commit

StartingPoint/lib/realtime/realtime.py

@@ -0,0 +1,35 @@
+import time
+import abc
+
+# Use time_scale different from 1.0 for scaled real-time execution:
+#   time_scale > 1 speeds up simulation
+#   0 < time_scale < 1 slows down simulation
+class WallClock:
+    def __init__(self, time_scale=1.0):
+        self.time_scale = time_scale
+        self.purposefully_behind = 0
+
+    def record_start_time(self):
+        self.start_time = time.perf_counter_ns()
+
+    def time_since_start(self):
+        time_since_start = time.perf_counter_ns() - self.start_time
+        return (time_since_start * self.time_scale) + self.purposefully_behind
+
+    def sleep_duration_until(self, earliest_event_time):
+        now = self.time_since_start()
+        sleep_duration = int((earliest_event_time - now) / self.time_scale)
+        # sleep_duration can be negative, if the next event is in the past
+        # This indicates that our computer is too slow, and cannot keep up with the simulation.
+        # Like all things fate-related, we embrace this slowness, rather than fighting it:
+        # We will temporarily run the simulation at a slower pace, which has the benefit of the simulation remaining responsive to user input.
+        self.purposefully_behind   = min(sleep_duration, 0) # see above comment
+        actual_sleep_duration      = max(sleep_duration, 0) # can never sleep less than 0
+        return actual_sleep_duration
+
+class AbstractRealTimeSimulation:
+    # Generate input event at the current wall clock time (with time-scale applied, of course)
+    # This method should be used for interactive simulation, for generating events that were caused by e.g., button clicks, key presses, ...
+    @abc.abstractmethod
+    def add_input_now(self, sc, event, value=None):
+        pass