Minor backend improvements: better color and textured handling, smooth shading, better demo

yacv_server/cad.py

@@ -78,7 +78,8 @@ def get_shape(obj: CADLike, error: bool = True) -> Optional[CADCoreLike]:
                 # Sorting is required to improve hashcode consistency
                 shapes_raw_filtered_sorted = sorted(shapes_raw_filtered, key=lambda x: _hashcode(x))
                 # Build a single compound shape (skip locations/axes here, they can't be in a Compound)
-                shapes_bd = [Compound(shape) for shape in shapes_raw_filtered_sorted if shape is not None and not isinstance(shape, TopLoc_Location)]
+                shapes_bd = [Compound(shape) for shape in shapes_raw_filtered_sorted if
+                             shape is not None and not isinstance(shape, TopLoc_Location)]
                 return get_shape(Compound(shapes_bd), error)
         except TypeError:
             pass
@@ -168,7 +169,7 @@ def image_to_gltf(source: str | bytes, center: any, width: Optional[float] = Non
         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),
         vert(plane.origin - plane.x_dir * width / 2 - plane.y_dir * height / 2),
-    ], [
+    ], [vert(plane.z_dir)] * 4, [
         (0, 2, 1),
         (0, 3, 2),
     ], [

yacv_server/gltf.py

@@ -4,10 +4,6 @@ import numpy as np
 from build123d import Location, Plane, Vector
 from pygltflib import *
 
-# PNG file containing 1x1 while pixel
-_default_tex = (b'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAwMCAO+ip1sAAAAASUVORK5CYII=')
-
-_default_color = (1.0, 0.75, 0.0, 1.0)
 
 def get_version() -> str:
     try:
@@ -25,6 +21,7 @@ class GLTFMgr:
     # - Face data
     face_indices: List[int]  # 3 indices per triangle
     face_positions: List[float]  # x, y, z
+    face_normals: 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
@@ -37,7 +34,7 @@ class GLTFMgr:
     vertex_positions: List[float]  # x, y, z
     vertex_colors: List[float]  # r, g, b, a
 
-    def __init__(self, image: Optional[Tuple[bytes, str]] = (_default_tex, 'image/png')):
+    def __init__(self, image: Optional[Tuple[bytes, str]] = None):
         self.gltf = GLTF2(
             asset=Asset(generator=f"yacv_server@{get_version()}"),
             scene=0,
@@ -55,6 +52,7 @@ class GLTFMgr:
         )
         self.face_indices = []
         self.face_positions = []
+        self.face_normals = []
         self.face_tex_coords = []
         self.face_colors = []
         self.image = image
@@ -77,24 +75,23 @@ class GLTFMgr:
     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[Vector], indices_raw: List[Tuple[int, int, int]],
-                 tex_coord_raw: List[Tuple[float, float]], color: Optional[Tuple[float, float, float, float]] = None):
+    def add_face(self, vertices_raw: List[Vector], normals: List[Vector], indices_raw: List[Tuple[int, int, int]],
+                 tex_coord_raw: List[Tuple[float, float]], color: Tuple[float, float, float, float]):
         """Add a face to the GLTF mesh"""
-        if color is None: color = _default_color
         # 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_normals.extend([n for t in normals for n 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[Tuple[float, float, float], Tuple[float, float, float]]],
-                 color: Optional[Tuple[float, float, float, float]] = None):
+                 color: Tuple[float, float, float, float]):
         """Add an edge to the GLTF mesh"""
-        if color is None: color = (0.1, 0.1, 1.0, 1.0)
         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))])
@@ -102,9 +99,8 @@ class GLTFMgr:
         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], color: Optional[Tuple[float, float, float, float]] = None):
+    def add_vertex(self, vertex: Tuple[float, float, float], color: Tuple[float, float, float, float]):
         """Add a vertex to the GLTF mesh"""
-        if color is None: color = (0.1, 0.1, 0.1, 1.0)
         base_index = len(self.vertex_positions) // 3
         self.vertex_indices.append(base_index)
         self.vertex_positions.extend(vertex)
@@ -118,10 +114,11 @@ class GLTFMgr:
             return v.X, v.Y, v.Z
 
         # 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))], 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))
+        # The colors are hardcoded. You can add vertices and edges manually to change them.
+        self.add_vertex(vert(pl.origin), color=(0.1, 0.1, 0.1, 1.0))
+        self.add_edge([(vert(pl.origin), vert(pl.origin + pl.x_dir))], color=(0.97, 0.24, 0.24, 1.0))
+        self.add_edge([(vert(pl.origin), vert(pl.origin + pl.y_dir))], color=(0.42, 0.8, 0.15, 1.0))
+        self.add_edge([(vert(pl.origin), vert(pl.origin + pl.z_dir))], color=(0.09, 0.55, 0.94, 1.0))
 
     def build(self) -> GLTF2:
         """Merge the intermediate data into the GLTF object and return it"""
@@ -132,6 +129,8 @@ class GLTFMgr:
             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.NORMAL = len(buffers_list)
+            buffers_list.append(_gen_buffer_metadata(self.face_normals, 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)

yacv_server/logo.py

@@ -6,24 +6,30 @@ from build123d import *
 ASSETS_DIR = os.getenv('ASSETS_DIR', os.path.join(os.path.dirname(__file__), '..', 'assets'))
 
 
-def build_logo(text: bool = True) -> Dict[str, Union[Part, Location, str]]:
+def build_logo(text: bool = True) -> Dict[str, Union[Compound, Location, str]]:
     """Builds the CAD part of the logo"""
     with BuildPart(Plane.XY.offset(50)) as logo_obj:
         Box(22, 40, 30)
         fillet(edges().filter_by(Axis.Y).group_by(Axis.Z)[-1], 10)
         offset(solid(), 2, openings=faces().group_by(Axis.Z)[0] + faces().filter_by(Plane.XZ))
         if text:
-            text_at_plane = Plane.YZ
-            text_at_plane.origin = faces().group_by(Axis.X)[-1].face().center()
-            with BuildSketch(text_at_plane.location):
+            with BuildSketch(Plane.YZ.move(Pos(faces().group_by(Axis.X)[-1].face().center()))):
                 Text('Yet Another\nCAD Viewer', 6, font_path='/usr/share/fonts/TTF/Hack-Regular.ttf')
             extrude(amount=1)
+        logo_face_curved_front = faces().filter_by(GeomType.CYLINDER).group_by(Axis.X)[-1].face()
 
     # Highlight text edges with a custom color
     to_highlight = logo_obj.edges().group_by(Axis.X)[-1]
     logo_obj_hl = Compound(to_highlight).translate((1e-3, 0, 0))  # To avoid z-fighting
     logo_obj_hl.color = (0, 0.3, 0.3, 1)
 
+    # Highlight face with custom texture
+    logo_face_curved_front.yacv_texture = \
+        'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAIAAAD91JpzAAAAF0lEQVQI12N49OjR////Gf' \
+        '/////48WMATwULS8tcyj8AAAAASUVORK5CYII='
+    logo_face_curved_front.color = (0, 0.5, 0.0, 1)
+    logo_obj = Compound(logo_obj.faces() - ShapeList([logo_face_curved_front]))  # Remove face from the main object
+
     # Add a logo image to the CAD part
     logo_img_location = logo_obj.faces().group_by(Axis.X)[0].face().center_location
     logo_img_location *= Location((0, 0, 4e-2), (0, 0, 90))  # Avoid overlapping and adjust placement
@@ -33,7 +39,8 @@ def build_logo(text: bool = True) -> Dict[str, Union[Part, Location, str]]:
     # Add an animated fox to the CAD part
     fox_glb_bytes = open(os.path.join(ASSETS_DIR, 'fox.glb'), 'rb').read()
 
-    return {'fox': fox_glb_bytes, 'logo': logo_obj, 'logo_hl': logo_obj_hl, 'location': logo_img_location, img_name: img_glb_bytes}
+    return {'fox': fox_glb_bytes, 'logo': logo_obj, 'logo_hl': logo_obj_hl, 'logo_hl_tex': logo_face_curved_front,
+            'location': logo_img_location, img_name: img_glb_bytes}
 
 
 if __name__ == "__main__":

yacv_server/main.py

@@ -1,6 +0,0 @@
-from os import system
-
-if __name__ == '__main__':
-    # Just a reminder that a hot-reloading server can be started with the following command:
-    # Need to disable auto-start to avoid conflicts with the hot-reloading server
-    system('YACV_DISABLE_SERVER=true aiohttp-devtools runserver __init__.py --port 32323 --app-factory _get_app')

yacv_server/tessellate.py

@@ -3,9 +3,11 @@ from typing import List, Dict, Tuple, Optional
 from OCP.BRep import BRep_Tool
 from OCP.BRepAdaptor import BRepAdaptor_Curve
 from OCP.GCPnts import GCPnts_TangentialDeflection
+from OCP.OCP.BRepLib import BRepLib_ToolTriangulatedShape
+from OCP.OCP.TopAbs import TopAbs_Orientation
 from OCP.TopLoc import TopLoc_Location
 from OCP.TopoDS import TopoDS_Face, TopoDS_Edge, TopoDS_Shape, TopoDS_Vertex
-from build123d import Vertex, Face, Location, Compound
+from build123d import Vertex, Face, Location, Compound, Vector
 from pygltflib import GLTF2
 
 from yacv_server.cad import CADCoreLike, ColorTuple
@@ -14,14 +16,9 @@ from yacv_server.mylogger import logger
 
 
 def tessellate(
-        cad_like: CADCoreLike,
-        tolerance: float = 0.1,
-        angular_tolerance: float = 0.1,
-        faces: bool = True,
-        edges: bool = True,
-        vertices: bool = True,
-        obj_color: Optional[ColorTuple] = None,
-        texture: Optional[Tuple[bytes, str]] = None,
+        cad_like: CADCoreLike, color_faces: ColorTuple, color_edges: ColorTuple, color_vertices: ColorTuple,
+        color_obj: Optional[ColorTuple] = None, tolerance: float = 0.1, angular_tolerance: float = 0.1,
+        faces: bool = True, edges: bool = True, vertices: bool = True, texture: Optional[Tuple[bytes, str]] = None,
 ) -> GLTF2:
     """Tessellate a whole shape into a list of triangle vertices and a list of triangle indices."""
     if texture is None:
@@ -41,23 +38,24 @@ def tessellate(
         if faces and hasattr(shape, 'faces'):
             shape_faces = shape.faces()
             for face in shape_faces:
-                _tessellate_face(mgr, face.wrapped, tolerance, angular_tolerance, obj_color)
+                _tessellate_face(mgr, face.wrapped, color_obj or color_faces, tolerance, angular_tolerance)
                 if edges:
                     for edge in face.edges():
                         edge_to_faces[edge.wrapped] = edge_to_faces.get(edge.wrapped, []) + [face.wrapped]
                 if vertices:
                     for vertex in face.vertices():
                         vertex_to_faces[vertex.wrapped] = vertex_to_faces.get(vertex.wrapped, []) + [face.wrapped]
-            if len(shape_faces) > 0: obj_color = None  # Don't color edges/vertices if faces are colored
+            if len(shape_faces) > 0: color_obj = None  # Don't color edges/vertices if faces are colored
         if edges and hasattr(shape, 'edges'):
             shape_edges = shape.edges()
             for edge in shape_edges:
-                _tessellate_edge(mgr, edge.wrapped, edge_to_faces.get(edge.wrapped, []), angular_tolerance,
-                                 angular_tolerance, obj_color)
-            if len(shape_edges) > 0: obj_color = None  # Don't color vertices if edges are colored
+                _tessellate_edge(mgr, edge.wrapped, edge_to_faces.get(edge.wrapped, []), color_obj or color_edges,
+                                 angular_tolerance, angular_tolerance)
+            if len(shape_edges) > 0: color_obj = None  # Don't color vertices if edges are colored
         if vertices and hasattr(shape, 'vertices'):
             for vertex in shape.vertices():
-                _tessellate_vertex(mgr, vertex.wrapped, vertex_to_faces.get(vertex.wrapped, []), obj_color)
+                _tessellate_vertex(mgr, vertex.wrapped, vertex_to_faces.get(vertex.wrapped, []),
+                                   color_obj or color_vertices)
 
     else:
         raise TypeError(f"Unsupported type: {type(cad_like)}: {cad_like}")
@@ -68,9 +66,9 @@ def tessellate(
 def _tessellate_face(
         mgr: GLTFMgr,
         ocp_face: TopoDS_Face,
+        color: ColorTuple,
         tolerance: float = 1e-3,
         angular_tolerance: float = 0.1,
-        color: Optional[ColorTuple] = None,
 ):
     face = Compound(ocp_face)
     # face.mesh(tolerance, angular_tolerance)
@@ -81,6 +79,14 @@ def _tessellate_face(
         logger.warn("No triangulation found for face")
         return GLTF2()
 
+    # Get the normal for each vertex (for smooth instead of flat shading!)
+    BRepLib_ToolTriangulatedShape.ComputeNormals_s(face.wrapped, poly)
+    reversed_face = face.wrapped.Orientation() == TopAbs_Orientation.TopAbs_REVERSED
+    normals = [
+        -Vector(v) if reversed_face else Vector(v)
+        for v in (poly.Normal(i) for i in range(1, poly.NbNodes() + 1))
+    ]
+
     # Get UV of each face from the parameters
     uv = [
         (v.X(), v.Y())
@@ -89,7 +95,7 @@ def _tessellate_face(
 
     vertices = tri_mesh[0]
     indices = tri_mesh[1]
-    mgr.add_face(vertices, indices, uv, color)
+    mgr.add_face(vertices, normals, indices, uv, color)
     return None
 
 
@@ -113,9 +119,9 @@ def _tessellate_edge(
         mgr: GLTFMgr,
         ocp_edge: TopoDS_Edge,
         faces: List[TopoDS_Face],
+        color: ColorTuple,
         angular_deflection: float = 0.1,
         curvature_deflection: float = 0.1,
-        color: Optional[ColorTuple] = None,
 ):
     # Use a curve discretizer to get the vertices
     curve = BRepAdaptor_Curve(ocp_edge)
@@ -136,9 +142,6 @@ def _tessellate_edge(
     mgr.add_edge(vertices, color)
 
 
-def _tessellate_vertex(mgr: GLTFMgr, ocp_vertex: TopoDS_Vertex, faces: List[TopoDS_Face],
-                          color: Optional[ColorTuple] = None):
+def _tessellate_vertex(mgr: GLTFMgr, ocp_vertex: TopoDS_Vertex, faces: List[TopoDS_Face], color: ColorTuple):
     c = Vertex(ocp_vertex).center()
     mgr.add_vertex(_push_point((c.X, c.Y, c.Z), faces), color)
-
-

yacv_server/yacv.py

@@ -20,7 +20,7 @@ from PIL import Image
 from build123d import Shape, Axis, Location, Vector
 from dataclasses_json import dataclass_json
 
-from yacv_server.cad import _hashcode, get_color
+from yacv_server.cad import _hashcode, get_color, ColorTuple
 from yacv_server.cad import get_shape, grab_all_cad, CADCoreLike, CADLike
 from yacv_server.gltf import get_version
 from yacv_server.myhttp import HTTPHandler
@@ -93,12 +93,39 @@ class YACV:
 
     texture: Optional[Tuple[bytes, str]]
     """Default texture to use for model faces, in (data, mimetype) format.
-    If left as None, a default checkerboard texture will be used.
+    If left as None, no texture will be used.
     
-    It can be set with the YACV_BASE_TEXTURE=<uri> and overridden by `show(..., texture="<uri>")`.
+    It can be set with the YACV_TEXTURE=<uri> and overridden by the custom `yacv_texture` attribute of an object.
     The <uri> can be file:<path> or data:<mime>;base64,<data> where <mime> is the mime type and 
     <data> is the base64 encoded image."""
 
+    color_faces: Optional[ColorTuple]
+    """Overrides the default color to use for model faces. Applies even if a texture is used. 
+    
+    You can use `show(..., color_faces=...)` or the standard way of setting colors for build123d/cadquery objects to 
+    override this color.
+    
+    It can be set with the YACV_COLOR_FACES=<color> environment variable, where <color> is a color
+    in the hexadecimal format #RRGGBB or #RRGGBBAA."""
+
+    color_edges: Optional[ColorTuple]
+    """Overrides the default color to use for model edges. 
+    
+    You can use `show(..., color_edges=...) or the standard way of setting colors for build123d/cadquery objects to
+    override this color.
+        
+    It can be set with the YACV_COLOR_EDGES=<color> environment variable, where <color> is a color
+    in the hexadecimal format #RRGGBB or #RRGGBBAA."""
+
+    color_vertices: Optional[ColorTuple]
+    """Overrides the default color to use for model vertices.
+    
+    You can use `show(..., color_vertices=...)` or the standard way of setting colors for build123d/cadquery objects to
+    override this color.
+    
+    It can be set with the YACV_COLOR_VERTICES=<color> environment variable, where <color> is a color
+    in the hexadecimal format #RRGGBB or #RRGGBBAA."""
+
     def __init__(self):
         self.server_thread = None
         self.server = None
@@ -109,7 +136,10 @@ class YACV:
         self.at_least_one_client = threading.Event()
         self.shutting_down = threading.Event()
         self.frontend_lock = RWLock()
-        self.texture = _read_texture_uri(os.getenv("YACV_BASE_TEXTURE"))
+        self.texture = _read_texture_uri(os.getenv("YACV_TEXTURE"))
+        self.color_faces = _read_color(os.getenv("YACV_COLOR_FACES", "#ffbf00"))  # Default yellow
+        self.color_edges = _read_color(os.getenv("YACV_COLOR_EDGES", "#1a1aff"))  # Default blue
+        self.color_vertices = _read_color(os.getenv("YACV_COLOR_VERTICES", "#1a1a1a"))  # Default dark gray
         logger.info('Using yacv-server v%s', get_version())
 
     def start(self):
@@ -201,8 +231,9 @@ class YACV:
         if isinstance(names, str):
             names = [names]
         assert len(names) == len(objs), 'Number of names must match the number of objects'
-        if 'color' in kwargs:
-            kwargs['color'] = get_color(kwargs['color'])
+        for color_name in ('color_faces', 'color_edges', 'color_vertices'):
+            if color_name in kwargs:
+                kwargs[color_name] = get_color(kwargs[color_name]) or _read_color(kwargs[color_name])
 
         # Handle auto clearing of previous objects
         if kwargs.get('auto_clear', True):
@@ -218,13 +249,15 @@ class YACV:
         # Publish the show event
         for obj, name in zip(objs, names):
             obj_color = get_color(obj)
+            # Some properties may be lost in preprocessing, so save them in kwargs
+            _kwargs = kwargs.copy()
             if obj_color is not None:
-                kwargs = kwargs.copy()
-                kwargs['color'] = obj_color
+                _kwargs['color_obj'] = obj_color # Only applies to highest-dimensional objects
+            _kwargs['texture'] = _read_texture_uri(getattr(obj, 'yacv_texture', None) or kwargs.get('texture', None))
             if not isinstance(obj, bytes):
-                obj = _preprocess_cad(obj, **kwargs)
-            _hash = _hashcode(obj, **kwargs)
-            event = UpdatesApiFullData(name=name, _hash=_hash, obj=obj, kwargs=kwargs or {})
+                obj = _preprocess_cad(obj, **_kwargs)
+            _hash = _hashcode(obj, **_kwargs)
+            event = UpdatesApiFullData(name=name, _hash=_hash, obj=obj, kwargs=_kwargs or {})
             self.show_events.publish(event)
 
         logger.info('show %s took %.3f seconds', names, time.time() - start)
@@ -309,17 +342,17 @@ class YACV:
                 if isinstance(event.obj, bytes):  # Already a GLTF
                     publish_to.publish(event.obj)
                 else:  # CAD object to tessellate and convert to GLTF
-                    texture_override_uri = event.kwargs.get('texture', None)
-                    texture_override = None
-                    if isinstance(texture_override_uri, str):
-                        texture_override = _read_texture_uri(texture_override_uri)
-                    gltf = tessellate(event.obj, tolerance=event.kwargs.get('tolerance', 0.1),
-                                      angular_tolerance=event.kwargs.get('angular_tolerance', 0.1),
-                                      faces=event.kwargs.get('faces', True),
-                                      edges=event.kwargs.get('edges', True),
-                                      vertices=event.kwargs.get('vertices', True),
-                                      obj_color=event.kwargs.get('color', None),
-                                      texture=texture_override or self.texture)
+                    gltf = tessellate(
+                        event.obj,
+                        color_faces=event.kwargs.get('color_faces', self.color_faces),
+                        color_edges=event.kwargs.get('color_edges', self.color_edges),
+                        color_vertices=event.kwargs.get('color_vertices', self.color_vertices),
+                        color_obj=event.kwargs.get('color_obj', None),
+                        tolerance=event.kwargs.get('tolerance', 0.1),
+                        angular_tolerance=event.kwargs.get('angular_tolerance', 0.1),
+                        faces=event.kwargs.get('faces', True), edges=event.kwargs.get('edges', True),
+                        vertices=event.kwargs.get('vertices', True),
+                        texture=event.kwargs.get('texture', self.texture))
                     glb_list_of_bytes = gltf.save_to_bytes()
                     glb_bytes = b''.join(glb_list_of_bytes)
                     publish_to.publish(glb_bytes)
@@ -355,7 +388,7 @@ def _read_texture_uri(uri: str) -> Optional[Tuple[bytes, str]]:
         img = Image.open(buf)
         mtype = img.get_format_mimetype()
         return data, mtype
-    if uri.startswith("data:"): # https://en.wikipedia.org/wiki/Data_URI_scheme#Syntax (limited)
+    if uri.startswith("data:"):  # https://en.wikipedia.org/wiki/Data_URI_scheme#Syntax (limited)
         mtype_and_data = uri[len("data:"):]
         mtype = mtype_and_data.split(";", 1)[0]
         data_str = mtype_and_data.split(",", 1)[1]
@@ -363,6 +396,20 @@ def _read_texture_uri(uri: str) -> Optional[Tuple[bytes, str]]:
         return data, mtype
     return None
 
+
+def _read_color(color: str) -> Optional[ColorTuple]:
+    """Reads a color from a string in the format #RRGGBB or #RRGGBBAA"""
+    if color is None:
+        return None
+    if not color.startswith('#') or len(color) not in (7, 9):
+        raise ValueError(f'Invalid color format: {color}')
+    r = float(int(color[1:3], 16)) / 255.0
+    g = float(int(color[3:5], 16)) / 255.0
+    b = float(int(color[5:7], 16)) / 255.0
+    a = float(int(color[7:9], 16)) / 255.0 if len(color) == 9 else 1.0
+    return r, g, b, a
+
+
 # noinspection PyUnusedLocal
 def _preprocess_cad(obj: CADLike, **kwargs) -> CADCoreLike:
     # Get the shape of a CAD-like object
@@ -384,6 +431,7 @@ def _preprocess_cad(obj: CADLike, **kwargs) -> CADCoreLike:
 
 _obj_name_counts = {}
 
+
 def _find_var_name(obj: any, avoid_levels: int = 2) -> str:
     """A hacky way to get a stable name for an object that may change over time"""