Default to assigning material set usages if assigning to an occurrence. See #7794.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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

@@ -210,14 +210,15 @@ class AssignMaterialToSelected(bpy.types.Operator, tool.Ifc.Operator):
     bl_idname = "bim.assign_material_to_selected"
     bl_label = "Assign Material To Selected"
     bl_description = (
-        "Assign currently selected material in Materials UI to the selected objects.\n\n"
+        "Assign currently selected material in Materials UI to the selected objects.\n"
-        "ALT+CLICK to assign material as a usage."
+        "Occurrences automatically get usages for layer/profile sets.\n\n"
+        "ALT+CLICK to assign without a usage."
     )
     bl_options = {"REGISTER", "UNDO"}
     material: bpy.props.IntProperty(name="Material IFC ID")
-    assign_as_usage: bpy.props.BoolProperty(
+    should_auto_assign_usage: bpy.props.BoolProperty(
-        name="Assign Material As A Usage",
+        name="Auto Assign Usage",
-        default=False,
+        default=True,
         options={"SKIP_SAVE"},
     )
 
@@ -230,25 +231,19 @@ class AssignMaterialToSelected(bpy.types.Operator, tool.Ifc.Operator):
 
     def invoke(self, context, event):
         if event.type == "LEFTMOUSE" and event.alt:
-            material_class = tool.Ifc.get().by_id(self.material).is_a()
+            self.should_auto_assign_usage = False
-            if material_class not in ("IfcMaterialProfileSet", "IfcMaterialLayerSet"):
-                self.report({"ERROR"}, f"{material_class} cannot be assigned as a usage.")
-                return {"CANCELLED"}
-            self.assign_as_usage = True
         return self.execute(context)
 
     def _execute(self, context):
         material = tool.Ifc.get().by_id(self.material)
         objects = tool.Blender.get_selected_objects()
-        material_type = material.is_a()
-        if self.assign_as_usage:
-            material_type += "Usage"
         core.assign_material(
             tool.Ifc,
             tool.Material,
-            material_type=material_type,
+            material_type=material.is_a(),
             objects=objects,
             material=material,
+            should_auto_assign_usage=self.should_auto_assign_usage,
         )
 
 

src/bonsai/bonsai/core/material.py

@@ -113,6 +113,7 @@ def assign_material(
     material_type: Union[str, None],
     objects: list[bpy.types.Object],
     material: Optional[ifcopenshell.entity_instance] = None,
+    should_auto_assign_usage: bool = True,
 ) -> None:
     """Assign material to the provided objects.
 
@@ -121,12 +122,18 @@ def assign_material(
     """
     material_type = material_type or material_tool.get_object_ui_material_type()
     material = material or material_tool.get_object_ui_active_material()
+    can_be_usage = should_auto_assign_usage and material_type in ("IfcMaterialLayerSet", "IfcMaterialProfileSet")
     for obj in objects:
         element = ifc.get_entity(obj)
         if not element:
             continue
 
-        ifc.run("material.assign_material", products=[element], type=material_type, material=material)
+        if can_be_usage and not material_tool.is_type_product(element):
+            element_material_type = material_type + "Usage"
+        else:
+            element_material_type = material_type
+
+        ifc.run("material.assign_material", products=[element], type=element_material_type, material=material)
         assigned_material = material_tool.get_material(element)
         assert assigned_material  # Type checker.
 
@@ -136,7 +143,7 @@ def assign_material(
             material_tool.add_material_to_set(material_set=material, material=default_material)
         elif material_tool.is_a_material_set(assigned_material):
             material_tool.add_material_to_set(material_set=assigned_material, material=material)
-        material_tool.ensure_material_assigned(elements=[element], material_type=material_type, material=material)
+        material_tool.ensure_material_assigned(elements=[element], material_type=element_material_type, material=material)
 
 
 def unassign_material(ifc: type[tool.Ifc], material_tool: type[tool.Material], objects: list[bpy.types.Object]) -> None:

src/bonsai/bonsai/core/tool.py

@@ -580,6 +580,7 @@ class Material:
     def import_material_definitions(cls, material_type: str): pass
     def is_a_flow_segment(cls, element): pass
     def is_a_material_set(cls, material): pass
+    def is_type_product(cls, element): pass
     def is_editing_materials(cls): pass
     def is_material_used_in_sets(cls, material): pass
     def load_material_attributes(cls, material): pass

src/bonsai/bonsai/tool/material.py

@@ -226,6 +226,10 @@ class Material(bonsai.core.tool.Material):
             "IfcMaterialProfileSet",
         ]
 
+    @classmethod
+    def is_type_product(cls, element: ifcopenshell.entity_instance) -> bool:
+        return element.is_a("IfcTypeProduct")
+
     @classmethod
     def add_material_to_set(
         cls, material_set: ifcopenshell.entity_instance, material: ifcopenshell.entity_instance