fix: enable scenario termination from closing display

src/scenic/core/simulators.py

@@ -328,6 +328,7 @@
         continueAfterDivergence=False,
         verbosity=0,
     ):
+        self.screen = None
         self.result = None
         self.scene = scene
         self.objects = []
@@ -430,6 +431,13 @@
                 terminationReason = newReason
                 terminationType = TerminationType.terminatedByMonitor
 
+            # Check if users manually closed out display for simulator
+            if "Dead" in str(self.screen):
+                return (
+                    TerminationType.terminatedByUser,
+                    "user manually terminated simulation",
+                )
+
             # "Always" and scenario-level requirements have been checked;
             # now safe to terminate if the top-level scenario has finished,
             # a monitor requested termination, or we've hit the timeout
@@ -866,6 +874,9 @@
     #: A :term:`dynamic behavior` used :keyword:`terminate simulation` to end the simulation.
     terminatedByBehavior = "a behavior terminated the simulation"
 
+    #: A user manually intervenes and closes display window
+    terminatedByUser = "manually terminated by user"
+
 
 class SimulationResult:
     """Result of running a simulation.

src/scenic/simulators/newtonian/simulator.py

@@ -70,6 +70,7 @@
     def __init__(self, scene, network, render, timestep, **kwargs):
         self.render = render
         self.network = network
+        self.screen = None
 
         if timestep is None:
             timestep = 0.1
@@ -186,6 +187,11 @@
             obj.heading += obj.angularSpeed * self.timestep
 
         if self.render:
+            # Handle closing out pygame screen
+            for event in pygame.event.get():
+                if event.type == pygame.QUIT:
+                    self.destroy()
+                    return
             self.draw_objects()
             pygame.event.pump()