Single function to load meshes from OBJs. join_meshes.

Summary:
Create the textures and the Meshes object from OBJ files in a single call.

There is functionality in OBJ files (like normals) which is ignored by this function.

Reviewed By: gkioxari

Differential Revision: D19691699

fbshipit-source-id: e26442ed80ff231b65b17d6c54c9d41e22b4e4a3

pytorch3d/io/__init__.py

@@ -1,7 +1,7 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
 
 
-from .obj_io import load_obj, save_obj
+from .obj_io import load_obj, load_objs_as_meshes, save_obj
 from .ply_io import load_ply, save_ply
 
 __all__ = [k for k in globals().keys() if not k.startswith("_")]

pytorch3d/io/obj_io.py

@@ -13,6 +13,8 @@ import torch
 from fvcore.common.file_io import PathManager
 from PIL import Image
 
+from pytorch3d.structures import Meshes, Textures, join_meshes
+
 
 def _read_image(file_name: str, format=None):
     """
@@ -90,7 +92,7 @@ def _open_file(f):
 
 def load_obj(f_obj, load_textures=True):
     """
-    Load a mesh and textures from a .obj and .mtl file.
+    Load a mesh from a .obj file and optionally textures from a .mtl file.
     Currently this handles verts, faces, vertex texture uv coordinates, normals,
     texture images and material reflectivity values.
 
@@ -208,6 +210,44 @@ def load_obj(f_obj, load_textures=True):
             f_obj.close()
 
 
+def load_objs_as_meshes(files: list, device=None, load_textures: bool = True):
+    """
+    Load meshes from a list of .obj files using the load_obj function, and
+    return them as a Meshes object. This only works for meshes which have a
+    single texture image for the whole mesh. See the load_obj function for more
+    details. material_colors and normals are not stored.
+
+    Args:
+        f: A list of file-like objects (with methods read, readline, tell,
+        and seek), pathlib paths or strings containing file names.
+        device: Desired device of returned Meshes. Default:
+            uses the current device for the default tensor type.
+        load_textures: Boolean indicating whether material files are loaded
+
+    Returns:
+        New Meshes object.
+    """
+    mesh_list = []
+    for f_obj in files:
+        verts, faces, aux = load_obj(f_obj, load_textures=load_textures)
+        verts = verts.to(device)
+        tex = None
+        tex_maps = aux.texture_images
+        if tex_maps is not None and len(tex_maps) > 0:
+            verts_uvs = aux.verts_uvs[None, ...].to(device)  # (1, V, 2)
+            faces_uvs = faces.textures_idx[None, ...].to(device)  # (1, F, 3)
+            image = list(tex_maps.values())[0].to(device)[None]
+            tex = Textures(verts_uvs=verts_uvs, faces_uvs=faces_uvs, maps=image)
+
+        mesh = Meshes(
+            verts=[verts], faces=[faces.verts_idx.to(device)], textures=tex
+        )
+        mesh_list.append(mesh)
+    if len(mesh_list) == 1:
+        return mesh_list[0]
+    return join_meshes(mesh_list)
+
+
 def _parse_face(
     line,
     material_idx,