Reimplement snowy NullHawk

now with 50% less hacks!
merry christmas

Author: YoshiRulz

Directory.Packages.props

@@ -11,6 +11,7 @@
 		<PackageVersion Include="Meziantou.Analyzer" Version="2.0.206" />
 		<PackageVersion Include="Meziantou.Polyfill" Version="1.0.50" />
 		<PackageVersion Include="Microsoft.Bcl.HashCode" Version="6.0.0" />
+		<PackageVersion Include="Microsoft.Bcl.Numerics" Version="10.0.1" />
 		<PackageVersion Include="Microsoft.CodeAnalysis.BannedApiAnalyzers" Version="3.3.4" />
 		<PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0" />
 		<PackageVersion Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.8.0" />

src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs

@@ -49,6 +49,8 @@ public DisplayManagerRenderTargetProvider(Func<Size, IRenderTarget> callback)
 
 		private IEmulator GlobalEmulator;
 
+		public SnowyNullVideo SnowyVP { get; private set; }
+
 		protected DisplayManagerBase(
 			Config config,
 			IEmulator emulator,
@@ -60,6 +62,10 @@ protected DisplayManagerBase(
 		{
 			GlobalConfig = config;
 			GlobalEmulator = emulator;
+			SnowyVP = new()
+			{
+				LiveSettings = GlobalConfig.GetCoreSettings<NullEmulator, SnowyNullVideo.Settings>() ?? new(),
+			};
 			OSD = new(config, emulator, inputManager, movieSession);
 			_gl = gl;
 			_renderer = renderer;
@@ -112,6 +118,10 @@ public void UpdateGlobals(Config config, IEmulator emulator)
 		{
 			GlobalConfig = config;
 			GlobalEmulator = emulator;
+			SnowyVP = new()
+			{
+				LiveSettings = GlobalConfig.GetCoreSettings<NullEmulator, SnowyNullVideo.Settings>() ?? new(),
+			};
 			OSD.UpdateGlobals(config, emulator);
 		}
 
@@ -466,12 +476,12 @@ public Point TransformPoint(Point p)
 		/// This will receive an emulated output frame from an IVideoProvider and run it through the complete frame processing pipeline
 		/// Then it will stuff it into the bound PresentationPanel.
 		/// </summary>
-		public void UpdateSource(IVideoProvider videoProvider)
+		public void UpdateSource(IVideoProvider videoProvider, bool useSnow = false)
 		{
 			var displayNothing = GlobalConfig.DispSpeedupFeatures == 0;
 			var job = new JobInfo
 			{
-				VideoProvider = videoProvider,
+				VideoProvider = useSnow ? SnowyVP : videoProvider,
 				Simulate = displayNothing,
 				ChainOutsize = GetGraphicsControlSize(),
 				IncludeOSD = true,

src/BizHawk.Client.Common/config/Config.cs

@@ -464,5 +464,7 @@ public void SetWindowScaleFor(string sysID, int windowScale)
 		public bool ScaleOSDWithSystemScale { get; set; } = true;
 
 		public int RelativeMouseSensitivity { get; set; } = 100;
+
+		public SnowyNullVideo.TriggerCriterion SnowyNullHawk { get; set; } = SnowyNullVideo.TriggerCriterion.WeekOfChristmas;
 	}
 }

src/BizHawk.Client.EmuHawk/MainForm.Events.cs

@@ -1306,6 +1306,7 @@ private void DisplayConfigMenuItem_Click(object sender, EventArgs e)
 			using DisplayConfig window = new(Config, DialogController, GL);
 			if (this.ShowDialogWithTempMute(window).IsOk())
 			{
+				DisplayManager.UpdateGlobals(Config, Emulator);
 				DisplayManager.RefreshUserShader();
 				FrameBufferResized();
 				SynchChrome();

src/BizHawk.Client.EmuHawk/MainForm.cs

@@ -2348,9 +2348,18 @@ private void SaveSlotSelectedMessage()
 			//rendering flakes out egregiously if we have a zero size
 			//can we fix it later not to?
 			if (isZero)
+			{
 				DisplayManager.Blank();
+			}
 			else
-				DisplayManager.UpdateSource(video);
+			{
+				DisplayManager.UpdateSource(video, useSnow: Emulator is NullEmulator && (Config.SnowyNullHawk switch
+				{
+					SnowyNullVideo.TriggerCriterion.Always => true,
+					SnowyNullVideo.TriggerCriterion.WeekOfChristmas => DateTime.Now.DayOfYear is >= 354/*Dec. 20*/ and <= 360/*Dec. 26*/,
+					_ => false,
+				}));
+			}
 		}
 
 		public static readonly FilesystemFilterSet ConfigFileFSFilterSet = new(

src/BizHawk.Client.EmuHawk/config/DisplayConfig.cs

@@ -6,6 +6,9 @@
 using BizHawk.Client.Common;
 using BizHawk.Client.Common.Filters;
 using BizHawk.Common;
+using BizHawk.Common.NumberExtensions;
+using BizHawk.Emulation.Common;
+using BizHawk.WinForms.Controls;
 
 namespace BizHawk.Client.EmuHawk
 {
@@ -21,6 +24,28 @@ public partial class DisplayConfig : Form, IDialogParent
 
 		private string _pathSelection;
 
+		private readonly RadioButtonGroupTracker _snowRadioTracker;
+
+		private readonly SzNUDEx nudSnowBias = new()
+		{
+			DecimalPlaces = 2,
+			Increment = 0.25m,
+			Maximum = 2.0m,
+			Minimum = -2.0m,
+			Size = new(48, 23),
+		};
+
+		private readonly SzNUDEx nudSnowIntensity = new()
+		{
+			DecimalPlaces = 1,
+			Increment = 0.1m,
+			Maximum = 1.0m,
+			Minimum = 0.1m,
+			Size = new(48, 23),
+		};
+
+		private readonly TransparentTrackBar tbSnowFramerate = new() { Maximum = 20, Minimum = 1, Size = new(160, 45) };
+
 		public IDialogController DialogController { get; }
 
 		public bool NeedReset { get; set; }
@@ -30,8 +55,61 @@ public DisplayConfig(Config config, IDialogController dialogController, IGL gl)
 			_config = config;
 			_gl = gl;
 			DialogController = dialogController;
+			var snowSettings = _config.GetCoreSettings<NullEmulator, SnowyNullVideo.Settings>() ?? new();
 
 			InitializeComponent();
+			LocSzGroupBoxEx grpSnow = new() { Location = new(6, 200), Size = new(371, 160), Text = "Snowy NullHawk" };
+			_snowRadioTracker = grpSnow.Tracker;
+			RadioButtonEx rbSnowAlways = new(_snowRadioTracker)
+			{
+				Checked = config.SnowyNullHawk is SnowyNullVideo.TriggerCriterion.Always,
+				Name = nameof(rbSnowAlways),
+				Tag = SnowyNullVideo.TriggerCriterion.Always,
+				Text = "Always",
+			};
+			RadioButtonEx rbSnowForChristmas = new(_snowRadioTracker)
+			{
+				Checked = config.SnowyNullHawk is SnowyNullVideo.TriggerCriterion.WeekOfChristmas,
+				Name = nameof(rbSnowForChristmas),
+				Tag = SnowyNullVideo.TriggerCriterion.WeekOfChristmas,
+				Text = "During Christmas (Dec. 20th through 26th)",
+			};
+			RadioButtonEx rbSnowNever = new(_snowRadioTracker)
+			{
+				Checked = config.SnowyNullHawk is SnowyNullVideo.TriggerCriterion.Never,
+				Name = nameof(rbSnowNever),
+				Tag = SnowyNullVideo.TriggerCriterion.Never,
+				Text = "Never",
+			};
+			LabelEx lblFramerate = new();
+			tbSnowFramerate.ValueChanged += (changedSender, _) =>
+			{
+				var val = ((TrackBar) changedSender).Value;
+				lblFramerate.Text = $"Framerate: {60.0 / val:F1} Hz";
+			};
+			tbSnowFramerate.Value = snowSettings.FramerateScalar;
+			nudSnowIntensity.Value = new(snowSettings.Intensity);
+			nudSnowBias.Value = new(snowSettings.Bias);
+			grpSnow.Controls.Add(new LocSzSingleColumnFLP
+			{
+				Controls =
+				{
+					new LabelEx { Text = "When no rom loaded, draw \"snow\" (white noise):" },
+					new SingleRowFLP { Controls = { rbSnowAlways, rbSnowNever } },
+					rbSnowForChristmas,
+					new SingleRowFLP { Controls =
+					{
+						new LabelEx { Text = "Brightness multiplier:" },
+						nudSnowIntensity,
+						new LabelEx { Text = "RNG bias:" },
+						nudSnowBias,
+					} },
+					new SingleRowFLP { Controls = { lblFramerate, tbSnowFramerate } },
+				},
+				Location = new(5, 15),
+				Size = new(320, 144),
+			});
+			tpMisc.Controls.Add(grpSnow);
 
 			rbNone.Checked = _config.TargetDisplayFilter == 0;
 			rbHq2x.Checked = _config.TargetDisplayFilter == 1;
@@ -170,6 +248,15 @@ private void BtnOk_Click(object sender, EventArgs e)
 
 			_config.UseStaticWindowTitles = cbStaticWindowTitles.Checked;
 
+			_config.SnowyNullHawk = _snowRadioTracker.GetSelectionTagAs<SnowyNullVideo.TriggerCriterion>()
+				?? SnowyNullVideo.TriggerCriterion.WeekOfChristmas;
+			_config.PutCoreSettings(
+				new SnowyNullVideo.Settings(
+					Bias: nudSnowBias.Value.ConvertToF32(),
+					FramerateScalar: tbSnowFramerate.Value,
+					Intensity: nudSnowIntensity.Value.ConvertToF32()),
+				typeof(NullEmulator));
+
 			if (rbUseRaw.Checked)
 				_config.DispManagerAR = EDispManagerAR.None;
 			else if (rbUseSystem.Checked)

src/BizHawk.Common/BizHawk.Common.csproj

@@ -10,6 +10,7 @@
 	<ItemGroup>
 		<PackageReference Include="CommunityToolkit.HighPerformance" />
 		<PackageReference Include="Microsoft.Bcl.HashCode" />
+		<PackageReference Include="Microsoft.Bcl.Numerics" />
 		<PackageReference Include="Microsoft.Win32.Registry" />
 		<PackageReference Include="PolySharp" />
 		<PackageReference Include="System.ComponentModel.Annotations" />

src/BizHawk.Emulation.Common/Base Implementations/SnowyNullVideo.cs

@@ -0,0 +1,69 @@
+namespace BizHawk.Emulation.Common
+{
+	/// <seealso cref="NullVideo"/>
+	public sealed class SnowyNullVideo : IVideoProvider
+	{
+		[CoreSettings]
+		public sealed record class Settings(
+			float Bias = -2.0f,
+			int FramerateScalar = 10,
+			float Intensity = 1.0f);
+
+		public enum TriggerCriterion : byte
+		{
+			Never = 0,
+			Always = 1,
+			WeekOfChristmas = 2,
+		}
+
+		private const int DefaultHeight = 192;
+
+		private const int DefaultWidth = 256;
+
+		private readonly int[] _buf = new int[DefaultWidth * DefaultHeight];
+
+		private int _rep = 0;
+
+		private readonly Random _rng = new(Seed: 0x4); // chosen by fair dice roll. guaranteed to be random.
+
+		public int BackgroundColor
+			=> 0;
+
+		public int BufferHeight
+			=> DefaultHeight;
+
+		public int BufferWidth
+			=> DefaultWidth;
+
+		public required Settings LiveSettings { get; set; }
+
+		public int VirtualHeight
+			=> DefaultHeight;
+
+		public int VirtualWidth
+			=> DefaultWidth;
+
+		public int VsyncDenominator
+			=> LiveSettings.FramerateScalar;
+
+		public int VsyncNumerator
+			=> 60;
+
+		public int[] GetVideoBuffer()
+		{
+			if (_rep++ > LiveSettings.FramerateScalar) _rep = 0;
+			if (_rep is not 0) return _buf;
+			var noise = new byte[_buf.Length];
+			_rng.NextBytes(noise);
+			for (var i = 0; i < _buf.Length; i++)
+			{
+				var sampleF = noise[i] / 255.0f;
+				sampleF = MathF.Pow(sampleF, MathF.Pow(10.0f, -LiveSettings.Bias)) * LiveSettings.Intensity;
+				var sample = (byte) (sampleF * 255.0f);
+				const int MASK = ~0xFFFFFF;
+				_buf[i] = MASK | sample << 16 | sample << 8 | sample; // ARGB
+			}
+			return _buf;
+		}
+	}
+}