feat(d3d12): unify resource mgmt & add pooling system

Refactored D3D12 resource and command management with a new D3D12Object<T> base class for unified lifetime and naming of COM objects. Introduced pooled command buffer and resource management in D3D12GraphicsEngine and ResourceManager, using frame-based return queues for safe reuse. Updated RenderSystem to use pooled command buffers and render requests, and to properly dispose of per-frame resources. Changed frame synchronization and resource release logic to use ulong fence/frame values for improved robustness. Refactored swap chain to DXGISwapChain and improved error handling and code clarity. Removed renderer management from IGraphicsEngine. Changed ResourceDesc, TextureDesc, and BufferDesc to record structs with equality and hashing for pooling.

BREAKING CHANGE: Renderer management APIs removed from IGraphicsEngine. Frame and resource synchronization now use ulong instead of uint. Resource pooling and command buffer pooling are now required for correct usage.

src/Runtime/Ghost.Graphics.D3D12/D3D12GraphicsEngine.cs

@@ -5,7 +5,6 @@
 using Ghost.Core;
 using Ghost.Graphics.Core;
 using Ghost.Graphics.RHI;
-using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 
@@ -22,6 +21,18 @@ public static class D3D12GraphicsEngineFactory
 
 internal class D3D12GraphicsEngine : IGraphicsEngine
 {
+    private readonly struct CommandBufferReturnEntry
+    {
+        public readonly ICommandBuffer commandBuffer;
+        public readonly ulong returnFrame;
+
+        public CommandBufferReturnEntry(ICommandBuffer commandBuffer, ulong returnFrame)
+        {
+            this.commandBuffer = commandBuffer;
+            this.returnFrame = returnFrame;
+        }
+    }
+
     private readonly GraphicsEngineDesc _desc;
 
 #if ENABLE_DEBUG_LAYER
@@ -34,8 +45,10 @@ internal class D3D12GraphicsEngine : IGraphicsEngine
     private readonly D3D12PipelineLibrary _pipelineLibrary;
     private readonly D3D12ResourceAllocator _resourceAllocator;
 
-    private ImmutableArray<IRenderer> _renderers;
+    private readonly Queue<ICommandBuffer> _commandBufferPool;
+    private readonly Queue<CommandBufferReturnEntry> _commandBufferReturnQueue;
 
+    private ulong _currentFrame;
     private bool _disposed;
 
     public IRenderDevice Device => _device;
@@ -59,9 +72,8 @@ internal class D3D12GraphicsEngine : IGraphicsEngine
         _pipelineLibrary = new D3D12PipelineLibrary(_device, _resourceDatabase);
         _resourceAllocator = new D3D12ResourceAllocator(_device, _descriptorAllocator, _resourceDatabase, _pipelineLibrary);
 
-        _renderers = ImmutableArray<IRenderer>.Empty;
-
-        _pipelineLibrary.InitializeLibrary(null);
+        _commandBufferPool = new Queue<ICommandBuffer>(4);
+        _commandBufferReturnQueue = new Queue<CommandBufferReturnEntry>(4);
     }
 
     ~D3D12GraphicsEngine()
@@ -76,27 +88,6 @@ internal class D3D12GraphicsEngine : IGraphicsEngine
         ObjectDisposedException.ThrowIf(_disposed, this);
     }
 
-    public IRenderer CreateRenderer()
-    {
-        ThrowIfDisposed();
-
-        var renderer = new D3D12Renderer(this);
-        ImmutableInterlocked.Update(ref _renderers, renderers => renderers.Add(renderer));
-        return renderer;
-    }
-
-    public void RemoveRenderer(IRenderer renderer)
-    {
-        ThrowIfDisposed();
-        ImmutableInterlocked.Update(ref _renderers, renderers => renderers.Remove(renderer));
-    }
-
-    public void ClearRenderers()
-    {
-        ThrowIfDisposed();
-        ImmutableInterlocked.Update(ref _renderers, renderers => renderers.Clear());
-    }
-
     public ICommandAllocator CreateCommandAllocator(CommandBufferType type = CommandBufferType.Graphics)
     {
         return new D3D12CommandAllocator(_device, type);
@@ -115,25 +106,51 @@ internal class D3D12GraphicsEngine : IGraphicsEngine
             type);
     }
 
+    public ICommandBuffer GetPooledCommandBuffer(CommandBufferType type = CommandBufferType.Graphics)
+    {
+        if (_commandBufferPool.TryDequeue(out var commandBuffer))
+        {
+            return commandBuffer;
+        }
+        else
+        {
+            return CreateCommandBuffer(type);
+        }
+    }
+
+    public void ReturnPooledCommandBuffer(ICommandBuffer commandBuffer)
+    {
+        _commandBufferReturnQueue.Enqueue(new CommandBufferReturnEntry(commandBuffer, _currentFrame));
+    }
+
+
     public ISwapChain CreateSwapChain(SwapChainDesc desc)
     {
         ThrowIfDisposed();
-        return new D3D12SwapChain(_resourceDatabase, _descriptorAllocator, _device, desc, _desc.FrameBufferCount);
+        return new DXGISwapChain(_resourceDatabase, _descriptorAllocator, _device, desc, _desc.FrameBufferCount);
     }
 
-    public Result BeginFrame(uint cpuFenceValue, uint gpuFenceValue)
+    public Result BeginFrame(ulong currentFrame)
     {
         ThrowIfDisposed();
 
-        _resourceDatabase.BeginFrame(cpuFenceValue);
+        _currentFrame = currentFrame;
+        _resourceDatabase.BeginFrame(currentFrame);
         return Result.Success();
     }
 
-    public Result EndFrame(uint cpuFenceValue, uint gpuFenceValue)
+    public Result EndFrame(ulong completedFrame)
     {
         ThrowIfDisposed();
 
-        _resourceDatabase.EndFrame(gpuFenceValue);
+        _resourceDatabase.EndFrame(completedFrame);
+
+        while (_commandBufferReturnQueue.TryPeek(out var entry) && entry.returnFrame <= completedFrame)
+        {
+            _commandBufferPool.Enqueue(entry.commandBuffer);
+            _commandBufferReturnQueue.Dequeue();
+        }
+
         return Result.Success();
     }
 
@@ -144,11 +161,6 @@ internal class D3D12GraphicsEngine : IGraphicsEngine
             return;
         }
 
-        foreach (var renderer in _renderers)
-        {
-            renderer.Dispose();
-        }
-
         _resourceDatabase.ReleaseAllResourcesImmediately();
 
         _resourceAllocator.Dispose();