Refactor, to make logic simpler.

Author: rwf-rr

Source/Orts.Simulation/Simulation/RollingStocks/MSTSLocomotive.cs

@@ -360,7 +360,7 @@ public bool LargeEjectorSoundOn
 
         protected float OdometerResetPositionM = 0;
         protected bool OdometerCountingUp = true;
-        protected bool OdometerCountingForwards = true;
+        protected bool OdometerDirectionForward = true; // direction of the train when odometer was reset
         public bool OdometerResetButtonPressed = false;
 
         public bool OdometerVisible { get; private set; }
@@ -371,7 +371,11 @@ public float OdometerM
                 if (Train == null)
                     return 0;
 
-                return OdometerCountingForwards ? Train.DistanceTravelledM - OdometerResetPositionM : OdometerResetPositionM - Train.DistanceTravelledM;
+                float odo;
+
+                if (OdometerDirectionForward ^ OdometerCountingUp) { odo = OdometerResetPositionM - Train.DistanceTravelledM; }
+                else { odo = Train.DistanceTravelledM - OdometerResetPositionM; }
+                return odo;
             }
         }
 
@@ -1364,7 +1368,7 @@ public override void Save(BinaryWriter outf)
             outf.Write(Wiper);
             outf.Write(OdometerResetPositionM);
             outf.Write(OdometerCountingUp);
-            outf.Write(OdometerCountingForwards);
+            outf.Write(OdometerDirectionForward);
             outf.Write(OdometerVisible);
             outf.Write(MainResPressurePSI);
             outf.Write(CompressorIsOn);
@@ -1418,7 +1422,7 @@ public override void Restore(BinaryReader inf)
             if (inf.ReadBoolean()) SignalEvent(Event.WiperOn);
             OdometerResetPositionM = inf.ReadSingle();
             OdometerCountingUp = inf.ReadBoolean();
-            OdometerCountingForwards = inf.ReadBoolean();
+            OdometerDirectionForward = inf.ReadBoolean();
             OdometerVisible = inf.ReadBoolean();
             MainResPressurePSI = inf.ReadSingle();
             CompressorIsOn = inf.ReadBoolean();
@@ -5049,57 +5053,48 @@ public virtual void Refuel()
             // Electric locos do nothing. Diesel and steam override this.
         }
 
+        /// <summary>
+        /// Show / hide the odometer.
+        /// </summary>
         public void OdometerToggle()
         {
             OdometerVisible = !OdometerVisible;
         }
 
         /// <summary>
-        /// Set odometer reference distance to actual travelled distance,
-        /// and set measuring direction to the actual direction
+        /// Reset the odometer. Sets a new reset position, adjusted by +/- the train length when counting down.
+        /// The odometer calculation is in OdometerM.get().
         /// </summary>
         public void OdometerReset(bool toState)
         {
             if (Train == null)
                 return;
+
             if (toState)
             {
-                if (OdometerCountingForwards != OdometerCountingUp ^ (Direction == Direction.Reverse))
-                {
-                    OdometerCountingForwards = !OdometerCountingForwards;
-                }
+                OdometerDirectionForward = (Direction == Direction.Reverse) ? false : true;
 
-                if (Direction == Direction.Reverse)
-                {
-                    if (OdometerCountingForwards)
-                        OdometerResetPositionM = Train.DistanceTravelledM - Train.Length;
-                    else
-                        OdometerResetPositionM = Train.DistanceTravelledM;
-                }
-                else
-                {
-                    if (OdometerCountingForwards)
-                        OdometerResetPositionM = Train.DistanceTravelledM;
-                    else
-                        OdometerResetPositionM = Train.DistanceTravelledM + Train.Length;
-                }
+                if (OdometerCountingUp) { OdometerResetPositionM = Train.DistanceTravelledM; }
+                else if (Direction == Direction.Reverse) { OdometerResetPositionM = Train.DistanceTravelledM - Train.Length; }
+                else { OdometerResetPositionM = Train.DistanceTravelledM + Train.Length; }
 
                 Simulator.Confirmer.Confirm(CabControl.Odometer, CabSetting.On);
             }
             OdometerResetButtonPressed = toState;
         }
 
+        /// <summary>
+        /// Change the odometer counting direction. Adjusts the reset position +/- the train length.
+        /// The odometer calculation is in OdometerM.get().
+        /// </summary>
         public void OdometerToggleDirection()
         {
             if (Train == null)
                 return;
 
-            // change the up/down flag for the reset logic (above)
-            // change the forward/reverse flag for OdometerM calculation (see OdometerM get() function)
-            // change the reference point to match the up/down flag
             OdometerCountingUp = !OdometerCountingUp;
-            OdometerCountingForwards = !OdometerCountingForwards;
-            OdometerResetPositionM = OdometerCountingUp ? OdometerResetPositionM - Train.Length : OdometerResetPositionM + Train.Length;
+            if (OdometerDirectionForward ^ OdometerCountingUp) { OdometerResetPositionM += Train.Length; }
+            else { OdometerResetPositionM -= Train.Length; }
 
             Simulator.Confirmer.Confirm(CabControl.Odometer, OdometerCountingUp ? CabSetting.Increase : CabSetting.Decrease);
         }