def thrust_direction(axis: int, force: float, pr: Projectile):
if pr.time < 1.2:
return spherical_to_planar_coord(axis, force, math.pi / 4, 0)
if (pr.position.alt > 100000
or pr.velocities[Z_INDEX] > 4000) and pr.pitch > 0.2:
spherical_to_planar_coord(axis, force, pr.pitch - 0.15, pr.yaw)
if pr.pitch < 0.15:
spherical_to_planar_coord(axis, force, pr.pitch + 0.17, pr.yaw)
return follow_path(axis, force, pr)
def follow_path(axis: int, force: float, pr: Projectile) -> float:
return spherical_to_planar_coord(axis, force, pr.pitch, pr.yaw)
def update_velocities(self, old_lat: np.float128, old_lon: np.float128,
radius: float, distance_m: float) -> None:
"""
Update velocities: take a look at the old position, current position, how much it has changed and calculate the
speed based on that. Effectively moves the local tangent plane. z-speed is not modified as it's unaffected by
moving of the tangent plane.
:param old_lat: previous latitude
:param old_lon: previous longitude
:param radius: earth radius + altitude
:param distance_m: distance travelled (could be calculated inside the function, but no need atm)
:return: nothing; updates the projectile's state
"""
old_vy = self.velocities[Y_INDEX]
self.velocities[Y_INDEX] = (radius * (self.position.lat - old_lat)
) / self.dt # usual case for correcting Vy
# our first and largest problem is detecting whether we've crossed the pole. I don't know a nice way for this,
# so we use the ugly way: statistics and prayers.
# ideally, change_radio should be 0 (meaning Vy won't be corrected)
if old_vy != 0:
change_ratio = fabs(self.velocities[Y_INDEX] / old_vy - 1)
else:
change_ratio = fabs(self.velocities[Y_INDEX])
if change_ratio > self.vy_corrective_change_threshold: # oops, we've modified Vy too much
actual_distance = haversine(self.position,
Position(old_lat, old_lon, 0), radius)
if self.crossed_the_pole: # if we've crossed the pole recently, we definitely don't want to do it again
print(
f"Warning! V_y has too extreme oscillations: {change_ratio}"
)
elif actual_distance < self.distance_stats.mean and self.distance_stats.is_outlier(
actual_distance):
# if we've travelled significantly less than usual (i.e. in y direction), assume we've crossed the pole
# conceptually simple, practically not-really-definable, but surprisingly effective
print(f"Crossing the pole: change ratio is {change_ratio}f")
# so now that we've crossed the pole, we want to reverse Vx and Vy and change longitude so we continue
# flying 'straight'. We're basically throwing away this iteration and using the data from the previous.
self.crossed_the_pole = True # this will prevent crossing the pole again if we're still too close
self.position.lon = divmod((old_lon + pi),
(2 * pi))[1] - 2 * pi
self.yaw = self.yaw - pi % (sgn(self.yaw - pi) * 2 * pi)
self.velocities[X_INDEX] = spherical_to_planar_coord(
X_INDEX, self.total_velocity, self.pitch, self.yaw)
self.velocities[Y_INDEX] = spherical_to_planar_coord(
Y_INDEX, self.total_velocity, self.pitch, self.yaw)
return # don't update X velocity!
elif actual_distance < self.distance_stats.mean:
# Vy changed a lot, but we're far away from the pole; can happen in e.g. polar circle even if we're not
# flying over the pole itself.
print(
f"Warning: Vy has extreme correction, but we're far from poles: {change_ratio}"
)
if self.crossed_the_pole:
self.crossed_the_pole = False
self.velocities[
Y_INDEX] = old_vy # don't correct speed if we've just skipped the pole
return
self.distance_stats.update(
distance_m) # we need to keep track of what's the 'usual' movement
# from now on, we take care of updating Vx
lon_radius = radius * cos(self.position.lat)
if lon_radius == 0:
# not much we can do if we're exactly at the pole, just use the last good number, it'll be close enough
lon_radius = radius * cos(old_lat)
if fabs(self.position.lon -
old_lon) < pi: # usual case for correcting Vx
self.velocities[X_INDEX] = (
lon_radius * (self.position.lon - old_lon)) / self.dt
else: # crossing the antimeridian: we haven't really moved for 2pi, so substract (or add) that
self.velocities[X_INDEX] = (
lon_radius *
(self.position.lon - old_lon +
2 * pi * sgn(old_lon - self.position.lon))) / self.dt