Add USD Material import support (#502)

Signed-off-by: JF Lafleche <jlafleche@nvidia.com>

docs/modules/kaolin.io.materials.rst

@@ -0,0 +1,32 @@
+.. _kaolin.io.materials:
+
+kaolin.io.materials
+===================
+
+.. currentmodule:: kaolin.io.materials
+
+API
+---
+
+Functions
+
+===================
+
+API
+---
+
+.. automodule:: kaolin.io.materials
+    :members:
+    :exclude-members:
+        MaterialError,
+        MaterialLoadError,
+        MaterialFileError,
+        MaterialNotFoundError
+
+Exceptions
+----------
+
+.. autoclass:: MaterialError
+.. autoclass:: MaterialLoadError
+.. autoclass:: MaterialFileError
+.. autoclass:: MaterialNotFoundError

docs/modules/kaolin.io.obj.rst

@@ -27,11 +27,3 @@ Error Handler
 
 .. autofunction:: skip_error_handler
 .. autofunction:: default_error_handler
-
-Exceptions
-----------
-
-.. autoclass:: MaterialError
-.. autoclass:: MaterialLoadError
-.. autoclass:: MaterialFileError
-.. autoclass:: MaterialNotFoundError

kaolin/io/obj.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2019-2020, NVIDIA CORPORATION. All rights reserved.
+# Copyright (c) 2019, 20-21, NVIDIA CORPORATION. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -20,30 +20,19 @@
 import torch
 from PIL import Image
 
+from kaolin.io.materials import MaterialLoadError, MaterialFileError, MaterialNotFoundError
+
+
 return_type = namedtuple('return_type',
                          ['vertices', 'faces', 'uvs', 'face_uvs_idx', 'materials',
                           'materials_order', 'vertex_normals', 'face_normals'])
 
 
-class MaterialError(Exception):
-    pass
-
-
-class MaterialLoadError(MaterialError):
-    pass
-
-
-class MaterialFileError(MaterialError):
-    pass
-
-
-class MaterialNotFoundError(MaterialError):
-    pass
-
 def ignore_error_handler(error, **kwargs):
     """Simple error handler to use in :func:`load_obj` that ignore all errors"""
     pass
 
+
 def skip_error_handler(error, **kwargs):
     """Simple error handler to use in :func:`load_obj` that skips all errors
     and logs them as warnings."""
@@ -82,7 +71,7 @@ def import_mesh(path, with_materials=False, with_normals=False,
         - **uvs** (torch.Tensor): of shape (num_uvs, 2)
         - **face_uvs_idx** (torch.LongTensor): of shape (num_faces, face_size)
         - **materials** (list of dict): a list of materials (see return values of :func:`load_mtl`)
-        - **materials_orders** (torch.LongTensor): of shape (num_same_material_groups, 2)
+        - **materials_order** (torch.LongTensor): of shape (num_same_material_groups, 2)
           showing the order in which materials are used over **face_uvs_idx** and the first indices
           in which they start to be used. A material can be used multiple times.
         - **vertex_normals** (torch.Tensor): of shape (num_vertices, 3)
@@ -105,7 +94,7 @@ def import_mesh(path, with_materials=False, with_normals=False,
     vertex_normals = []
     # 3 values per face
     face_normals = []
-    textures = []
+    # textures = []
     mtl_path = None
     materials_order = []
     materials_dict = {}