Properly reimplement taking screenshots

NitroSharp.sln.DotSettings

@@ -13,6 +13,7 @@
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpUseContinuousIndentInsideBracesMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EMigrateBlankLinesAroundFieldToBlankLinesAroundProperty/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Ascender/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Autosave/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Bezier/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=blit/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=boxblur/@EntryIndexedValue">True</s:Boolean>

src/NitroSharp.NsScript/VM/BuiltInFunctionDispatcher.cs

@@ -162,6 +162,9 @@ private void SetResult(in ConstantValue value)
                 case BuiltInFunction.WaitText:
                     WaitText(ref args);
                     break;
+                case BuiltInFunction.Draw:
+                    Draw();
+                    break;
 
                 case BuiltInFunction.CreateSound:
                     CreateSound(ref args);
@@ -311,6 +314,11 @@ private void SetResult(in ConstantValue value)
             return result;
         }
 
+        private void Draw()
+        {
+            _impl.Draw();
+        }
+
         private void Shake(ref ArgConsumer args)
         {
             EntityQuery query = args.TakeEntityQuery();

src/NitroSharp.NsScript/VM/BuiltInFunctions.cs

@@ -171,5 +171,7 @@ public virtual void DeleteSave(uint slot) { }
 
         public virtual float X360_GetTriggerAxis(XboxTrigger trigger) => 0;
         public virtual void Reset() { }
+
+        public virtual void Draw() { }
     }
 }

src/NitroSharp/Builtins.Graphics.cs

@@ -2,11 +2,11 @@
 using System.Collections.Immutable;
 using System.Numerics;
 using NitroSharp.Graphics;
+using NitroSharp.Graphics.Core;
 using NitroSharp.NsScript;
 using NitroSharp.NsScript.Primitives;
 using NitroSharp.NsScript.VM;
 using NitroSharp.Text;
-using Veldrid;
 
 namespace NitroSharp
 {
@@ -225,10 +225,12 @@ public override void CreateSprite(
         {
             if (src is "SCREEN" or "Screen" or "VIDEO" or "Video")
             {
-                Texture screenshotTexture = _renderCtx.CreateFullscreenTexture();
-                var result = SpriteTexture.FromStandalone(screenshotTexture);
-                _ctx.Defer(DeferredOperation.CaptureFramebuffer(screenshotTexture));
-                return result;
+                GameProcess process = src.Equals("SCREEN", StringComparison.OrdinalIgnoreCase)
+                    ? _ctx.ActiveProcess
+                    : _ctx.MainProcess;
+
+                PooledTexture texture = _ctx.RenderToTexture(process);
+                return SpriteTexture.FromPooledTexture(texture);
             }
 
             if (_ctx.Content.RequestTexture(src) is { } asset)
@@ -396,6 +398,11 @@ public override void WaitText(EntityQuery query, TimeSpan timeout)
             _ctx.Wait(CurrentThread, WaitCondition.EntityIdle, null, query);
         }
 
+        public override void Draw()
+        {
+            Delay(TimeSpan.FromMicroseconds(1));
+        }
+
         public override void CreateAlphaMask(
             in EntityPath entityPath,
             int priority,

src/NitroSharp/Content/ContentManager.cs

@@ -108,10 +108,13 @@ public Texture LoadTexture(string path, bool staging)
             return _textureLoader.LoadTexture(stream, staging);
         }
 
+        public T? TryGet<T>(AssetRef<T> assetRef) where T : class, IDisposable
+            => _cache.Get(assetRef.Handle).Asset as T;
+
         public T Get<T>(AssetRef<T> assetRef)
             where T : class, IDisposable
         {
-            if (!(_cache.Get(assetRef.Handle).Asset is T loadedAsset))
+            if (_cache.Get(assetRef.Handle).Asset is not T loadedAsset)
             {
                 throw new InvalidOperationException(
                     $"BUG: asset '{assetRef.Path}' is missing from the cache."
@@ -220,7 +223,7 @@ public bool ResolveAssets()
             }
         }
 
-        public Stream OpenStream(string path)
+        private Stream OpenStream(string path)
         {
             string fsPath = path;
             if (Path.GetDirectoryName(path) is { } dir && Path.GetFileName(path) is { } filename)

src/NitroSharp/Entity.cs

@@ -186,7 +186,7 @@ internal static class MouseStateEntities
     public static readonly string[] All = { MouseUsual, MouseClick, MouseOver, MouseLeave };
 
     public static bool IsMouseStateEntity(this Entity? entity)
-        => entity is { Id.Name: MouseUsual or MouseClick  or MouseOver or MouseLeave };
+        => entity is { Id.Name: MouseUsual or MouseClick or MouseOver or MouseLeave };
 }
 
 internal interface EntityInternal

src/NitroSharp/GameContext.cs

@@ -9,6 +9,7 @@
 using System.Threading.Tasks;
 using NitroSharp.Content;
 using NitroSharp.Graphics;
+using NitroSharp.Graphics.Core;
 using NitroSharp.Media;
 using NitroSharp.NsScript;
 using NitroSharp.NsScript.Compiler;
@@ -31,35 +32,24 @@ internal readonly record struct FrameStamp(long FrameId, long StopwatchTicks)
 
     internal enum DeferredOperationKind
     {
-        CaptureFramebuffer,
         SaveGame,
         LoadGame
     }
 
     internal readonly struct DeferredOperation
     {
         public DeferredOperationKind Kind { get; private init; }
-        public Texture? ScreenshotTexture { get; private init; }
         public uint? SaveSlot { get; private init; }
 
-        public static DeferredOperation CaptureFramebuffer(Texture dstTexture) => new()
-        {
-            Kind = DeferredOperationKind.CaptureFramebuffer,
-            ScreenshotTexture = dstTexture,
-            SaveSlot = null
-        };
-
         public static DeferredOperation SaveGame(uint slot) => new()
         {
             Kind = DeferredOperationKind.SaveGame,
-            ScreenshotTexture = null,
             SaveSlot = slot
         };
 
         public static DeferredOperation LoadGame(uint slot) => new()
         {
             Kind = DeferredOperationKind.LoadGame,
-            ScreenshotTexture = null,
             SaveSlot = slot
         };
     }
@@ -74,6 +64,7 @@ public sealed class GameContext : IAsyncDisposable
         private (string, MediaStream?) _activeVoice;
         private readonly Queue<DeferredOperation> _deferredOperations = new();
         private bool _clearFramebuffer;
+        private FrameStamp _now;
 
         private GameContext(
             Logger logger,
@@ -126,7 +117,7 @@ private GameContext(
 
         internal bool Skipping { get; private set; }
         internal bool Advance { get; set; }
-        internal Texture? LastScreenshot { get; private set; }
+
         internal EntityId FocusedUiElement { get; set; }
         internal NsFocusDirection? RequestedFocusChange { get; set; }
 
@@ -152,7 +143,6 @@ public static async Task<GameContext> Create(GameWindow window, Config config, G
             var saveManager = new GameSaveManager(profile);
             var renderContext = new RenderContext(
                 window,
-                config,
                 profile,
                 gd,
                 swapchain,
@@ -473,6 +463,7 @@ private void MainLoop()
         // necessary or until the engine is both feature-complete and stable.
         private void Tick(FrameStamp framestamp, float dt)
         {
+            _now = framestamp;
             RenderContext.BeginFrame(framestamp, _clearFramebuffer);
             _clearFramebuffer = true;
             InputContext.Update(VM.SystemVariables);
@@ -518,15 +509,21 @@ private void Tick(FrameStamp framestamp, float dt)
             ProcessSounds(world, dt);
             RenderFrame(framestamp, world.RenderItems, dt, assetsReady);
             HandleInput();
-            RunDeferredOperations();
 
             if (assetsReady)
             {
                 ActiveProcess.ProcessWaitOperations(this);
             }
+
+            if (assetsReady)
+            {
+                RunDeferredOperations();
+            }
+
+            RenderContext.EndFrame();
+
             try
             {
-                RenderContext.EndFrame();
                 RenderContext.Present();
             }
             catch (VeldridException e)
@@ -556,7 +553,7 @@ private void RenderFrame(
 
             foreach (RenderItem ri in active)
             {
-                ri.Render(RenderContext, assetsReady);
+                ri.Render(RenderContext);
             }
 
             RenderContext.TextureCache.BeginFrame(frameStamp);
@@ -626,8 +623,7 @@ private void CreateSysProcess(string mainModule)
             //_context.SysProcess?.Dispose();
             if (SysProcess is null)
             {
-                LastScreenshot ??= RenderContext.CreateFullscreenTexture(staging: true);
-                RenderContext.CaptureFramebuffer(LastScreenshot);
+                //LastScreenshot ??= TakeScreenshot(MainProcess);
                 MainProcess.VmProcess.Suspend();
                 SysProcess = CreateProcess(VM, mainModule, _fontSettings);
                 _clearFramebuffer = false;
@@ -641,10 +637,6 @@ private void RunDeferredOperations()
             {
                 switch (op.Kind)
                 {
-                    case DeferredOperationKind.CaptureFramebuffer:
-                        Debug.Assert(op.ScreenshotTexture is not null);
-                        RenderContext.CaptureFramebuffer(op.ScreenshotTexture);
-                        break;
                     case DeferredOperationKind.SaveGame:
                         Debug.Assert(op.SaveSlot is not null);
                         SaveManager.Save(this, op.SaveSlot.Value);
@@ -662,6 +654,27 @@ private void RunDeferredOperations()
             }
         }
 
+        internal PooledTexture RenderToTexture(GameProcess process)
+        {
+            return RenderContext.RenderToTexture(batch =>
+            {
+                ReadOnlySpan<RenderItem> activeItems = process.World.RenderItems.SortActive();
+                foreach (RenderItem renderItem in activeItems)
+                {
+                    renderItem.PerformLayout(this);
+                }
+
+                RenderContext.ResolveGlyphs();
+
+                foreach (RenderItem renderItem in activeItems)
+                {
+                    renderItem.Render(RenderContext, batch);
+                }
+
+                RenderContext.TextureCache.BeginFrame(_now);
+            });
+        }
+
         internal void Defer(in DeferredOperation operation)
         {
             ActiveProcess.VmProcess.Suspend();

src/NitroSharp/Graphics/Core/PooledTexture.cs

@@ -0,0 +1,23 @@
+using System;
+using Veldrid;
+
+namespace NitroSharp.Graphics.Core;
+
+internal readonly struct PooledTexture : IDisposable
+{
+    private readonly ResourcePool<Texture> _pool;
+    private readonly Texture _texture;
+
+    public PooledTexture(ResourcePool<Texture> pool, Texture texture)
+    {
+        _pool = pool;
+        _texture = texture;
+    }
+
+    public Texture Get() => _texture;
+
+    public void Dispose()
+    {
+        _pool.Return(_texture);
+    }
+}

src/NitroSharp/Graphics/DrawBatch.cs

@@ -173,7 +173,7 @@ internal sealed class DrawBatch : IDisposable
     {
         private readonly RenderContext _ctx;
         private CommandList? _commandList;
-
+        private bool _began;
         private Draw _lastDraw;
         private Vector2 _lastAlphaMaskPosition = new(float.NaN);
 
@@ -187,13 +187,16 @@ public DrawBatch(RenderContext context)
 
         public void Begin(CommandList commandList, RenderTarget target, RgbaFloat? clearColor)
         {
+            Debug.Assert(!_began);
             _commandList = commandList;
             commandList.SetFramebuffer(target.Framebuffer);
             Target = target;
             if (clearColor is { } clear)
             {
                 commandList.ClearColorTarget(0, clear);
             }
+
+            _began = true;
         }
 
         public void UpdateBuffer<T>(GpuBuffer<T> buffer, in T data)
@@ -218,7 +221,7 @@ public void PushQuad(
             QuadShaderResources resources = _ctx.ShaderResources.Quad;
             if (alphaMaskPosition != _lastAlphaMaskPosition)
             {
-                Vector4 newValue = new Vector4(alphaMaskPosition, 0, 0);
+                var newValue = new Vector4(alphaMaskPosition, 0, 0);
                 UpdateBuffer(resources.AlphaMaskPositionBuffer, newValue);
                 _lastAlphaMaskPosition = alphaMaskPosition;
             }
@@ -357,7 +360,15 @@ void setResources(uint slot, ResourceSetKey? rsKeyOpt)
             _lastDraw = default;
         }
 
-        public void End() => Flush();
-        public void Dispose() => Flush();
+        public void End()
+        {
+            Flush();
+            _began = false;
+        }
+
+        public void Dispose()
+        {
+            End();
+        }
     }
 }

src/NitroSharp/Graphics/Icon.cs

@@ -56,7 +56,7 @@ public static Icon Load(RenderContext renderContext, IconPathPattern pathPattern
             ContentManager content = renderContext.Content;
             ResourceFactory rf = renderContext.ResourceFactory;
             Texture? texture = null;
-            CommandList cl = renderContext.RentCommandList();
+            CommandList cl = renderContext.CommandListPool.Rent();
             cl.Begin();
             uint layer = 0;
             foreach (string path in pathPattern.EnumeratePaths())
@@ -80,7 +80,7 @@ public static Icon Load(RenderContext renderContext, IconPathPattern pathPattern
             }
             cl.End();
             renderContext.GraphicsDevice.SubmitCommands(cl);
-            renderContext.ReturnCommandList(cl);
+            renderContext.CommandListPool.Return(cl);
 
             Debug.Assert(texture is not null);
             return new Icon(texture);