disable editing rep item style if it comes from material constituent through shape aspect

src/blenderbim/blenderbim/bim/module/geometry/operator.py

@@ -1649,11 +1649,43 @@ class RemoveRepresentationItem(bpy.types.Operator, Operator):
         bpy.ops.bim.enable_editing_representation_items()
 
 
+def poll_editing_representaiton_item_style(cls, context):
+    if not (obj := getattr(context, "active_object", None)):
+        return False
+    props = obj.BIMGeometryProperties
+    if not props.is_editing:
+        return False
+    if not 0 <= props.active_item_index < len(props.items):
+        return False
+    item = props.items[props.active_item_index]
+    shape_aspect = item.shape_aspect
+    if shape_aspect == "":
+        return True
+
+    from blenderbim.bim.module.material.data import ObjectMaterialData
+
+    if not ObjectMaterialData.is_loaded:
+        ObjectMaterialData.load()
+    constituents = ObjectMaterialData.data["active_material_constituents"]
+    if any(c for c in constituents if c == shape_aspect):
+        cls.poll_message_set(
+            "Style comes from item's shape aspect related to the material constituent "
+            "with the same name and cannot be edited on representation item directly - "
+            "you can change it from the material constituent"
+        )
+        return False
+    return True
+
+
 class EnableEditingRepresentationItemStyle(bpy.types.Operator, Operator):
     bl_idname = "bim.enable_editing_representation_item_style"
     bl_label = "Enable Editing Representation Item Style"
     bl_options = {"REGISTER", "UNDO"}
 
+    @classmethod
+    def poll(cls, context):
+        return poll_editing_representaiton_item_style(cls, context)
+
     def _execute(self, context):
         props = context.active_object.BIMGeometryProperties
         props.is_editing_item_style = True
@@ -1704,6 +1736,10 @@ class UnassignRepresentationItemStyle(bpy.types.Operator, Operator):
     bl_label = "Unassign Representation Item Style"
     bl_options = {"REGISTER", "UNDO"}
 
+    @classmethod
+    def poll(cls, context):
+        return poll_editing_representaiton_item_style(cls, context)
+
     def _execute(self, context):
         obj = context.active_object
         props = obj.BIMGeometryProperties

src/blenderbim/blenderbim/bim/module/material/data.py

@@ -152,6 +152,7 @@ class ObjectMaterialData:
         cls.data["materials"] = cls.materials()
         cls.data["type_material"] = cls.type_material()
         cls.data["material_type"] = cls.material_type()
+        cls.data["active_material_constituents"] = cls.active_material_constituents()
         cls.is_loaded = True
 
     @classmethod
@@ -318,3 +319,10 @@ class ObjectMaterialData:
         if version == "IFC2X3":
             material_types = ["IfcMaterial", "IfcMaterialLayerSet", "IfcMaterialList"]
         return [(m, m, ifcopenshell.util.doc.get_entity_doc(version, m).get("description", "")) for m in material_types]
+
+    @classmethod
+    def active_material_constituents(cls):
+        material = cls.material
+        if not material.is_a("IfcMaterialConstituentSet"):
+            return []
+        return [m.Name for m in material.MaterialConstituents if m.Name]