Cache the last vehicle in a consist to have a visual effect

src/roadveh_cmd.cpp

@@ -224,6 +224,7 @@ void RoadVehUpdateCache(RoadVehicle *v, bool same_length)
 
 	v->gcache.cached_total_length = 0;
 
+	Vehicle *last_vis_effect = v;
 	for (RoadVehicle *u = v; u != NULL; u = u->Next()) {
 		/* Check the v->first cache. */
 		assert(u->First() == v);
@@ -241,10 +242,13 @@ void RoadVehUpdateCache(RoadVehicle *v, bool same_length)
 
 		/* Update visual effect */
 		u->UpdateVisualEffect();
+		ClrBit(u->vcache.cached_veh_flags, VCF_LAST_VISUAL_EFFECT);
+		if (!(HasBit(u->vcache.cached_vis_effect, VE_ADVANCED_EFFECT) && GB(u->vcache.cached_vis_effect, 0, VE_ADVANCED_EFFECT) == VESM_NONE)) last_vis_effect = u;
 
 		/* Update cargo aging period. */
 		u->vcache.cached_cargo_age_period = GetVehicleProperty(u, PROP_ROADVEH_CARGO_AGE_PERIOD, EngInfo(u->engine_type)->cargo_age_period);
 	}
+	SetBit(last_vis_effect->vcache.cached_veh_flags, VCF_LAST_VISUAL_EFFECT);
 
 	uint max_speed = GetVehicleProperty(v, PROP_ROADVEH_SPEED, 0);
 	v->vcache.cached_max_speed = (max_speed != 0) ? max_speed * 4 : RoadVehInfo(v->engine_type)->max_speed;

src/train_cmd.cpp

@@ -214,6 +214,7 @@ void Train::ConsistChanged(ConsistChangeFlags allowed_changes)
 		}
 	}
 
+	Vehicle *last_vis_effect = this;
 	for (Train *u = this; u != NULL; u = u->Next()) {
 		const Engine *e_u = u->GetEngine();
 		const RailVehicleInfo *rvi_u = &e_u->u.rail;
@@ -228,6 +229,8 @@ void Train::ConsistChanged(ConsistChangeFlags allowed_changes)
 
 		/* Update powered-wagon-status and visual effect */
 		u->UpdateVisualEffect(true);
+		ClrBit(u->vcache.cached_veh_flags, VCF_LAST_VISUAL_EFFECT);
+		if (!(HasBit(u->vcache.cached_vis_effect, VE_ADVANCED_EFFECT) && GB(u->vcache.cached_vis_effect, 0, VE_ADVANCED_EFFECT) == VESM_NONE)) last_vis_effect = u;
 
 		if (rvi_v->pow_wag_power != 0 && rvi_u->railveh_type == RAILVEH_WAGON &&
 				UsesWagonOverride(u) && !HasBit(u->vcache.cached_vis_effect, VE_DISABLE_WAGON_POWER)) {
@@ -298,6 +301,7 @@ void Train::ConsistChanged(ConsistChangeFlags allowed_changes)
 		this->InvalidateNewGRFCache();
 		u->InvalidateNewGRFCache();
 	}
+	SetBit(last_vis_effect->vcache.cached_veh_flags, VCF_LAST_VISUAL_EFFECT);
 
 	/* store consist weight/max speed in cache */
 	this->vcache.cached_max_speed = max_speed;

src/vehicle.cpp

@@ -413,6 +413,7 @@ Vehicle::Vehicle(VehicleType type)
 	this->last_station_visited = INVALID_STATION;
 	this->last_loading_station = INVALID_STATION;
 	this->cur_image_valid_dir  = INVALID_DIR;
+	this->vcache.cached_veh_flags = 0;
 }
 
 /**
@@ -3486,6 +3487,8 @@ void Vehicle::ShowVisualEffect() const
 
 			CreateEffectVehicleRel(v, x, y, 10, evt);
 		}
+
+		if (HasBit(v->vcache.cached_veh_flags, VCF_LAST_VISUAL_EFFECT)) break;
 	} while ((v = v->Next()) != NULL);
 
 	if (sound) PlayVehicleSound(this, VSE_VISUAL_EFFECT);
@@ -3668,6 +3671,8 @@ char *Vehicle::DumpVehicleFlags(char *b, const char *last) const
 	dump('x', HasBit(this->vehicle_flags, VF_LAST_LOAD_ST_SEP));
 	dump('s', HasBit(this->vehicle_flags, VF_TIMETABLE_SEPARATION));
 	dump('a', HasBit(this->vehicle_flags, VF_AUTOMATE_TIMETABLE));
+	b += seprintf(b, last, ", vcf:");
+	dump('l', HasBit(this->vcache.cached_veh_flags, VCF_LAST_VISUAL_EFFECT));
 	if (this->IsGroundVehicle()) {
 		uint16 gv_flags = this->GetGroundVehicleFlags();
 		b += seprintf(b, last, ", gvf:");

src/vehicle_base.h

@@ -130,12 +130,20 @@ enum GroundVehicleSubtypeFlags {
 	GVSF_VIRTUAL          = 6, ///< Used for virtual trains during template design, it is needed to skip checks for tile or depot status
 };
 
+/**
+ * Enum to handle vehicle cache flags.
+ */
+enum VehicleCacheFlags {
+	VCF_LAST_VISUAL_EFFECT      = 0, ///< Last vehicle in the consist with a visual effect.
+};
+
 /** Cached often queried values common to all vehicles. */
 struct VehicleCache {
 	uint16 cached_max_speed;        ///< Maximum speed of the consist (minimum of the max speed of all vehicles in the consist).
 	uint16 cached_cargo_age_period; ///< Number of ticks before carried cargo is aged.
 
 	byte cached_vis_effect;  ///< Visual effect to show (see #VisualEffect)
+	byte cached_veh_flags;   ///< Vehicle cache flags (see #VehicleCacheFlags)
 };
 
 /** Sprite sequence for a vehicle part. */