ignore_unknown: bool = False
) -> WavefrontOBJDict:
"""
Read wavefront .obj file.
Parameters
----
- `file` (str, Path, TextIOWrapper): filepath or file object
- `encoding` (str, optional): file encoding
- `ignore_unknown` (bool): whether to ignore unknown keywords in .obj file. Default to False.
Returns
----
A dictionary maybe containing the following fields. Note that some fields may be absent if not present in the .obj file:
Vertices and attributes data:
- `v` (ndarray): (N_v, 3 or 4) vertex coordinates.
- `vt` (ndarray): (N_vt, 2 or 3). vertex texture coordinates.
- `vn` (ndarray): (N_vn, 3). vertex normals.
Primitive definitions (face/line). NOTE: all indices are 0-based, unlike the 1-based indexing in .obj file.
- `f` (ndarray): Vertex indices in each face.
- If all faces have the same number of vertices: (M, K)
- If faces have different numbers of vertices: a tuple of segmented array:
- `data` (ndarray): flattened array of shape (sum(K_i),)
- `offsets` (ndarray): shape (M + 1,), offsets of each face in the flattened array
- `ft` (ndarray): Vertex texture coordinate indices of each face. The same format as `f`.
- `fn` (ndarray): Vertex normal indices of each face. The same format as `f`.
- `l` (ndarray): Vertex indices of each line segment.
- If all lines have the same number of vertices: (L, K_line)
- If lines have different numbers of vertices: a tuple of segmented array:
- `data` (ndarray): flattened array of shape (sum(K_line_i),)
- `offsets` (ndarray): shape (L + 1,), offsets of each line in the flattened array
- `lt` (ndarray): Vertex texture coordinate indices of each line. The same format as `l`.
- `p` (ndarray): Vertex indices of each point. 1D array of shape (N_p,)
- `pt` (ndarray): Vertex texture coordinate indices of each point. The same format as `p`.
Object/Group/Material info:
- `o` (Dict[str, Dict[Literal['f', 'l', 'p'], slice]]). The objects and their corresponding faces/lines/points. E.g. `o['object_A']['f']` gives the slice of faces belonging to object_A.
- `g` (Dict[str, Dict[Literal['f', 'l', 'p'], slice]]). The groups and their corresponding faces/lines/points. E.g. `g['group_A']['f']` gives the slice of faces belonging to group_A.
- `usemtl` (Dict[str, Dict[Literal['f', 'l', 'p'], slice]]). The materials and their corresponding faces/lines/points. E.g. `usemtl['material_A']['f']` gives the slice of faces using material_A.
Here, `names` is a list of names, and `offsets` is an array of shape (num_entities + 1,) indicating the start and end indices of faces belonging to each object/group/material.
For example, the second material has name `material_names[1]`, and its faces are `f[material_offsets[1]:material_offsets[2]]`.
Material library:
- `mtllib` (List[str]): list of material library filenames - `mtllib` lines in .obj file.
"""
if hasattr(file,'read'):
lines = file.read().splitlines()
else:
with open(file, 'r', encoding=encoding) as fp:
lines = fp.read().splitlines()
mtllib = []
v, vt, vn = [], [], [] # Vertex coordinates, Vertex texture coordinate, Vertex normal
f, ft, fn = [], [], [] # Face indices, Face texture indices, Face normal indices
l, lt = [], [] # Line indices, Line texture indices
p, pt = [], [] # Point indices, Point texture indices
o = {}
o_names, o_offsets = [], []
g = {}
g_names, g_offsets = [], []
usemtl = {}
usemtl_names, usemtl_offsets = [], []
int_ = lambda x: int(x) if x != '' else 0
pad = lambda l, n, x = 0: l + [x] * (n - len(l))
# Read the lines
for i, line in enumerate(lines):
keyword, *seq = line.strip().split()
if len(seq) == 0:
continue
if keyword == 'v':
assert 3 <= len(seq) <= 4, f'Invalid format of line {i}: {line}'
v.append([float(e) for e in seq])
elif keyword == 'vt':
assert 3 <= len(seq) <= 4, f'Invalid format of line {i}: {line}'
vt.append([float(e) for e in seq])
elif keyword == 'vn':
assert len(seq) == 3, f'Invalid format of line {i}: {line}'
vn.append([float(e) for e in seq])
elif keyword == 'f':
elems = [pad(list(map(int_, item.split('/'))), 3) for item in seq]
f.append([e[0] for e in elems])
ft.append([e[1] for e in elems])
fn.append([e[2] for e in elems])
elif keyword == 'l':
elems = [pad(list(map(int_, item.split('/'))), 2) for item in seq]
l.append([e[0] for e in elems])
lt.append([e[1] for e in elems])
elif keyword == 'p':
elems = [pad(list(map(int_, item.split('/'))), 2) for item in seq]
p.extend([e[0] for e in elems])
pt.extend([e[1] for e in elems])
elif keyword == 'o':
assert len(seq) == 1, f'Invalid format of line {i}: {line}'
o_names.append(seq[0])
o_offsets.append((len(f), len(l), len(p)))
elif keyword == 'g':
assert len(seq) == 1, f'Invalid format of line {i}: {line}'
g_names.append(seq[0])
g_offsets.append((len(f), len(l), len(p)))
elif keyword == 'usemtl':
assert len(seq) == 1, f'Invalid format of line {i}: {line}'
usemtl_names.append(seq[0])
usemtl_offsets.append((len(f), len(l), len(p)))
elif keyword == 'mtllib':
mtllib.extend(seq)
elif keyword[0] == '#':
continue
else:
if not ignore_unknown:
raise Exception(f'Unknown keyword {keyword} in line {i}: {line}')
# Process vertex data
if len(v) > 0:
max_v_dim = max(map(len, v)) if len(v) > 0 else 0
v = np.array([v_ + [1.0] * (max_v_dim - len(v_)) for v_ in v], dtype=np.float32)
else:
v = None
if len(vt) > 0:
max_vt_dim = max(map(len, vt)) if len(vt) > 0 else 0
vt = np.array([vt_ + [0.0] * (max_vt_dim - len(vt_)) for vt_ in vt], dtype=np.float32)
else:
vt = None
if len(vn) > 0:
vn = np.array(vn, dtype=np.float32)
else:
vn = None
# Process face data
if len(f) > 0:
f_lengths = np.array(list(map(len, f)))
f = np.array(list(chain.from_iterable(f)), dtype=np.int32) - 1
ft = np.array(list(chain.from_iterable(ft)), dtype=np.int32) - 1
fn = np.array(list(chain.from_iterable(fn)), dtype=np.int32) - 1
# If all indices are -1, set to None
if (f == -1).all():
f = None
if (ft == -1).all():
ft = None
if (fn == -1).all():
fn = None
if (f_lengths == f_lengths[0]).all():
f_len = f_lengths[0]
f = f.reshape(-1, f_len) if f is not None else None
ft = ft.reshape(-1, f_len) if ft is not None else None
fn = fn.reshape(-1, f_len) if fn is not None else None
else:
f_offsets = np.concatenate([[0], np.cumsum(f_lengths)])
f = (f, f_offsets) if f is not None else None
ft = (ft, f_offsets) if ft is not None else None
fn = (fn, f_offsets) if fn is not None else None
else:
f = None
ft = None
fn = None
# Process line data
if len(l) > 0:
l_lengths = np.array(list(map(len, l)))
l = np.array(list(chain.from_iterable(l)), dtype=np.int32) - 1
lt = np.array(list(chain.from_iterable(lt)), dtype=np.int32) - 1
if (l == -1).all():
l = None
if (lt == -1).all():
lt = None
if (l_lengths == l_lengths[0]).all():
l_len = l_lengths[0]
l = l.reshape(-1, l_len) if l is not None else None
lt = lt.reshape(-1, l_len) if lt is not None else None
else:
l_offsets = np.concatenate([[0], np.cumsum(l_lengths)])
l = (l, l_offsets) if l is not None else None
lt = (lt, l_offsets) if lt is not None else None
else:
l = None
lt = None
# Process point data
if len(p) > 0:
p = np.array(p, dtype=np.int32) - 1
pt = np.array(pt, dtype=np.int32) - 1
if (p == -1).all():
p = None
if (pt == -1).all():
pt = None
else:
p = None
pt = None
# Process object/group/material info
if len(o_names) > 0:
o_offsets.append(len(f))
for i in range(len(o_names)):
start_f, start_l, start_p = o_offsets[i]
end_f, end_l, end_p = o_offsets[i + 1]
o_i = {}
if f is not None and end_f > start_f:
o_i['f'] = slice(start_f, end_f)
if l is not None and end_l > start_l:
o_i['l'] = slice(start_l, end_l)
if p is not None and end_p > start_p:
o_i['p'] = slice(start_p, end_p)
o[o_names[i]] = o_i
else:
o = None
if len(g_names) > 0:
g_offsets.append(len(f))
for i in range(len(g_names)):
start_f, start_l, start_p = g_offsets[i]
end_f, end_l, end_p = g_offsets[i + 1]
g_i = {}
if f is not None and end_f > start_f:
g_i['f'] = slice(start_f, end_f)
if l is not None and end_l > start_l:
g_i['l'] = slice(start_l, end_l)
if p is not None and end_p > start_p:
g_i['p'] = slice(start_p, end_p)
g[g_names[i]] = g_i
else:
g = None
if len(usemtl_names) > 0:
usemtl_offsets.append(len(f))
for i in range(len(usemtl_names)):
start_f, start_l, start_p = usemtl_offsets[i]
end_f, end_l, end_p = usemtl_offsets[i + 1]
usemtl_i = {}
if f is not None and end_f > start_f:
usemtl_i['f'] = slice(start_f, end_f)
if l is not None and end_l > start_l:
usemtl_i['l'] = slice(start_l, end_l)
if p is not None and end_p > start_p:
usemtl_i['p'] = slice(start_p, end_p)
usemtl[usemtl_names[i]] = usemtl_i
else:
usemtl = None
output = {'mtllib': mtllib, 'v': v, 'vt': vt, 'vn': vn, 'f': f, 'ft': ft, 'fn': fn, 'l': l, 'lt': lt, 'p': p, 'pt': pt, 'o': o, 'g': g, 'usemtl': usemtl}
output = {k: v for k, v in output.items() if v is not None}
return output
def write_obj(
file: Union[str, Path, os.PathLike],
obj: WavefrontOBJDict,
encoding: Union[str, None] = None
):
if isinstance(file, (str, Path, os.PathLike)):
fp = Path(file).open('w', encoding=encoding)
else:
fp = file
with fp:
# Write mtllib
if 'mtllib' in obj:
for mtllib in obj.get('mtllib', []):
print('mtllib', mtllib, file=fp)
# Write vertices and attributes
for k in ['v', 'vt', 'vn', 'vp']:
if k not in obj:
continue
for v in obj[k]:
print(k, *map(float, v), file=fp)
# Write faces
if 'f' in obj or 'ft' in obj or 'fn' in obj:
f = obj.get('f', None)
if isinstance(f, tuple):
f_data, f_offsets = f
f = np.split(f_data, f_offsets[1:-1])
ft = obj.get('ft', None)
if isinstance(ft, tuple):
ft_data, f_offsets = ft
ft = np.split(ft_data, f_offsets[1:-1])
fn = obj.get('fn', None)
if isinstance(fn, tuple):
fn_data, f_offsets = fn
fn = np.split(fn_data, f_offsets[1:-1])
for i, (f_i, ft_i, fn_i) in enumerate(zip(f if f is not None else repeat(None), ft if ft is not None else repeat(None), fn if fn is not None else repeat(None))):
if f_i is not None and ft_i is None and fn_i is None:
print('f', ' '.join(f'{f_ij + 1}' for f_ij in f_i), file=fp)
else:
print('f', ' '.join(f'{f_ij}/{ft_ij}/{fn_ij}' for f_ij, ft_ij, fn_ij in zip(f_i if f_i is not None else repeat(''), ft_i if ft_i is not None else repeat(''), fn_i if fn_i is not None else repeat(''))))
# Write lines
if 'l' in obj or 'lt' in obj:
l = obj.get('l', None)
if isinstance(l, tuple):
l_data, l_offsets = l
l = np.split(l_data, l_offsets[1:-1])
lt = obj.get('lt', None)
if isinstance(lt, tuple):
lt_data, l_offsets = lt
lt = np.split(lt_data, l_offsets[1:-1])
for i, (l_i, lt_i) in enumerate(zip(l if l is not None else repeat(None), lt if lt is not None else repeat(None))):
if l_i is not None and lt_i is None:
print('l', ' '.join(f'{l_ij + 1}' for l_ij in l_i), file=fp)
else:
print('l', ' '.join(f'{l_ij + 1}/{lt_ij + 1}' for l_ij, lt_ij in zip(l_i if l_i is not None else repeat(''), lt_i if lt_i is not None else repeat(''))))
# Write points
if 'p' in obj or 'pt' in obj:
p = obj.get('p', None)
pt = obj.get('pt', None)
for i, (p_i, pt_i) in enumerate(zip(p if p is not None else repeat(None), pt if pt is not None else repeat(None))):
if p_i is not None and pt_i is None:
print('p', f'{p_i + 1}', file=fp)
else:
print('p', f'{p_i + 1}/{pt_i + 1}', file=fp) |