game state system

src/Game.cs

@@ -9,12 +9,11 @@ using System.Diagnostics;
 
 namespace MoonWorks
 {
-	public abstract class Game
+	public class Game
 	{
 		public TimeSpan MAX_DELTA_TIME = TimeSpan.FromMilliseconds(100);
 
 		private bool quit = false;
-		bool debugMode;
 
 		private Stopwatch gameTimer;
 		private TimeSpan timestep;
@@ -32,6 +31,8 @@ namespace MoonWorks
 		public AudioDevice AudioDevice { get; }
 		public Inputs Inputs { get; }
 
+		private GameState GameState = null;
+
 		private Dictionary<PresentMode, RefreshCS.Refresh.PresentMode> moonWorksToRefreshPresentMode = new Dictionary<PresentMode, RefreshCS.Refresh.PresentMode>
 		{
 			{ PresentMode.Immediate, RefreshCS.Refresh.PresentMode.Immediate },
@@ -74,13 +75,36 @@ namespace MoonWorks
 			);
 
 			AudioDevice = new AudioDevice();
-
-			this.debugMode = debugMode;
 		}
 
 		public void Run()
 		{
+			#if DEBUG
+			if (GameState == null)
+			{
+				throw new NullReferenceException("Must call SetState before Run!");
+			}
+			#endif
+
 			while (!quit)
+			{
+				Tick();
+			}
+
+			AudioDevice.Dispose();
+			GraphicsDevice.Dispose();
+			Window.Dispose();
+
+			SDL.SDL_Quit();
+		}
+
+		public void SetState(GameState gameState)
+		{
+			GameState = gameState;
+			GameState.Start();
+		}
+
+		private void Tick()
 		{
 			AdvanceElapsedTime();
 
@@ -125,27 +149,17 @@ namespace MoonWorks
 					Inputs.Update();
 					AudioDevice.Update();
 
-						Update(timestep);
+					GameState.Update(timestep);
 
 					accumulatedElapsedTime -= timestep;
 				}
 
 				var alpha = accumulatedElapsedTime / timestep;
 
-					Draw(timestep, alpha);
-
+				GameState.Draw(timestep, alpha);
 			}
 		}
 
-			OnDestroy();
-
-			AudioDevice.Dispose();
-			GraphicsDevice.Dispose();
-			Window.Dispose();
-
-			SDL.SDL_Quit();
-		}
-
 		private void HandleSDLEvents()
 		{
 			while (SDL.SDL_PollEvent(out var _event) == 1)
@@ -167,14 +181,6 @@ namespace MoonWorks
 			}
 		}
 
-		protected abstract void Update(TimeSpan dt);
-
-		// alpha refers to a percentage value between the current and next state
-		protected abstract void Draw(TimeSpan dt, double alpha);
-
-		// Clean up any objects you created in this function
-		protected abstract void OnDestroy();
-
 		private void HandleTextInput(SDL2.SDL.SDL_Event evt)
 		{
 			// Based on the SDL2# LPUtf8StrMarshaler

src/GameState.cs

@@ -0,0 +1,26 @@
+using System;
+using MoonWorks.Audio;
+using MoonWorks.Graphics;
+using MoonWorks.Input;
+
+namespace MoonWorks
+{
+    public abstract class GameState
+    {
+		protected readonly Game Game;
+
+		public Window Window => Game.Window;
+		public GraphicsDevice GraphicsDevice => Game.GraphicsDevice;
+		public AudioDevice AudioDevice => Game.AudioDevice;
+		public Inputs Inputs => Game.Inputs;
+
+		public GameState(Game game)
+        {
+			Game = game;
+		}
+
+		public abstract void Start();
+		public abstract void Update(TimeSpan delta);
+		public abstract void Draw(TimeSpan delta, double alpha);
+	}
+}