From 5241b7dd4e03ee3d7fdec4b1258da05c299eb98c Mon Sep 17 00:00:00 2001
From: Daisy <zhusilizsl@gmail.com>
Date: Fri, 7 May 2021 05:01:20 -0700
Subject: [PATCH] Handle header has no newline or space after OFF. (#665)

Summary:
Allow a line like `OFF10 10 10` as the start of an OFF file. Such things apparently occur in ModelNet40.

This resolves https://github.com/facebookresearch/pytorch3d/issues/663.

Pull Request resolved: https://github.com/facebookresearch/pytorch3d/pull/665

Test Plan: New test

Reviewed By: nikhilaravi

Differential Revision: D28180006

Pulled By: bottler

fbshipit-source-id: 7f474c6a262e32da012217e09f76e8672a7f0278
---
 pytorch3d/io/off_io.py | 17 +++++++++++------
 tests/test_io_off.py   |  5 +++++
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/pytorch3d/io/off_io.py b/pytorch3d/io/off_io.py
index 30244370..822946ae 100644
--- a/pytorch3d/io/off_io.py
+++ b/pytorch3d/io/off_io.py
@@ -6,6 +6,9 @@
 """
 This module implements utility functions for loading and saving
 meshes as .off files.
+
+This format is introduced, for example, at
+http://www.geomview.org/docs/html/OFF.html .
 """
 import warnings
 from pathlib import Path
@@ -226,15 +229,17 @@ def _load_off_stream(file) -> dict:
         faces_colors: FloatTensor of shape (F, C), where C is 3 or 4.
     """
     header = file.readline()
-    if header.lower() in (b"off\n", b"off\r\n", "off\n"):
-        header = file.readline()
 
     while _is_line_empty(header):
         header = file.readline()
 
-    items = header.split(b" ")
-    if len(items) and items[0].lower() in ("off", b"off"):
-        items = items[1:]
+    if header[:3].lower() == b"off":
+        header = header[3:]
+
+    while _is_line_empty(header):
+        header = file.readline()
+
+    items = header.split()
     if len(items) < 3:
         raise ValueError("Invalid counts line: %s" % header)
 
@@ -247,7 +252,7 @@ def _load_off_stream(file) -> dict:
     except ValueError:
         raise ValueError("Invalid counts line: %s" % header)
 
-    if (len(items) > 3 and not items[3].startswith("#")) or n_verts < 0 or n_faces < 0:
+    if (len(items) > 3 and not items[3].startswith(b"#")) or n_verts < 0 or n_faces < 0:
         raise ValueError("Invalid counts line: %s" % header)
 
     verts, verts_colors = _read_verts(file, n_verts)
diff --git a/tests/test_io_off.py b/tests/test_io_off.py
index 16cf766d..c28fe7fd 100644
--- a/tests/test_io_off.py
+++ b/tests/test_io_off.py
@@ -254,6 +254,11 @@ class TestMeshOffIO(TestCaseMixin, unittest.TestCase):
         lines2[0] = "OFF " + lines[0]
         load(lines2)
 
+        # OFF line can be merged in to the first line with no space
+        lines2 = lines.copy()
+        lines2[0] = "OFF" + lines[0]
+        load(lines2)
+
         with self.assertRaisesRegex(ValueError, "Not enough face data."):
             load(lines[:-1])