Lua API: rename SystemBody.volatileGas -> atmosDensity

- Rename misleading volatileGas field to atmospheric density (its real value)
- Add surfacePressure field

data/meta/SystemBody.lua

@@ -42,12 +42,15 @@
 --- The measure of metallicity of the body's crust:
 --- 0.0 = light (Al, SiO2, etc), 1.0 = heavy (Fe, heavy metals)
 ---@field metallicity number
---- The measure of volatile gas present in the atmosphere of the body:
---- 0.0 = no atmosphere, 1.0 = earth atmosphere density, 4.0+ ~= venus
----@field volatileGas number
+--- The atmospheric density at "surface level" of the body:
+--- 0.0 = no atmosphere, 1.225 = earth atmosphere density, 64 ~= venus
+---@field atmosDensity number
 --- The compositional value of any atmospheric gasses in the bodys atmosphere (if any):
 --- 0.0 = reducing (H2, NH3, etc), 1.0 = oxidising (CO2, O2, etc)
 ---@field atmosOxidizing number
+--- The pressure of the atmosphere at the body's mean "surface level":
+--- 1.0atm = earth
+---@field surfacePressure number
 --- The measure of volatile liquids present on the body:
 --- 0.0 = none, 1.0 = waterworld (earth = 70%)
 ---@field volatileLiquid number

data/modules/Scout/Scout.lua

@@ -330,7 +330,7 @@ local function calcSurfaceScanMission(sBody, difficulty, reward)
 
 	-- Calculate parameters which make approaching the body to scan it more difficult
 	local bodyDifficulty = (1 + sBody.gravity / EARTH_G)
-		* (1 + math.max(math.log(sBody.volatileGas), 0.0) * 0.5)
+		* (1 + math.max(math.log(sBody.atmosDensity), 0.0) * 0.5)
 		* (1 + sBody.eccentricity * 0.5)
 
 	local bodyReward = 1

src/lua/LuaSystemBody.cpp

@@ -483,10 +483,10 @@ static int l_sbody_attr_metallicity(lua_State *l)
 }
 
 /*
- * Attribute: volatileGas
+ * Attribute: atmosDensity
  *
- * Returns the measure of volatile gas present in the atmosphere of the body
- * 0.0 = no atmosphere, 1.0 = earth atmosphere density, 4.0+ ~= venus
+ * Returns the atmospheric density at "surface level" of the body
+ * 0.0 = no atmosphere, 1.225 = earth atmosphere density, 64+ ~= venus
  *
  * Availability:
  *
@@ -496,10 +496,10 @@ static int l_sbody_attr_metallicity(lua_State *l)
  *
  *   experimental
  */
-static int l_sbody_attr_volatileGas(lua_State *l)
+static int l_sbody_attr_atmosDensity(lua_State *l)
 {
 	SystemBody *sbody = LuaObject<SystemBody>::CheckFromLua(1);
-	lua_pushnumber(l, sbody->GetVolatileGas());
+	lua_pushnumber(l, sbody->GetAtmSurfaceDensity());
 	return 1;
 }
 
@@ -524,6 +524,26 @@ static int l_sbody_attr_atmosOxidizing(lua_State *l)
 	return 1;
 }
 
+/*
+ * Attribute: surfacePressure
+ *
+ * The pressure of the atmosphere at the surface of the body (atm).
+ *
+ * Availability:
+ *
+ *   2024
+ *
+ * Status:
+ *
+ *   experimental
+ */
+static int l_sbody_attr_surfacePressure(lua_State *l)
+{
+	SystemBody *sbody = LuaObject<SystemBody>::CheckFromLua(1);
+	lua_pushnumber(l, sbody->GetAtmSurfacePressure());
+	return 1;
+}
+
 /*
  * Attribute: volatileLiquid
  *
@@ -810,8 +830,9 @@ void LuaObject<SystemBody>::RegisterClass()
 		{ "axialTilt", l_sbody_attr_axial_tilt },
 		{ "averageTemp", l_sbody_attr_average_temp },
 		{ "metallicity", l_sbody_attr_metallicity },
-		{ "volatileGas", l_sbody_attr_volatileGas },
+		{ "atmosDensity", l_sbody_attr_atmosDensity },
 		{ "atmosOxidizing", l_sbody_attr_atmosOxidizing },
+		{ "surfacePressure", l_sbody_attr_surfacePressure },
 		{ "volatileLiquid", l_sbody_attr_volatileLiquid },
 		{ "volatileIces", l_sbody_attr_volatileIces },
 		{ "volcanicity", l_sbody_attr_volcanicity },