Fix #6334: Preserve annotation vertex order during subdivision to prevent arrow/text flip

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

@@ -2409,6 +2409,14 @@ class OverrideModeSetObject(bpy.types.Operator, tool.Ifc.Operator):
         props = tool.Geometry.get_geometry_props()
         item = tool.Geometry.get_active_representation(obj)
         assert item
+        
+        # Fix vertex order for annotation items
+        rep_obj = props.representation_obj
+        if rep_obj:
+            element = tool.Ifc.get_entity(rep_obj)
+            if element and self._is_annotation_object(element):
+                tool.Geometry.ensure_annotation_vertex_order(obj)
+        
         if tool.Geometry.is_meshlike_item(item):
             if tool.Geometry.is_geometric_data(obj.data) and (
                 item.is_a("IfcVertex") or item.is_a("IfcEdge") or obj.data.polygons
@@ -2548,6 +2556,31 @@ class OverrideModeSetObject(bpy.types.Operator, tool.Ifc.Operator):
             props.mode = "EDIT"
         props.is_changing_mode = False
 
+    def _is_annotation_object(self, element: ifcopenshell.entity_instance) -> bool:
+        """Check if element is an annotation object that needs vertex order preservation."""
+        if not element.is_a("IfcAnnotation"):
+            return False
+        
+        # Object types that have semantic vertex order (arrow direction, text position)
+        annotation_types_with_order = {
+            "TEXT_LEADER",
+            "DIMENSION",
+            "RADIUS", 
+            "DIAMETER",
+            "ANGLE",
+            "FALL",
+            "SLOPE_ANGLE",
+            "SLOPE_FRACTION",
+            "SLOPE_PERCENT",
+            "STAIR_ARROW",
+            "PLAN_LEVEL",
+            "SECTION_LEVEL",
+            "SECTION",
+            "ELEVATION",
+        }
+        
+        return element.ObjectType in annotation_types_with_order
+
 
 class DirectProfileEdit(bpy.types.Operator, tool.Ifc.Operator):
     bl_idname = "bim.direct_profile_edit"
@@ -3374,6 +3407,17 @@ class ImportRepresentationItems(bpy.types.Operator, tool.Ifc.Operator):
 
         tool.Root.reload_item_decorator()
 
+        element = tool.Ifc.get_entity(obj)
+        if element and element.is_a("IfcAnnotation") and element.ObjectType in {
+            "TEXT_LEADER", "DIMENSION", "RADIUS", "DIAMETER", "ANGLE",
+            "FALL", "SLOPE_ANGLE", "SLOPE_FRACTION", "SLOPE_PERCENT",
+            "STAIR_ARROW", "PLAN_LEVEL", "SECTION_LEVEL", "SECTION", "ELEVATION"
+        }:
+            for item_obj_data in props.item_objs:
+                item_obj = item_obj_data.obj
+                if item_obj and isinstance(item_obj.data, bpy.types.Mesh) and item_obj.data.vertices:
+                    item_obj.data["bonsai_first_vert_co"] = item_obj.data.vertices[0].co[:]
+
 
 class UpdateItemAttributes(bpy.types.Operator, tool.Ifc.Operator):
     bl_idname = "bim.update_item_attributes"

src/bonsai/bonsai/tool/geometry.py

@@ -1904,6 +1904,17 @@ class Geometry(bonsai.core.tool.Geometry):
                 obj.data.transform(transformation_i)
             cls.record_object_position(obj)
 
+        # ADD THIS AT THE END - Store initial vertex order for annotations
+        if rep_obj and (element := tool.Ifc.get_entity(rep_obj)):
+            if element.is_a("IfcAnnotation") and element.ObjectType in {
+                "TEXT_LEADER", "DIMENSION", "RADIUS", "DIAMETER", "ANGLE",
+                "FALL", "SLOPE_ANGLE", "SLOPE_FRACTION", "SLOPE_PERCENT",
+                "STAIR_ARROW", "PLAN_LEVEL", "SECTION_LEVEL", "SECTION", "ELEVATION"
+            }:
+                # Store the initial first vertex position
+                if isinstance(obj.data, bpy.types.Mesh) and obj.data.vertices:
+                    obj.data["bonsai_first_vert_co"] = obj.data.vertices[0].co[:]
+
     @classmethod
     def disable_item_mode(cls) -> None:
         props = tool.Geometry.get_geometry_props()
@@ -2340,3 +2351,94 @@ class Geometry(bonsai.core.tool.Geometry):
                 continue
             objects.add(obj)
         return objects
+
+    @classmethod
+    def ensure_annotation_vertex_order(cls, obj: bpy.types.Object) -> None:
+        """
+        Ensure vertices form a continuous path from start to end.
+        Uses the original first vertex position as a reference point.
+        """
+        mesh = obj.data
+        if not isinstance(mesh, bpy.types.Mesh):
+            return
+        
+        # Get the original first vertex position from custom properties
+        if "bonsai_first_vert_co" in mesh:
+            original_first_co = Vector(mesh["bonsai_first_vert_co"])
+        else:
+            # Store it for next time
+            if mesh.vertices:
+                original_first_co = Vector(mesh.vertices[0].co)
+                mesh["bonsai_first_vert_co"] = original_first_co[:]
+            else:
+                return
+        
+        bm = bmesh.new()
+        bm.from_mesh(mesh)
+        bm.verts.ensure_lookup_table()
+        bm.edges.ensure_lookup_table()
+        
+        if len(bm.verts) == 0:
+            bm.free()
+            return
+        
+        # Find endpoints (vertices with only one connected edge)
+        endpoints = [v for v in bm.verts if len(v.link_edges) == 1]
+        
+        # Choose the endpoint closest to the original first vertex position
+        if len(endpoints) == 0:
+            # Closed loop - pick any vertex as start
+            start_vert = bm.verts[0]
+        elif len(endpoints) == 1:
+            # Single endpoint
+            start_vert = endpoints[0]
+        else:
+            # Choose endpoint closest to where the original first vertex was
+            start_vert = min(endpoints, key=lambda v: (v.co - original_first_co).length)
+        
+        # Build ordered vertex list by following edges
+        ordered_verts = [start_vert]
+        current_vert = start_vert
+        visited_edges = set()
+        
+        while True:
+            # Find next unvisited edge
+            next_edge = None
+            for edge in current_vert.link_edges:
+                if edge not in visited_edges:
+                    next_edge = edge
+                    break
+            
+            if not next_edge:
+                break
+            
+            visited_edges.add(next_edge)
+            next_vert = next_edge.other_vert(current_vert)
+            
+            # Avoid going back on ourselves
+            if next_vert not in ordered_verts:
+                ordered_verts.append(next_vert)
+            
+            current_vert = next_vert
+        
+        # Store vertex coordinates in the correct order
+        new_verts_co = [v.co.copy() for v in ordered_verts]
+        
+        # Update the stored first vertex position to the new first vertex
+        mesh["bonsai_first_vert_co"] = new_verts_co[0][:]
+        
+        # Clear and rebuild mesh with correct vertex order
+        bm.clear()
+        
+        # Create new vertices in order
+        new_verts = [bm.verts.new(co) for co in new_verts_co]
+        bm.verts.ensure_lookup_table()
+        
+        # Create edges connecting consecutive vertices
+        for i in range(len(new_verts) - 1):
+            bm.edges.new([new_verts[i], new_verts[i + 1]])
+        
+        # Write back to mesh
+        bm.to_mesh(mesh)
+        bm.free()
+        mesh.update()