Strengthens implementation of station_to_string. Adds alignment name to stationing referent.

src/ifcopenshell-python/ifcopenshell/api/alignment/create.py

@@ -51,6 +51,10 @@ def create(
 
     If geometric representations are created, the alignment stationing referent is also created using the start_station value. IfcReferent.ObjectPlacement
     is required for linear positiion elements and IfcLinearPlacement is defined relative to alignment curve geometry.
+    This referent's Name follows the same "<alignment name> <station>" convention update_key_point_referents() uses
+    for its own key-point referents (e.g. "MyAlignment 49+00.00"), so that every referent nested under an alignment
+    is identifiable by name alone, without needing to inspect its Pset_Stationing or placement to know which
+    alignment it belongs to.
 
     :param file:
     :param name: name assigned to IfcAlignment.Name
@@ -86,7 +90,7 @@ def create(
     if include_geometry:
         _create_geometric_representation(file, alignment)
 
-    referent_name = ifcopenshell.util.alignment.station_as_string(file, start_station)
+    referent_name = f"{name} {ifcopenshell.util.alignment.station_as_string(file, start_station)}"
     referent = ifcopenshell.api.alignment.add_stationing_referent(file, referent_name, alignment, 0.0, start_station)
 
     for layout in alignment_layouts:

src/ifcopenshell-python/ifcopenshell/api/alignment/create_as_polyline.py

@@ -128,6 +128,11 @@ def create_as_polyline(
 
     The IfcAlignment is aggreated to IfcProject
 
+    The stationing referent created from start_station has Name "<alignment name> <station>"
+    (e.g. "MyAlignment 49+00.00"), the same convention update_key_point_referents() and
+    create() use for their own referents, so every referent nested under an alignment is
+    identifiable by name alone.
+
     :param file:
     :param name: name assigned to IfcAlignment.Name
     :param points: sequence of points defining the polyline
@@ -142,8 +147,8 @@ def create_as_polyline(
     _create_polyline_representation(file, alignment, points)
 
     # define stationing
-    name = ifcopenshell.util.alignment.station_as_string(file, start_station)
-    referent = ifcopenshell.api.alignment.add_stationing_referent(file, name, alignment, 0.0, start_station)
+    referent_name = f"{alignment.Name} {ifcopenshell.util.alignment.station_as_string(file, start_station)}"
+    referent = ifcopenshell.api.alignment.add_stationing_referent(file, referent_name, alignment, 0.0, start_station)
 
     # IFC 4.1.4.1.1 Alignment Aggregation To Project
     project = file.by_type("IfcProject")[0]

src/ifcopenshell-python/ifcopenshell/util/alignment.py

@@ -69,21 +69,21 @@ def station_as_string(file: ifcopenshell.file, sta: float):
     Returns a stringized version of a station. Example 100.0 is 1+00.00 as a stationing string.
     If the project units are SI-based, the string is in the format xxx+yyy.zzz
     If the project units are Emperial-based, the string is in the format xx+yy.zz
+
     :param station: the station to be stringized
     :return: stringized station
     """
 
     unit_type = ifcopenshell.util.unit.get_project_unit(file, "LENGTHUNIT")
+    project_unit_to_metres = ifcopenshell.util.unit.calculate_unit_scale(file)
     if unit_type.is_a("IfcConversionBasedUnit"):
-        station = ifcopenshell.util.unit.convert(
-            sta, from_unit=unit_type.Name, from_prefix=None, to_unit="foot", to_prefix=None
-        )
+        # xx+yy.zz display is inherently foot-based, regardless of which foot variant
+        # (international vs. US survey, etc.) the project's own unit actually is.
+        station = sta * project_unit_to_metres / 0.3048
         plus_seperator = 2
         precision = 2
     else:
-        station = ifcopenshell.util.unit.convert(
-            sta, from_unit=unit_type.Name, from_prefix=unit_type.Prefix, to_unit="meter", to_prefix=None
-        )
+        station = sta * project_unit_to_metres
         plus_seperator = 3
         precision = 3