store ship base-price as a double in C++ (to match Lua)

fixes #3129

src/LuaShipDef.cpp

@@ -214,7 +214,7 @@ void LuaShipDef::Register()
 		pi_lua_settable(l, "capacity",          st.capacity);
 		pi_lua_settable(l, "hullMass",          st.hullMass);
 		pi_lua_settable(l, "fuelTankMass",      st.fuelTankMass);
-		pi_lua_settable(l, "basePrice",         double(st.baseprice)*0.01);
+		pi_lua_settable(l, "basePrice",         st.baseprice);
 		pi_lua_settable(l, "minCrew",           st.minCrew);
 		pi_lua_settable(l, "maxCrew",           st.maxCrew);
 		pi_lua_settable(l, "hyperdriveClass",   st.hyperdriveClass);

src/ShipType.cpp

@@ -41,7 +41,7 @@ static double GetEffectiveExhaustVelocity(double fuelTankMass, double thrusterFu
 static bool ShipIsUnbuyable(const ShipType::Id &id)
 {
 	const ShipType &t = ShipType::types[id];
-	return (t.baseprice == 0);
+	return is_zero_exact(t.baseprice);
 }
 
 static std::string s_currentShipFile;
@@ -115,8 +115,7 @@ int _define_ship(lua_State *L, ShipType::Tag tag, std::vector<ShipType::Id> *lis
 			Output("Warning: Both thruster_fuel_use and effective_exhaust_velocity defined for %s, using effective_exhaust_velocity.\n", s.modelName.c_str());
 	}
 
-	s.baseprice = t.Get("price", 0);
-	s.baseprice *= 100; // in hundredths of credits
+	s.baseprice = t.Get("price", 0.0);
 
 	s.minCrew = t.Get("min_crew", 1);
 	s.maxCrew = t.Get("max_crew", 1);

src/ShipType.h

@@ -59,7 +59,11 @@ struct ShipType {
 	int hullMass;
 	float effectiveExhaustVelocity; // velocity at which the propellant escapes the engines
 	int fuelTankMass; //full fuel tank mass, on top of hullMass
-	int baseprice;
+
+	// storing money as a double is weird, but the value is a double on the Lua side anyway,
+	// so we don't lose anything by storing it as a double here too
+	double baseprice;
+
 	int hyperdriveClass;
 	vector3d cameraOffset;
 	int minCrew, maxCrew; // XXX really only for Lua, but needs to be declared in the ship def