Updates alignment api. Fixes bugs authoring semantic-only alignment

src/ifcopenshell-python/test/api/alignment/test_add_segment_to_layout.py

@@ -38,6 +38,12 @@ def test_add_segment_to_layout():
     )
 
     alignment = ifcopenshell.api.alignment.create(file, "")
+
+    referent_nest = ifcopenshell.api.alignment.get_referent_nest(file, alignment)
+    assert (
+        len(referent_nest.RelatedObjects) == 1
+    )  # the alignment creates the stationing nest and it has one referent to defined the stationing for the alignment
+
     horizontal_alignment = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
 
     design_parameters = file.create_entity(
@@ -70,7 +76,7 @@ def test_add_segment_to_layout():
     segment_nest = ifcopenshell.api.alignment.get_alignment_segment_nest(horizontal_alignment)
     assert len(segment_nest.RelatedObjects) == 2
     referent_nest = ifcopenshell.api.alignment.get_referent_nest(file, alignment)
-    assert len(referent_nest.RelatedObjects) == 3
+    assert len(referent_nest.RelatedObjects) == 1  # test this a second time to make sure that it is still true
 
 
 test_add_segment_to_layout()

src/ifcopenshell-python/test/api/alignment/test_add_vertical_alignment.py

@@ -37,7 +37,9 @@ def test_add_vertical_alignment():
     assert len(layout_nest.RelatedObjects) == 1
     assert layout_nest.RelatedObjects[0].is_a("IfcAlignmentHorizontal")
     referent_nest = ifcopenshell.api.alignment.get_referent_nest(file, alignment)
-    assert len(referent_nest.RelatedObjects) == 2
+    assert (
+        len(referent_nest.RelatedObjects) == 1
+    )  # the alignment creates the stationing nest and it has one referent to defined the stationing for the alignment
     assert referent_nest.RelatedObjects[0].is_a("IfcReferent")
 
     curve = ifcopenshell.api.alignment.get_curve(alignment)
@@ -62,7 +64,7 @@ def test_add_vertical_alignment():
 
     for child_alignment in alignment.IsDecomposedBy[0].RelatedObjects:
         assert child_alignment.is_a("IfcAlignment")
-        assert len(child_alignment.IsNestedBy) == 2
+        assert len(child_alignment.IsNestedBy) == 1
         child_layout_nest = ifcopenshell.api.alignment.get_alignment_layout_nest(child_alignment)
         assert len(child_layout_nest.RelatedObjects) == 1  # The IfcAlignmentVertical
         assert child_layout_nest.RelatedObjects[0].is_a("IfcAlignmentVertical")

src/ifcopenshell-python/test/api/alignment/test_create_by_pi_method.py

@@ -52,7 +52,7 @@ def test_create_by_pi_method():
     assert len(layout_nest.RelatedObjects) == 2
 
     referent_nest = ifcopenshell.api.alignment.get_referent_nest(file, alignment)
-    assert len(referent_nest.RelatedObjects) == 19
+    assert len(referent_nest.RelatedObjects) == 1
 
     horizontal_layout = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
     horizontal_segment_nest = ifcopenshell.api.alignment.get_alignment_segment_nest(horizontal_layout)

src/ifcopenshell-python/test/api/alignment/test_create_layout_segment.py

@@ -73,9 +73,16 @@ def _test_horizontal() -> ifcopenshell.file:
     assert y == 0.0
     assert z == 0.0
 
+    # check the start point of the zero length segment
+    assert horizontal_alignment.IsNestedBy[0].RelatedObjects[1].DesignParameters.SegmentLength == 0.0
+    assert horizontal_alignment.IsNestedBy[0].RelatedObjects[1].DesignParameters.StartPoint.Coordinates[0] == x
+    assert horizontal_alignment.IsNestedBy[0].RelatedObjects[1].DesignParameters.StartPoint.Coordinates[1] == y
+
     curve = ifcopenshell.api.alignment.get_curve(ali)
     assert curve.is_a("IfcCompositeCurve")
     assert len(curve.Segments) == 2
+    assert curve.Segments[0].Transition == "CONTSAMEGRADIENTSAMECURVATURE"
+    assert curve.Segments[1].Transition == "DISCONTINUOUS"
 
     design_parameters = file.create_entity(
         type="IfcAlignmentHorizontalSegment",
@@ -101,9 +108,16 @@ def _test_horizontal() -> ifcopenshell.file:
     assert y == 50.0 * math.sin(math.pi / 6)
     assert z == 0.0
 
+    # check the start point of the zero length segment
+    assert horizontal_alignment.IsNestedBy[0].RelatedObjects[2].DesignParameters.SegmentLength == 0.0
+    assert horizontal_alignment.IsNestedBy[0].RelatedObjects[2].DesignParameters.StartPoint.Coordinates[0] == x
+    assert horizontal_alignment.IsNestedBy[0].RelatedObjects[2].DesignParameters.StartPoint.Coordinates[1] == y
+
     curve = ifcopenshell.api.alignment.get_curve(ali)
     assert curve.is_a("IfcCompositeCurve")
     assert len(curve.Segments) == 3
+    assert curve.Segments[1].Transition == "CONTSAMEGRADIENTSAMECURVATURE"
+    assert curve.Segments[2].Transition == "DISCONTINUOUS"
 
     return file
 

src/ifcopenshell-python/test/api/alignment/test_create_no_geometry.py

@@ -50,7 +50,14 @@ def test_create_no_geometry():
         PredefinedType="LINE",
     )
     end = ifcopenshell.api.alignment.create_layout_segment(file, horizontal_alignment, design_parameters)
-    assert end == None
+
+    x = end[0, 3]
+    y = end[1, 3]
+    z = end[2, 3]
+
+    assert x == 100.0
+    assert y == 0.0
+    assert z == 0.0
 
     design_parameters = file.createIfcAlignmentVerticalSegment(
         StartDistAlong=0.0,
@@ -61,7 +68,14 @@ def test_create_no_geometry():
         PredefinedType="CONSTANTGRADIENT",
     )
     end = ifcopenshell.api.alignment.create_layout_segment(file, vertical_alignment, design_parameters)
-    assert end == None
+
+    x = end[0, 3]
+    y = end[1, 3]
+    z = end[2, 3]
+
+    assert x == 50.0
+    assert y == 20.0 + 50.0 * 1.0 / 100.0
+    assert z == 0.0
 
 
 test_create_no_geometry()

src/ifcopenshell-python/test/api/alignment/test_create_representation.py

@@ -0,0 +1,443 @@
+# 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 math
+
+import pytest
+import ifcopenshell
+import ifcopenshell.api.alignment
+import ifcopenshell.api.unit
+import numpy as np
+
+
+def test_create_representation():
+    # expected values for horizontal segment ends points (X,Y,dx,dy)
+    h_expected = [
+        (500.0, 2500.0, math.cos(math.radians(327.0613)), math.sin(math.radians(327.0613))),
+        (2142.2378194934668, 1436.0145490066361, 0.8392527899703555, -0.5437414408769801),
+        (3660.446048592728, 2050.735651565721, 0.22453168741127044, 0.9744667882222808),
+        (4084.1161141648777, 3889.4623490042068, 0.22453168741127047, 0.9744667882222809),
+        (5469.395455576321, 4847.565492667097, 0.9910142023415828, -0.13375668490687387),
+        (7019.971720182908, 4638.284999653966, 0.9910142023415827, -0.13375668490687387),
+        (7790.932377201981, 4006.729563689594, 0.32621900658961334, -0.9452942186111613),
+        (8479.999918938518, 2009.9986857258034, 0.32621900658961345, -0.9452942186111613),
+    ]
+
+    # expected values for vertical segment ends points (X,Y,dx,dy)
+    v_expected = [
+        (0.0, 100.0, 0.999846910161925, 0.01749732092783369),
+        (1200.0, 121.0, 0.999846910161925, 0.01749732092783369),
+        (2799.99999384661, 127.00000006153391, 0.9999500037507449, -0.009999499931751348),
+        (4399.99999384661, 111.00000023075212, 0.999950003750745, -0.009999499931751352),
+        (5599.9999883553455, 117.00000018438367, 0.999800059982751, 0.019996001062400855),
+        (6399.999988355345, 133.0000000745584, 0.999800059982751, 0.019996001062400855),
+        (8399.99998428796, 133.00000001862446, 0.999800059981633, -0.019996001118301257),
+        (9399.99998428796, 113.00000009997211, 0.999800059981633, -0.019996001118301257),
+        (10199.99998062693, 103.00000015081635, 0.9999875002340269, -0.004999937569813611),
+        (12799.99998062693, 89.99999997234107, 0.9999875002340269, -0.004999937569813611),
+    ]
+
+    file = ifcopenshell.file(schema="IFC4X3_ADD2")
+    file.header.file_description.description = ["ViewDefinition [Alignment-basedView]"]
+
+    project = file.createIfcProject(GlobalId=ifcopenshell.guid.new(), Name="FHWA Alignment")
+    # ifcopenshell.api.unit.assign_unit(file)
+    # length = ifcopenshell.api.unit.add_si_unit(file,unit_type="LENGTHUNIT")
+    length = ifcopenshell.api.unit.add_conversion_based_unit(file, name="foot")
+    ifcopenshell.api.unit.assign_unit(file, units=[length])
+    geometric_representation_context = ifcopenshell.api.context.add_context(file, context_type="Model")
+    axis_model_representation_subcontext = ifcopenshell.api.context.add_context(
+        file,
+        context_type="Model",
+        context_identifier="Axis",
+        target_view="MODEL_VIEW",
+        parent=geometric_representation_context,
+    )
+
+    site = file.createIfcSite(GlobalId=ifcopenshell.guid.new(), Name="Site")
+    ifcopenshell.api.aggregate.assign_object(file, relating_object=project, products=[site])
+
+    alignment = ifcopenshell.api.alignment.create(
+        file, "E-Line", include_vertical=True, start_station=10000.0, include_geometry=False
+    )
+
+    # alignment is referenced into spatial structure of site per CT 4.1.5.1
+    ifcopenshell.api.spatial.reference_structure(file, products=[alignment], relating_structure=site)
+
+    layout = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    segment1 = file.createIfcAlignmentHorizontalSegment(
+        StartPoint=file.createIfcCartesianPoint(Coordinates=((500.0, 2500.0))),
+        StartDirection=math.radians(327.0613),
+        StartRadiusOfCurvature=0.0,
+        EndRadiusOfCurvature=0.0,
+        SegmentLength=1956.785654,
+        PredefinedType="LINE",
+    )
+
+    end = ifcopenshell.api.alignment.create_layout_segment(file, layout, segment1)
+
+    unit_scale = ifcopenshell.util.unit.calculate_unit_scale(file)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    dir = math.atan2(dy, dx)
+    assert (
+        pytest.approx(h_expected[1][0]) == x
+        and pytest.approx(h_expected[1][1]) == y
+        and pytest.approx(h_expected[1][2]) == dx
+        and pytest.approx(h_expected[1][3]) == dy
+    )
+    segment2 = file.createIfcAlignmentHorizontalSegment(
+        StartPoint=file.createIfcCartesianPoint((x, y)),
+        StartDirection=dir,
+        StartRadiusOfCurvature=1000.0,
+        EndRadiusOfCurvature=1000.0,
+        SegmentLength=1919.222667,
+        PredefinedType="CIRCULARARC",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, layout, segment2)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    dir = math.atan2(dy, dx)
+    assert (
+        pytest.approx(h_expected[2][0]) == x
+        and pytest.approx(h_expected[2][1]) == y
+        and pytest.approx(h_expected[2][2]) == dx
+        and pytest.approx(h_expected[2][3]) == dy
+    )
+    segment3 = file.createIfcAlignmentHorizontalSegment(
+        StartPoint=file.createIfcCartesianPoint((x, y)),
+        StartDirection=dir,
+        StartRadiusOfCurvature=0.0,
+        EndRadiusOfCurvature=0.0,
+        SegmentLength=1886.905454,
+        PredefinedType="LINE",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, layout, segment3)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    dir = math.atan2(dy, dx)
+    assert (
+        pytest.approx(h_expected[3][0]) == x
+        and pytest.approx(h_expected[3][1]) == y
+        and pytest.approx(h_expected[3][2]) == dx
+        and pytest.approx(h_expected[3][3]) == dy
+    )
+    segment4 = file.createIfcAlignmentHorizontalSegment(
+        StartPoint=file.createIfcCartesianPoint((x, y)),
+        StartDirection=dir,
+        StartRadiusOfCurvature=-1250.0,
+        EndRadiusOfCurvature=-1250.0,
+        SegmentLength=1848.115835,
+        PredefinedType="CIRCULARARC",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, layout, segment4)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    dir = math.atan2(dy, dx)
+    assert (
+        pytest.approx(h_expected[4][0]) == x
+        and pytest.approx(h_expected[4][1]) == y
+        and pytest.approx(h_expected[4][2]) == dx
+        and pytest.approx(h_expected[4][3]) == dy
+    )
+    segment5 = file.createIfcAlignmentHorizontalSegment(
+        StartPoint=file.createIfcCartesianPoint((x, y)),
+        StartDirection=dir,
+        StartRadiusOfCurvature=0.0,
+        EndRadiusOfCurvature=0.0,
+        SegmentLength=1564.635765,
+        PredefinedType="LINE",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, layout, segment5)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    dir = math.atan2(dy, dx)
+    assert (
+        pytest.approx(h_expected[5][0]) == x
+        and pytest.approx(h_expected[5][1]) == y
+        and pytest.approx(h_expected[5][2]) == dx
+        and pytest.approx(h_expected[5][3]) == dy
+    )
+    segment6 = file.createIfcAlignmentHorizontalSegment(
+        StartPoint=file.createIfcCartesianPoint((x, y)),
+        StartDirection=dir,
+        StartRadiusOfCurvature=-950.0,
+        EndRadiusOfCurvature=-950.0,
+        SegmentLength=1049.119737,
+        PredefinedType="CIRCULARARC",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, layout, segment6)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    dir = math.atan2(dy, dx)
+    assert (
+        pytest.approx(h_expected[6][0]) == x
+        and pytest.approx(h_expected[6][1]) == y
+        and pytest.approx(h_expected[6][2]) == dx
+        and pytest.approx(h_expected[6][3]) == dy
+    )
+    segment7 = file.createIfcAlignmentHorizontalSegment(
+        StartPoint=file.createIfcCartesianPoint((x, y)),
+        StartDirection=dir,
+        StartRadiusOfCurvature=0.0,
+        EndRadiusOfCurvature=0.0,
+        SegmentLength=2112.285084,
+        PredefinedType="LINE",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, layout, segment7)
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(h_expected[7][0]) == x
+        and pytest.approx(h_expected[7][1]) == y
+        and pytest.approx(h_expected[7][2]) == dx
+        and pytest.approx(h_expected[7][3]) == dy
+    )
+
+    vlayout = ifcopenshell.api.alignment.get_vertical_layout(alignment)
+
+    segment1 = file.createIfcAlignmentVerticalSegment(
+        StartDistAlong=0.0,
+        HorizontalLength=1200.0,
+        StartHeight=100.0,
+        StartGradient=1.75 / 100.0,
+        EndGradient=1.75 / 100.0,
+        PredefinedType="CONSTANTGRADIENT",
+    )
+
+    end = ifcopenshell.api.alignment.create_layout_segment(file, vlayout, segment1)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(v_expected[1][0]) == x
+        and pytest.approx(v_expected[1][1]) == y
+        and pytest.approx(v_expected[1][2]) == dx
+        and pytest.approx(v_expected[1][3]) == dy
+    )
+    segment2 = file.createIfcAlignmentVerticalSegment(
+        StartDistAlong=x,
+        HorizontalLength=1600.0,
+        StartHeight=y,
+        StartGradient=dy / dx,
+        EndGradient=-1.0 / 100.0,
+        PredefinedType="PARABOLICARC",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, vlayout, segment2)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(v_expected[2][0]) == x
+        and pytest.approx(v_expected[2][1]) == y
+        and pytest.approx(v_expected[2][2]) == dx
+        and pytest.approx(v_expected[2][3]) == dy
+    )
+    segment3 = file.createIfcAlignmentVerticalSegment(
+        StartDistAlong=x,
+        HorizontalLength=1600.0,
+        StartHeight=y,
+        StartGradient=dy / dx,
+        EndGradient=-1.0 / 100.0,
+        PredefinedType="CONSTANTGRADIENT",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, vlayout, segment3)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(v_expected[3][0]) == x
+        and pytest.approx(v_expected[3][1]) == y
+        and pytest.approx(v_expected[3][2]) == dx
+        and pytest.approx(v_expected[3][3]) == dy
+    )
+    segment4 = file.createIfcAlignmentVerticalSegment(
+        StartDistAlong=x,
+        HorizontalLength=1200.0,
+        StartHeight=y,
+        StartGradient=dy / dx,
+        EndGradient=2.0 / 100.0,
+        PredefinedType="PARABOLICARC",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, vlayout, segment4)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(v_expected[4][0]) == x
+        and pytest.approx(v_expected[4][1]) == y
+        and pytest.approx(v_expected[4][2]) == dx
+        and pytest.approx(v_expected[4][3]) == dy
+    )
+    segment5 = file.createIfcAlignmentVerticalSegment(
+        StartDistAlong=x,
+        HorizontalLength=800.0,
+        StartHeight=y,
+        StartGradient=dy / dx,
+        EndGradient=2.0 / 100.0,
+        PredefinedType="CONSTANTGRADIENT",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, vlayout, segment5)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(v_expected[5][0]) == x
+        and pytest.approx(v_expected[5][1]) == y
+        and pytest.approx(v_expected[5][2]) == dx
+        and pytest.approx(v_expected[5][3]) == dy
+    )
+    segment6 = file.createIfcAlignmentVerticalSegment(
+        StartDistAlong=x,
+        HorizontalLength=2000.0,
+        StartHeight=y,
+        StartGradient=dy / dx,
+        EndGradient=-2.0 / 100.0,
+        PredefinedType="PARABOLICARC",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, vlayout, segment6)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(v_expected[6][0]) == x
+        and pytest.approx(v_expected[6][1]) == y
+        and pytest.approx(v_expected[6][2]) == dx
+        and pytest.approx(v_expected[6][3]) == dy
+    )
+    segment7 = file.createIfcAlignmentVerticalSegment(
+        StartDistAlong=x,
+        HorizontalLength=1000.0,
+        StartHeight=y,
+        StartGradient=dy / dx,
+        EndGradient=-2.0 / 100.0,
+        PredefinedType="CONSTANTGRADIENT",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, vlayout, segment7)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(v_expected[7][0]) == x
+        and pytest.approx(v_expected[7][1]) == y
+        and pytest.approx(v_expected[7][2]) == dx
+        and pytest.approx(v_expected[7][3]) == dy
+    )
+    segment8 = file.createIfcAlignmentVerticalSegment(
+        StartDistAlong=x,
+        HorizontalLength=800.0,
+        StartHeight=y,
+        StartGradient=dy / dx,
+        EndGradient=-0.5 / 100.0,
+        PredefinedType="PARABOLICARC",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, vlayout, segment8)
+
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(v_expected[8][0]) == x
+        and pytest.approx(v_expected[8][1]) == y
+        and pytest.approx(v_expected[8][2]) == dx
+        and pytest.approx(v_expected[8][3]) == dy
+    )
+    segment9 = file.createIfcAlignmentVerticalSegment(
+        StartDistAlong=x,
+        HorizontalLength=2600.0,
+        StartHeight=y,
+        StartGradient=dy / dx,
+        EndGradient=-0.5 / 100.0,
+        PredefinedType="CONSTANTGRADIENT",
+    )
+    end = ifcopenshell.api.alignment.create_layout_segment(file, vlayout, segment9)
+    x = float(end[0, 3]) / unit_scale
+    y = float(end[1, 3]) / unit_scale
+    dx = float(end[0, 0])
+    dy = float(end[1, 0])
+    assert (
+        pytest.approx(v_expected[9][0]) == x
+        and pytest.approx(v_expected[9][1]) == y
+        and pytest.approx(v_expected[9][2]) == dx
+        and pytest.approx(v_expected[9][3]) == dy
+    )
+
+    ifcopenshell.api.alignment.create_representation(file, alignment)
+
+    curve = ifcopenshell.api.alignment.get_basis_curve(alignment)
+    assert curve.is_a("IfcCompositeCurve")
+    for s in curve.Segments:
+        assert len(s.UsingCurves) == 1
+
+    curve = ifcopenshell.api.alignment.get_layout_curve(layout)
+    assert curve.is_a("IfcCompositeCurve")
+    for index, s in enumerate(curve.Segments):
+        assert len(s.UsingCurves) == 1
+        assert s.Placement.Location.Coordinates[0] == pytest.approx(h_expected[index][0])
+        assert s.Placement.Location.Coordinates[1] == pytest.approx(h_expected[index][1])
+        assert s.Placement.RefDirection.DirectionRatios[0] == pytest.approx(h_expected[index][2])
+        assert s.Placement.RefDirection.DirectionRatios[1] == pytest.approx(h_expected[index][3])
+
+    curve = ifcopenshell.api.alignment.get_layout_curve(vlayout)
+    assert curve.is_a("IfcGradientCurve")
+    for index, s in enumerate(curve.Segments):
+        assert len(s.UsingCurves) == 1
+        assert s.Placement.Location.Coordinates[0] == pytest.approx(v_expected[index][0])
+        assert s.Placement.Location.Coordinates[1] == pytest.approx(v_expected[index][1])
+        assert s.Placement.RefDirection.DirectionRatios[0] == pytest.approx(v_expected[index][2])
+        assert s.Placement.RefDirection.DirectionRatios[1] == pytest.approx(v_expected[index][3])
+
+
+test_create_representation()

src/ifcopenshell-python/test/api/alignment/test_vertical_layout_by_pi_method.py

@@ -65,7 +65,7 @@ def test_vertical_layout_by_pi_method():
     assert len(layout_nest.RelatedObjects) == 2
 
     referent_nest = ifcopenshell.api.alignment.get_referent_nest(file, alignment)
-    assert len(referent_nest.RelatedObjects) == 6
+    assert len(referent_nest.RelatedObjects) == 1
 
     segment_nest = ifcopenshell.api.alignment.get_alignment_segment_nest(vlayout)
     assert len(segment_nest.RelatedObjects) == 3