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/structures/__init__.py

@@ -1,6 +1,6 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
 
-from .meshes import Meshes
+from .meshes import Meshes, join_meshes
 from .textures import Textures
 from .utils import (
     list_to_packed,

pytorch3d/structures/meshes.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 # Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
 
+from typing import List
 import torch
 
 from pytorch3d import _C
@@ -1365,3 +1366,77 @@ class Meshes(object):
         if self.textures is not None:
             tex = self.textures.extend(N)
         return Meshes(verts=new_verts_list, faces=new_faces_list, textures=tex)
+
+
+def join_meshes(meshes: List[Meshes], include_textures: bool = True):
+    """
+    Merge multiple Meshes objects, i.e. concatenate the meshes objects. They
+    must all be on the same device. If include_textures is true, they must all
+    be compatible, either all or none having textures, and all the Textures
+    objects having the same members. If  include_textures is False, textures are
+    ignored.
+
+    Args:
+        meshes: list of meshes.
+        include_textures: (bool) whether to try to join the textures.
+
+    Returns:
+        new Meshes object containing all the meshes from all the inputs.
+    """
+    if isinstance(meshes, Meshes):
+        # Meshes objects can be iterated and produce single Meshes. We avoid
+        # letting join_meshes(mesh1, mesh2) silently do the wrong thing.
+        raise ValueError("Wrong first argument to join_meshes.")
+    verts = [v for mesh in meshes for v in mesh.verts_list()]
+    faces = [f for mesh in meshes for f in mesh.faces_list()]
+    if len(meshes) == 0 or not include_textures:
+        return Meshes(verts=verts, faces=faces)
+
+    if meshes[0].textures is None:
+        if any(mesh.textures is not None for mesh in meshes):
+            raise ValueError("Inconsistent textures in join_meshes.")
+        return Meshes(verts=verts, faces=faces)
+
+    if any(mesh.textures is None for mesh in meshes):
+        raise ValueError("Inconsistent textures in join_meshes.")
+
+    # Now we know there are multiple meshes and they have textures to merge.
+    first = meshes[0].textures
+    kwargs = {}
+    if first.maps_padded() is not None:
+        if any(mesh.textures.maps_padded() is None for mesh in meshes):
+            raise ValueError("Inconsistent maps_padded in join_meshes.")
+        maps = [m for mesh in meshes for m in mesh.textures.maps_padded()]
+        kwargs["maps"] = maps
+    elif any(mesh.textures.maps_padded() is not None for mesh in meshes):
+        raise ValueError("Inconsistent maps_padded in join_meshes.")
+
+    if first.verts_uvs_padded() is not None:
+        if any(mesh.textures.verts_uvs_padded() is None for mesh in meshes):
+            raise ValueError("Inconsistent verts_uvs_padded in join_meshes.")
+        uvs = [uv for mesh in meshes for uv in mesh.textures.verts_uvs_list()]
+        V = max(uv.shape[0] for uv in uvs)
+        kwargs["verts_uvs"] = struct_utils.list_to_padded(uvs, (V, 2), -1)
+    elif any(mesh.textures.verts_uvs_padded() is not None for mesh in meshes):
+        raise ValueError("Inconsistent verts_uvs_padded in join_meshes.")
+
+    if first.faces_uvs_padded() is not None:
+        if any(mesh.textures.faces_uvs_padded() is None for mesh in meshes):
+            raise ValueError("Inconsistent faces_uvs_padded in join_meshes.")
+        uvs = [uv for mesh in meshes for uv in mesh.textures.faces_uvs_list()]
+        F = max(uv.shape[0] for uv in uvs)
+        kwargs["faces_uvs"] = struct_utils.list_to_padded(uvs, (F, 3), -1)
+    elif any(mesh.textures.faces_uvs_padded() is not None for mesh in meshes):
+        raise ValueError("Inconsistent faces_uvs_padded in join_meshes.")
+
+    if first.verts_rgb_padded() is not None:
+        if any(mesh.textures.verts_rgb_padded() is None for mesh in meshes):
+            raise ValueError("Inconsistent verts_rgb_padded in join_meshes.")
+        rgb = [i for mesh in meshes for i in mesh.textures.verts_rgb_list()]
+        V = max(i.shape[0] for i in rgb)
+        kwargs["verts_rgb"] = struct_utils.list_to_padded(rgb, (V, 3))
+    elif any(mesh.textures.verts_rgb_padded() is not None for mesh in meshes):
+        raise ValueError("Inconsistent verts_rgb_padded in join_meshes.")
+
+    tex = Textures(**kwargs)
+    return Meshes(verts=verts, faces=faces, textures=tex)