Set Mobile.IsMoving to "true" if queueing a turn that takes only a si…

…ngle tick

At the end of L-turns, actors often end up with an internal facing not 100% matching the direction of the next cell on their path.
As a result, if they haven't reached their destination yet, Move queues a quick Turn as ChildActivity, which previously was not considered as IsMoving.
However, we don't want those mini-turns to interrupt move animations, so we now consider them a move as well. Additionally, to avoid any issues, we make these mini-turns non-interruptible, just like the MovePart activities already are.

OpenRA.Mods.Common/Activities/Move/Move.cs

@@ -224,7 +224,21 @@ public override Activity Tick(Actor self)
 			if (firstFacing != mobile.Facing)
 			{
 				path.Add(nextCell.Value.First);
-				QueueChild(new Turn(self, firstFacing));
+
+				// HACK: To fix visual hiccups on actors with move animations during "L-turn to next part of movement" transitions
+				// or invisible mini-turns (due to less sprite facings than internal facings), we set IsMoving to  'true' during Turn activity
+				// when the facing delta is low enough to be covered with a single Turn tick.
+				// To avoid issues, we make these mini-turns uninterruptible (like MovePart activities) to ensure the actor
+				// finishes that mini-turn before starting something else.
+				var facingWithinTolerance = Util.FacingWithinTolerance(mobile.Facing, firstFacing, mobile.TurnSpeed);
+				if (facingWithinTolerance)
+				{
+					mobile.IsMoving = true;
+					QueueChild(new Turn(self, firstFacing, false));
+				}
+				else
+					QueueChild(new Turn(self, firstFacing));
+
 				ChildActivity = ActivityUtils.RunActivity(self, ChildActivity);
 				return this;
 			}

OpenRA.Mods.Common/Activities/Turn.cs

@@ -44,5 +44,15 @@ public override Activity Tick(Actor self)
 
 			return this;
 		}
+
+		protected override void OnLastRun(Actor self)
+		{
+			// If Mobile.IsMoving was set to 'true' from the parent Move activity, we want to reset it to 'false' before the next tick,
+			// but as late as possible on this tick, to make sure any places looking up IsMoving will still see it as 'true'
+			// on the last tick this activity runs.
+			var mobile = self.TraitOrDefault<Mobile>();
+			if (mobile != null && mobile.IsMoving)
+				self.World.AddFrameEndTask(w => mobile.IsMoving = false);
+		}
 	}
 }