coarse rasterization bug fix

Summary:
Fix a bug which resulted in a rendering artifacts if the image size was not a multiple of 16.
Fix: Revert coarse rasterization to original implementation and only update fine rasterization to reverse the ordering of Y and X axis. This is much simpler than the previous approach!

Additional changes:
- updated mesh rendering end-end tests to check outputs from both naive and coarse to fine rasterization.
- added pointcloud rendering end-end tests

Reviewed By: gkioxari

Differential Revision: D21102725

fbshipit-source-id: 2e7e1b013dd6dd12b3a00b79eb8167deddb2e89a

tests/common_testing.py

@@ -1,10 +1,20 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
 
 import unittest
+from pathlib import Path
 from typing import Callable, Optional, Union
 
 import numpy as np
 import torch
+from PIL import Image
+
+
+def load_rgb_image(filename: str, data_dir: Union[str, Path]):
+    filepath = data_dir / filename
+    with Image.open(filepath) as raw_image:
+        image = torch.from_numpy(np.array(raw_image) / 255.0)
+    image = image.to(dtype=torch.float32)
+    return image[..., :3]
 
 
 TensorOrArray = Union[torch.Tensor, np.ndarray]