resouces filenames with spaces (#358)

Summary:
I'm constantly encountering 3D models with resources that have spaces in their filenames (especially on Windows) and therefore they can't be loaded in pytorch3d. Let me know what you think.

Thanks

Pull Request resolved: #358

Reviewed By: bottler

Differential Revision: D23798492

Pulled By: nikhilaravi

fbshipit-source-id: 4d85b7ee05339486d2e5ef53a531f8e6052251c5

pytorch3d/io/mtl_io.py

@@ -399,7 +399,9 @@ def _parse_mtl(f, device="cpu") -> Tuple[MaterialProperties, TextureFiles]:
                 material_properties[material_name] = {}
             elif tokens[0] == "map_Kd":
                 # Diffuse texture map
-                texture_files[material_name] = tokens[1]
+                # Account for the case where filenames might have spaces
+                filename = line.strip()[7:]
+                texture_files[material_name] = filename
             elif tokens[0] == "Kd":
                 # RGB diffuse reflectivity
                 kd = np.array(tokens[1:4]).astype(np.float32)

tests/test_obj_io.py

@@ -12,6 +12,7 @@
 from pytorch3d.io.mtl_io import (
     _bilinear_interpolation_grid_sample,
     _bilinear_interpolation_vectorized,
+    _parse_mtl,
 )
 from pytorch3d.renderer import TexturesAtlas, TexturesUV, TexturesVertex
 from pytorch3d.structures import Meshes, join_meshes_as_batch
@@ -442,6 +443,51 @@ def test_load_mtl(self):
                     torch.allclose(materials[n1][k1], expected_materials[n2][k2])
                 )
 
+    def test_load_mtl_with_spaces_in_resource_filename(self):
+        """
+        Check that the texture image for materials in mtl files
+        is loaded correctly even if there is a space in the file name
+        e.g. material 1.png
+        """
+        mtl_file = "\n".join(
+            [
+                "newmtl material_1",
+                "map_Kd material 1.png",
+                "Ka 1.000 1.000 1.000",  # white
+                "Kd 1.000 1.000 1.000",  # white
+                "Ks 0.000 0.000 0.000",  # black
+                "Ns 10.0",
+            ]
+        )
+        mtl_file = StringIO(mtl_file)
+        material_properties, texture_files = _parse_mtl(mtl_file, device="cpu")
+
+        dtype = torch.float32
+        expected_materials = {
+            "material_1": {
+                "ambient_color": torch.tensor([1.0, 1.0, 1.0], dtype=dtype),
+                "diffuse_color": torch.tensor([1.0, 1.0, 1.0], dtype=dtype),
+                "specular_color": torch.tensor([0.0, 0.0, 0.0], dtype=dtype),
+                "shininess": torch.tensor([10.0], dtype=dtype),
+            }
+        }
+        # Check that there is a material with name material_1
+        self.assertTrue(tuple(texture_files.keys()) == ("material_1",))
+        # Check that there is an image with name material 1.png
+        self.assertTrue(texture_files["material_1"] == "material 1.png")
+
+        # Check all keys and values in dictionary are the same.
+        for n1, n2 in zip(material_properties.keys(), expected_materials.keys()):
+            self.assertTrue(n1 == n2)
+            for k1, k2 in zip(
+                material_properties[n1].keys(), expected_materials[n2].keys()
+            ):
+                self.assertTrue(
+                    torch.allclose(
+                        material_properties[n1][k1], expected_materials[n2][k2]
+                    )
+                )
+
     def test_load_mtl_texture_atlas_compare_softras(self):
         # Load saved texture atlas created with SoftRas.
         device = torch.device("cuda:0")