Adding save mesh into glb file in TexturesVertex format

Summary:
Added a suit of functions and code additions to experimental_gltf_io.py file to enable saving Meshes in TexturesVertex format into .glb file.
Also added a test to tets_io_gltf.py to check the functionality with the test described in Test Plane.

Reviewed By: bottler

Differential Revision: D44969144

fbshipit-source-id: 9ce815a1584b510442fa36cc4dbc8d41cc3786d5

pytorch3d/io/experimental_gltf_io.py

@@ -393,7 +393,7 @@ class _GLTFLoader:
         attributes = primitive["attributes"]
         vertex_colors = self._get_primitive_attribute(attributes, "COLOR_0", np.float32)
         if vertex_colors is not None:
-            return TexturesVertex(torch.from_numpy(vertex_colors))
+            return TexturesVertex([torch.from_numpy(vertex_colors)])
 
         vertex_texcoords_0 = self._get_primitive_attribute(
             attributes, "TEXCOORD_0", np.float32
@@ -559,12 +559,26 @@ class _GLTFWriter:
         meshes = defaultdict(list)
         # pyre-fixme[6]: Incompatible parameter type
         meshes["name"] = "Node-Mesh"
+        if isinstance(self.mesh.textures, TexturesVertex):
+            primitives = {
+                "attributes": {"POSITION": 0, "COLOR_0": 2},
+                "indices": 1,
+                "mode": _PrimitiveMode.TRIANGLES,
+            }
+        elif isinstance(self.mesh.textures, TexturesUV):
             primitives = {
                 "attributes": {"POSITION": 0, "TEXCOORD_0": 2},
                 "indices": 1,
-            "material": 0,  # default material
+                "mode": _PrimitiveMode.TRIANGLES,
+                "material": 0,
+            }
+        else:
+            primitives = {
+                "attributes": {"POSITION": 0},
+                "indices": 1,
                 "mode": _PrimitiveMode.TRIANGLES,
             }
+
         meshes["primitives"].append(primitives)
         self._json_data["meshes"].append(meshes)
 
@@ -610,6 +624,14 @@ class _GLTFWriter:
             element_min = list(map(float, np.min(data, axis=0)))
             element_max = list(map(float, np.max(data, axis=0)))
             byte_per_element = 2 * _DTYPE_BYTES[_ITEM_TYPES[_ComponentType.FLOAT]]
+        elif key == "texvertices":
+            component_type = _ComponentType.FLOAT
+            data = self.mesh.textures.verts_features_list()[0].cpu().numpy()
+            element_type = "VEC3"
+            buffer_view = 2
+            element_min = list(map(float, np.min(data, axis=0)))
+            element_max = list(map(float, np.max(data, axis=0)))
+            byte_per_element = 3 * _DTYPE_BYTES[_ITEM_TYPES[_ComponentType.FLOAT]]
         elif key == "indices":
             component_type = _ComponentType.UNSIGNED_SHORT
             data = (
@@ -646,8 +668,10 @@ class _GLTFWriter:
         return (byte_length, data)
 
     def _write_bufferview(self, key: str, **kwargs):
-        if key not in ["positions", "texcoords", "indices"]:
-            raise ValueError("key must be one of positions, texcoords or indices")
+        if key not in ["positions", "texcoords", "texvertices", "indices"]:
+            raise ValueError(
+                "key must be one of positions, texcoords, texvertices or indices"
+            )
 
         bufferview = {
             "name": "bufferView_%s" % key,
@@ -661,6 +685,10 @@ class _GLTFWriter:
             byte_per_element = 2 * _DTYPE_BYTES[_ITEM_TYPES[_ComponentType.FLOAT]]
             target = _TargetType.ARRAY_BUFFER
             bufferview["byteStride"] = int(byte_per_element)
+        elif key == "texvertices":
+            byte_per_element = 3 * _DTYPE_BYTES[_ITEM_TYPES[_ComponentType.FLOAT]]
+            target = _TargetType.ELEMENT_ARRAY_BUFFER
+            bufferview["byteStride"] = int(byte_per_element)
         elif key == "indices":
             byte_per_element = (
                 3 * _DTYPE_BYTES[_ITEM_TYPES[_ComponentType.UNSIGNED_SHORT]]
@@ -701,12 +729,15 @@ class _GLTFWriter:
         pos_byte, pos_data = self._write_accessor_json("positions")
         idx_byte, idx_data = self._write_accessor_json("indices")
         include_textures = False
-        if (
-            self.mesh.textures is not None
-            and self.mesh.textures.verts_uvs_list()[0] is not None
-        ):
+        if self.mesh.textures is not None:
+            if hasattr(self.mesh.textures, "verts_features_list"):
+                tex_byte, tex_data = self._write_accessor_json("texvertices")
+                include_textures = True
+                texcoords = False
+            elif self.mesh.textures.verts_uvs_list()[0] is not None:
                 tex_byte, tex_data = self._write_accessor_json("texcoords")
                 include_textures = True
+                texcoords = True
 
         # bufferViews for positions, texture coords and indices
         byte_offset = 0
@@ -717,17 +748,19 @@ class _GLTFWriter:
         byte_offset += idx_byte
 
         if include_textures:
+            if texcoords:
                 self._write_bufferview(
                     "texcoords", byte_length=tex_byte, offset=byte_offset
                 )
+            else:
+                self._write_bufferview(
+                    "texvertices", byte_length=tex_byte, offset=byte_offset
+                )
             byte_offset += tex_byte
 
         # image bufferView
         include_image = False
-        if (
-            self.mesh.textures is not None
-            and self.mesh.textures.maps_list()[0] is not None
-        ):
+        if self.mesh.textures is not None and hasattr(self.mesh.textures, "maps_list"):
             include_image = True
             image_byte, image_data = self._write_image_buffer(offset=byte_offset)
             byte_offset += image_byte

tests/test_io_gltf.py

@@ -120,6 +120,7 @@ class TestMeshGltfIO(TestCaseMixin, unittest.TestCase):
         The scene is "already lit", i.e. the textures reflect the lighting
         already, so we want to render them with full ambient light.
         """
+
         self.skipTest("Data not available")
 
         glb = DATA_DIR / "apartment_1.glb"
@@ -266,3 +267,117 @@ class TestMeshGltfIO(TestCaseMixin, unittest.TestCase):
             expected = np.array(f)
 
         self.assertClose(image, expected)
+
+    def test_load_save_load_cow_texturesvertex(self):
+        """
+        Load the cow as converted to a single mesh in a glb file and then save it to a glb file.
+        """
+
+        glb = DATA_DIR / "cow.glb"
+        self.assertTrue(glb.is_file())
+        device = torch.device("cuda:0")
+        mesh = _load(glb, device=device, include_textures=False)
+        self.assertEqual(len(mesh), 1)
+        self.assertIsNone(mesh.textures)
+
+        self.assertEqual(mesh.faces_packed().shape, (5856, 3))
+        self.assertEqual(mesh.verts_packed().shape, (3225, 3))
+        mesh_obj = _load(TUTORIAL_DATA_DIR / "cow_mesh/cow.obj")
+        self.assertClose(mesh.get_bounding_boxes().cpu(), mesh_obj.get_bounding_boxes())
+
+        mesh.textures = TexturesVertex(0.5 * torch.ones_like(mesh.verts_padded()))
+
+        image = _render(mesh, "cow_gray")
+
+        with Image.open(DATA_DIR / "glb_cow_gray.png") as f:
+            expected = np.array(f)
+
+        self.assertClose(image, expected)
+
+        # save the mesh to a glb file
+        glb = DATA_DIR / "cow_write_texturesvertex.glb"
+        _write(mesh, glb)
+
+        # reload the mesh glb file saved in TexturesVertex format
+        glb = DATA_DIR / "cow_write_texturesvertex.glb"
+        self.assertTrue(glb.is_file())
+        mesh_dash = _load(glb, device=device)
+        self.assertEqual(len(mesh_dash), 1)
+
+        self.assertEqual(mesh_dash.faces_packed().shape, (5856, 3))
+        self.assertEqual(mesh_dash.verts_packed().shape, (3225, 3))
+        self.assertEqual(mesh_dash.textures.verts_features_list()[0].shape, (3225, 3))
+
+        # check the re-rendered image with expected
+        image_dash = _render(mesh, "cow_gray_texturesvertex")
+        self.assertClose(image_dash, expected)
+
+    def test_save_toy(self):
+        """
+        Construct a simple mesh and save it to a glb file in TexturesVertex mode.
+        """
+
+        example = {}
+        example["POSITION"] = torch.tensor(
+            [
+                [
+                    [0.0, 0.0, 0.0],
+                    [-1.0, 0.0, 0.0],
+                    [-1.0, 0.0, 1.0],
+                    [0.0, 0.0, 1.0],
+                    [0.0, 1.0, 0.0],
+                    [-1.0, 1.0, 0.0],
+                    [-1.0, 1.0, 1.0],
+                    [0.0, 1.0, 1.0],
+                ]
+            ]
+        )
+        example["indices"] = torch.tensor(
+            [
+                [
+                    [1, 4, 2],
+                    [4, 3, 2],
+                    [3, 7, 2],
+                    [7, 6, 2],
+                    [3, 4, 7],
+                    [4, 8, 7],
+                    [8, 5, 7],
+                    [5, 6, 7],
+                    [5, 2, 6],
+                    [5, 1, 2],
+                    [1, 5, 4],
+                    [5, 8, 4],
+                ]
+            ]
+        )
+        example["indices"] -= 1
+        example["COLOR_0"] = torch.tensor(
+            [
+                [
+                    [1.0, 0.0, 0.0],
+                    [1.0, 0.0, 0.0],
+                    [1.0, 0.0, 0.0],
+                    [1.0, 0.0, 0.0],
+                    [1.0, 0.0, 0.0],
+                    [1.0, 0.0, 0.0],
+                    [1.0, 0.0, 0.0],
+                    [1.0, 0.0, 0.0],
+                ]
+            ]
+        )
+        # example['prop'] = {'material':
+        #                       {'pbrMetallicRoughness':
+        #                           {'baseColorFactor':
+        #                                torch.tensor([[0.7, 0.7, 1, 0.5]]),
+        #                            'metallicFactor': torch.tensor([1]),
+        #                            'roughnessFactor': torch.tensor([0.1])},
+        #                    'alphaMode': 'BLEND',
+        #                    'doubleSided': True}}
+
+        texture = TexturesVertex(example["COLOR_0"])
+        mesh = Meshes(
+            verts=example["POSITION"], faces=example["indices"], textures=texture
+        )
+
+        glb = DATA_DIR / "example_write_texturesvertex.glb"
+        _write(mesh, glb)