Added constant and variable time-step update logic to GameWindow. Updated examples to use the new GameWindow UpdateFrame and RenderFrame events.

Source/Examples/Tests/S02_RawInput_Logger.cs

@@ -87,7 +87,7 @@ namespace Examples.Tests
             GL.ClearColor(0.0f, 0.0f, 0.0f, 0.0f);
         }
 
-        public override void OnRenderFrame(EventArgs e)
+        public override void OnRenderFrame(RenderFrameEventArgs e)
         {
             base.OnRenderFrame(e);
 

Source/Examples/Tests/S03_Stack_Imbalance.cs

@@ -30,7 +30,7 @@ namespace Examples.Tests
         }
 
         float[] proj = new float[16];
-        public override void OnRenderFrame(EventArgs e)
+        public override void OnRenderFrame(RenderFrameEventArgs e)
         {
             GL.Clear(GL.Enums.ClearBufferMask.COLOR_BUFFER_BIT);
 

Source/Examples/Tutorial/T01_Simple_Window.cs

@@ -51,7 +51,7 @@ namespace Examples.Tutorial
         /// will be notified of frame rendering events!
         /// </summary>
         /// <param name="e">Not used.</param>
-        public override void OnRenderFrame(EventArgs e)
+        public override void OnRenderFrame(RenderFrameEventArgs e)
         {
             GL.Clear(GL.Enums.ClearBufferMask.COLOR_BUFFER_BIT);
 

Source/Examples/Tutorial/T02_Vertex_Array_Cube.cs

@@ -92,16 +92,8 @@ namespace Examples.Tutorial
                 Fullscreen = !Fullscreen;
             }
 
-            GL.MatrixMode(GL.Enums.MatrixMode.MODELVIEW);
+            //angle += 180.0f * (float)e.Time;
-            GL.LoadIdentity();
+            angle += 3.0f;
-            Glu.LookAt(
-                0.0, 5.0, 5.0,
-                0.0, 0.0, 0.0,
-                0.0, 1.0, 0.0
-            );
-
-            GL.Rotate(angle, 0.0f, 1.0f, 0.0f);
-            angle += 180.0f * e.Time;
             if (angle > 720.0f)
                 angle -= 720.0f;
         }
@@ -113,21 +105,23 @@ namespace Examples.Tutorial
         /// <summary>
         /// Place your rendering code here.
         /// </summary>
-        public override void OnRenderFrame(EventArgs e)
+        public override void OnRenderFrame(RenderFrameEventArgs e)
         {
             GL.Clear(GL.Enums.ClearBufferMask.COLOR_BUFFER_BIT | GL.Enums.ClearBufferMask.DEPTH_BUFFER_BIT);
 
-            unsafe
+            GL.MatrixMode(GL.Enums.MatrixMode.MODELVIEW);
-            {
+            GL.LoadIdentity();
-                fixed (ushort* index_pointer = Shapes.Cube.Indices)
+            Glu.LookAt(
-                {
+                0.0, 5.0, 5.0,
+                0.0, 0.0, 0.0,
+                0.0, 1.0, 0.0
+            );
+            GL.Rotate(angle, 0.0f, 1.0f, 0.0f);
+
             GL.DrawElements(GL.Enums.BeginMode.TRIANGLES, Shapes.Cube.Indices.Length,
-                        GL.Enums.All.UNSIGNED_SHORT, index_pointer);
+                GL.Enums.All.UNSIGNED_SHORT, Shapes.Cube.Indices);
-                }
-            }
 
             Context.SwapBuffers();
-            Thread.Sleep(0);
         }
 
         #endregion
@@ -142,7 +136,8 @@ namespace Examples.Tutorial
         /// </remarks>
         public void Launch()
         {
-            Run();
+            // Run the main loop calling UpdateFrame and RenderFrame 60 times per second.
+            Run(60.0, 60.0);
         }
 
         #endregion

Source/Examples/Tutorial/T03_Immediate_Mode_Cube.cs

@@ -118,7 +118,7 @@ namespace Examples.Tutorial
         /// <summary>
         /// Place your rendering code here.
         /// </summary>
-        public override void OnRenderFrame(EventArgs e)
+        public override void OnRenderFrame(RenderFrameEventArgs e)
         {
             GL.Clear(GL.Enums.ClearBufferMask.COLOR_BUFFER_BIT | GL.Enums.ClearBufferMask.DEPTH_BUFFER_BIT);
 

Source/Examples/Tutorial/T07_Display_Lists_Flower.cs

@@ -137,7 +137,7 @@ namespace Examples.Tutorial
 
         #region OnRenderFrame
 
-        public override void OnRenderFrame(EventArgs e)
+        public override void OnRenderFrame(RenderFrameEventArgs e)
         {
             base.OnRenderFrame(e);
 

Source/Examples/Tutorial/T08_VBO.cs

@@ -153,7 +153,7 @@ namespace Examples.Tutorial
 
         #region OnRenderFrame
 
-        public override void OnRenderFrame(EventArgs e)
+        public override void OnRenderFrame(RenderFrameEventArgs e)
         {
             base.OnRenderFrame(e);
 

Source/Examples/Tutorial/T10_GLSL_Cube.cs

@@ -172,7 +172,7 @@ namespace Examples.Tutorial
 
         #region OnRenderFrame
 
-        public override void OnRenderFrame(EventArgs e)
+        public override void OnRenderFrame(RenderFrameEventArgs e)
         {
  	        base.OnRenderFrame(e);
 

Source/OpenTK/GameWindow.cs

@@ -29,6 +29,8 @@ namespace OpenTK
         private bool isExiting;
         private bool disposed;
 
+        private double updateTime, renderTime, eventTime, frameTime;
+
         #endregion
 
         #region --- Contructors ---
@@ -293,7 +295,7 @@ namespace OpenTK
         #region public virtual void Run()
 
         /// <summary>
-        /// Runs the default game loop on GameWindow (process event->update frame->render frame).
+        /// Runs the default game loop on GameWindow at the maximum possible update and render speed.
         /// </summary>
         /// <remarks>
         /// <para>
@@ -307,7 +309,18 @@ namespace OpenTK
         /// to Operating System events.
         /// </para>
         /// </remarks>
-        public virtual void Run()
+        /// <see cref="public virtual void Run(float update_frequency, float render_frequency)"/>
+        public void Run()
+        {
+            Run(0.0f, 0.0f);
+        }
+
+        /// <summary>
+        /// Runs the default game loop on GameWindow at the specified update and render speed.
+        /// </summary>
+        /// <param name="update_frequency">Indicates how many times UpdateFrame will be called per second.</param>
+        /// <param name="render_frequency">Indicates how many times RenderFrame will be called per second.</param>
+        public virtual void Run(double update_frequency, double render_frequency)
         {
             this.OnLoad(EventArgs.Empty);
             resizeEventArgs.Width = this.Width;
@@ -316,20 +329,65 @@ namespace OpenTK
 
             Debug.Print("Entering main loop");
 
-            System.Diagnostics.Stopwatch watch = new Stopwatch();
+            Stopwatch watch = new Stopwatch();
-            watch.Reset();
             UpdateFrameEventArgs updateArgs = new UpdateFrameEventArgs();
+            RenderFrameEventArgs renderArgs = new RenderFrameEventArgs();
+
+            double update_target = 0.0, render_target = 0.0, next_update = 0.0, next_render = 0.0;
+            double time, total_time;
+
+            if (update_frequency > 0.0)
+            {
+                next_update = update_target = 1.0 / update_frequency;
+            }
+            if (render_frequency > 0.0)
+            {
+                next_render = render_target = 1.0 / render_frequency;
+            }
 
             while (this.Exists && !IsExiting)
             {
-                this.ProcessEvents();
+                total_time = frameTime = watch.Elapsed.TotalSeconds;
-                if (!IsExiting)
+                if (total_time > 0.1)
-                {
+                    total_time = 0.1;
-                    updateArgs.Time = watch.ElapsedMilliseconds / 1000.0f;
+                updateArgs.Time = renderArgs.Time = total_time;
+
                 watch.Reset();
                 watch.Start();
+
+                time = watch.Elapsed.TotalSeconds;
+                this.ProcessEvents();
+                eventTime = watch.Elapsed.TotalSeconds - time;
+
+                if (!IsExiting)
+                {
+                    time = watch.Elapsed.TotalSeconds;
+                    next_update -= (total_time + time);
+                    while (next_update <= 0.0)
+                    {
+                        updateArgs.Time += watch.Elapsed.TotalSeconds;
                         this.OnUpdateFrame(updateArgs);
-                    this.OnRenderFrame(EventArgs.Empty);
+                        if (update_target == 0.0)
+                            break;
+                        next_update += update_target;
+                    }
+                    updateTime = watch.Elapsed.TotalSeconds - time;
+
+                    time = watch.Elapsed.TotalSeconds;
+                    next_render -= (total_time + time);
+                    if (next_render <= 0.0)
+                    {
+                        renderArgs.Time += time;
+                        this.OnRenderFrame(renderArgs);
+                        next_render += render_target;
+                    }
+                    renderTime = watch.Elapsed.TotalSeconds - time;
+
+                    if (renderTime < render_target && updateTime < update_target)
+                    {
+                        Thread.Sleep((int)(1000.0 * System.Math.Min(
+                            render_target - renderTime, update_target - updateTime)));
+                    }
                 }
             }
 
@@ -367,7 +425,7 @@ namespace OpenTK
 
         #endregion
 
-        #region public virtual void OnRenderFrame(EventArgs e)
+        #region public virtual void OnRenderFrame(RenderFrameEventArgs e)
 
         /// <summary>
         /// Raises the RenderFrame event. Override in derived classes to render a frame.
@@ -376,7 +434,7 @@ namespace OpenTK
         /// If overriden, the base.OnRenderFrame() function should be called, to ensure
         /// listeners are notified of RenderFrame events.
         /// </remarks>
-        public virtual void OnRenderFrame(EventArgs e)
+        public virtual void OnRenderFrame(RenderFrameEventArgs e)
         {
             if (!this.Exists && !this.IsExiting)
             {
@@ -626,12 +684,26 @@ namespace OpenTK
 
     public class UpdateFrameEventArgs : EventArgs
     {
-        private float time;
+        private double time;
 
         /// <summary>
         /// Gets the Time elapsed between frame updates, in seconds.
         /// </summary>
-        public float Time
+        public double Time
+        {
+            get { return time; }
+            internal set { time = value; }
+        }
+    }
+
+    public class RenderFrameEventArgs : EventArgs
+    {
+        private double time;
+
+        /// <summary>
+        /// Gets the Time elapsed between frame updates, in seconds.
+        /// </summary>
+        public double Time
         {
             get { return time; }
             internal set { time = value; }

Source/OpenTK/Platform/IGLContext.cs

@@ -62,12 +62,12 @@ namespace OpenTK.Platform
         void CreateContext(bool direct, IGLContext source);
 
         /// <summary>
-        /// Swaps buffers on a context. This presents the rendered scene to the user.
+        /// Swaps buffers, presenting the rendered scene to the user.
         /// </summary>
         void SwapBuffers();
 
         /// <summary>
-        /// Makes this context the current rendering target.
+        /// Makes the Context current in the calling thread, i.e. future OpenGL commands will affect this Context.
         /// </summary>
         void MakeCurrent();
 

Source/OpenTK/Platform/IGameWindow.cs

@@ -14,11 +14,13 @@ namespace OpenTK.Platform
     {
         void Run();
 
-        void OnRenderFrame(EventArgs e);
+        void OnRenderFrame(RenderFrameEventArgs e);
         void OnUpdateFrame(UpdateFrameEventArgs e);
         void OnLoad(EventArgs e);
         void Exit();
 
+        void SwapBuffers();
+
         event UpdateFrameEvent UpdateFrame;
         event RenderFrameEvent RenderFrame;
         event LoadEvent Load;
@@ -28,6 +30,6 @@ namespace OpenTK.Platform
     }
 
     public delegate void UpdateFrameEvent(object sender, UpdateFrameEventArgs e);
-    public delegate void RenderFrameEvent(object sender, EventArgs e);
+    public delegate void RenderFrameEvent(object sender, RenderFrameEventArgs e);
     public delegate void LoadEvent(object sender, EventArgs e);
 }