From 30d62899429d4022d8659fd1ebaf6a15d63828c5 Mon Sep 17 00:00:00 2001
From: Dion Moult <dion@thinkmoult.com>
Date: Mon, 6 Mar 2023 17:47:22 +1100
Subject: [PATCH] New utility to quickly get the grid north or true north
 angles.

---
 .../ifcopenshell/util/geolocation.py          | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/ifcopenshell-python/ifcopenshell/util/geolocation.py b/src/ifcopenshell-python/ifcopenshell/util/geolocation.py
index 141b2e8a06..2f739ad306 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/geolocation.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/geolocation.py
@@ -166,3 +166,24 @@ def yaxis2angle(x, y):
     elif angle > 180:
         angle -= 360
     return angle
+
+
+def get_grid_north(ifc_file):
+    try:
+        conversion = ifc_file.by_type("IfcMapConversion")[0]
+    except:
+        return 0
+    if not conversion.XAxisAbscissa or not conversion.XAxisOrdinate:
+        return 0
+    return xaxis2angle(conversion.XAxisAbscissa, conversion.XAxisOrdinate)
+
+
+def get_true_north(ifc_file):
+    try:
+        for context in ifc_file.by_type("IfcGeometricRepresentationContext", include_subtypes=False):
+            if not context.TrueNorth:
+                continue
+            return yaxis2angle(*context.TrueNorth.DirectionRatios[0:2])
+    except:
+        return 0
+    return 0