fix(face): Add core geometry properties to assist with DOE-2 translation

ladybug_geometry/geometry3d/face.py

@@ -466,9 +466,14 @@ def azimuth(self):
 
     @property
     def altitude(self):
-        """Get the altitude of the Face3D (between Pi/2 and -Pi/2)."""
+        """Get the altitude of the Face3D. Between Pi/2 (up) and -Pi/2 (down)."""
         return self.plane.altitude
 
+    @property
+    def tilt(self):
+        """Get the tilt of the Face3D. Between 0 (up) and Pi (down)."""
+        return self.plane.tilt
+
     @property
     def is_clockwise(self):
         """Boolean for whether the face vertices and boundary are in clockwise order.

ladybug_geometry/geometry3d/plane.py

@@ -139,7 +139,10 @@ def y(self):
 
     @property
     def azimuth(self):
-        """Get the azimuth of the plane (between 0 and 2 * Pi).
+        """Get the azimuth of the plane.
+        
+        This is always between 0, indicating the positive Y-axis, and moving clockwise
+        up to 2 * Pi, which indicates a return to the positive Y-axis.
 
         This will be zero if the plane is perfectly horizontal.
         """
@@ -153,11 +156,16 @@ def azimuth(self):
 
     @property
     def altitude(self):
-        """Get the altitude of the plane (between Pi/2 and -Pi/2)."""
+        """Get the altitude of the plane. Between Pi/2 (up) and -Pi/2 (down)."""
         if self._altitude is None:
             self._altitude = self.n.angle(Vector3D(0, 0, -1)) - math.pi / 2
         return self._altitude
 
+    @property
+    def tilt(self):
+        """Get the tilt of the plane. Between 0 (up) and Pi (down)."""
+        return abs(self.altitude - (math.pi / 2))
+
     @property
     def min(self):
         """Returns the Plane origin."""