Adds update_alignment_parameter_segment_tags function

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

@@ -25,7 +25,7 @@ are automatically created and maintained.
 
 Alignments are created with stationing referents. Each layout segment is assigned a position referent that informs about
 the start point of the segment. An example is the point of curvature of a horizontal circular curve. The referent is
-nested to the segment representing the circular arc and is named with a indicator of the position and the station, e.g. "P.C. (145+98.32)"
+nested to the segment representing the circular arc and is named with the alignment name and an indicator of the position and the station, e.g. "MyAlignment 145+98.32 (P.C.)"
 
 This API does not determine alignment parameters based on rules, such as minimum curve radius as a function of design speed or sight distance.
 
@@ -89,6 +89,7 @@ from .layout_vertical_alignment_by_pi_method import (
     layout_vertical_alignment_by_pi_method,
 )
 from .name_segments import name_segments
+from .update_alignment_parameter_segment_tags import update_alignment_parameter_segment_tags
 from .update_end_point import update_end_point
 from .update_fallback_position import update_fallback_position
 from .update_key_point_referents import update_key_point_referents
@@ -132,6 +133,7 @@ __all__ = [
     "layout_vertical_alignment_by_pi_method",
     "name_segments",
     "register_referent_name_callback",
+    "update_alignment_parameter_segment_tags",
     "update_end_point",
     "update_fallback_position",
     "update_key_point_referents",

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

@@ -0,0 +1,30 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import ifcopenshell
+import ifcopenshell.util.alignment
+
+
+def _get_key_point_tag(file: ifcopenshell.file, label: str, station: float) -> str:
+    """
+    Builds the station-and-label text shared by update_alignment_parameter_segment_tags (used
+    directly as IfcAlignmentParameterSegment.StartTag/EndTag) and update_key_point_referents (used,
+    prefixed with the alignment name, as IfcReferent.Name): "<station> (<label>)", e.g.
+    "145+98.32 (P.O.B.)".
+    """
+    return f"{ifcopenshell.util.alignment.station_as_string(file, station)} ({label})"

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

@@ -0,0 +1,100 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import ifcopenshell
+import ifcopenshell.api.alignment
+from ifcopenshell import entity_instance
+from ifcopenshell.api.alignment._get_key_point_tag import _get_key_point_tag
+from ifcopenshell.api.alignment._get_segment_start_point_label import (
+    _get_segment_start_point_label,
+)
+
+
+def update_alignment_parameter_segment_tags(file: ifcopenshell.file, layout: entity_instance) -> None:
+    """
+    Sets IfcAlignmentParameterSegment.StartTag/EndTag for every segment transition in an alignment
+    layout. Unlike update_key_point_referents, this does not create any IfcReferent or IfcRelNests --
+    it only mutates the StartTag/EndTag string attributes already present on each segment's
+    DesignParameters.
+
+    For each transition between two consecutive segments, the outgoing segment's EndTag and the
+    incoming segment's StartTag are both set to the same computed tag (they describe the same
+    physical point), using the same label-and-station format as update_key_point_referents' Name
+    minus the alignment name (via _get_key_point_tag), e.g. "145+98.32 (P.C.)". Every real segment
+    ends up with both StartTag and EndTag populated: the first segment's StartTag and the last
+    segment's EndTag come from the "Beginning of Alignment"/"End of Alignment" boundary labels.
+
+    Labels come from _get_segment_start_point_label -- if a callback has been registered via
+    register_referent_name_callback(), its output is used instead of the built-in labels, exactly as
+    in update_key_point_referents.
+
+    :param layout: IfcAlignmentHorizontal, IfcAlignmentVertical, or IfcAlignmentCant
+    :return: None -- this function mutates segment.DesignParameters.StartTag/EndTag in place
+
+    Example:
+
+    .. code:: python
+
+        horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+        ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(model, horizontal)
+    """
+
+    expected_types = ["IfcAlignmentHorizontal", "IfcAlignmentVertical", "IfcAlignmentCant"]
+    if not layout.is_a() in expected_types:
+        raise TypeError(
+            f"Expected entity type to be one of {[_ for _ in expected_types]}, instead received {layout.is_a()}"
+        )
+
+    alignment = ifcopenshell.api.alignment.get_alignment(layout)
+    if alignment is None:
+        raise ValueError(f"{layout.is_a()} #{layout.id()} is not nested under an IfcAlignment.")
+
+    segments = list(ifcopenshell.api.alignment.get_layout_segments(layout))
+    if segments and ifcopenshell.api.alignment.has_zero_length_segment(layout):
+        segments = segments[:-1]
+
+    if not segments:
+        return
+
+    start_station = ifcopenshell.api.alignment.get_alignment_start_station(file, alignment)
+    is_horizontal = layout.is_a("IfcAlignmentHorizontal")
+
+    distance_along = 0.0
+    prev_segment = None
+    for segment in segments:
+        dp = segment.DesignParameters
+        seg_distance_along = distance_along if is_horizontal else dp.StartDistAlong
+
+        label = _get_segment_start_point_label(prev_segment, segment)
+        station = start_station + seg_distance_along
+        tag = _get_key_point_tag(file, label, station)
+
+        dp.StartTag = tag
+        if prev_segment is not None:
+            prev_segment.DesignParameters.EndTag = tag
+
+        if is_horizontal:
+            distance_along += dp.SegmentLength
+        else:
+            distance_along = dp.StartDistAlong + dp.HorizontalLength
+
+        prev_segment = segment
+
+    label = _get_segment_start_point_label(prev_segment, None)
+    station = start_station + distance_along
+    prev_segment.DesignParameters.EndTag = _get_key_point_tag(file, label, station)

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

@@ -22,9 +22,9 @@ import ifcopenshell
 import ifcopenshell.api.alignment
 import ifcopenshell.api.pset
 import ifcopenshell.guid
-import ifcopenshell.util.alignment
 import ifcopenshell.util.element
 from ifcopenshell import entity_instance
+from ifcopenshell.api.alignment._get_key_point_tag import _get_key_point_tag
 from ifcopenshell.api.alignment._get_segment_start_point_label import (
     _get_segment_start_point_label,
 )
@@ -76,7 +76,7 @@ def _create_key_point_referent(
             ),
         )
 
-    name = f"{label} ({ifcopenshell.util.alignment.station_as_string(file, station)})"
+    name = f"{alignment.Name} {_get_key_point_tag(file, label, station)}"
 
     referent = file.createIfcReferent(
         GlobalId=ifcopenshell.guid.new(),
@@ -105,7 +105,8 @@ def update_key_point_referents(
     Creates IfcReferent key-point markers for every segment transition in an alignment layout.
 
     Labels are derived from _get_segment_start_point_label (e.g. "P.C.", "P.T.", "P.O.B.",
-    "P.V.C.", ...), with the station appended, e.g. "P.C. (145+98.32)". Different jurisdictions use
+    "P.V.C.", ...), and combined with the alignment name and station to build the Name, e.g.
+    "MyAlignment 145+98.32 (P.C.)". Different jurisdictions use
     different naming systems for these key points -- register_referent_name_callback() lets a
     caller override the default horizontal/vertical/cant labeling before calling this function; if
     a callback is registered, its output is used here instead of the built-in labels. Referents are
@@ -145,7 +146,7 @@ def update_key_point_referents(
         ifcopenshell.api.alignment.register_referent_name_callback(horizontal=my_horizontal_labels)
         horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
         nest = ifcopenshell.api.alignment.update_key_point_referents(model, horizontal)
-        # nest.RelatedObjects[0].Name starts with "Start (" instead of the default "P.O.B. ("
+        # nest.RelatedObjects[0].Name ends with "(Start)" instead of the default "(P.O.B.)"
     """
 
     expected_types = ["IfcAlignmentHorizontal", "IfcAlignmentVertical", "IfcAlignmentCant"]