lots of performance improvements, bug fixes and some new features

yacv_server/__init__.py

@@ -15,7 +15,7 @@ if 'YACV_DISABLE_SERVER' not in os.environ:
 # Expose some nice aliases using the default server instance
 show = yacv.show
 show_all = yacv.show_cad_all
-prepare_image = image_to_gltf
+image_to_gltf = image_to_gltf
 export_all = yacv.export_all
 remove = yacv.remove
 clear = yacv.clear

yacv_server/cad.py

@@ -60,7 +60,8 @@ def grab_all_cad() -> List[Tuple[str, CADCoreLike]]:
 
 
 def image_to_gltf(source: str | bytes, center: any, width: Optional[float] = None, height: Optional[float] = None,
-                  name: Optional[str] = None, save_mime: str = 'image/jpeg') -> Tuple[bytes, str]:
+                  name: Optional[str] = None, save_mime: str = 'image/jpeg', power_of_two: bool = True) \
+        -> Tuple[bytes, str]:
     """Convert an image to a GLTF CAD object."""
     from PIL import Image
     import io
@@ -101,17 +102,27 @@ def image_to_gltf(source: str | bytes, center: any, width: Optional[float] = Non
     # Load the image to a byte buffer
     img = Image.open(source)
     img_buf = io.BytesIO()
-    img.save(img_buf, format=format)
-    img_buf = img_buf.getvalue()
 
-    # Build the gltf
-    mgr = GLTFMgr(image=(img_buf, save_mime))
+    # Use the original dimensions for scaling the model
     if width is None and height is None:
         raise ValueError('At least one of width or height must be specified')  # Fallback to pixels == mm?
     elif width is None:
         width = img.width / img.height * height
     elif height is None:
         height = height or img.height / img.width * width  # Apply default aspect ratio if unspecified
+
+    # Resize the image to a power of two if requested (recommended for GLTF)
+    if power_of_two:
+        new_width = 2 ** (img.width - 1).bit_length()
+        new_height = 2 ** (img.height - 1).bit_length()
+        img = img.resize((new_width, new_height))
+
+    # Save the image to a buffer
+    img.save(img_buf, format=format)
+    img_buf = img_buf.getvalue()
+
+    # Build the gltf
+    mgr = GLTFMgr(image=(img_buf, save_mime))
     mgr.add_face([
         vert(plane.origin - plane.x_dir * width / 2 - plane.y_dir * height / 2),
         vert(plane.origin + plane.x_dir * width / 2 - plane.y_dir * height / 2),
@@ -125,7 +136,7 @@ def image_to_gltf(source: str | bytes, center: any, width: Optional[float] = Non
         (1, 0),
         (1, 1),
         (0, 1),
-    ])
+    ], (1, 1, 1, 1))
 
     # Return the GLTF binary blob and the suggested name of the image
-    return b''.join(mgr.gltf.save_to_bytes()), name
+    return b''.join(mgr.build().save_to_bytes()), name

yacv_server/gltf.py

@@ -12,45 +12,95 @@ _checkerboard_image_bytes = base64.decodebytes(
 class GLTFMgr:
     """A utility class to build our GLTF2 objects easily and incrementally"""
 
-    def __init__(self, image: Tuple[bytes, str] = (_checkerboard_image_bytes, 'image/png')):
+    gltf: GLTF2
+
+    # Intermediate data to be filled by the add_* methods and merged into the GLTF object
+    # - Face data
+    face_indices: List[int]  # 3 indices per triangle
+    face_positions: List[float]  # x, y, z
+    face_tex_coords: List[float]  # u, v
+    face_colors: List[float]  # r, g, b, a
+    image: Optional[Tuple[bytes, str]]  # image/png
+    # - Edge data
+    edge_indices: List[int]  # 2 indices per edge
+    edge_positions: List[float]  # x, y, z
+    edge_colors: List[float]  # r, g, b, a
+    # - Vertex data
+    vertex_indices: List[int]  # 1 index per vertex
+    vertex_positions: List[float]  # x, y, z
+    vertex_colors: List[float]  # r, g, b, a
+
+    def __init__(self, image: Optional[Tuple[bytes, str]] = (_checkerboard_image_bytes, 'image/png')):
         self.gltf = GLTF2(
             asset=Asset(generator=f"yacv_server@{importlib.metadata.version('yacv_server')}"),
             scene=0,
             scenes=[Scene(nodes=[0])],
-            nodes=[Node(mesh=0)],
-            meshes=[Mesh(primitives=[])],
-            accessors=[],
-            bufferViews=[BufferView(buffer=0, byteLength=len(image[0]), byteOffset=0)],
-            buffers=[Buffer(byteLength=len(image[0]))],
-            samplers=[Sampler(magFilter=NEAREST)],
-            textures=[Texture(source=0, sampler=0)],
-            images=[Image(bufferView=0, mimeType=image[1])],
+            nodes=[Node(mesh=0)],  # TODO: Server-side detection of shallow copies --> nodes
+            meshes=[Mesh(primitives=[
+                Primitive(indices=-1, attributes=Attributes(), mode=TRIANGLES, material=0,
+                          extras={"face_triangles_end": []}),
+                Primitive(indices=-1, attributes=Attributes(), mode=LINES, material=0,
+                          extras={"edge_points_end": []}),
+                Primitive(indices=-1, attributes=Attributes(), mode=POINTS, material=0),
+            ])],
+            materials=[Material(pbrMetallicRoughness=PbrMetallicRoughness(metallicFactor=0.1, roughnessFactor=1.0),
+                                alphaCutoff=None)],
         )
-        # TODO: Reduce the number of draw calls by merging all faces into a single primitive, and using
-        #  color attributes + extension? to differentiate them (same for edges and vertices)
-        self.gltf.set_binary_blob(image[0])
+        self.face_indices = []
+        self.face_positions = []
+        self.face_tex_coords = []
+        self.face_colors = []
+        self.image = image
+        self.edge_indices = []
+        self.edge_positions = []
+        self.edge_colors = []
+        self.vertex_indices = []
+        self.vertex_positions = []
+        self.vertex_colors = []
+
+    @property
+    def _faces_primitive(self) -> Primitive:
+        return [p for p in self.gltf.meshes[0].primitives if p.mode == TRIANGLES][0]
+
+    @property
+    def _edges_primitive(self) -> Primitive:
+        return [p for p in self.gltf.meshes[0].primitives if p.mode == LINES][0]
+
+    @property
+    def _vertices_primitive(self) -> Primitive:
+        return [p for p in self.gltf.meshes[0].primitives if p.mode == POINTS][0]
 
     def add_face(self, vertices_raw: List[Tuple[float, float, float]], indices_raw: List[Tuple[int, int, int]],
-                 tex_coord_raw: List[Tuple[float, float]]):
-        """Add a face to the GLTF as a new primitive of the unique mesh"""
-        vertices = np.array([[v[0], v[1], v[2]] for v in vertices_raw], dtype=np.float32)
-        indices = np.array([[i[0], i[1], i[2]] for i in indices_raw], dtype=np.uint32)
-        tex_coord = np.array([[t[0], t[1]] for t in tex_coord_raw], dtype=np.float32)
-        self._add_any(vertices, indices, tex_coord, mode=TRIANGLES, material="face")
+                 tex_coord_raw: List[Tuple[float, float]],
+                 color: Tuple[float, float, float, float] = (1.0, 0.75, 0.0, 1.0)):
+        """Add a face to the GLTF mesh"""
+        # assert len(vertices_raw) == len(tex_coord_raw), f"Vertices and texture coordinates have different lengths"
+        # assert min([i for t in indices_raw for i in t]) == 0, f"Face indices start at {min(indices_raw)}"
+        # assert max([e for t in indices_raw for e in t]) < len(vertices_raw), f"Indices have non-existing vertices"
+        base_index = len(self.face_positions) // 3  # All the new indices reference the new vertices
+        self.face_indices.extend([base_index + i for t in indices_raw for i in t])
+        self.face_positions.extend([v for t in vertices_raw for v in t])
+        self.face_tex_coords.extend([c for t in tex_coord_raw for c in t])
+        self.face_colors.extend([col for _ in range(len(vertices_raw)) for col in color])
+        self._faces_primitive.extras["face_triangles_end"].append(len(self.face_indices))
 
-    def add_edge(self, vertices_raw: List[Tuple[float, float, float]], mat: str = None):
-        """Add an edge to the GLTF as a new primitive of the unique mesh"""
-        vertices = np.array([[v[0], v[1], v[2]] for v in vertices_raw], dtype=np.float32)
-        indices = np.array(list(map(lambda i: [i, i + 1], range(len(vertices) - 1))), dtype=np.uint32)
-        tex_coord = np.array([])
-        self._add_any(vertices, indices, tex_coord, mode=LINE_STRIP, material=mat or "edge")
+    def add_edge(self, vertices_raw: List[Tuple[Tuple[float, float, float], Tuple[float, float, float]]],
+                 color: Tuple[float, float, float, float] = (0.1, 0.1, 0.4, 1.0)):
+        """Add an edge to the GLTF mesh"""
+        vertices_flat = [v for t in vertices_raw for v in t]  # Line from 0 to 1, 2 to 3, 4 to 5, etc.
+        base_index = len(self.edge_positions) // 3
+        self.edge_indices.extend([base_index + i for i in range(len(vertices_flat))])
+        self.edge_positions.extend([v for t in vertices_flat for v in t])
+        self.edge_colors.extend([col for _ in range(len(vertices_flat)) for col in color])
+        self._edges_primitive.extras["edge_points_end"].append(len(self.edge_indices))
 
-    def add_vertex(self, vertex: Tuple[float, float, float]):
-        """Add a vertex to the GLTF as a new primitive of the unique mesh"""
-        vertices = np.array([[vertex[0], vertex[1], vertex[2]]])
-        indices = np.array([[0]], dtype=np.uint32)
-        tex_coord = np.array([], dtype=np.float32)
-        self._add_any(vertices, indices, tex_coord, mode=POINTS, material="vertex")
+    def add_vertex(self, vertex: Tuple[float, float, float],
+                   color: Tuple[float, float, float, float] = (0.1, 0.4, 0.1, 1.0)):
+        """Add a vertex to the GLTF mesh"""
+        base_index = len(self.vertex_positions) // 3
+        self.vertex_indices.append(base_index)
+        self.vertex_positions.extend(vertex)
+        self.vertex_colors.extend(color)
 
     def add_location(self, loc: Location):
         """Add a location to the GLTF as a new primitive of the unique mesh"""
@@ -61,120 +111,91 @@ class GLTFMgr:
 
         # Add 1 origin vertex and 3 edges with custom colors to identify the X, Y and Z axis
         self.add_vertex(vert(pl.origin))
-        self.add_edge([vert(pl.origin), vert(pl.origin + pl.x_dir)], mat="locX")
-        self.add_edge([vert(pl.origin), vert(pl.origin + pl.y_dir)], mat="locY")
-        self.add_edge([vert(pl.origin), vert(pl.origin + pl.z_dir)], mat="locZ")
+        self.add_edge([(vert(pl.origin), vert(pl.origin + pl.x_dir))], color=(0.97, 0.24, 0.24, 1))
+        self.add_edge([(vert(pl.origin), vert(pl.origin + pl.y_dir))], color=(0.42, 0.8, 0.15, 1))
+        self.add_edge([(vert(pl.origin), vert(pl.origin + pl.z_dir))], color=(0.09, 0.55, 0.94, 1))
 
-    def add_material(self, kind: str) -> int:
-        """It is important to use a different material for each primitive to be able to change them at runtime"""
-        new_material: Material
-        if kind == "face":
-            new_material = Material(name="face", alphaCutoff=None, pbrMetallicRoughness=PbrMetallicRoughness(
-                baseColorTexture=TextureInfo(index=0), baseColorFactor=[1, 1, 0.5, 1]), doubleSided=True)
-        elif kind == "edge":
-            new_material = Material(name="edge", alphaCutoff=None, pbrMetallicRoughness=PbrMetallicRoughness(
-                baseColorFactor=[0, 0, 0.5, 1]))
-        elif kind == "vertex":
-            new_material = Material(name="vertex", alphaCutoff=None, pbrMetallicRoughness=PbrMetallicRoughness(
-                baseColorFactor=[0, 0.3, 0.3, 1]))
-        elif kind == "locX":
-            new_material = Material(name="locX", alphaCutoff=None, pbrMetallicRoughness=PbrMetallicRoughness(
-                baseColorFactor=[0.97, 0.24, 0.24, 1]))
-        elif kind == "locY":
-            new_material = Material(name="locY", alphaCutoff=None, pbrMetallicRoughness=PbrMetallicRoughness(
-                baseColorFactor=[0.42, 0.8, 0.15, 1]))
-        elif kind == "locZ":
-            new_material = Material(name="locZ", alphaCutoff=None, pbrMetallicRoughness=PbrMetallicRoughness(
-                baseColorFactor=[0.09, 0.55, 0.94, 1]))
+    def build(self) -> GLTF2:
+        """Merge the intermediate data into the GLTF object and return it"""
+        buffers_list: List[Tuple[Accessor, BufferView, bytes]] = []
+
+        if len(self.face_indices) > 0:
+            self._faces_primitive.indices = len(buffers_list)
+            buffers_list.append(_gen_buffer_metadata(self.face_indices, 1))
+            self._faces_primitive.attributes.POSITION = len(buffers_list)
+            buffers_list.append(_gen_buffer_metadata(self.face_positions, 3))
+            self._faces_primitive.attributes.TEXCOORD_0 = len(buffers_list)
+            buffers_list.append(_gen_buffer_metadata(self.face_tex_coords, 2))
+            self._faces_primitive.attributes.COLOR_0 = len(buffers_list)
+            buffers_list.append(_gen_buffer_metadata(self.face_colors, 4))
         else:
-            raise ValueError(f"Unknown material kind {kind}")
-        self.gltf.materials.append(new_material)
-        return len(self.gltf.materials) - 1
+            self.image = None  # Unused image
+            self.gltf.meshes[0].primitives = list(  # Remove unused faces primitive
+                filter(lambda p: p.mode != TRIANGLES, self.gltf.meshes[0].primitives))
 
-    def _add_any(self, vertices: np.ndarray, indices: np.ndarray, tex_coord: np.ndarray, mode: int = TRIANGLES,
-                 material: str = "face"):
-        assert vertices.ndim == 2
-        assert vertices.shape[1] == 3
-        vertices = vertices.astype(np.float32)
-        vertices_blob = vertices.tobytes()
+        edges_and_vertices_mat = 0
+        if self.image is not None and (len(self.edge_indices) > 0 or len(self.vertex_indices) > 0):
+            # Create a material without texture for edges and vertices
+            edges_and_vertices_mat = len(self.gltf.materials)
+            new_mat = copy.deepcopy(self.gltf.materials[0])
+            new_mat.pbrMetallicRoughness.baseColorTexture = None
+            self.gltf.materials.append(new_mat)
 
-        assert indices.ndim == 2
-        assert indices.shape[1] == 3 and mode == TRIANGLES or indices.shape[1] == 2 and mode == LINE_STRIP or \
-               indices.shape[1] == 1 and mode == POINTS
-        indices = indices.astype(np.uint32)
-        indices_blob = indices.flatten().tobytes()
+        # Treat edges and vertices the same way
+        for (indices, positions, colors, primitive, kind) in [
+            (self.edge_indices, self.edge_positions, self.edge_colors, self._edges_primitive, LINES),
+            (self.vertex_indices, self.vertex_positions, self.vertex_colors, self._vertices_primitive, POINTS)
+        ]:
+            if len(indices) > 0:
+                primitive.material = edges_and_vertices_mat
+                primitive.indices = len(buffers_list)
+                buffers_list.append(_gen_buffer_metadata(indices, 1))
+                primitive.attributes.POSITION = len(buffers_list)
+                buffers_list.append(_gen_buffer_metadata(positions, 3))
+                primitive.attributes.COLOR_0 = len(buffers_list)
+                buffers_list.append(_gen_buffer_metadata(colors, 4))
+            else:
+                self.gltf.meshes[0].primitives = list(  # Remove unused edges primitive
+                    filter(lambda p: p.mode != kind, self.gltf.meshes[0].primitives))
 
-        # Check that all vertices are referenced by the indices
-        # This can happen on broken faces like on some fonts
-        # assert indices.max() == len(vertices) - 1, f"{indices.max()} != {len(vertices) - 1}"
-        # assert indices.min() == 0, f"min({indices}) != 0"
-        # assert np.unique(indices.flatten()).size == len(vertices)
+        if self.image is not None:  # Add texture last as it creates a fake accessor that is not added!
+            self.gltf.images = [Image(bufferView=len(buffers_list), mimeType=self.image[1])]
+            self.gltf.textures = [Texture(source=0, sampler=0)]
+            self.gltf.samplers = [Sampler(magFilter=NEAREST)]
+            self.gltf.materials[0].pbrMetallicRoughness.baseColorTexture = TextureInfo(index=0)
+            buffers_list.append((Accessor(), BufferView(), self.image[0]))
 
-        assert len(tex_coord) == 0 or tex_coord.ndim == 2
-        assert len(tex_coord) == 0 or tex_coord.shape[1] == 2
-        tex_coord = tex_coord.astype(np.float32)
-        tex_coord_blob = tex_coord.tobytes()
-
-        accessor_base = len(self.gltf.accessors)
-        self.gltf.meshes[0].primitives.append(
-            Primitive(
-                attributes=Attributes(POSITION=accessor_base + 1, TEXCOORD_0=accessor_base + 2)
-                if len(tex_coord) > 0 else Attributes(POSITION=accessor_base + 1),
-                indices=accessor_base,
-                mode=mode,
-                material=self.add_material(material),
-            )
-        )
-
-        buffer_view_base = len(self.gltf.bufferViews)
-        self.gltf.accessors.extend([it for it in [
-            Accessor(
-                bufferView=buffer_view_base,
-                componentType=UNSIGNED_INT,
-                count=indices.size,
-                type=SCALAR,
-                max=[int(indices.max())],
-                min=[int(indices.min())],
-            ),
-            Accessor(
-                bufferView=buffer_view_base + 1,
-                componentType=FLOAT,
-                count=len(vertices),
-                type=VEC3,
-                max=vertices.max(axis=0).tolist(),
-                min=vertices.min(axis=0).tolist(),
-            ),
-            Accessor(
-                bufferView=buffer_view_base + 2,
-                componentType=FLOAT,
-                count=len(tex_coord),
-                type=VEC2,
-                max=tex_coord.max(axis=0).tolist(),
-                min=tex_coord.min(axis=0).tolist(),
-            ) if len(tex_coord) > 0 else None
-        ] if it is not None])
-
-        prev_binary_blob = self.gltf.binary_blob()
+        # Once all the data is ready, we can concatenate the buffers updating the accessors and views
+        prev_binary_blob = self.gltf.binary_blob() or b''
         byte_offset_base = len(prev_binary_blob)
-        self.gltf.bufferViews.extend([bv for bv in [
-            BufferView(
-                buffer=0,
-                byteOffset=byte_offset_base,
-                byteLength=len(indices_blob),
-                target=ELEMENT_ARRAY_BUFFER,
-            ),
-            BufferView(
-                buffer=0,
-                byteOffset=byte_offset_base + len(indices_blob),
-                byteLength=len(vertices_blob),
-                target=ARRAY_BUFFER,
-            ),
-            BufferView(
-                buffer=0,
-                byteOffset=byte_offset_base + len(indices_blob) + len(vertices_blob),
-                byteLength=len(tex_coord_blob),
-                target=ARRAY_BUFFER,
-            )
-        ] if bv.byteLength > 0])
+        for accessor, bufferView, blob in buffers_list:
 
-        self.gltf.set_binary_blob(prev_binary_blob + indices_blob + vertices_blob + tex_coord_blob)
+            if accessor.componentType is not None:  # Remove accessor of texture
+                buffer_view_base = len(self.gltf.bufferViews)
+                accessor.bufferView = buffer_view_base
+                self.gltf.accessors.append(accessor)
+
+            bufferView.buffer = 0
+            bufferView.byteOffset = byte_offset_base
+            bufferView.byteLength = len(blob)
+            self.gltf.bufferViews.append(bufferView)
+
+            byte_offset_base += len(blob)
+            prev_binary_blob += blob
+
+        self.gltf.buffers.append(Buffer(byteLength=byte_offset_base))
+        self.gltf.set_binary_blob(prev_binary_blob)
+
+        return self.gltf
+
+
+def _gen_buffer_metadata(data: List[any], chunk: int) -> Tuple[Accessor, BufferView, bytes]:
+    return Accessor(
+        componentType={1: UNSIGNED_INT, 2: FLOAT, 3: FLOAT, 4: FLOAT}[chunk],
+        count=len(data) // chunk,
+        type={1: SCALAR, 2: VEC2, 3: VEC3, 4: VEC4}[chunk],
+        max=[max(data[i::chunk]) for i in range(chunk)],
+        min=[min(data[i::chunk]) for i in range(chunk)],
+    ), BufferView(
+        target={1: ELEMENT_ARRAY_BUFFER, 2: ARRAY_BUFFER, 3: ARRAY_BUFFER, 4: ARRAY_BUFFER}[chunk],
+    ), np.array(data, dtype={1: np.uint32, 2: np.float32, 3: np.float32, 4: np.float32}[chunk]).tobytes()

yacv_server/logo.py

@@ -24,11 +24,11 @@ def build_logo(text: bool = True) -> Dict[str, Union[Part, Location, str]]:
                                         logo_img_location.position.Z)
 
     logo_img_path = os.path.join(ASSETS_DIR, 'img.jpg')
-    img_bytes, img_name = prepare_image(logo_img_path, logo_img_location, height=18)
+    img_glb_bytes, img_name = image_to_gltf(logo_img_path, logo_img_location, height=18)
 
     fox_glb_bytes = open(os.path.join(ASSETS_DIR, 'fox.glb'), 'rb').read()
 
-    return {'fox': fox_glb_bytes, 'logo': logo_obj, 'location': logo_img_location, img_name: img_bytes}
+    return {'fox': fox_glb_bytes, 'logo': logo_obj, 'location': logo_img_location, img_name: img_glb_bytes}
 
 
 if __name__ == "__main__":
@@ -43,7 +43,7 @@ if __name__ == "__main__":
         # If this is not set, the server will auto-start on import and show_* calls will provide live updates
         os.environ['YACV_DISABLE_SERVER'] = 'True'
 
-    from yacv_server import export_all, remove, prepare_image, show
+    from yacv_server import export_all, show, image_to_gltf
 
     # Build the CAD part of the logo
     logo = build_logo()
@@ -52,7 +52,8 @@ if __name__ == "__main__":
     show(*[obj for obj in logo.values()], names=[name for name in logo.keys()])
 
     if testing_server:
-        remove('location')  # Test removing a part
+        # remove('location')  # Test removing a part
+        pass
     else:
         # Save the complete logo to multiple GLB files
         export_all(os.path.join(ASSETS_DIR, 'logo_build'))

yacv_server/tessellate.py

@@ -36,26 +36,26 @@ def tessellate(
         shape = Shape(cad_like)
 
         # Perform tessellation tasks
-        edge_to_faces: Dict[TopoDS_Edge, List[TopoDS_Face]] = {}
-        vertex_to_faces: Dict[TopoDS_Vertex, List[TopoDS_Face]] = {}
+        edge_to_faces: Dict[str, List[TopoDS_Face]] = {}
+        vertex_to_faces: Dict[str, List[TopoDS_Face]] = {}
         if faces:
             for face in shape.faces():
                 _tessellate_face(mgr, face.wrapped, tolerance, angular_tolerance)
                 if edges:
                     for edge in face.edges():
-                        edge_to_faces[edge.wrapped] = edge_to_faces.get(edge.wrapped, []) + [face.wrapped]
+                        edge_to_faces[_hashcode(edge.wrapped)] = edge_to_faces.get(_hashcode(edge.wrapped), []) + [face.wrapped]
                 if vertices:
                     for vertex in face.vertices():
-                        vertex_to_faces[vertex.wrapped] = vertex_to_faces.get(vertex.wrapped, []) + [face.wrapped]
+                        vertex_to_faces[_hashcode(vertex.wrapped)] = vertex_to_faces.get(_hashcode(vertex.wrapped), []) + [face.wrapped]
         if edges:
             for edge in shape.edges():
-                _tessellate_edge(mgr, edge.wrapped, edge_to_faces.get(edge.wrapped, []), angular_tolerance,
+                _tessellate_edge(mgr, edge.wrapped, edge_to_faces.get(_hashcode(edge.wrapped), []), angular_tolerance,
                                  angular_tolerance)
         if vertices:
             for vertex in shape.vertices():
-                _tessellate_vertex(mgr, vertex.wrapped, vertex_to_faces.get(vertex.wrapped, []))
+                _tessellate_vertex(mgr, vertex.wrapped, vertex_to_faces.get(_hashcode(vertex.wrapped), []))
 
-    return mgr.gltf
+    return mgr.build()
 
 
 def _tessellate_face(
@@ -91,9 +91,9 @@ def _push_point(v: Tuple[float, float, float], faces: List[TopoDS_Face]) -> Tupl
         push_dir = (push_dir[0] + normal.X, push_dir[1] + normal.Y, push_dir[2] + normal.Z)
     if push_dir != (0, 0, 0):
         # Normalize the push direction by the number of faces and a constant factor
-        # NOTE: Don't overdo it, or metrics will be wrong
-        n = len(faces) / 1e-3
-        push_dir = (push_dir[0] / n, push_dir[1] / n, push_dir[2] / n)
+        # NOTE: Don't overdo it, or metrics will be (more) wrong
+        n = 1e-3 / len(faces)
+        push_dir = (push_dir[0] * n, push_dir[1] * n, push_dir[2] * n)
         # Push the vertex by the normal
         v = (v[0] + push_dir[0], v[1] + push_dir[1], v[2] + push_dir[2])
     return v
@@ -119,6 +119,9 @@ def _tessellate_edge(
             for i in range(1, discretizer.NbPoints() + 1)
         )
     ]
+
+    # Convert strip of vertices to a list of pairs of vertices
+    vertices = [(vertices[i], vertices[i + 1]) for i in range(len(vertices) - 1)]
     mgr.add_edge(vertices)