getitem for textures

Summary: Make Meshes.__getitem__ carry texture information to the new mesh.

Reviewed By: gkioxari

Differential Revision: D20283976

fbshipit-source-id: d9ee0580c11ac5b4384df9d8158a07e6eb8d00fe

pytorch3d/structures/meshes.py

@@ -415,10 +415,12 @@ class Meshes(object):
         else:
             raise IndexError(index)
 
+        textures = None if self.textures is None else self.textures[index]
+
         if torch.is_tensor(verts) and torch.is_tensor(faces):
-            return Meshes(verts=[verts], faces=[faces])
+            return Meshes(verts=[verts], faces=[faces], textures=textures)
         elif isinstance(verts, list) and isinstance(faces, list):
-            return Meshes(verts=verts, faces=faces)
+            return Meshes(verts=verts, faces=faces, textures=textures)
         else:
             raise ValueError("(verts, faces) not defined correctly")
 

pytorch3d/structures/textures.py

@@ -115,8 +115,14 @@ class Textures(object):
         self._verts_rgb_padded = verts_rgb
         self._maps_padded = maps
         self._num_faces_per_mesh = None
+        self._set_num_faces_per_mesh()
 
+    def _set_num_faces_per_mesh(self) -> None:
+        """
+        Determines and sets the number of textured faces for each mesh.
+        """
         if self._faces_uvs_padded is not None:
+            faces_uvs = self._faces_uvs_padded
             self._num_faces_per_mesh = faces_uvs.gt(-1).all(-1).sum(-1).tolist()
 
     def clone(self):
@@ -134,6 +140,18 @@ class Textures(object):
                 setattr(self, k, v.to(device))
         return self
 
+    def __getitem__(self, index):
+        other = Textures()
+        for key in dir(self):
+            value = getattr(self, key)
+            if torch.is_tensor(value):
+                if isinstance(index, int):
+                    setattr(other, key, value[index][None])
+                else:
+                    setattr(other, key, value[index])
+        other._set_num_faces_per_mesh()
+        return other
+
     def faces_uvs_padded(self) -> torch.Tensor:
         return self._faces_uvs_padded