def frame(self):
while self.dataReady("position"):
self.position = Vector(*self.recv("position"))
if self.lastValidPos is None:
self.lastValidPos = self.position.copy()
while self.dataReady("inbox"):
msg = self.recv("inbox")
if msg == "ACK":
self.lastValidPos = self.position.copy()
elif msg == "INVALID":
diff = self.lastValidPos - self.position
diff.z = 0
self.send(diff.toTuple(), "movement")
