See #6404. See #1227. Create axis context if it does not exist for walls.

src/ifcopenshell-python/ifcopenshell/api/geometry/regenerate_wall_representation.py

@@ -73,6 +73,9 @@ def regenerate_wall_representation(
     0.0)). This is a logical, consistent, and useful placement coordinate
     (especially for apps that can pivot using this point).
 
+    All this functionality relies on the Plan/Axis/GRAPH_VIEW representation
+    context. It will be created if it does not exist.
+
     :param wall: The IfcWall for the representation,
         only Model/Body/MODEL_VIEW type of representations are currently supported.
     :param length: If the wall doesn't have an axis length, this is the default
@@ -94,6 +97,13 @@ class Regenerator:
         self.unit_scale = ifcopenshell.util.unit.calculate_unit_scale(file)
         self.is_angled = False
 
+        if not self.axis:
+            if not (plan := ifcopenshell.util.representation.get_context(file, "Plan")):
+                plan = ifcopenshell.api.context.add_context(file, context_type="Plan")
+            self.axis = ifcopenshell.api.context.add_context(
+                file, context_type="Plan", context_identifier="Axis", target_view="GRAPH_VIEW", parent=plan
+            )
+
     def regenerate(self, wall, length=1.0, height=1.0, angle=None):
         print("-" * 100)
         print(wall)

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

@@ -19,6 +19,7 @@
 import numpy as np
 import numpy.typing as npt
 import ifcopenshell
+import ifcopenshell.util.shape
 import ifcopenshell.util.placement
 from typing import Optional, Union, TypedDict, Literal, Generator, Sequence
 
@@ -488,4 +489,13 @@ def get_reference_line(wall: ifcopenshell.entity_instance, fallback_length: floa
             if points[0][0] < points[1][0]:  # An axis always goes in the +X direction
                 return [np.array(points[0]), np.array(points[1])]
             return [np.array(points[1]), np.array(points[0])]
+    elif extrusions := ifcopenshell.util.shape.get_base_extrusions(wall):
+        for item in extrusions:
+            if item.is_a("IfcPolyline"):
+                x = [p[0][0] for p in item.Points]
+            elif item.is_a("IfcIndexedPolyCurve"):
+                x = [p[0] for p in item.Points.CoordList]
+            else:
+                continue
+            return [np.array((min(x), 0.0)), np.array((max(x), 0.0))]
     return [np.array((0.0, 0.0)), np.array((fallback_length, 0.0))]