Replacing ImSim setAdvancing log with workaround hack.

Author: bryanedds

Nu/Nu/Core/GameTime.fs

@@ -166,6 +166,7 @@ and [<Struct; CustomEquality; CustomComparison; TypeConverter (typeof<GameTimeCo
     static member isZero time = GameTime.unary isZero isZero time
     static member notZero time = GameTime.unary notZero notZero time
     static member zero = GameTime.ofSeconds 0.0f
+    static member epsilon = match Constants.GameTime.DesiredFrameRate with StaticFrameRate _ -> UpdateTime 1L | DynamicFrameRate _ -> TickTime 1L
     static member min (left : GameTime) right = if left <= right then left else right
     static member max (left : GameTime) right = if left >= right then left else right
     static member MinValue = GameTime.make Int64.MinValue Single.MinValue

Nu/Nu/World/WorldModule.fs

@@ -153,9 +153,15 @@ module WorldModule =
 
         /// Set whether the world state is advancing.
         static member setAdvancing advancing (world : World) =
-            if world.ContextImSim.Names.Length = 0
-            then World.defer (World.mapAmbientState (AmbientState.setAdvancing advancing)) Game.Handle world
-            else Log.error "Cannot call World.setAdvancing in an ImSim context."
+            if world.ContextImSim.Names.Length = 0 then
+                World.defer (World.mapAmbientState (AmbientState.setAdvancing advancing)) Game.Handle world
+            else
+                // HACK: in order to avoid unintentional interaction with the ImSim hack that clears and restores
+                // advancement state ImSim contexts, we schedule the advancement change outside of the normal workflow.
+                // Also note how this hack put type declaration order in a sloppy state (World.addTasklet is defined
+                // _after_ World.setAdvancing).
+                let time = if EndFrameProcessingStarted && world.Advancing then GameTime.epsilon else GameTime.zero
+                World.addTasklet Game.Handle { ScheduledTime = time; ScheduledOp = World.mapAmbientState (AmbientState.setAdvancing advancing) } world
 
         /// Set whether the world's frame rate is being explicitly paced based on clock progression.
         static member setFramePacing clockPacing (world : World) =
@@ -400,7 +406,7 @@ module WorldModule =
             World.mapAmbientState (AmbientState.restoreTasklets tasklets) world
 
         /// Add a tasklet to be executed by the engine at the scheduled time.
-        static member addTasklet simulant tasklet world =
+        static member addTasklet (simulant : Simulant) tasklet world =
             World.mapAmbientState (AmbientState.addTasklet simulant tasklet) world
 
         /// Schedule an operation to be executed by the engine with the given delay.
@@ -443,12 +449,7 @@ module WorldModule =
         /// When called in an ImSim Process context, will provide the ImSim simulant context and declared values from
         /// World that were active in that Process context as well as time and advancement state.
         static member defer operation (simulant : Simulant) (world : World) =
-            let time =
-                if EndFrameProcessingStarted && world.Advancing then
-                    match Constants.GameTime.DesiredFrameRate with
-                    | StaticFrameRate _ -> UpdateTime 1L
-                    | DynamicFrameRate _ -> TickTime 1L
-                else GameTime.zero
+            let time = if EndFrameProcessingStarted && world.Advancing then GameTime.epsilon else GameTime.zero
             World.schedule time operation simulant world
 
         /// Attempt to get the window flags.

Nu/Nu/World/WorldModule2.fs

@@ -275,6 +275,19 @@ module WorldModule2 =
                             | DesireNone -> ()
                             | DesireIgnore -> ()
 
+        static member private updateScreenTransition world =
+            match World.getSelectedScreenOpt world with
+            | Some selectedScreen ->
+                match selectedScreen.GetTransitionState world with
+                | IncomingState transitionTime -> World.updateScreenIncoming transitionTime selectedScreen world
+                | IdlingState transitionTime -> World.updateScreenIdling transitionTime selectedScreen world
+                | OutgoingState transitionTime -> World.updateScreenOutgoing transitionTime selectedScreen world
+            | None ->
+                match World.getDesiredScreen world with
+                | Desire desiredScreen -> World.transitionScreen desiredScreen world
+                | DesireNone -> ()
+                | DesireIgnore -> ()
+
         static member private updateScreenRequestedSong world =
             match World.getSelectedScreenOpt world with
             | Some selectedScreen ->
@@ -296,18 +309,9 @@ module WorldModule2 =
                 | RequestIgnore -> ()
             | None -> ()
 
-        static member private updateScreenTransition world =
-            match World.getSelectedScreenOpt world with
-            | Some selectedScreen ->
-                match selectedScreen.GetTransitionState world with
-                | IncomingState transitionTime -> World.updateScreenIncoming transitionTime selectedScreen world
-                | IdlingState transitionTime -> World.updateScreenIdling transitionTime selectedScreen world
-                | OutgoingState transitionTime -> World.updateScreenOutgoing transitionTime selectedScreen world
-            | None ->
-                match World.getDesiredScreen world with
-                | Desire desiredScreen -> World.transitionScreen desiredScreen world
-                | DesireNone -> ()
-                | DesireIgnore -> ()
+        static member private processScreenTransitioning world =
+            World.updateScreenTransition world
+            World.updateScreenRequestedSong world
 
         /// Try to transition to the given screen if no other transition is in progress.
         static member tryTransitionScreen destination world =
@@ -1867,9 +1871,9 @@ module WorldModule2 =
                 world.Timers.PreProcessTimer.Stop ()
                 if world.Alive then
 
-                    // update screen transitioning process
-                    World.updateScreenTransition world
-                    World.updateScreenRequestedSong world
+                    // process screen transitioning
+                    // NOTE: not bothering to do timing on this.
+                    World.processScreenTransitioning world
                     if world.Alive then
 
                         // process HID inputs

Nu/Nu/World/WorldPrelude.fs

@@ -641,7 +641,7 @@ module internal AmbientState =
     let internal restoreTasklets tasklets state =
         { state with Tasklets = tasklets }
 
-    let internal addTasklet simulant tasklet state =
+    let internal addTasklet (simulant : Simulant) tasklet state =
         { state with
             Tasklets =
                 match state.Tasklets.TryGetValue simulant with