Migrate pressure to a typed unit.

game/utils.py

@@ -16,6 +16,9 @@ KPH_TO_KNOTS = 1 / KNOTS_TO_KPH
 MS_TO_KPH = 3.6
 KPH_TO_MS = 1 / MS_TO_KPH
 
+INHG_TO_HPA = 33.86389
+INHG_TR_MMHG = 25.400002776728
+
 
 def heading_sum(h: int, a: int) -> int:
     h += a
@@ -181,6 +184,27 @@ def mach(value: float, altitude: Distance) -> Speed:
 SPEED_OF_SOUND_AT_SEA_LEVEL = knots(661.5)
 
 
+@dataclass(frozen=True, order=True)
+class Pressure:
+    pressure_in_inches_hg: float
+
+    @property
+    def inches_hg(self) -> float:
+        return self.pressure_in_inches_hg
+
+    @property
+    def mm_hg(self) -> float:
+        return self.pressure_in_inches_hg * INHG_TR_MMHG
+
+    @property
+    def hecto_pascals(self) -> float:
+        return self.pressure_in_inches_hg * INHG_TO_HPA
+
+
+def inches_hg(value: float) -> Pressure:
+    return Pressure(value)
+
+
 def pairwise(iterable: Iterable[Any]) -> Iterable[tuple[Any, Any]]:
     """
     itertools recipe

game/weather.py

@@ -5,13 +5,14 @@ import logging
 import random
 from dataclasses import dataclass, field
 from enum import Enum
-from typing import Optional, TYPE_CHECKING
+from typing import Optional, TYPE_CHECKING, Any
 
 from dcs.cloud_presets import Clouds as PydcsClouds
 from dcs.weather import CloudPreset, Weather as PydcsWeather, Wind
 
+from game.savecompat import has_save_compat_for
 from game.settings import Settings
-from game.utils import Distance, meters, interpolate
+from game.utils import Distance, meters, interpolate, Pressure, inches_hg
 
 if TYPE_CHECKING:
     from game.theater import ConflictTheater
@@ -27,11 +28,19 @@ class TimeOfDay(Enum):
 
 @dataclass(frozen=True)
 class AtmosphericConditions:
-    #: Pressure at sea level in inches of mercury.
-    qnh_inches_mercury: float
+    #: Pressure at sea level.
+    qnh: Pressure
+
     #: Temperature at sea level in Celcius.
     temperature_celsius: float
 
+    @has_save_compat_for(5)
+    def __setstate__(self, state: dict[str, Any]) -> None:
+        if "qnh" not in state:
+            state["qnh"] = inches_hg(state["qnh_inches_mercury"])
+            del state["qnh_inches_mercury"]
+        self.__dict__.update(state)
+
 
 @dataclass(frozen=True)
 class WindConditions:
@@ -111,7 +120,7 @@ class Weather:
         pressure += self.pressure_adjustment
         temperature += self.temperature_adjustment
         conditions = AtmosphericConditions(
-            qnh_inches_mercury=self.random_pressure(pressure),
+            qnh=self.random_pressure(pressure),
             temperature_celsius=self.random_temperature(temperature),
         )
         return conditions
@@ -162,14 +171,14 @@ class Weather:
         return random.randint(100, 400)
 
     @staticmethod
-    def random_pressure(average_pressure: float) -> float:
+    def random_pressure(average_pressure: float) -> Pressure:
         # "Safe" constants based roughly on ME and viper altimeter.
         # Units are inches of mercury.
         SAFE_MIN = 28.4
         SAFE_MAX = 30.9
         # Use normalvariate to get normal distribution, more realistic than uniform
         pressure = random.normalvariate(average_pressure, 0.1)
-        return max(SAFE_MIN, min(SAFE_MAX, pressure))
+        return inches_hg(max(SAFE_MIN, min(SAFE_MAX, pressure)))
 
     @staticmethod
     def random_temperature(average_temperature: float) -> float: