Test gltf texture without renderer.

Summary:
Change the cow gltf loading test to validate the texture values and not to validate the renderer output because it has an unstable pixel.

Also a couple of lints.

Reviewed By: patricklabatut

Differential Revision: D29131260

fbshipit-source-id: 5e11f066a2a638588aacb09776cc842173ef669f

pytorch3d/renderer/blending.py

@@ -6,6 +6,7 @@ from typing import NamedTuple, Sequence, Union
 import torch
 from pytorch3d import _C  # pyre-fixme[21]: Could not find name `_C` in `pytorch3d`.
 
+
 # Example functions for blending the top K colors per pixel using the outputs
 # from rasterization.
 # NOTE: All blending function should return an RGBA image per batch element

pytorch3d/renderer/mesh/rasterize_meshes.py

@@ -401,7 +401,7 @@ def pix_to_non_square_ndc(i, S1, S2):
     return -offset + (ndc_range * i + offset) / S1
 
 
-def rasterize_meshes_python(
+def rasterize_meshes_python(  # noqa: C901
     meshes,
     image_size: Union[int, Tuple[int, int]] = 256,
     blur_radius: float = 0.0,