(svn r3944) -Feature: it's now possible to turn a single unit in a train

	control-click on a unit in a train in a depot will make the click unit turn around
	this is useful if you want "normal" engines to act as dualheaded (one each way) or similar
	this only works on single unit units. Multiheaded and articulated engines get a red error box
	this is based on a quick hack peter1138 while I made it network safe and correctly handling of multible unit engines

4 files changed, 38 insertions, 7 deletions

diff --git a/lang/english.txt b/lang/english.txt
index 5347a46a8..14682cd4b 100644
--- a/lang/english.txt
+++ b/lang/english.txt
@@ -2530,6 +2530,7 @@ STR_9030_CITIZENS_CELEBRATE_FIRST                               :{BLACK}{BIGFONT
 STR_9031_ROAD_VEHICLE_CRASH_DRIVER                              :{BLACK}{BIGFONT}Road Vehicle Crash!{}Driver dies in fireball after collision with train
 STR_9032_ROAD_VEHICLE_CRASH_DIE                                 :{BLACK}{BIGFONT}Road Vehicle Crash!{}{COMMA} die in fireball after collision with train
 STR_9033_CAN_T_MAKE_VEHICLE_TURN                                :{WHITE}Can't make vehicle turn around...
+STR_ONLY_TURN_SINGLE_UNIT                                       :{WHITE}Can't turn vehicles consisting of multiple units
 STR_9034_RENAME                                                 :{BLACK}Rename
 STR_9035_RENAME_ROAD_VEHICLE_TYPE                               :{BLACK}Rename road vehicle type
 STR_9036_RENAME_ROAD_VEHICLE_TYPE                               :{WHITE}Rename road vehicle type
diff --git a/train_cmd.c b/train_cmd.c
index 7bff82804..b38089300 100644
--- a/train_cmd.c
+++ b/train_cmd.c
@@ -26,6 +26,7 @@
 #include "train.h"
 #include "newgrf_callbacks.h"
 #include "newgrf_engine.h"
+#include "direction.h"
 
 static bool TrainCheckIfLineEnds(Vehicle *v);
 static void TrainController(Vehicle *v);
@@ -379,6 +380,8 @@ int GetTrainImage(const Vehicle* v, Direction direction)
 	int img = v->spritenum;
 	int base;
 
+	if (HASBIT(v->u.rail.flags, VRF_REVERSE_DIRECTION)) direction = ReverseDir(direction);
+
 	if (is_custom_sprite(img)) {
 		base = GetCustomVehicleSprite(v, direction + 4 * IS_CUSTOM_SECONDHEAD_SPRITE(img));
 		if (base != 0) return base;
@@ -1579,7 +1582,7 @@ static void ReverseTrainDirection(Vehicle *v)
 /** Reverse train.
  * @param x,y unused
  * @param p1 train to reverse
- * @param p2 unused
+ * @param p2 if true, reverse a unit in a train (needs to be in a depot)
  */
  int32 CmdReverseTrainDirection(int x, int y, uint32 flags, uint32 p1, uint32 p2)
 {
@@ -1591,18 +1594,35 @@ static void ReverseTrainDirection(Vehicle *v)
 
 	if (v->type != VEH_Train || !CheckOwnership(v->owner)) return CMD_ERROR;
 
+	if (p2) {
+		Vehicle *front;
+
+		if (IsMultiheaded(v) || HASBIT(RailVehInfo(v->engine_type)->callbackmask, CBM_ARTIC_ENGINE)) {
+			return_cmd_error(STR_ONLY_TURN_SINGLE_UNIT);
+		}
+
+		front = GetFirstVehicleInChain(v);
+		// make sure the vehicle is stopped in the depot
+		if (CheckTrainStoppedInDepot(front) < 0) {
+			return_cmd_error(STR_881A_TRAINS_CAN_ONLY_BE_ALTERED);
+		}
+	}
 //	if (v->u.rail.track & 0x80 || IsTileDepotType(v->tile, TRANSPORT_RAIL))
 //		return CMD_ERROR;
 
 	if (v->u.rail.crash_anim_pos != 0 || v->breakdown_ctr != 0) return CMD_ERROR;
 
 	if (flags & DC_EXEC) {
-		if (_patches.realistic_acceleration && v->cur_speed != 0) {
-			TOGGLEBIT(v->u.rail.flags, VRF_REVERSING);
+		if (p2) {
+			v->u.rail.flags ^= 1 << VRF_REVERSE_DIRECTION;
 		} else {
-			v->cur_speed = 0;
-			SetLastSpeed(v, 0);
-			ReverseTrainDirection(v);
+			if (_patches.realistic_acceleration && v->cur_speed != 0) {
+				TOGGLEBIT(v->u.rail.flags, VRF_REVERSING);
+			} else {
+				v->cur_speed = 0;
+				SetLastSpeed(v, 0);
+				ReverseTrainDirection(v);
+			}
 		}
 	}
 	return 0;
@@ -1898,6 +1918,11 @@ static void HandleLocomotiveSmokeCloud(const Vehicle* v)
 		x = _vehicle_smoke_pos[v->direction] * effect_offset;
 		y = _vehicle_smoke_pos[(v->direction + 2) % 8] * effect_offset;
 
+		if (HASBIT(v->u.rail.flags, VRF_REVERSE_DIRECTION)) {
+			x = -x;
+			y = -y;
+		}
+
 		switch (effect_type) {
 		case 0:
 			// steam smoke.
diff --git a/train_gui.c b/train_gui.c
index 6325db403..51565980b 100644
--- a/train_gui.c
+++ b/train_gui.c
@@ -724,7 +724,9 @@ static void TrainDepotWndProc(Window *w, WindowEvent *e)
 
 				if (GetVehicleFromTrainDepotWndPt(w, e->dragdrop.pt.x, e->dragdrop.pt.y, &gdvp) == 0 &&
 						sel != INVALID_VEHICLE) {
-					if (gdvp.wagon == NULL || gdvp.wagon->index != sel) {
+					if (gdvp.wagon != NULL && gdvp.wagon->index == sel && _ctrl_pressed) {
+						DoCommandP(GetVehicle(sel)->tile, GetVehicle(sel)->index, true, NULL, CMD_REVERSE_TRAIN_DIRECTION | CMD_MSG(STR_9033_CAN_T_MAKE_VEHICLE_TURN));
+					} else if (gdvp.wagon == NULL || gdvp.wagon->index != sel) {
 						TrainDepotMoveVehicle(gdvp.wagon, sel, gdvp.head);
 					} else if (gdvp.head != NULL && IsFrontEngine(gdvp.head)) {
 						ShowTrainViewWindow(gdvp.head);
diff --git a/vehicle.h b/vehicle.h
index 71e5c8c41..ecc250963 100644
--- a/vehicle.h
+++ b/vehicle.h
@@ -88,6 +88,9 @@ enum {
 
 	// used to store if a wagon is powered or not
 	VRF_POWEREDWAGON = 3,
+
+	// used to reverse the visible direction of the vehicle
+	VRF_REVERSE_DIRECTION = 4,
 };
 
 typedef struct VehicleAir {