Fix TrainCarOperations undesired camera3 camera2 behavior.

Author: mbm-OR

Source/RunActivity/Viewer3D/Cameras.cs

@@ -987,6 +987,7 @@ public enum AttachedTo { Front, Rear }
         protected float LowWagonOffsetLimit;
         protected float HighWagonOffsetLimit;
         public int oldCarPosition;
+        public bool IsCameraFront;
         public override bool IsUnderground
         {
             get

Source/RunActivity/Viewer3D/Popups/TrainCarOperationsViewerWindow.cs

@@ -482,7 +482,11 @@ public override void PrepareFrame(ElapsedTime elapsedTime, bool updateFull)
                     }
                     else if (OldCarPosition != CarPosition || (trainCarOperations.CarIdClicked && CarPosition == 0))
                     {
-                        Owner.Viewer.FrontCamera.Activate();
+                        if (Owner.Viewer.FrontCamera.AttachedCar != null && Owner.Viewer.FrontCamera.IsCameraFront)
+                            Owner.Viewer.FrontCamera.Activate();
+
+                        if (Owner.Viewer.BackCamera.AttachedCar != null && !Owner.Viewer.FrontCamera.IsCameraFront)
+                            Owner.Viewer.BackCamera.Activate();
                     }
                     OldCarPosition = CarPosition;
                     Layout();

Source/RunActivity/Viewer3D/Viewer.cs

@@ -1087,11 +1087,13 @@ void HandleUserInput(ElapsedTime elapsedTime)
             }
             if (UserInput.IsPressed(UserCommand.CameraOutsideFront))
             {
+                FrontCamera.IsCameraFront = true;
                 CheckReplaying();
                 new UseFrontCameraCommand(Log);
             }
             if (UserInput.IsPressed(UserCommand.CameraOutsideRear))
             {
+                FrontCamera.IsCameraFront = false;
                 CheckReplaying();
                 new UseBackCameraCommand(Log);
             }