(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

1 files changed, 31 insertions, 6 deletions

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.