3 files changed, 66 insertions, 17 deletions

diff --git a/src/articulated_vehicles.cpp b/src/articulated_vehicles.cpp
index c2ca4c7ec..c4947bc3b 100644
--- a/src/articulated_vehicles.cpp
+++ b/src/articulated_vehicles.cpp
@@ -34,6 +34,42 @@ uint CountArticulatedParts(EngineID engine_type, bool purchase_window)
 	return i - 1;
 }
 
+
+uint16 *GetCapacityOfArticulatedParts(EngineID engine, VehicleType type)
+{
+	static uint16 capacity[NUM_CARGO];
+	memset(capacity, 0, sizeof(capacity));
+
+	if (type == VEH_TRAIN) {
+		const RailVehicleInfo *rvi = RailVehInfo(engine);
+		capacity[rvi->cargo_type] = rvi->capacity;
+		if (rvi->railveh_type == RAILVEH_MULTIHEAD) capacity[rvi->cargo_type] += rvi->capacity;
+	} else if (type == VEH_ROAD) {
+		const RoadVehicleInfo *rvi = RoadVehInfo(engine);
+		capacity[rvi->cargo_type] = rvi->capacity;
+	}
+
+	if (!HasBit(EngInfo(engine)->callbackmask, CBM_VEHICLE_ARTIC_ENGINE)) return capacity;
+
+	for (uint i = 1; i < MAX_UVALUE(EngineID); i++) {
+		uint16 callback = GetVehicleCallback(CBID_VEHICLE_ARTIC_ENGINE, i, 0, engine, NULL);
+		if (callback == CALLBACK_FAILED || callback == 0xFF) break;
+
+		EngineID artic_engine = GetFirstEngineOfType(type) + GB(callback, 0, 7);
+
+		if (type == VEH_TRAIN) {
+			const RailVehicleInfo *rvi = RailVehInfo(artic_engine);
+			capacity[rvi->cargo_type] += GetEngineProperty(artic_engine, 0x14, rvi->capacity);
+		} else if (type == VEH_ROAD) {
+			const RoadVehicleInfo *rvi = RoadVehInfo(artic_engine);
+			capacity[rvi->cargo_type] += GetEngineProperty(artic_engine, 0x0F, rvi->capacity);
+		}
+	}
+
+	return capacity;
+}
+
+
 void AddArticulatedParts(Vehicle **vl, VehicleType type)
 {
 	const Vehicle *v = vl[0];
diff --git a/src/articulated_vehicles.h b/src/articulated_vehicles.h
index c448532bb..6db647df1 100644
--- a/src/articulated_vehicles.h
+++ b/src/articulated_vehicles.h
@@ -8,6 +8,7 @@
 #include "vehicle_type.h"
 
 uint CountArticulatedParts(EngineID engine_type, bool purchase_window);
+uint16 *GetCapacityOfArticulatedParts(EngineID engine, VehicleType type);
 void AddArticulatedParts(Vehicle **vl, VehicleType type);
 
 #endif /* ARTICULATED_VEHICLES_H */
diff --git a/src/build_vehicle_gui.cpp b/src/build_vehicle_gui.cpp
index 2922f301b..1ddfb0d62 100644
--- a/src/build_vehicle_gui.cpp
+++ b/src/build_vehicle_gui.cpp
@@ -530,6 +530,26 @@ static const StringID _sort_listing[][11] = {{
 	INVALID_STRING_ID
 }};
 
+static int DrawCargoCapacityInfo(int x, int y, EngineID engine, VehicleType type, bool refittable)
+{
+	uint16 *cap = GetCapacityOfArticulatedParts(engine, type);
+
+	for (uint c = 0; c < NUM_CARGO; c++) {
+		if (cap[c] == 0) continue;
+
+		SetDParam(0, c);
+		SetDParam(1, cap[c]);
+		SetDParam(2, refittable ? STR_9842_REFITTABLE : STR_EMPTY);
+		DrawString(x, y, STR_PURCHASE_INFO_CAPACITY, TC_FROMSTRING);
+		y += 10;
+
+		/* Only show as refittable once */
+		refittable = false;
+	}
+
+	return y;
+}
+
 /* Draw rail wagon specific details */
 static int DrawRailWagonPurchaseInfo(int x, int y, EngineID engine_number, const RailVehicleInfo *rvi)
 {
@@ -615,13 +635,7 @@ static int DrawRoadVehPurchaseInfo(int x, int y, EngineID engine_number, const R
 	y += 10;
 
 	/* Cargo type + capacity */
-	SetDParam(0, rvi->cargo_type);
-	SetDParam(1, GetEngineProperty(engine_number, 0x0F, rvi->capacity));
-	SetDParam(2, refittable ? STR_9842_REFITTABLE : STR_EMPTY);
-	DrawString(x, y, STR_PURCHASE_INFO_CAPACITY, TC_FROMSTRING);
-	y += 10;
-
-	return y;
+	return DrawCargoCapacityInfo(x, y, engine_number, VEH_ROAD, refittable);
 }
 
 /* Draw ship specific details */
@@ -703,7 +717,7 @@ int DrawVehiclePurchaseInfo(int x, int y, uint w, EngineID engine_number)
 			const RailVehicleInfo *rvi = RailVehInfo(engine_number);
 			uint capacity = GetEngineProperty(engine_number, 0x14, rvi->capacity);
 
-			refitable = (EngInfo(engine_number)->refit_mask != 0) && (capacity > 0);
+			bool refitable = (EngInfo(engine_number)->refit_mask != 0) && (capacity > 0);
 
 			if (rvi->railveh_type == RAILVEH_WAGON) {
 				y = DrawRailWagonPurchaseInfo(x, y, engine_number, rvi);
@@ -712,20 +726,18 @@ int DrawVehiclePurchaseInfo(int x, int y, uint w, EngineID engine_number)
 			}
 
 			/* Cargo type + capacity, or N/A */
-			if (rvi->capacity == 0) {
+			int new_y = DrawCargoCapacityInfo(x, y, engine_number, VEH_TRAIN, refitable);
+
+			if (new_y == y) {
 				SetDParam(0, CT_INVALID);
 				SetDParam(2, STR_EMPTY);
+				DrawString(x, y, STR_PURCHASE_INFO_CAPACITY, TC_FROMSTRING);
+				y += 10;
 			} else {
-				int multihead = (rvi->railveh_type == RAILVEH_MULTIHEAD ? 1 : 0);
-
-				SetDParam(0, rvi->cargo_type);
-				SetDParam(1, (capacity * (CountArticulatedParts(engine_number, true) + 1)) << multihead);
-				SetDParam(2, refitable ? STR_9842_REFITTABLE : STR_EMPTY);
+				y = new_y;
 			}
-			DrawString(x, y, STR_PURCHASE_INFO_CAPACITY, TC_FROMSTRING);
-			y += 10;
-		}
 			break;
+		}
 		case VEH_ROAD:
 			y = DrawRoadVehPurchaseInfo(x, y, engine_number, RoadVehInfo(engine_number));
 			refitable = true;