Fix #5544. Assign / add of objects with styles are now supported.

src/bonsai/bonsai/bim/module/root/operator.py

@@ -210,12 +210,7 @@ class AssignClass(bpy.types.Operator, tool.Ifc.Operator):
                 ifc_representation_class=self.ifc_representation_class,
             )
             if self.should_add_representation and obj.data and len(obj.data.vertices):
-                builder = ifcopenshell.util.shape_builder.ShapeBuilder(tool.Ifc.get())
-                unit_scale = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
-                verts = [v.co / unit_scale for v in obj.data.vertices]
-                faces = [p.vertices[:] for p in obj.data.polygons]
-                item = builder.mesh(verts, faces)
-                representation = builder.get_representation(ifc_context, [item])
+                representation = tool.Geometry.export_mesh_to_tessellation(obj, ifc_context)
                 ifcopenshell.api.geometry.assign_representation(tool.Ifc.get(), element, representation)
                 bonsai.core.geometry.switch_representation(
                     tool.Ifc,
@@ -373,16 +368,7 @@ class AddElement(bpy.types.Operator, tool.Ifc.Operator):
             pass
         elif representation_template == "OBJ" and props.representation_obj:
             obj.matrix_world = props.representation_obj.matrix_world
-            builder = ifcopenshell.util.shape_builder.ShapeBuilder(tool.Ifc.get())
-            unit_scale = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
-            items = []
-            meshes = tool.Geometry.split_by_loose_parts(props.representation_obj)
-            for mesh in meshes:
-                verts = [v.co / unit_scale for v in mesh.vertices]
-                faces = [p.vertices[:] for p in mesh.polygons]
-                items.append(builder.mesh(verts, faces))
-                bpy.data.meshes.remove(mesh)
-            representation = builder.get_representation(ifc_context, items)
+            representation = tool.Geometry.export_mesh_to_tessellation(props.representation_obj, ifc_context)
             ifcopenshell.api.geometry.assign_representation(tool.Ifc.get(), element, representation)
             bonsai.core.geometry.switch_representation(
                 tool.Ifc,

src/bonsai/bonsai/tool/geometry.py

@@ -27,6 +27,7 @@ import multiprocessing
 import ifcopenshell
 import ifcopenshell.api
 import ifcopenshell.api.grid
+import ifcopenshell.api.style
 import ifcopenshell.geom
 import ifcopenshell.guid
 import ifcopenshell.util.element
@@ -1600,3 +1601,34 @@ class Geometry(bonsai.core.tool.Geometry):
     @classmethod
     def reload_representation_item_ids(cls, representation: ifcopenshell.entity_instance, data: bpy.types.Mesh) -> None:
         data["ios_item_ids"] = [i["item"].id() for i in ifcopenshell.util.representation.resolve_items(representation)]
+
+    @classmethod
+    def export_mesh_to_tessellation(cls, obj: bpy.types.Object, ifc_context) -> ifcopenshell.entity_instance:
+        builder = ifcopenshell.util.shape_builder.ShapeBuilder(tool.Ifc.get())
+        unit_scale = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
+        items = []
+        meshes = cls.split_by_loose_parts(obj)
+        for mesh in meshes:
+            verts = [v.co / unit_scale for v in mesh.vertices]
+            faces = [p.vertices[:] for p in mesh.polygons]
+            item = builder.mesh(verts, faces)
+            items.append(item)
+            material_index = mesh.polygons[0].material_index
+            if materials := list(mesh.materials):
+                material = materials[material_index]
+                if not (style := tool.Style.get_style(material)):
+                    style = ifcopenshell.api.run("style.add_style", tool.Ifc.get(), name=material.name)
+                    if material.use_nodes:
+                        ifc_class = "IfcSurfaceStyleRendering"
+                        attributes = tool.Style.get_surface_rendering_attributes(material)
+                    else:
+                        ifc_class = "IfcSurfaceStyleShading"
+                        attributes = tool.Style.get_surface_shading_attributes(material)
+                    ifcopenshell.api.style.add_surface_style(
+                        tool.Ifc.get(), style=style, ifc_class=ifc_class, attributes=attributes
+                    )
+                    tool.Ifc.link(style, material)
+                    material.use_fake_user = True
+                ifcopenshell.api.style.assign_item_style(tool.Ifc.get(), item=item, style=style)
+            bpy.data.meshes.remove(mesh)
+        return builder.get_representation(ifc_context, items)

src/bonsai/bonsai/tool/style.py

@@ -594,55 +594,9 @@ class Style(bonsai.core.tool.Style):
 
     @classmethod
     def assign_style_to_representation_item(
-        cls, representation_item: ifcopenshell.entity_instance, style: Optional[ifcopenshell.entity_instance] = None
+        cls, item: ifcopenshell.entity_instance, style: Optional[ifcopenshell.entity_instance] = None
     ) -> None:
-        """Assign specified style to a representation item and unassign all previously assigned styles."""
-        ifc_file = representation_item.file
-        if not (styled_item := next(iter(representation_item.StyledByItem), None)):
-            if style is None:
-                return
-            if ifc_file.schema == "IFC2X3":
-                style = ifc_file.create_entity("IfcPresentationStyleAssignment", (style,))
-            ifc_file.create_entity("IfcStyledItem", representation_item, (style,))
-            return
-
-        styled_item_styles = styled_item.Styles
-        if style and styled_item_styles == (style,):
-            return
-
-        if ifc_file.schema == "IFC4X3":
-            if style is None:
-                ifc_file.remove(styled_item)
-                return
-            styled_item.Styles = (style,)
-            return
-
-        # < IFC4X3
-        # Can't just remove a styled item or assign a style
-        # since we need to remove/change the possible style assignments.
-        assignment = None
-        for style_ in styled_item_styles:
-            if not style_.is_a("IfcPresentationStyleAssignment"):
-                continue
-            # Remove second assignment.
-            if style is None or assignment:
-                ifc_file.remove(style_)
-            else:
-                assignment = style_
-                if assignment.Styles != (style,):
-                    assignment.Styles = (style,)
-
-        if style is None:
-            ifc_file.remove(styled_item)
-            return
-
-        if assignment:
-            if styled_item_styles == (assignment,):
-                return
-            styled_item.Styles = (assignment,)
-            return
-
-        styled_item.Styles = (style,)
+        return ifcopenshell.api.style.assign_item_style(tool.Ifc.get(), item=item, style=style)
 
     @classmethod
     def get_representation_item_style(

src/ifcopenshell-python/ifcopenshell/api/style/__init__.py

@@ -27,6 +27,7 @@ from .. import wrap_usecases
 from .add_style import add_style
 from .add_surface_style import add_surface_style
 from .add_surface_textures import add_surface_textures
+from .assign_item_style import assign_item_style
 from .assign_material_style import assign_material_style
 from .assign_representation_styles import assign_representation_styles
 from .edit_presentation_style import edit_presentation_style
@@ -43,6 +44,7 @@ __all__ = [
     "add_style",
     "add_surface_style",
     "add_surface_textures",
+    "assign_item_style",
     "assign_material_style",
     "assign_representation_styles",
     "edit_presentation_style",

src/ifcopenshell-python/ifcopenshell/api/style/assign_item_style.py

@@ -0,0 +1,132 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2021 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+import ifcopenshell
+from typing import Optional, Union
+
+
+def assign_item_style(
+    file: ifcopenshell.file,
+    item: ifcopenshell.entity_instance,
+    style: Optional[ifcopenshell.entity_instance],
+    should_use_presentation_style_assignment: bool = False,
+) -> Union[ifcopenshell.entity_instance, None]:
+    """Assigns a style directly to a representation item
+
+    A style may either be assigned directly to an object's representation
+    items, or to a material which is then associated with the object. If both
+    exist, then the style assigned directly to the object's representation
+    takes precedence. It is recommended to use materials and assign styles to
+    materials. However, sometimes you may want to assign colours directly to
+    the object representation as an override. This API function provides that
+    capability.
+
+    If you want to assign styles to a material instead (recommended), then
+    please see ifcopenshell.api.style.assign_material_style.
+
+    :param item: The IfcRepresentationItem of the object
+        that you want to assign styles to.
+    :param style: A presentation style, typically IfcSurfaceStyle. None if you
+        want to remove an existing style from the item.
+    :return: Created or existing IfcStyledItem, or None if the style was removed.
+
+    Example:
+
+    .. code:: python
+
+        # A model context is needed to store 3D geometry
+        model3d = ifcopenshell.api.context.add_context(model, context_type="Model")
+
+        # Specifically, we want to store body geometry
+        body = ifcopenshell.api.context.add_context(model,
+            context_type="Model", context_identifier="Body", target_view="MODEL_VIEW", parent=model3d)
+
+        # Let's create a new wall. The wall does not have any geometry yet.
+        wall = ifcopenshell.api.root.create_entity(model, ifc_class="IfcWall")
+
+        # Let's use the "3D Body" representation we created earlier to add a
+        # new wall-like body geometry, 5 meters long, 3 meters high, and
+        # 200mm thick
+        representation = ifcopenshell.api.geometry.add_wall_representation(model,
+            context=body, length=5, height=3, thickness=0.2)
+
+        # Assign our new body geometry back to our wall
+        ifcopenshell.api.geometry.assign_representation(model,
+            product=wall, representation=representation)
+
+        # Place our wall at the origin
+        ifcopenshell.api.geometry.edit_object_placement(model, product=wall)
+
+        # Create a new surface style
+        style = ifcopenshell.api.style.add_style(model)
+
+        # Create a simple grey shading colour and transparency.
+        ifcopenshell.api.style.add_surface_style(model,
+            style=style, ifc_class="IfcSurfaceStyleShading", attributes={
+                "SurfaceColour": { "Name": None, "Red": 0.5, "Green": 0.5, "Blue": 0.5 },
+                "Transparency": 0., # 0 is opaque, 1 is transparent
+            })
+
+        # Now specifically our wall only will be coloured grey.
+        ifcopenshell.api.style.assign_representation_styles(model,
+            shape_representation=representation, styles=[style])
+    """
+    if not (styled_item := next(iter(item.StyledByItem), None)):
+        if style is None:
+            return
+        if file.schema == "IFC2X3":
+            style = file.create_entity("IfcPresentationStyleAssignment", (style,))
+        return file.create_entity("IfcStyledItem", item, (style,))
+
+    styled_item_styles = styled_item.Styles
+    if style and styled_item_styles == (style,):
+        return styled_item
+
+    if file.schema == "IFC4X3":
+        if style is None:
+            file.remove(styled_item)
+            return
+        styled_item.Styles = (style,)
+        return styled_item
+
+    # < IFC4X3
+    # Can't just remove a styled item or assign a style
+    # since we need to remove/change the possible style assignments.
+    assignment = None
+    for style_ in styled_item_styles:
+        if not style_.is_a("IfcPresentationStyleAssignment"):
+            continue
+        # Remove second assignment.
+        if style is None or assignment:
+            file.remove(style_)
+        else:
+            assignment = style_
+            if assignment.Styles != (style,):
+                assignment.Styles = (style,)
+
+    if style is None:
+        file.remove(styled_item)
+        return
+
+    if assignment:
+        if styled_item_styles == (assignment,):
+            return styled_item
+        styled_item.Styles = (assignment,)
+        return styled_item
+
+    styled_item.Styles = (style,)
+    return styled_item