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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,129 @@ | ||
| // Licensed to the .NET Foundation under one or more agreements. | ||
| // The .NET Foundation licenses this file to you under the MIT license. | ||
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| using System; | ||
| using System.Diagnostics; | ||
| using System.Runtime.CompilerServices; | ||
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| namespace Silk.NET.Core; | ||
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| /// <summary> | ||
| /// Represents a window/interval of time in which the caller can execute. | ||
| /// </summary> | ||
| /// <example> | ||
| /// To create a 60 FPS loop: | ||
| /// <code> | ||
| /// var window = new TimeWindow(); | ||
| /// window.Window = TimeSpan.FromSeconds(1.0 / 60.0); | ||
| /// while (true) | ||
| /// { | ||
| /// if (window.BeginWindow()) | ||
| /// { | ||
| /// // It's time for the next piece of work (e.g. rendering the next frame) | ||
| /// window.EndWindow(); // don't forget this! | ||
| /// } | ||
| /// // Anything that isn't necessarily dependent on a time window goes here. | ||
| /// // In most cases, BeginWindow will sleep and always return true. This is not guaranteed, however, so anything | ||
| /// // "real-time" (e.g. event processing) should be done here. | ||
| /// } | ||
| /// </code> | ||
| /// </example> | ||
| public class TimeWindow | ||
| { | ||
| #if NET7_0_OR_GREATER | ||
| private readonly BreakneckSleep _sleep = new(); | ||
| #endif | ||
| private readonly Stopwatch _sw = Stopwatch.StartNew(); | ||
| /// <summary> | ||
| /// Creates a <see cref="TimeWindow"/>. | ||
| /// </summary> | ||
| /// <param name="sleeping"> | ||
| /// Whether <see cref="BeginWindow"/> should sleep until the next window is due to start. | ||
| /// </param> | ||
| // ReSharper disable once UnusedParameter.Local | ||
| public TimeWindow(bool sleeping = true) | ||
| { | ||
| #if NET7_0_OR_GREATER | ||
| Sleeping = sleeping; | ||
| #endif | ||
| } | ||
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| /// <summary> | ||
| /// The duration of a single window. For example, if you wanted to render 60 frames per second, a single frame shall | ||
| /// be thought of as being rendered in a <c>1.0 / 60.0</c> second window. | ||
| /// </summary> | ||
| public TimeSpan Window { get; set; } = TimeSpan.FromSeconds(1.0 / 60.0); | ||
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| /// <summary> | ||
| /// The offset from the point at which this <see cref="TimeWindow"/> was constructed (or the last time | ||
| /// <see cref="Reset"/> was called) at which the next window is due to begin. | ||
| /// </summary> | ||
| public TimeSpan NextWindowStart { get; private set; } = TimeSpan.Zero; | ||
|
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| /// <summary> | ||
| /// The offset from the point at which this <see cref="TimeWindow"/> was constructed (or the last time | ||
| /// <see cref="Reset"/> was called) at which the next window is due to begin. | ||
| /// </summary> | ||
| public TimeSpan NextWindowEnd | ||
| { | ||
| [MethodImpl(MethodImplOptions.AggressiveInlining | (MethodImplOptions)768)] | ||
| get => NextWindowStart + Window; | ||
| } | ||
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| /// <summary> | ||
| /// The offset from the point at which this <see cref="TimeWindow"/> was constructed (or the last time | ||
| /// <see cref="Reset"/> was called). | ||
| /// </summary> | ||
| public TimeSpan CurrentTime | ||
| { | ||
| [MethodImpl(MethodImplOptions.AggressiveInlining | (MethodImplOptions)768)] | ||
| get => _sw.Elapsed; | ||
| } | ||
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| #if NET7_0_OR_GREATER | ||
| /// <summary> | ||
| /// Whether <see cref="BeginWindow"/> should use <see cref="BreakneckSleep"/>. | ||
| /// </summary> | ||
| private bool Sleeping { get; } | ||
| #endif | ||
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| /// <summary> | ||
| /// Resets the <see cref="NextWindowStart"/> to zero and the offset from which <see cref="CurrentTime"/> is | ||
| /// measured. | ||
| /// </summary> | ||
| [MethodImpl(MethodImplOptions.AggressiveInlining | (MethodImplOptions)768)] | ||
| public void Reset() | ||
| { | ||
| _sw.Restart(); | ||
| NextWindowStart = TimeSpan.Zero; | ||
| } | ||
|
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| /// <summary> | ||
| /// Determines whether the next window is due. | ||
| /// </summary> | ||
| /// <returns>True if the next window is due or overdue, false otherwise.</returns> | ||
| /// <remarks> | ||
| /// If false, do any time-independent, real-time work and call this method again. | ||
| /// </remarks> | ||
| [MethodImpl(MethodImplOptions.AggressiveInlining | (MethodImplOptions)768)] | ||
| public bool BeginWindow() | ||
| { | ||
| #if NET7_0_OR_GREATER | ||
| var ct = CurrentTime; | ||
| if (Sleeping && ct < NextWindowStart) | ||
| { | ||
| _sleep.Sleep(NextWindowStart - ct); | ||
| } | ||
| #endif | ||
| return CurrentTime >= NextWindowStart; | ||
| } | ||
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| /// <summary> | ||
| /// Completes this time window. | ||
| /// </summary> | ||
| [MethodImpl(MethodImplOptions.AggressiveInlining | (MethodImplOptions)768)] | ||
| public void EndWindow() | ||
| { | ||
| NextWindowStart += Window; | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
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| @@ -1,16 +1,47 @@ | ||
| // See https://aka.ms/new-console-template for more information | ||
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| using System.Collections.Concurrent; | ||
| using System.Diagnostics; | ||
| using Silk.NET.Core; | ||
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| for (var fps = 60; fps < 61440; fps *= 2) | ||
| var timeWindow = new TimeWindow(); | ||
| var bag = new ConcurrentBag<double>(); | ||
| var sw = new Stopwatch(); | ||
| Console.Write("Enter frames per second: "); | ||
| timeWindow.Window = TimeSpan.FromSeconds(1 / double.Parse(Console.ReadLine()!)); | ||
| Console.WriteLine("Press Ctrl+C to measure statistics."); | ||
| Console.CancelKeyPress += (_, _) => | ||
| { | ||
| var sleep = new BreakneckSleep(); | ||
| for (var t = 0; t < 5; t++) | ||
| var overshoots = bag.ToList(); | ||
| var count = overshoots.Count; | ||
| sw.Stop(); | ||
| Console.WriteLine($"Run time: {sw.Elapsed.TotalSeconds}"); | ||
| Console.WriteLine($"Frames: {overshoots.Count}"); | ||
| Console.WriteLine($"Expected Frames: {sw.Elapsed.TotalSeconds / timeWindow.Window.TotalSeconds}"); | ||
| Console.WriteLine($"Overshoots: {overshoots.Count(x => x > 0)}"); | ||
| Console.WriteLine($"Undershoots: {overshoots.Count(x => x < 0)}"); | ||
| Console.WriteLine($"Max overshoot: {overshoots.Max()}"); | ||
| Console.WriteLine($"Max undershoot: {overshoots.Min()}"); | ||
| Console.WriteLine($"Mean overshoot/undershoot: {overshoots.Sum() / overshoots.Count}"); | ||
| Console.WriteLine($"Median overshoot/undershoot: {overshoots.Order().ElementAt(overshoots.Count / 2)}"); | ||
| Console.WriteLine($"Overshoot/undershoot range: {overshoots.Max() - overshoots.Min()}"); | ||
| overshoots.RemoveAll(x => x < 0); | ||
| Console.WriteLine($"Min overshoot/wasted time per frame: {overshoots.Min()}"); | ||
| Console.WriteLine($"Mean wasted time per frame: {overshoots.Sum() / overshoots.Count}"); | ||
| Console.WriteLine($"Median wasted time per frame: {overshoots.Order().ElementAt(overshoots.Count / 2)}"); | ||
| Console.WriteLine($"Range for wasted time per frame: {overshoots.Max() - overshoots.Min()}"); | ||
| Console.WriteLine($"Final FPS: {1 / (sw.Elapsed.TotalSeconds / count)}"); | ||
| }; | ||
| sw.Start(); | ||
| while (true) | ||
| { | ||
| if (timeWindow.BeginWindow()) | ||
| { | ||
| bag.Add((timeWindow.CurrentTime - timeWindow.NextWindowStart).TotalSeconds); | ||
| timeWindow.EndWindow(); | ||
| } | ||
| else | ||
| { | ||
| var now = Stopwatch.GetTimestamp(); | ||
| sleep.Sleep(TimeSpan.FromSeconds(1 / (double)fps)); | ||
| Console.WriteLine | ||
| ($"{fps} FPS = {1 / Stopwatch.GetElapsedTime(now, Stopwatch.GetTimestamp()).TotalSeconds} FPS"); | ||
| bag.Add(-(timeWindow.NextWindowStart - timeWindow.CurrentTime).TotalSeconds); | ||
| } | ||
| } |