util.py 文件源码

def current(self, deltat=None):
        """Return current wind speed and direction as a tuple
        speed is in m/s, direction in degrees."""
        if deltat is None:
            tnow = time.time()
            deltat = tnow - self.tlast
            self.tlast = tnow

        # update turbulance random walk
        w_delta = math.sqrt(deltat) * (1.0 - random.gauss(1.0, self.turbulance))
        w_delta -= (self.turbulance_mul - 1.0) * (deltat / self.turbulance_time_constant)
        self.turbulance_mul += w_delta
        speed = self.speed * math.fabs(self.turbulance_mul)
        return (speed, self.direction)

    # Calculate drag.