Multi-cargo ships: Sprite group cargo thresholds refer to entire ship

docs/newgrf-additions-nml.html

@@ -83,6 +83,8 @@
 		The default graphics chain for the primary vehicle may check the cargo states of the other ship parts if required.<br />
 		Additional ship parts may be refitted individually.
 		<p>This requires the <span class="code">multi_part_ships</span> feature.</p>
+
+		<p>From version 3 of the <span class="code">multi_part_ships</span> feature, spritegroup loading/loaded cargo thresholds refer to the entire ship, not just the first vehicle.</p>
 	</p>
 	<p>
 		Added callback: <span class="code">refit_part_name</span><br />

docs/newgrf-additions.html

@@ -975,6 +975,7 @@
 	Additional ship parts may be refitted individually.
 	</p>
 	<p>This is indicated by the feature name: <font face="monospace">multi_part_ships</font>, version 1</p>
+	<p>From version 3 of the <font face="monospace">multi_part_ships</font> feature, Action 2 loadtypes/loadingtypes cargo thresholds refer to the entire ship, not just the first vehicle.</p>
 	<p><b>Callback EC008002 - Ship part name for refit window</b><br />
 	This callback is called on the primary vehicle to get the name of each part of the ship (e.g. the name of each cargo hold) in the refit window.<br />
 	This is not called for ships of only one part.<br />

src/newgrf_engine.cpp

@@ -1151,8 +1151,18 @@ static uint32_t VehicleGetVariable(Vehicle *v, const VehicleScopeResolver *objec
 	uint totalsets = in_motion ? (uint)group->loaded.size() : (uint)group->loading.size();
 
 	if (totalsets == 0) return nullptr;
+	if (totalsets == 1) return in_motion ? group->loaded[0] : group->loading[0];
+
+	uint stored = v->cargo.StoredCount();
+	uint capacity = v->cargo_cap;
+	if (v->type == VEH_SHIP) {
+		for (const Vehicle *u = v->Next(); u != nullptr; u = u->Next()) {
+			stored += u->cargo.StoredCount();
+			capacity += u->cargo_cap;
+		}
+	}
 
-	uint set = (v->cargo.StoredCount() * totalsets) / std::max<uint16_t>(1u, v->cargo_cap);
+	uint set = (stored * totalsets) / std::max<uint16_t>(1u, capacity);
 	set = std::min(set, totalsets - 1);
 
 	return in_motion ? group->loaded[set] : group->loading[set];

src/newgrf_extension.cpp

@@ -72,7 +72,7 @@ extern const GRFFeatureInfo _grf_feature_list[] = {
 	GRFFeatureInfo("town_zone_callback", 1, GFTOF_TOWN_ZONE_CALLBACK),
 	GRFFeatureInfo("varaction2_towns_town_xy", 1),
 	GRFFeatureInfo("more_varaction2_types", 1, GFTOF_MORE_VARACTION2_TYPES),
-	GRFFeatureInfo("multi_part_ships", 2, GFTOF_MULTI_PART_SHIPS),
+	GRFFeatureInfo("multi_part_ships", 3, GFTOF_MULTI_PART_SHIPS),
 	GRFFeatureInfo("more_stations_per_grf", 1),
 	GRFFeatureInfo(),
 };