fix: adding offset to fault

offsets can be used to shift the location of the faulted surface
discontinuity

Author: lachlangrose

LoopStructural/modelling/features/fault/_fault_segment.py

@@ -47,6 +47,7 @@ def __init__(
         self.builder = None
         self.splay = {}
         self.abut = {}
+        self.fault_offset = 0.0
 
     @property
     def faultfunction(self):
@@ -109,6 +110,9 @@ def fault_centre(self):
     def displacementfeature(self):
         return FaultDisplacementFeature(self, self.faultfunction, name=self.name, model=self.model)
 
+    def set_fault_offset(self, offset: float):
+        self.fault_offset = offset
+
     def set_model(self, model):
         """
         Link a geological model to the feature
@@ -263,7 +267,7 @@ def evaluate_displacement(self, points):
         gx_mask[mask] = gx[mask] > 0
         d[gx_mask] = 1.0
         if self.faultfunction is not None:
-            d[mask] = self.faultfunction(gx[mask], gy[mask], gz[mask])
+            d[mask] = self.faultfunction(gx[mask] + self.fault_offset, gy[mask], gz[mask])
         return d * self.displacement
 
     def apply_to_points(self, points, reverse=False):