Add: ScriptCargo::GetWeight to get cargo weights

src/script/api/ai_changelog.hpp

@@ -17,6 +17,8 @@
  *
  * This version is not yet released. The following changes are not set in stone yet.
  *
+ * API additions:
+ * \li AICargo::GetWeight
  * \li AIIndustryType::ResolveNewGRFID
  * \li AIObjectType::ResolveNewGRFID
  *

src/script/api/game_changelog.hpp

@@ -17,6 +17,8 @@
  *
  * This version is not yet released. The following changes are not set in stone yet.
  *
+ * API additions:
+ * \li GSCargo::GetWeight
  * \li GSIndustryType::ResolveNewGRFID
  * \li GSObjectType::ResolveNewGRFID
  *

src/script/api/script_cargo.cpp

@@ -81,3 +81,9 @@
 	if (!ScriptCargo::IsValidCargo(cargo_type)) return INVALID_DISTRIBUTION_TYPE;
 	return (ScriptCargo::DistributionType)_settings_game.linkgraph.GetDistributionType(cargo_type);
 }
+
+/* static */ int64 ScriptCargo::GetWeight(CargoID cargo_type, uint32 amount)
+{
+	if (!IsValidCargo(cargo_type)) return -1;
+	return ::CargoSpec::Get(cargo_type)->weight * static_cast<int64>(amount) / 16;
+}

src/script/api/script_cargo.hpp

@@ -153,6 +153,16 @@ public:
 	 * @return The cargo distribution type for the given cargo.
 	 */
 	static DistributionType GetDistributionType(CargoID cargo_type);
+
+	/**
+	 * Get the weight in tonnes for the given amount of
+	 *   cargo for the specified type.
+	 * @param cargo_type The cargo to check on.
+	 * @param amount The quantity of cargo.
+	 * @pre ScriptCargo::IsValidCargo(cargo_type).
+	 * @return The weight in tonnes for that quantity of cargo.
+	 */
+	static int64 GetWeight(CargoID cargo_type, uint32 amount);
 };
 
 #endif /* SCRIPT_CARGO_HPP */