Implements business 2 geometry mapping for Viennese Bend for horizontal and cant layouts

2026-08-11 02:02:22 +00:00 · 2025-08-09 14:03:19 -07:00
parent 9d2a79803a
commit 762f4ff975
6 changed files with 1023 additions and 23 deletions
@@ -0,0 +1,77 @@
+# 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
+import ifcopenshell.api.geometry
+from ifcopenshell import entity_instance
+
+import math
+from collections.abc import Sequence
+
+
+def _get_cant_segment(horizontal_segment: entity_instance) -> entity_instance:
+    """
+    Returns the IfcAlignmentSegment from the cant layout that corresponds to horizontal_segment.
+    Returns None if the cant segment cannot be found
+    """
+
+    expected_type = "IfcAlignmentSegment"
+    if not horizontal_segment.is_a(expected_type):
+        raise TypeError(f"Expected {expected_type} but got {horizontal_segment.is_a()}")
+    
+    if not horizontal_segment.DesignParameters.is_a("IfcAlignmentHorizontalSegment"):
+        raise TypeError(f"Expect DesignParameter to be IfcAlignmentHorizontal but got {horizontal_segment.DesignParameters.is_a()}")
+    
+    # get the index of horizontal_segment in the horizontal_layout
+    horizontal_layout = horizontal_segment.Nests[0].RelatingObject
+    index = 0
+    for segment in horizontal_layout.IsNestedBy[0].RelatedObjects:
+        if segment == horizontal_segment:
+            break
+        else:
+            index += 1
+
+    cant_segment = None
+
+    # first check CT 4.1.4.4.1.1 Alignment Layout - Horizontal, Vertical and Cant
+    nests_layouts = horizontal_layout.Nests[0]
+    for layout in nests_layouts.RelatedObjects:
+        if layout.is_a("IfcAlignmentCant"):
+            cant_segment = layout.IsNestedBy[0].RelatedObjects[index]
+            break
+
+    # if a cant_segment wasn't found, check CT 4.1.4.4.1.2 Alignment Layout - Reusing Horizontal Layout
+    # Note that nothing forbids multiple child alignments to have cant layouts. However, this would not make
+    # sense for Viennese Bend because the Viennese Bend cant segment influences the geometry of the horizontal
+    # Viennese Bend transition curve segment. The horizontal geometry would not be unique if there are
+    # multiple child alignments with cant layouts.
+    # For this reason, use the first cant layout found
+    if cant_segment == None:
+        alignment = ifcopenshell.api.alignment.get_alignment(horizontal_layout)
+        for child_alignment in alignment.IsDecomposedBy[0].RelatedObjects:
+            for layout in child_alignment.Nests[0].RelatedObjects:
+                if layout.is_a("IfcAlignmentCant"):
+                    cant_segment = layout.IsNestedBy[0].RelatedObjects[index]
+                    break
+            if cant_segment:
+                break
+        
+
+    return cant_segment
+