Fixed multiple simulation handling in external parameters.

Author: Eric-Vin

src/scenic/core/external_params.py

@@ -270,6 +270,7 @@ def __init__(self, params, globalParams):
 
         self._lastSample = None
         self._lastDynamicSample = None
+        self._lastSimulation = None
         self._lastTime = -1
 
     def nextSample(self, feedback):
@@ -285,6 +286,10 @@ def nextDynamicSample(self):
 
         assert veneer.currentSimulation is not None
 
+        if self._lastSimulation is not veneer.currentSimulation:
+            self._lastSimulation = veneer.currentSimulation
+            self._lastTime = -1
+
         if veneer.currentSimulation.currentTime > self._lastTime:
             feedback = veneer.currentSimulation
             self._lastDynamicSample = self.cachedSample.getDynamicSample(feedback)