Closes #3764: When switching an instance to a different beam type, preserve the CardinalPoint.

src/bonsai/bonsai/core/type.py

@@ -19,6 +19,7 @@
 from __future__ import annotations
 import bonsai.core.geometry
 from typing import TYPE_CHECKING, Optional
+import ifcopenshell.util.element
 
 if TYPE_CHECKING:
     import bpy
@@ -32,14 +33,34 @@ def assign_type(
     element: ifcopenshell.entity_instance,
     type: ifcopenshell.entity_instance,
 ) -> None:
+    
+    
+    # Get the instance's current CardinalPoint before type assignment
+    instance_cardinal_point = None
+    instance_material = ifcopenshell.util.element.get_material(element)
+    if instance_material and instance_material.is_a("IfcMaterialProfileSetUsage"):
+        instance_cardinal_point = instance_material.CardinalPoint
+    
     ifc.run("type.assign_type", related_objects=[element], relating_type=type)
     obj = ifc.get_object(element)
+    
     if type_tool.has_material_usage(element):
-        pass  # for now, representation regeneration handled by API listeners
+        # Restore the instance's CardinalPoint to the new material usage
+        if instance_cardinal_point is not None:
+            new_instance_material = ifcopenshell.util.element.get_material(element)
+            if new_instance_material and new_instance_material.is_a("IfcMaterialProfileSetUsage"):
+                if new_instance_material.CardinalPoint != instance_cardinal_point:
+                    new_instance_material.CardinalPoint = instance_cardinal_point
+                    
+                    # Force representation regeneration
+                    from bonsai.bim.module.model.profile import DumbProfileRecalculator
+                    DumbProfileRecalculator().recalculate([obj])
+        # for now, representation regeneration handled by API listeners
     else:
         type_data = type_tool.get_object_data(ifc.get_object(type))
         if type_data:
             type_tool.change_object_data(obj, type_data, is_global=False)
+    
     type_tool.disable_editing(obj)