PLY TexturesVertex loading

Summary:
Include TexturesVertex colors when loading and saving Meshes to PLY files.

A couple of other improvements to the internals of ply_io, including using `None` instead of empty tensors for some missing data.

Reviewed By: gkioxari

Differential Revision: D27765260

fbshipit-source-id: b9857dc777c244b9d7d6643b608596d31435ecda

tests/test_io_ply.py

@@ -1,5 +1,6 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
 
+import itertools
 import struct
 import unittest
 from io import BytesIO, StringIO
@@ -12,7 +13,8 @@ from common_testing import TestCaseMixin
 from iopath.common.file_io import PathManager
 from pytorch3d.io import IO
 from pytorch3d.io.ply_io import load_ply, save_ply
-from pytorch3d.structures import Pointclouds
+from pytorch3d.renderer.mesh import TexturesVertex
+from pytorch3d.structures import Meshes, Pointclouds
 from pytorch3d.utils import torus
 
 
@@ -189,6 +191,57 @@ class TestMeshPlyIO(TestCaseMixin, unittest.TestCase):
             ):
                 io.load_mesh(f3.name)
 
+    def test_save_too_many_colors(self):
+        verts = torch.tensor(
+            [[0, 0, 0], [0, 0, 1], [0, 1, 0], [1, 0, 0]], dtype=torch.float32
+        )
+        faces = torch.tensor([[0, 1, 2], [0, 2, 3]])
+        vert_colors = torch.rand((4, 7))
+        texture_with_seven_colors = TexturesVertex(verts_features=[vert_colors])
+
+        mesh = Meshes(
+            verts=[verts],
+            faces=[faces],
+            textures=texture_with_seven_colors,
+        )
+
+        io = IO()
+        msg = "Texture will not be saved as it has 7 colors, not 3."
+        with NamedTemporaryFile(mode="w", suffix=".ply") as f:
+            with self.assertWarnsRegex(UserWarning, msg):
+                io.save_mesh(mesh.cuda(), f.name)
+
+    def test_save_load_meshes(self):
+        verts = torch.tensor(
+            [[0, 0, 0], [0, 0, 1], [0, 1, 0], [1, 0, 0]], dtype=torch.float32
+        )
+        faces = torch.tensor([[0, 1, 2], [0, 2, 3]])
+        vert_colors = torch.rand_like(verts)
+        texture = TexturesVertex(verts_features=[vert_colors])
+
+        for do_textures in itertools.product([True, False]):
+            mesh = Meshes(
+                verts=[verts],
+                faces=[faces],
+                textures=texture if do_textures else None,
+            )
+            device = torch.device("cuda:0")
+
+            io = IO()
+            with NamedTemporaryFile(mode="w", suffix=".ply") as f:
+                io.save_mesh(mesh.cuda(), f.name)
+                f.flush()
+                mesh2 = io.load_mesh(f.name, device=device)
+            self.assertEqual(mesh2.device, device)
+            mesh2 = mesh2.cpu()
+            self.assertClose(mesh2.verts_padded(), mesh.verts_padded())
+            self.assertClose(mesh2.faces_padded(), mesh.faces_padded())
+            if do_textures:
+                self.assertIsInstance(mesh2.textures, TexturesVertex)
+                self.assertClose(mesh2.textures.verts_features_list()[0], vert_colors)
+            else:
+                self.assertIsNone(mesh2.textures)
+
     def test_save_ply_invalid_shapes(self):
         # Invalid vertices shape
         with self.assertRaises(ValueError) as error: