Elevated segment curve transition code to a public function

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

@@ -61,6 +61,7 @@ from .create_representation import create_representation
 from .distance_along_from_station import distance_along_from_station
 from .get_alignment import get_alignment
 from .get_alignment_station import get_alignment_station
+from .get_curve_segment_transition_code import get_curve_segment_transition_code
 from .get_layout_segments import get_layout_segments
 from .get_horizontal_layout import get_horizontal_layout
 from .get_vertical_layout import get_vertical_layout
@@ -103,6 +104,7 @@ __all__ = [
     "get_cant_layout",
     "get_child_alignments",
     "get_curve",
+    "get_curve_segment_transition_code",
     "get_horizontal_layout",
     "get_layout_curve",
     "get_layout_segments",

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

@@ -158,7 +158,7 @@ def _map_circular_arc(file: ifcopenshell.file, design_parameters: entity_instanc
 
     parent_curve = file.createIfcCircle(
         Position=file.createIfcAxis2Placement2D(
-            Location=file.createIfcCartesianPoint((x, y)),
+            Location=file.createIfcCartesianPoint((0.0,0.0)),
             RefDirection=file.createIfcDirection((1.0, 0.0)),
         ),
         Radius=radius,

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

@@ -17,7 +17,7 @@
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
 import ifcopenshell
-import ifcopenshell.api
+import ifcopenshell.api.alignment
 from ifcopenshell import ifcopenshell_wrapper
 import ifcopenshell.geom
 from ifcopenshell import entity_instance
@@ -30,47 +30,4 @@ def _update_curve_segment_transition_code(prev_segment: entity_instance, segment
     Updates IfcCurveSegment.Transition of prev_segment based on a comparison of
     the position, ref. direction, and curvature at the end of the prev_segment and the start of segment.
     """
-    expected_type = "IfcCurveSegment"
+    prev_segment.Transition = ifcopenshell.api.alignment.get_curve_segment_transition_code(prev_segment,segment)
-    if not prev_segment.is_a(expected_type):
-        raise TypeError(f"Expected to see '{expected_type}', instead received '{prev_segment.is_a()}'.")
-
-    if not segment.is_a(expected_type):
-        raise TypeError(f"Expected to see '{expected_type}', instead received '{segment.is_a()}'.")
-
-    if len(prev_segment.UsingCurves) != 1:
-        raise TypeError("prev_segment must belong to exactly one curve")
-
-    if len(segment.UsingCurves) != 1:
-        raise TypeError("segment must belong to exactly one curve")
-
-    if prev_segment.UsingCurves[0] != segment.UsingCurves[0]:
-        raise TypeError("Both segments must belong to the same curve")
-
-    settings = ifcopenshell.geom.settings()
-    settings.set("COMPUTE_CURVATURE", True)
-
-    prev_segment_fn = ifcopenshell_wrapper.map_shape(settings, prev_segment.wrapped_data)
-    prev_segment_evaluator = ifcopenshell_wrapper.function_item_evaluator(settings, prev_segment_fn)
-    e = prev_segment_evaluator.evaluate(prev_segment_fn.end())
-    end = np.array(e)
-
-    # must add the new segment to the container before mapping it, otherwise the segment doesn't
-    # have enough context to know if it is for horizontal, vertical, cant
-
-    segment_fn = ifcopenshell_wrapper.map_shape(settings, segment.wrapped_data)
-    segment_evaluator = ifcopenshell_wrapper.function_item_evaluator(settings, segment_fn)
-    s = segment_evaluator.evaluate(segment_fn.start())
-    start = np.array(s)
-
-    same_position = True if np.allclose(end[:3, 3], start[:3, 3]) else False
-    same_gradient = True if np.allclose(end[:3, 0], start[:3, 0]) else False
-    same_curvature = True if np.allclose(end[3:, :3], start[3:, :3]) else False
-
-    if same_position:
-        prev_segment.Transition = "CONTINUOUS"
-        if same_gradient:
-            prev_segment.Transition = "CONTSAMEGRADIENT"
-            if same_curvature:
-                prev_segment.Transition = "CONTSAMEGRADIENTSAMECURVATURE"
-    else:
-        prev_segment.Transition = "DISCONTINUOUS"

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

@@ -0,0 +1,79 @@
+# 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
+from ifcopenshell import ifcopenshell_wrapper
+import ifcopenshell.geom
+from ifcopenshell import entity_instance
+import numpy as np
+import math
+
+
+def get_curve_segment_transition_code(prev_segment: entity_instance, segment: entity_instance, tolerance:float = 5.0e-4) -> str:
+    """
+    Returns the  IfcCurveSegment.Transition of prev_segment based on a comparison of
+    the position, ref. direction, and curvature at the end of the prev_segment and the start of segment.
+    """
+    expected_type = "IfcCurveSegment"
+    if not prev_segment.is_a(expected_type):
+        raise TypeError(f"Expected to see '{expected_type}', instead received '{prev_segment.is_a()}'.")
+
+    if not segment.is_a(expected_type):
+        raise TypeError(f"Expected to see '{expected_type}', instead received '{segment.is_a()}'.")
+
+    if len(prev_segment.UsingCurves) != 1:
+        raise TypeError("prev_segment must belong to exactly one curve")
+
+    if len(segment.UsingCurves) != 1:
+        raise TypeError("segment must belong to exactly one curve")
+
+    if prev_segment.UsingCurves[0] != segment.UsingCurves[0]:
+        raise TypeError("Both segments must belong to the same curve")
+
+    settings = ifcopenshell.geom.settings()
+    settings.set("COMPUTE_CURVATURE", True)
+
+    prev_segment_fn = ifcopenshell_wrapper.map_shape(settings, prev_segment.wrapped_data)
+    prev_segment_evaluator = ifcopenshell_wrapper.function_item_evaluator(settings, prev_segment_fn)
+    e = prev_segment_evaluator.evaluate(prev_segment_fn.end())
+    end = np.array(e)
+
+    # must add the new segment to the container before mapping it, otherwise the segment doesn't
+    # have enough context to know if it is for horizontal, vertical, cant
+
+    segment_fn = ifcopenshell_wrapper.map_shape(settings, segment.wrapped_data)
+    segment_evaluator = ifcopenshell_wrapper.function_item_evaluator(settings, segment_fn)
+    s = segment_evaluator.evaluate(segment_fn.start())
+    start = np.array(s)
+
+    same_position = True if np.allclose(end[:3, 3], start[:3, 3], atol=tolerance) else False
+    same_gradient = True if np.allclose(end[:3, 0], start[:3, 0], atol=tolerance) else False
+    same_curvature = True if np.allclose(end[3:, :3], start[3:, :3], atol=tolerance) else False
+
+    transition_code = ""
+    if same_position:
+        transition_code = "CONTINUOUS"
+        if same_gradient:
+            transition_code = "CONTSAMEGRADIENT"
+            if same_curvature:
+                transition_code = "CONTSAMEGRADIENTSAMECURVATURE"
+    else:
+        transition_code = "DISCONTINUOUS"
+
+    return transition_code