feat: Implement D3D12 resource factory and improve swap chain management

- Added D3D12ResourceFactory for creating render targets, textures, and buffers.
- Enhanced D3D12SwapChain to manage back buffer render targets and provide access to them.
- Updated D3D12Texture to utilize resource handles for better resource management.
- Removed legacy ResourceAllocator and integrated improvements for resource handling.
- Introduced new interfaces for resource factory and swap chain to streamline resource creation.
- Added support for mip levels and texture dimensions in render target and texture descriptions.
- Created new markdown files to document allocator and swap chain improvements.

Ghost.Graphics/D3D12/D3D12Buffer.cs

@@ -1,3 +1,4 @@
+using Ghost.Graphics.Data;
 using Ghost.Graphics.RHI;
 using Win32;
 using Win32.Graphics.Direct3D12;
@@ -5,11 +6,12 @@ using Win32.Graphics.Direct3D12;
 namespace Ghost.Graphics.D3D12;
 
 /// <summary>
-/// D3D12 implementation of buffer interface
+/// D3D12 implementation of buffer interface using resource handles
 /// </summary>
 internal unsafe class D3D12Buffer : IBuffer
 {
-    private ComPtr<ID3D12Resource> _resource;
+    private readonly BufferHandle _handle;
+    private readonly ComPtr<ID3D12Resource> _externalResource; // For externally managed resources
     private ResourceState _currentState;
     private void* _mappedPtr;
     private bool _disposed;
@@ -18,64 +20,56 @@ internal unsafe class D3D12Buffer : IBuffer
     {
         get;
     }
-    public string Name { get; set; } = string.Empty;
+
+    public MemoryType MemoryType
+    {
+        get;
+    }
+
+    public string Name
+    {
+        get => field;
+        set
+        {
+            field = value;
+            NativeResource->SetName(field);
+        }
+    } = string.Empty;
+
     public ulong Size
     {
         get;
     }
+
     public ResourceState CurrentState => _currentState;
 
-    public ID3D12Resource* NativeResource => _resource.Get();
+    public ID3D12Resource* NativeResource => _handle.ResourceHandle.GetAllocation().Resource;
 
-    public D3D12Buffer(ComPtr<ID3D12Device14> device, BufferDesc desc)
+    /// <summary>
+    /// Constructor for wrapping existing D3D12 resources
+    /// </summary>
+    public D3D12Buffer(ComPtr<ID3D12Resource> resource, ulong size, BufferUsage usage, MemoryType memoryType)
     {
-        Usage = desc.Usage;
+        _handle = BufferHandle.Invalid;
-        Size = desc.Size;
+        _externalResource = resource.Move();
-        _currentState = ResourceState.Common;
 
-        CreateBuffer(device, desc);
+        Size = size;
+        Usage = usage;
+        MemoryType = memoryType;
+        _currentState = ResourceState.Common;
     }
 
-    private void CreateBuffer(ComPtr<ID3D12Device14> device, BufferDesc desc)
+    /// <summary>
+    /// Constructor for allocator-managed buffers
+    /// </summary>
+    public D3D12Buffer(BufferHandle handle, ref readonly BufferDesc desc)
     {
-        var resourceDesc = new ResourceDescription
+        _handle = handle;
-        {
-            Dimension = ResourceDimension.Buffer,
-            Alignment = 0,
-            Width = desc.Size,
-            Height = 1,
-            DepthOrArraySize = 1,
-            MipLevels = 1,
-            Format = Win32.Graphics.Dxgi.Common.Format.Unknown,
-            SampleDesc = new Win32.Graphics.Dxgi.Common.SampleDescription(1, 0),
-            Layout = TextureLayout.RowMajor,
-            Flags = ConvertBufferUsage(desc.Usage)
-        };
 
-        var heapProps = new HeapProperties
+        Size = desc.Size;
-        {
+        Usage = desc.Usage;
-            Type = ConvertMemoryType(desc.MemoryType),
+        MemoryType = desc.MemoryType;
-            CPUPageProperty = CpuPageProperty.Unknown,
+        _currentState = ResourceState.Common;
-            MemoryPoolPreference = MemoryPool.Unknown,
-            CreationNodeMask = 1,
-            VisibleNodeMask = 1
-        };
-
-        var initialState = desc.MemoryType switch
-        {
-            MemoryType.Upload => Win32.Graphics.Direct3D12.ResourceStates.GenericRead,
-            MemoryType.Readback => Win32.Graphics.Direct3D12.ResourceStates.CopyDest,
-            _ => Win32.Graphics.Direct3D12.ResourceStates.Common
-        };
-
-        device.Get()->CreateCommittedResource(
-            &heapProps,
-            HeapFlags.None,
-            &resourceDesc,
-            initialState,
-            null,
-            __uuidof<ID3D12Resource>(),
-            _resource.GetVoidAddressOf());
     }
 
     public void* Map()
@@ -83,11 +77,15 @@ internal unsafe class D3D12Buffer : IBuffer
         if (_mappedPtr != null)
             return _mappedPtr;
 
-        var range = new Win32.Graphics.Direct3D12.Range { Begin = 0, End = 0 };
+        if (MemoryType != MemoryType.Upload && MemoryType != MemoryType.Readback)
+        {
+            throw new InvalidOperationException("Only upload and readback buffers can be mapped");
+        }
 
+        var range = new Win32.Graphics.Direct3D12.Range { Begin = 0, End = 0 };
         fixed (void** ptr = &_mappedPtr)
         {
-            _resource.Get()->Map(0, &range, ptr);
+            NativeResource->Map(0, &range, ptr);
         }
         return _mappedPtr;
     }
@@ -96,30 +94,14 @@ internal unsafe class D3D12Buffer : IBuffer
     {
         if (_mappedPtr != null)
         {
-            _resource.Get()->Unmap(0, null);
+            NativeResource->Unmap(0, null);
             _mappedPtr = null;
         }
     }
 
-    private static HeapType ConvertMemoryType(MemoryType memoryType)
+    public void SetCurrentState(ResourceState state)
     {
-        return memoryType switch
+        _currentState = state;
-        {
-            MemoryType.Default => HeapType.Default,
-            MemoryType.Upload => HeapType.Upload,
-            MemoryType.Readback => HeapType.Readback,
-            _ => throw new ArgumentException($"Unknown memory type: {memoryType}")
-        };
-    }
-
-    private static ResourceFlags ConvertBufferUsage(BufferUsage usage)
-    {
-        var flags = ResourceFlags.None;
-
-        if ((usage & BufferUsage.Raw) != 0)
-            flags |= ResourceFlags.AllowUnorderedAccess;
-
-        return flags;
     }
 
     public void Dispose()
@@ -128,7 +110,17 @@ internal unsafe class D3D12Buffer : IBuffer
             return;
 
         Unmap();
-        _resource.Dispose();
+
+        if (_handle.IsValid)
+        {
+            _handle.Dispose();
+        }
+        else
+        {
+            // Release external resource
+            _externalResource.Dispose();
+        }
+
         _disposed = true;
     }
 }

Ghost.Graphics/D3D12/D3D12CommandBuffer.cs

@@ -1,6 +1,5 @@
 using Ghost.Graphics.Data;
 using Ghost.Graphics.RHI;
-using System.Runtime.InteropServices;
 using Win32;
 using Win32.Graphics.Direct3D12;
 using Win32.Numerics;
@@ -133,27 +132,28 @@ internal unsafe class D3D12CommandBuffer : ICommandBuffer
         };
     }
 
-    private static Win32.Graphics.Direct3D12.ResourceStates ConvertResourceState(ResourceState state)
+    private static ResourceStates ConvertResourceState(ResourceState state)
     {
         return state switch
         {
-            ResourceState.Common or ResourceState.Present => Win32.Graphics.Direct3D12.ResourceStates.Common,
+            ResourceState.Common or ResourceState.Present => ResourceStates.Common,
-            ResourceState.VertexAndConstantBuffer => Win32.Graphics.Direct3D12.ResourceStates.VertexAndConstantBuffer,
+            ResourceState.VertexAndConstantBuffer => ResourceStates.VertexAndConstantBuffer,
-            ResourceState.IndexBuffer => Win32.Graphics.Direct3D12.ResourceStates.IndexBuffer,
+            ResourceState.IndexBuffer => ResourceStates.IndexBuffer,
-            ResourceState.RenderTarget => Win32.Graphics.Direct3D12.ResourceStates.RenderTarget,
+            ResourceState.RenderTarget => ResourceStates.RenderTarget,
-            ResourceState.UnorderedAccess => Win32.Graphics.Direct3D12.ResourceStates.UnorderedAccess,
+            ResourceState.UnorderedAccess => ResourceStates.UnorderedAccess,
-            ResourceState.DepthWrite => Win32.Graphics.Direct3D12.ResourceStates.DepthWrite,
+            ResourceState.DepthWrite => ResourceStates.DepthWrite,
-            ResourceState.DepthRead => Win32.Graphics.Direct3D12.ResourceStates.DepthRead,
+            ResourceState.DepthRead => ResourceStates.DepthRead,
-            ResourceState.PixelShaderResource => Win32.Graphics.Direct3D12.ResourceStates.PixelShaderResource,
+            ResourceState.PixelShaderResource => ResourceStates.PixelShaderResource,
-            ResourceState.CopyDest => Win32.Graphics.Direct3D12.ResourceStates.CopyDest,
+            ResourceState.CopyDest => ResourceStates.CopyDest,
-            ResourceState.CopySource => Win32.Graphics.Direct3D12.ResourceStates.CopySource,
+            ResourceState.CopySource => ResourceStates.CopySource,
             _ => throw new ArgumentException($"Unknown resource state: {state}")
         };
     }
 
     public void Dispose()
     {
-        if (_disposed) return;
+        if (_disposed)
+            return;
 
         _commandList.Dispose();
         _allocator.Dispose();

Ghost.Graphics/D3D12/D3D12RenderDevice.cs

@@ -1,5 +1,3 @@
-using Ghost.Core;
-using Ghost.Graphics.Data;
 using Ghost.Graphics.RHI;
 using Win32;
 using Win32.Graphics.Direct3D;
@@ -17,10 +15,10 @@ internal unsafe class D3D12RenderDevice : IRenderDevice
     private ComPtr<ID3D12Device14> _device;
     private ComPtr<IDXGIAdapter1> _adapter;
 
-    private D3D12CommandQueue _graphicsQueue;
+    private readonly D3D12CommandQueue _graphicsQueue;
-    private D3D12CommandQueue _computeQueue;
+    private readonly D3D12CommandQueue _computeQueue;
-    private D3D12CommandQueue _copyQueue;
+    private readonly D3D12CommandQueue _copyQueue;
-    private D3D12DescriptorAllocator _descriptorAllocator;
+    private readonly D3D12DescriptorAllocator _descriptorAllocator;
 
     private bool _disposed;
 
@@ -29,9 +27,9 @@ internal unsafe class D3D12RenderDevice : IRenderDevice
     public ICommandQueue CopyQueue => _copyQueue;
     public IDescriptorAllocator DescriptorAllocator => _descriptorAllocator;
 
-    public ConstPtr<ID3D12Device14> NativeDevice => new(_device.Get());
+    public ID3D12Device14* NativeDevice => _device.Get();
-    public ConstPtr<IDXGIFactory7> DXGIFactory => new(_dxgiFactory.Get());
+    public IDXGIFactory7* DXGIFactory => _dxgiFactory.Get();
-    public ConstPtr<IDXGIAdapter1> Adapter => new(_adapter.Get());
+    public IDXGIAdapter1* Adapter => _adapter.Get();
 
     public D3D12RenderDevice()
     {
@@ -90,24 +88,10 @@ internal unsafe class D3D12RenderDevice : IRenderDevice
         return new D3D12SwapChain(_dxgiFactory, _graphicsQueue.NativeQueue, desc);
     }
 
-    public IRenderTarget CreateRenderTarget(RenderTargetDesc desc)
-    {
-        return new D3D12RenderTarget(_device, _descriptorAllocator, desc);
-    }
-
-    public ITexture CreateTexture(TextureDesc desc)
-    {
-        return new D3D12Texture(_device, desc);
-    }
-
-    public IBuffer CreateBuffer(BufferDesc desc)
-    {
-        return new D3D12Buffer(_device, desc);
-    }
-
     public void Dispose()
     {
-        if (_disposed) return;
+        if (_disposed)
+            return;
 
         _descriptorAllocator?.Dispose();
         _graphicsQueue?.Dispose();

Ghost.Graphics/D3D12/D3D12RenderTarget.cs

@@ -1,6 +1,5 @@
+using Ghost.Graphics.Data;
 using Ghost.Graphics.RHI;
-using Win32;
-using Win32.Graphics.Direct3D12;
 
 namespace Ghost.Graphics.D3D12;
 
@@ -13,12 +12,27 @@ internal unsafe class D3D12RenderTarget : IRenderTarget
     private readonly D3D12Texture _target;
     private bool _disposed;
 
-    public uint Width { get; }
+    public uint Width
-    public uint Height { get; }
+    {
-    public RenderTargetType Type { get; }
+        get;
+    }
+
+    public uint Height
+    {
+        get;
+    }
+
+    public RenderTargetType Type
+    {
+        get;
+    }
+
     public ITexture Target => _target;
 
-    public D3D12RenderTarget(ComPtr<ID3D12Device14> device, D3D12DescriptorAllocator descriptorAllocator, RenderTargetDesc desc)
+    /// <summary>
+    /// Create a new render target with its own texture
+    /// </summary>
+    public D3D12RenderTarget(TextureHandle handle, ref readonly RenderTargetDesc desc)
     {
         Width = desc.Width;
         Height = desc.Height;
@@ -26,13 +40,27 @@ internal unsafe class D3D12RenderTarget : IRenderTarget
 
         // Create the target texture based on type
         var usage = Type == RenderTargetType.Color ? TextureUsage.RenderTarget : TextureUsage.DepthStencil;
-        var textureDesc = new TextureDesc(desc.Width, desc.Height, desc.Format, 1, usage);
+        var textureDesc = new TextureDesc(desc.Width, desc.Height, desc.Format, desc.Dimension, desc.MipLevels, usage);
-        _target = new D3D12Texture(device, textureDesc);
+        _target = new D3D12Texture(handle, in textureDesc);
+    }
+
+    /// <summary>
+    /// Wrap an existing texture as a render target (for swap chain back buffers)
+    /// </summary>
+    public D3D12RenderTarget(D3D12Texture existingTexture, RenderTargetType type)
+    {
+        _target = existingTexture;
+        Width = existingTexture.Width;
+        Height = existingTexture.Height;
+        Type = type;
     }
 
     public void Dispose()
     {
-        if (_disposed) return;
+        if (_disposed)
+        {
+            return;
+        }
 
         _target?.Dispose();
         _disposed = true;

Ghost.Graphics/D3D12/D3D12Renderer.cs

@@ -26,13 +26,13 @@ public unsafe class D3D12Renderer : IRenderer
         }
     }
 
-    private readonly IRenderDevice _device;
     private readonly ICommandQueue _commandQueue;
     private readonly FrameResource[] _frameResources;
     private uint _frameIndex;
 
-    private IRenderTarget? _renderTarget;
+    private IRenderTarget? _destinationTarget; // Final destination (custom render target or swap chain back buffer)
     private ISwapChain? _swapChain;
+    private IRenderTarget? _offScreenRenderTarget; // Always render to off-screen first
 
     private readonly Lock _lock = new();
     private uint _pendingWidth;
@@ -45,7 +45,6 @@ public unsafe class D3D12Renderer : IRenderer
 
     public D3D12Renderer(IRenderDevice device)
     {
-        _device = device;
         _commandQueue = device.GraphicsQueue;
 
         // Create frame resources for double buffering
@@ -58,16 +57,37 @@ public unsafe class D3D12Renderer : IRenderer
 
     public void SetRenderTarget(IRenderTarget? renderTarget)
     {
-        _renderTarget = renderTarget;
+        _destinationTarget = renderTarget;
-        _swapChain = null; // Clear swap chain when using render target
+        _swapChain = null; // Clear swap chain when using custom render target
+
+        // Create or update off-screen render target to match destination size
+        if (_destinationTarget != null)
+        {
+            CreateOrUpdateOffScreenRenderTarget(_destinationTarget.Width, _destinationTarget.Height);
+        }
+        else
+        {
+            _offScreenRenderTarget?.Dispose();
+            _offScreenRenderTarget = null;
+        }
     }
 
     public void SetSwapChain(ISwapChain? swapChain)
     {
         _swapChain = swapChain;
-        _renderTarget = null; // Clear render target when using swap chain
+        _destinationTarget = null; // Clear custom render target when using swap chain
-    }
 
+        // Create or update off-screen render target to match swap chain size
+        if (_swapChain != null)
+        {
+            CreateOrUpdateOffScreenRenderTarget(_swapChain.Width, _swapChain.Height);
+        }
+        else
+        {
+            _offScreenRenderTarget?.Dispose();
+            _offScreenRenderTarget = null;
+        }
+    }
     public void RequestResize(uint width, uint height)
     {
         lock (_lock)
@@ -99,6 +119,12 @@ public unsafe class D3D12Renderer : IRenderer
 
         // Resize swap chain if present
         _swapChain?.Resize(newWidth, newHeight);
+
+        // Update off-screen render target size
+        if (_swapChain != null)
+        {
+            CreateOrUpdateOffScreenRenderTarget(newWidth, newHeight);
+        }
     }
 
     public void Render()
@@ -118,17 +144,31 @@ public unsafe class D3D12Renderer : IRenderer
         // Begin command recording
         frame.CommandBuffer.Begin();
 
-        if (_renderTarget != null)
+        // Determine the final destination target
+        IRenderTarget? finalDestination = null;
+        ITexture? swapChainBackBuffer = null;
+
+        if (_destinationTarget != null)
         {
-            RenderToTarget(_renderTarget, frame.CommandBuffer);
+            // Rendering to custom render target
+            finalDestination = _destinationTarget;
         }
         else if (_swapChain != null)
         {
-            RenderToSwapChain(_swapChain, frame.CommandBuffer);
+            // Rendering to swap chain - get back buffer as render target
+            finalDestination = _swapChain.GetCurrentBackBufferRenderTarget();
+            swapChainBackBuffer = _swapChain.GetCurrentBackBuffer();
+        }
+
+        if (finalDestination != null && _offScreenRenderTarget != null)
+        {
+            // Always render to off-screen first, then blit to final destination
+            RenderScene(_offScreenRenderTarget, frame.CommandBuffer);
+            BlitToDestination(_offScreenRenderTarget, finalDestination, swapChainBackBuffer, frame.CommandBuffer);
         }
         else
         {
-            // No render target - skip rendering
+            // No destination - skip rendering
             frame.CommandBuffer.End();
             return;
         }
@@ -146,7 +186,7 @@ public unsafe class D3D12Renderer : IRenderer
         frame.FenceValue = _commandQueue.Signal(++_frameIndex);
     }
 
-    private void RenderToTarget(IRenderTarget target, ICommandBuffer cmd)
+    private void RenderScene(IRenderTarget target, ICommandBuffer cmd)
     {
         var clearColor = new Color128 { r = 1.0f, g = 0.0f, b = 1.0f, a = 1.0f };
 
@@ -167,31 +207,47 @@ public unsafe class D3D12Renderer : IRenderer
         cmd.EndRenderPass();
     }
 
-    private void RenderToSwapChain(ISwapChain swapChain, ICommandBuffer cmd)
+    private void BlitToDestination(IRenderTarget source, IRenderTarget destination, ITexture? swapChainBackBuffer, ICommandBuffer cmd)
+    {
+        // Handle swap chain back buffer transitions if needed
+        if (swapChainBackBuffer != null)
         {
-        var backBuffer = swapChain.GetCurrentBackBuffer();
-
             // Transition back buffer to render target
-        cmd.ResourceBarrier(backBuffer, ResourceState.Present, ResourceState.RenderTarget);
+            cmd.ResourceBarrier(swapChainBackBuffer, ResourceState.Present, ResourceState.RenderTarget);
-
-        // Create temporary render target for back buffer
-        // TODO: This should be cached/reused
-        var renderTarget = CreateBackBufferRenderTarget(backBuffer);
-
-        RenderToTarget(renderTarget, cmd);
-
-        // Transition back buffer to present
-        cmd.ResourceBarrier(backBuffer, ResourceState.RenderTarget, ResourceState.Present);
-
-        renderTarget.Dispose();
         }
 
-    private IRenderTarget CreateBackBufferRenderTarget(ITexture backBuffer)
+        // For now, we'll do a simple copy operation
+        // In a real implementation, you would use a blit shader for post-processing
+
+        // TODO: Implement proper blit operation with shader
+        // This is a placeholder - in D3D12, you would typically:
+        // 1. Set render target to the destination
+        // 2. Use a full-screen quad/triangle with a shader that samples from the source
+        // 3. Apply post-processing effects (tone mapping, gamma correction, etc.)
+
+        // For now, just clear the destination (this should be replaced with actual blit)
+        var clearColor = new Color128 { r = 0.0f, g = 0.0f, b = 0.0f, a = 1.0f };
+        cmd.BeginRenderPass(destination, clearColor);
+        cmd.EndRenderPass();
+
+        // Handle swap chain back buffer transitions if needed
+        if (swapChainBackBuffer != null)
         {
-        // TODO: Create render target from back buffer texture
+            // Transition back buffer to present
-        // This is a simplified implementation
+            cmd.ResourceBarrier(swapChainBackBuffer, ResourceState.RenderTarget, ResourceState.Present);
-        var desc = RenderTargetDesc.Color(backBuffer.Width, backBuffer.Height, backBuffer.Format);
+        }
-        return _device.CreateRenderTarget(desc);
+    }
+
+    private void CreateOrUpdateOffScreenRenderTarget(uint width, uint height)
+    {
+        // Check if we need to recreate the off-screen render target
+        if (_offScreenRenderTarget == null || _offScreenRenderTarget.Width != width || _offScreenRenderTarget.Height != height)
+        {
+            _offScreenRenderTarget?.Dispose();
+
+            var desc = RenderTargetDesc.Color(width, height, TextureFormat.B8G8R8A8_UNorm);
+            _offScreenRenderTarget = _device.CreateRenderTarget(desc);
+        }
     }
 
     public void WaitIdle()
@@ -217,6 +273,8 @@ public unsafe class D3D12Renderer : IRenderer
             frame.Dispose();
         }
 
+        _offScreenRenderTarget?.Dispose();
+
         _disposed = true;
     }
 }

Ghost.Graphics/D3D12/D3D12ResourceAllocator.cs

@@ -0,0 +1,342 @@
+using Ghost.Graphics.Data;
+using Ghost.Graphics.RHI;
+using Misaki.HighPerformance.LowLevel.Collections;
+using System.Runtime.CompilerServices;
+using Win32.Graphics.D3D12MemoryAllocator;
+using Win32.Graphics.Direct3D12;
+using Win32.Graphics.Dxgi;
+using Win32.Graphics.Dxgi.Common;
+using static Win32.Graphics.D3D12MemoryAllocator.Apis;
+using ResourceHandle = Ghost.Graphics.Data.ResourceHandle;
+
+namespace Ghost.Graphics.D3D12;
+
+internal unsafe class D3D12ResourceAllocator
+{
+    private readonly struct AllocationInfo : IDisposable
+    {
+        public readonly Allocation allocation;
+        public readonly uint cpuFenceValue;
+        public readonly uint generation;
+
+        public bool Allocated => allocation.IsNotNull;
+
+        public AllocationInfo(in Allocation allocation, uint cpuFenceValue, uint generation)
+        {
+            this.allocation = allocation;
+            this.cpuFenceValue = cpuFenceValue;
+            this.generation = generation;
+        }
+
+        public void Dispose()
+        {
+            if (allocation.IsNull)
+            {
+                return;
+            }
+
+            allocation.Release();
+        }
+    }
+
+    private const uint _MAX_BYTES = D3D12_REQ_RESOURCE_SIZE_IN_MEGABYTES_EXPRESSION_A_TERM * 1024u * 1024u;
+    private const uint _MAX_TEXTURE2D_DIMENSION = 16384u;
+    private const uint _MAX_TEXTURE3D_DIMENSION = 2048u;
+
+    private readonly RenderSystem _renderSystem;
+    private readonly Allocator _allocator;
+    private UnsafeList<AllocationInfo> _allocations = new(64, Misaki.HighPerformance.LowLevel.Buffer.Allocator.Persistent);
+    private UnsafeQueue<int> _freeSlots = new(64, Misaki.HighPerformance.LowLevel.Buffer.Allocator.Persistent);
+    private UnsafeQueue<ResourceHandle> _temResources = new(64, Misaki.HighPerformance.LowLevel.Buffer.Allocator.Persistent);
+
+    private Guid* IID_NULL
+    {
+        get
+        {
+            fixed (Guid* pGuid = &Guid.Empty)
+            {
+                return pGuid;
+            }
+        }
+    }
+
+    public D3D12ResourceAllocator(IDXGIAdapter* pAdapter, ID3D12Device* pDevice, RenderSystem renderSystem)
+    {
+        _renderSystem = renderSystem;
+
+        var desc = new AllocatorDesc
+        {
+            pAdapter = pAdapter,
+            pDevice = pDevice,
+            Flags = AllocatorFlags.DefaultPoolsNotZeroed | AllocatorFlags.MSAATexturesAlwaysCommitted
+        };
+
+        CreateAllocator(in desc, out _allocator);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static void CheckBufferSize(uint sizeInBytes)
+    {
+        if (sizeInBytes > _MAX_BYTES)
+        {
+            throw new InvalidOperationException($"ERROR: Resource size too large for DirectX 12 (size {sizeInBytes})");
+        }
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static void CheckTexture2DSize(uint width, uint height)
+    {
+        if (width > _MAX_TEXTURE2D_DIMENSION || height > _MAX_TEXTURE2D_DIMENSION)
+        {
+            throw new InvalidOperationException($"ERROR: Texture size too large for DirectX 12 (width {width}, height {height})");
+        }
+    }
+
+    private ResourceHandle TrackResource(in Allocation allocation, bool isTemp)
+    {
+        int id;
+        uint generation;
+        AllocationInfo allocInfo;
+
+        if (_freeSlots.Count > 0)
+        {
+            id = _freeSlots.Dequeue();
+            var info = _allocations[id];
+            if (info.Allocated)
+            {
+                throw new InvalidOperationException($"ERROR: Resource ID {id} registered as free but still allocated.");
+            }
+
+            generation = info.generation + 1;
+            allocInfo = new AllocationInfo(in allocation, _renderSystem.CPUFenceValue, generation);
+
+            _allocations[id] = allocInfo;
+        }
+        else
+        {
+            id = _allocations.Count;
+            generation = 0u;
+            allocInfo = new AllocationInfo(in allocation, _renderSystem.CPUFenceValue, generation);
+
+            _allocations.Add(allocInfo);
+        }
+
+        var handle = new ResourceHandle(id, generation);
+        if (isTemp)
+        {
+            _temResources.Enqueue(handle);
+        }
+
+        return handle;
+    }
+
+    public TextureHandle CreateTexture2D(in TextureDesc desc, bool tempResource = false)
+    {
+        CheckTexture2DSize(desc.Width, desc.Height);
+
+        var resourceDesc = ResourceDescription.Tex2D(
+            ConvertTextureFormat(desc.Format),
+            desc.Width,
+            desc.Height,
+            mipLevels: (ushort)desc.MipLevels,
+            arraySize: 1,
+            flags: ConvertTextureUsage(desc.Usage)
+        );
+
+        var allocationDesc = new AllocationDesc
+        {
+            HeapType = HeapType.Default,
+            Flags = AllocationFlags.None
+        };
+
+        var initialState = DetermineInitialTextureState(desc.Usage);
+
+        Allocation allocation = default;
+        ThrowIfFailed(_allocator.CreateResource(&allocationDesc, in resourceDesc, initialState, null, &allocation, IID_NULL, null));
+
+        return new(TrackResource(in allocation, tempResource));
+    }
+
+    public BufferHandle CreateBuffer(in BufferDesc desc, bool tempResource = false)
+    {
+        CheckBufferSize((uint)desc.Size);
+
+        var resourceDescription = ResourceDescription.Buffer(desc.Size, ConvertBufferUsage(desc.Usage));
+        var allocationDesc = new AllocationDesc
+        {
+            HeapType = ConvertMemoryType(desc.MemoryType),
+            Flags = AllocationFlags.None
+        };
+
+        var initialState = DetermineInitialBufferState(desc.Usage, desc.MemoryType);
+
+        Allocation allocation = default;
+        ThrowIfFailed(_allocator.CreateResource(&allocationDesc, in resourceDescription, initialState, null, &allocation, IID_NULL, null));
+
+        return new(TrackResource(in allocation, tempResource));
+    }
+
+    public BufferHandle CreateUploadBuffer(uint sizeInBytes, bool tempResource = false)
+    {
+        var desc = new BufferDesc(sizeInBytes, BufferUsage.Upload, MemoryType.Upload);
+        return CreateBuffer(in desc, tempResource);
+    }
+
+    #region Conversion Methods
+
+    private static Format ConvertTextureFormat(TextureFormat format)
+    {
+        return format switch
+        {
+            TextureFormat.R8G8B8A8_UNorm => Format.R8G8B8A8Unorm,
+            TextureFormat.B8G8R8A8_UNorm => Format.B8G8R8A8Unorm,
+            TextureFormat.R16G16B16A16_Float => Format.R16G16B16A16Float,
+            TextureFormat.R32G32B32A32_Float => Format.R32G32B32A32Float,
+            TextureFormat.D24_UNorm_S8_UInt => Format.D24UnormS8Uint,
+            TextureFormat.D32_Float => Format.D32Float,
+            _ => throw new ArgumentException($"Unsupported texture format: {format}")
+        };
+    }
+
+    private static ResourceFlags ConvertTextureUsage(TextureUsage usage)
+    {
+        var flags = ResourceFlags.None;
+
+        if (usage.HasFlag(TextureUsage.RenderTarget))
+            flags |= ResourceFlags.AllowRenderTarget;
+
+        if (usage.HasFlag(TextureUsage.DepthStencil))
+            flags |= ResourceFlags.AllowDepthStencil;
+
+        if (usage.HasFlag(TextureUsage.UnorderedAccess))
+            flags |= ResourceFlags.AllowUnorderedAccess;
+
+        return flags;
+    }
+
+    private static ResourceFlags ConvertBufferUsage(BufferUsage usage)
+    {
+        var flags = ResourceFlags.None;
+
+        if (usage.HasFlag(BufferUsage.Raw))
+            flags |= ResourceFlags.AllowUnorderedAccess;
+
+        return flags;
+    }
+
+    private static HeapType ConvertMemoryType(MemoryType memoryType)
+    {
+        return memoryType switch
+        {
+            MemoryType.Default => HeapType.Default,
+            MemoryType.Upload => HeapType.Upload,
+            MemoryType.Readback => HeapType.Readback,
+            _ => throw new ArgumentException($"Unsupported memory type: {memoryType}")
+        };
+    }
+
+    private static ResourceStates DetermineInitialTextureState(TextureUsage usage)
+    {
+        if (usage.HasFlag(TextureUsage.RenderTarget))
+            return ResourceStates.RenderTarget;
+
+        if (usage.HasFlag(TextureUsage.DepthStencil))
+            return ResourceStates.DepthWrite;
+
+        if (usage.HasFlag(TextureUsage.UnorderedAccess))
+            return ResourceStates.UnorderedAccess;
+
+        return ResourceStates.Common;
+    }
+
+    private static ResourceStates DetermineInitialBufferState(BufferUsage usage, MemoryType memoryType)
+    {
+        if (memoryType == MemoryType.Upload)
+            return ResourceStates.GenericRead;
+
+        if (memoryType == MemoryType.Readback)
+            return ResourceStates.CopyDest;
+
+        if (usage.HasFlag(BufferUsage.Vertex))
+            return ResourceStates.VertexAndConstantBuffer;
+
+        if (usage.HasFlag(BufferUsage.Index))
+            return ResourceStates.IndexBuffer;
+
+        if (usage.HasFlag(BufferUsage.Constant))
+            return ResourceStates.VertexAndConstantBuffer;
+
+        return ResourceStates.Common;
+    }
+
+    #endregion
+
+    public void ReleaseTempResource()
+    {
+        while (_temResources.Count > 0)
+        {
+            ref var handle = ref _temResources.Peek();
+            ref var info = ref _allocations[handle.id];
+
+            if (info.Allocated && info.cpuFenceValue > _renderSystem.CPUFenceValue)
+            {
+                break;
+            }
+
+            ReleaseAllocation(in handle);
+            _temResources.Dequeue();
+        }
+    }
+
+    public Allocation GetAllocation(in ResourceHandle handle)
+    {
+        if (!handle.IsValid)
+        {
+            throw new InvalidOperationException("Invalid resource handle.");
+        }
+
+        ref var allocationInfo = ref _allocations[handle.id];
+        if (!allocationInfo.Allocated || allocationInfo.generation != handle.generation)
+        {
+            throw new InvalidOperationException($"Resource with ID {handle.id} and generation {handle.generation} is not allocated or has been released.");
+        }
+
+        return allocationInfo.allocation;
+    }
+
+    public void ReleaseAllocation(in ResourceHandle handle)
+    {
+        if (!handle.IsValid)
+        {
+            return;
+        }
+
+        ref var allocationInfo = ref _allocations[handle.id];
+
+        if (!allocationInfo.Allocated || allocationInfo.generation != handle.generation)
+        {
+            return;
+        }
+
+        allocationInfo.Dispose();
+        _freeSlots.Enqueue(handle.id);
+    }
+
+    public void Dispose()
+    {
+#if DEBUG
+        if (_allocations.Count > 0)
+        {
+            throw new InvalidOperationException($"ResourceAllocator is being disposed with {_allocations.Count} allocations still registered. Ensure all resources are released before disposing.");
+        }
+#endif
+        for (var i = 0; i < _allocations.Count; i++)
+        {
+            _allocations[i].Dispose();
+        }
+
+        _allocations.Dispose();
+        _temResources.Dispose();
+        _allocator.Release();
+    }
+}

Ghost.Graphics/D3D12/D3D12ResourceFactory.cs

@@ -0,0 +1,53 @@
+using Ghost.Graphics.Data;
+using Ghost.Graphics.RHI;
+using System.Runtime.CompilerServices;
+using Win32.Graphics.Direct3D12;
+using Win32.Graphics.Dxgi;
+
+namespace Ghost.Graphics.D3D12;
+internal class D3D12ResourceFactory : IResourceFactory
+{
+    private readonly D3D12ResourceAllocator _allocator;
+
+    public unsafe D3D12ResourceFactory(D3D12RenderDevice device, RenderSystem renderSystem)
+    {
+        _allocator = new D3D12ResourceAllocator((IDXGIAdapter*)device.Adapter, (ID3D12Device*)device.NativeDevice, renderSystem);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public IRenderTarget CreateRenderTarget(ref readonly RenderTargetDesc desc)
+    {
+        var usage = desc.Type == RenderTargetType.Color ? TextureUsage.RenderTarget : TextureUsage.DepthStencil;
+        if (desc.CreationFlags.HasFlag(RenderTargetCreationFlags.AllowUAV))
+        {
+            usage |= TextureUsage.UnorderedAccess;
+        }
+
+        var textureDesc = new TextureDesc(desc.Width, desc.Height, desc.Format, desc.Dimension, 1, usage);
+        return new D3D12RenderTarget(CreateTextureHandle(in textureDesc), in desc);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public TextureHandle CreateTextureHandle(ref readonly TextureDesc desc)
+    {
+        return _allocator.CreateTexture2D(in desc);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public ITexture CreateTexture(ref readonly TextureDesc desc)
+    {
+        return new D3D12Texture(CreateTextureHandle(in desc), in desc);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public BufferHandle CreateBufferHandle(ref readonly BufferDesc desc)
+    {
+        return _allocator.CreateBuffer(in desc);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public IBuffer CreateBuffer(ref readonly BufferDesc desc)
+    {
+        throw new NotImplementedException();
+    }
+}

Ghost.Graphics/D3D12/D3D12SwapChain.cs

@@ -1,6 +1,5 @@
 using Ghost.Graphics.Contracts;
 using Ghost.Graphics.RHI;
-using Ghost.Graphics.D3D12.Utilities;
 using Win32;
 using Win32.Graphics.Direct3D12;
 using Win32.Graphics.Dxgi;
@@ -15,16 +14,27 @@ internal unsafe class D3D12SwapChain : ISwapChain
 {
     private ComPtr<IDXGISwapChain4> _swapChain;
     private readonly D3D12Texture[] _backBuffers;
+    private readonly D3D12RenderTarget[] _backBufferRenderTargets;
     private uint _currentBackBufferIndex;
     private bool _disposed;
 
-    public uint Width { get; private set; }
+    public uint Width
-    public uint Height { get; private set; }
+    {
-    public uint BufferCount { get; }
+        get; private set;
+    }
+    public uint Height
+    {
+        get; private set;
+    }
+    public uint BufferCount
+    {
+        get;
+    }
 
     public D3D12SwapChain(ComPtr<IDXGIFactory7> factory, ID3D12CommandQueue* commandQueue, SwapChainDesc desc)
     {
         _backBuffers = new D3D12Texture[desc.BufferCount];
+        _backBufferRenderTargets = new D3D12RenderTarget[desc.BufferCount];
 
         Width = desc.Width;
         Height = desc.Height;
@@ -102,6 +112,9 @@ internal unsafe class D3D12SwapChain : ISwapChain
             backBuffer.Get()->SetName($"SwapChain_BackBuffer_{i}");
 
             _backBuffers[i] = new D3D12Texture(backBuffer.Move(), Width, Height, TextureFormat.B8G8R8A8_UNorm);
+
+            // Create render target wrapper for the back buffer
+            _backBufferRenderTargets[i] = new D3D12RenderTarget(_backBuffers[i], RenderTargetType.Color);
         }
     }
 
@@ -111,6 +124,12 @@ internal unsafe class D3D12SwapChain : ISwapChain
         return _backBuffers[_currentBackBufferIndex];
     }
 
+    public IRenderTarget GetCurrentBackBufferRenderTarget()
+    {
+        _currentBackBufferIndex = _swapChain.Get()->GetCurrentBackBufferIndex();
+        return _backBufferRenderTargets[_currentBackBufferIndex];
+    }
+
     public void Present(bool vsync = true)
     {
         var presentFlags = PresentFlags.None;
@@ -127,9 +146,10 @@ internal unsafe class D3D12SwapChain : ISwapChain
         if (Width == width && Height == height)
             return;
 
-        // Release old back buffers
+        // Release old back buffers and render targets
-        for (int i = 0; i < _backBuffers.Length; i++)
+        for (var i = 0; i < _backBuffers.Length; i++)
         {
+            _backBufferRenderTargets[i]?.Dispose();
             _backBuffers[i]?.Dispose();
         }
 
@@ -161,10 +181,14 @@ internal unsafe class D3D12SwapChain : ISwapChain
 
     public void Dispose()
     {
-        if (_disposed) return;
+        if (_disposed)
-
-        for (int i = 0; i < _backBuffers.Length; i++)
         {
+            return;
+        }
+
+        for (var i = 0; i < _backBuffers.Length; i++)
+        {
+            _backBufferRenderTargets[i]?.Dispose();
             _backBuffers[i]?.Dispose();
         }
 

Ghost.Graphics/D3D12/D3D12Texture.cs

@@ -1,3 +1,4 @@
+using Ghost.Graphics.Data;
 using Ghost.Graphics.RHI;
 using Win32;
 using Win32.Graphics.Direct3D12;
@@ -5,110 +6,85 @@ using Win32.Graphics.Direct3D12;
 namespace Ghost.Graphics.D3D12;
 
 /// <summary>
-/// D3D12 implementation of texture interface
+/// D3D12 implementation of texture interface using resource handles
 /// </summary>
 internal unsafe class D3D12Texture : ITexture
 {
-    private ComPtr<ID3D12Resource> _resource;
+    private readonly TextureHandle _handle;
+    private readonly ComPtr<ID3D12Resource> _externalResource;
     private ResourceState _currentState;
     private bool _disposed;
 
-    public uint Width { get; }
+    public uint Width
-    public uint Height { get; }
+    {
-    public TextureFormat Format { get; }
+        get;
-    public uint MipLevels { get; }
+    }
-    public string Name { get; set; } = string.Empty;
+
-    public ulong Size { get; }
+    public uint Height
+    {
+        get;
+    }
+
+    public TextureFormat Format
+    {
+        get;
+    }
+
+    public uint MipLevels
+    {
+        get;
+    }
+
+    public string Name
+    {
+        get; set;
+    } = string.Empty;
+
+    public ulong Size
+    {
+        get;
+    }
+
     public ResourceState CurrentState => _currentState;
 
-    public ID3D12Resource* NativeResource => _resource.Get();
+    public ID3D12Resource* NativeResource => _handle.IsValid ? _handle.ResourceHandle.GetAllocation().Resource : _externalResource.Get();
 
     public D3D12Texture(ComPtr<ID3D12Resource> resource, uint width, uint height, TextureFormat format, uint mipLevels = 1)
     {
-        _resource = resource.Move();
+        _handle = TextureHandle.Invalid;
+        _externalResource = resource.Move();
+
         Width = width;
         Height = height;
         Format = format;
         MipLevels = mipLevels;
         _currentState = ResourceState.Common;
-
+        Size = Width * Height * GetBytesPerPixel(Format);
-        var desc = _resource.Get()->GetDesc();
-        Size = (ulong)(desc.Width * desc.Height * GetBytesPerPixel(format));
     }
 
-    public D3D12Texture(ComPtr<ID3D12Device14> device, TextureDesc desc)
+    public D3D12Texture(TextureHandle handle, ref readonly TextureDesc desc)
     {
+        _handle = handle;
+        _externalResource = default;
+
         Width = desc.Width;
         Height = desc.Height;
         Format = desc.Format;
-        MipLevels = desc.MipLevels;
+
+        var mipLevels = desc.MipLevels;
+        if (mipLevels <= 0)
+        {
+            mipLevels = (uint)(Math.Floor(Math.Log2(Math.Max(Width, Height))) + 1);
+        }
+
+        MipLevels = mipLevels;
         _currentState = ResourceState.Common;
-
+        Size = Width * Height * GetBytesPerPixel(Format);
-        CreateTexture(device, desc);
-        Size = (ulong)(Width * Height * GetBytesPerPixel(Format));
     }
 
-    private void CreateTexture(ComPtr<ID3D12Device14> device, TextureDesc desc)
+    ~D3D12Texture()
     {
-        var resourceDesc = new ResourceDescription
+        Dispose();
-        {
-            Dimension = ResourceDimension.Texture2D,
-            Alignment = 0,
-            Width = desc.Width,
-            Height = desc.Height,
-            DepthOrArraySize = 1,
-            MipLevels = (ushort)desc.MipLevels,
-            Format = ConvertTextureFormat(desc.Format),
-            SampleDesc = new Win32.Graphics.Dxgi.Common.SampleDescription(1, 0),
-            Layout = TextureLayout.Unknown,
-            Flags = ConvertTextureUsage(desc.Usage)
-        };
-
-        var heapProps = new HeapProperties
-        {
-            Type = HeapType.Default,
-            CPUPageProperty = CpuPageProperty.Unknown,
-            MemoryPoolPreference = MemoryPool.Unknown,
-            CreationNodeMask = 1,
-            VisibleNodeMask = 1
-        };
-
-        device.Get()->CreateCommittedResource(
-            &heapProps,
-            HeapFlags.None,
-            &resourceDesc,
-            Win32.Graphics.Direct3D12.ResourceStates.Common,
-            null,
-            __uuidof<ID3D12Resource>(),
-            _resource.GetVoidAddressOf());
-    }
-
-    private static Win32.Graphics.Dxgi.Common.Format ConvertTextureFormat(TextureFormat format)
-    {
-        return format switch
-        {
-            TextureFormat.R8G8B8A8_UNorm => Win32.Graphics.Dxgi.Common.Format.R8G8B8A8Unorm,
-            TextureFormat.B8G8R8A8_UNorm => Win32.Graphics.Dxgi.Common.Format.B8G8R8A8Unorm,
-            TextureFormat.R16G16B16A16_Float => Win32.Graphics.Dxgi.Common.Format.R16G16B16A16Float,
-            TextureFormat.R32G32B32A32_Float => Win32.Graphics.Dxgi.Common.Format.R32G32B32A32Float,
-            TextureFormat.D24_UNorm_S8_UInt => Win32.Graphics.Dxgi.Common.Format.D24UnormS8Uint,
-            TextureFormat.D32_Float => Win32.Graphics.Dxgi.Common.Format.D32Float,
-            _ => throw new ArgumentException($"Unsupported texture format: {format}")
-        };
-    }
-
-    private static ResourceFlags ConvertTextureUsage(TextureUsage usage)
-    {
-        var flags = ResourceFlags.None;
-
-        if ((usage & TextureUsage.RenderTarget) != 0)
-            flags |= ResourceFlags.AllowRenderTarget;
-        if ((usage & TextureUsage.DepthStencil) != 0)
-            flags |= ResourceFlags.AllowDepthStencil;
-        if ((usage & TextureUsage.UnorderedAccess) != 0)
-            flags |= ResourceFlags.AllowUnorderedAccess;
-
-        return flags;
     }
 
     private static uint GetBytesPerPixel(TextureFormat format)
@@ -125,11 +101,29 @@ internal unsafe class D3D12Texture : ITexture
         };
     }
 
+    public void SetCurrentState(ResourceState state)
+    {
+        _currentState = state;
+    }
+
     public void Dispose()
     {
-        if (_disposed) return;
+        if (_disposed)
+        {
+            return;
+        }
+
+        if (_handle.IsValid)
+        {
+            _handle.Dispose();
+        }
+        else
+        {
+            _externalResource.Dispose();
+        }
 
-        _resource.Dispose();
         _disposed = true;
+
+        GC.SuppressFinalize(this);
     }
 }

Ghost.Graphics/D3D12/ResourceAllocator.cs

@@ -1,249 +0,0 @@
-using Ghost.Graphics.Data;
-using Misaki.HighPerformance.LowLevel.Collections;
-using System.Runtime.CompilerServices;
-using Win32.Graphics.D3D12MemoryAllocator;
-using Win32.Graphics.Direct3D12;
-using Win32.Graphics.Dxgi;
-using Win32.Graphics.Dxgi.Common;
-using static Win32.Graphics.D3D12MemoryAllocator.Apis;
-using ResourceHandle = Ghost.Graphics.Data.ResourceHandle;
-
-namespace Ghost.Graphics.D3D12;
-
-internal unsafe class ResourceAllocator
-{
-    private readonly struct AllocationInfo : IDisposable
-    {
-        public readonly Allocation allocation;
-        public readonly uint cpuFenceValue;
-        public readonly uint generation;
-
-        public bool Allocated => allocation.IsNotNull;
-
-        public AllocationInfo(in Allocation allocation, uint cpuFenceValue, uint generation)
-        {
-            this.allocation = allocation;
-            this.cpuFenceValue = cpuFenceValue;
-            this.generation = generation;
-        }
-
-        public AllocationInfo(in Allocation allocation, uint generation)
-            : this(allocation, 0 /* TODO: Use proper fence value from render system */, generation)
-        {
-        }
-
-        public void Dispose()
-        {
-            if (allocation.IsNull)
-            {
-                return;
-            }
-
-            allocation.Release();
-        }
-    }
-
-    private const uint _MAX_BYTES = D3D12_REQ_RESOURCE_SIZE_IN_MEGABYTES_EXPRESSION_A_TERM * 1024u * 1024u;
-    private const uint _MAX_TEXTURE2D_DIMENSION = 16384u;
-    private const uint _MAX_TEXTURE3D_DIMENSION = 2048u;
-
-    private readonly Allocator _allocator;
-    private UnsafeList<AllocationInfo> _allocations = new(64, Misaki.HighPerformance.LowLevel.Buffer.Allocator.Persistent);
-    private UnsafeQueue<int> _freeSlots = new(64, Misaki.HighPerformance.LowLevel.Buffer.Allocator.Persistent);
-    private UnsafeQueue<ResourceHandle> _temResources = new(64, Misaki.HighPerformance.LowLevel.Buffer.Allocator.Persistent);
-
-    private readonly Lock _lock = new();
-
-    private Guid* IID_NULL
-    {
-        get
-        {
-            fixed (Guid* pGuid = &Guid.Empty)
-            {
-                return pGuid;
-            }
-        }
-    }
-
-    public ResourceAllocator(IDXGIAdapter* pAdapter, ID3D12Device* pDevice)
-    {
-        var desc = new AllocatorDesc
-        {
-            pAdapter = pAdapter,
-            pDevice = pDevice,
-            Flags = AllocatorFlags.DefaultPoolsNotZeroed | AllocatorFlags.MSAATexturesAlwaysCommitted
-        };
-
-        CreateAllocator(in desc, out _allocator);
-    }
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static void CheckBufferSize(uint sizeInBytes)
-    {
-        if (sizeInBytes > _MAX_BYTES)
-        {
-            throw new InvalidOperationException($"ERROR: Resource size too large for DirectX 12 (size {sizeInBytes})");
-        }
-    }
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static void CheckTexture2DSize(uint width, uint height)
-    {
-        if (width > _MAX_TEXTURE2D_DIMENSION || height > _MAX_TEXTURE2D_DIMENSION)
-        {
-            throw new InvalidOperationException($"ERROR: Texture size too large for DirectX 12 (width {width}, height {height})");
-        }
-    }
-
-    private ResourceHandle TrackResource(in Allocation allocation, bool isTemp)
-    {
-        int id;
-        uint generation;
-        AllocationInfo allocInfo;
-
-        lock (_lock)
-        {
-            if (_freeSlots.Count > 0)
-            {
-                id = _freeSlots.Dequeue();
-                var info = _allocations[id];
-                if (info.Allocated)
-                {
-                    throw new InvalidOperationException($"ERROR: Resource ID {id} registered as free but still allocated.");
-                }
-
-                generation = info.generation + 1;
-                allocInfo = new AllocationInfo(in allocation, generation);
-
-                _allocations[id] = allocInfo;
-            }
-            else
-            {
-                id = _allocations.Count;
-                generation = 0u;
-                allocInfo = new AllocationInfo(in allocation, generation);
-
-                _allocations.Add(allocInfo);
-            }
-
-            var handle = new ResourceHandle(id, generation);
-            if (isTemp)
-            {
-                _temResources.Enqueue(handle);
-            }
-
-            return handle;
-        }
-    }
-
-    public TextureHandle CreateTexture2D(uint width, uint height, ushort mipLevels, Format format = Format.R8G8B8A8Unorm, ResourceFlags resFlags = ResourceFlags.None, AllocationFlags allocFlags = AllocationFlags.None, ResourceStates state = ResourceStates.Common, bool tempResource = false)
-    {
-        CheckTexture2DSize(width, height);
-
-        var resourceDesc = ResourceDescription.Tex2D(format, width, height, mipLevels: mipLevels, arraySize: 1, flags: resFlags);
-        var allocationDesc = new AllocationDesc
-        {
-            HeapType = HeapType.Default,
-            Flags = allocFlags
-        };
-
-        Allocation allocation = default;
-        ThrowIfFailed(_allocator.CreateResource(&allocationDesc, in resourceDesc, state, null, &allocation, IID_NULL, null));
-
-        return new(TrackResource(in allocation, tempResource));
-    }
-
-    public BufferHandle CreateBuffer(uint sizeInBytes, HeapType heapType = HeapType.Default, ResourceFlags resFlags = ResourceFlags.None, AllocationFlags allocFlags = AllocationFlags.None, ResourceStates initialState = ResourceStates.Common, bool tempResource = false)
-    {
-        CheckBufferSize(sizeInBytes);
-
-        var resourceDescription = ResourceDescription.Buffer(sizeInBytes, resFlags);
-        var allocationDesc = new AllocationDesc
-        {
-            HeapType = heapType,
-            Flags = allocFlags
-        };
-
-        Allocation allocation = default;
-        ThrowIfFailed(_allocator.CreateResource(&allocationDesc, in resourceDescription, initialState, null, &allocation, IID_NULL, null));
-
-        return new(TrackResource(in allocation, tempResource));
-    }
-
-    public BufferHandle CreateUploadBuffer(uint sizeInBytes, bool tempResource = false)
-    {
-        return CreateBuffer(sizeInBytes, HeapType.Upload, ResourceFlags.None, AllocationFlags.None, ResourceStates.GenericRead, tempResource);
-    }
-
-    public void ReleaseTempResource()
-    {
-        while (_temResources.Count > 0)
-        {
-            ref var handle = ref _temResources.Peek();
-            ref var info = ref _allocations[handle.id];
-            // TODO: Implement proper fence-based cleanup with RenderSystem
-            // For now, just release all temp resources
-
-            ReleaseAllocation(in handle);
-            _temResources.Dequeue();
-        }
-    }
-
-    public Allocation GetAllocation(in ResourceHandle handle)
-    {
-        if (!handle.IsValid)
-        {
-            throw new InvalidOperationException("Invalid resource handle.");
-        }
-
-        lock (_lock)
-        {
-            ref var allocationInfo = ref _allocations[handle.id];
-            if (!allocationInfo.Allocated || allocationInfo.generation != handle.generation)
-            {
-                throw new InvalidOperationException($"Resource with ID {handle.id} and generation {handle.generation} is not allocated or has been released.");
-            }
-
-            return allocationInfo.allocation;
-        }
-    }
-
-    public void ReleaseAllocation(in ResourceHandle handle)
-    {
-        if (!handle.IsValid)
-        {
-            return;
-        }
-
-        lock (_lock)
-        {
-            ref var allocationInfo = ref _allocations[handle.id];
-
-            if (!allocationInfo.Allocated || allocationInfo.generation != handle.generation)
-            {
-                return;
-            }
-
-            allocationInfo.Dispose();
-            _freeSlots.Enqueue(handle.id);
-        }
-    }
-
-    public void Dispose()
-    {
-#if DEBUG
-        if (_allocations.Count > 0)
-        {
-            throw new InvalidOperationException($"ResourceAllocator is being disposed with {_allocations.Count} allocations still registered. Ensure all resources are released before disposing.");
-        }
-#endif
-        for (var i = 0; i < _allocations.Count; i++)
-        {
-            _allocations[i].Dispose();
-        }
-
-        _allocations.Dispose();
-        _temResources.Dispose();
-        _allocator.Release();
-    }
-}

Ghost.Graphics/Data/ResourceHandle.cs

@@ -81,6 +81,8 @@ public readonly struct TextureHandle : IEquatable<TextureHandle>, IDisposable
 
     internal ResourceHandle ResourceHandle => _resourceHandle;
 
+    public static TextureHandle Invalid => new(ResourceHandle.Invalid);
+
     internal TextureHandle(ResourceHandle resourceHandle)
     {
         _resourceHandle = resourceHandle;
@@ -125,6 +127,8 @@ public readonly struct BufferHandle : IEquatable<BufferHandle>, IDisposable
 
     internal ResourceHandle ResourceHandle => _resourceHandle;
 
+    public static BufferHandle Invalid => new(ResourceHandle.Invalid);
+
     internal BufferHandle(ResourceHandle resourceHandle)
     {
         _resourceHandle = resourceHandle;

Ghost.Graphics/GraphicsPipeline.cs

@@ -21,7 +21,7 @@ public static class GraphicsPipeline
 
     private static GraphicsDevice? s_graphicsDevice;
     private static DescriptorAllocator? s_descriptorAllocator;
-    private static ResourceAllocator? s_resourceAllocator;
+    private static D3D12ResourceAllocator? s_resourceAllocator;
     private static ResourceUploadBatch? s_uploadBatch;
 
     // New RHI-based device for modern usage
@@ -31,7 +31,7 @@ public static class GraphicsPipeline
     private static bool s_initialized;
 
     internal static GraphicsDevice GraphicsDevice => s_graphicsDevice ?? throw new InvalidOperationException("Graphics device is not initialized.");
-    internal static ResourceAllocator ResourceAllocator => s_resourceAllocator ?? throw new InvalidOperationException("Resource allocator is not initialized.");
+    internal static D3D12ResourceAllocator ResourceAllocator => s_resourceAllocator ?? throw new InvalidOperationException("Resource allocator is not initialized.");
     internal static DescriptorAllocator DescriptorAllocator => s_descriptorAllocator ?? throw new InvalidOperationException("Descriptor allocator is not initialized.");
 
     /// <summary>
@@ -66,7 +66,7 @@ public static class GraphicsPipeline
         // Initialize legacy components for compatibility
         s_graphicsDevice = new GraphicsDevice();
         s_descriptorAllocator = new DescriptorAllocator();
-        s_resourceAllocator = new ResourceAllocator((IDXGIAdapter*)s_graphicsDevice.Adapter.Ptr, (ID3D12Device*)s_graphicsDevice.NativeDevice.Ptr);
+        s_resourceAllocator = new D3D12ResourceAllocator((IDXGIAdapter*)s_graphicsDevice.Adapter.Ptr, (ID3D12Device*)s_graphicsDevice.NativeDevice.Ptr);
 
         // Initialize modern RHI components
         s_renderDevice = new D3D12.D3D12RenderDevice();

Ghost.Graphics/REFACTORING_SUMMARY.md

@@ -1,160 +0,0 @@
-# Ghost Engine Graphics Refactoring Summary
-
-## 🎯 Refactoring Goals Completed
-
-✅ **1. Create a new RHI folder with interfaces for all abstractions**
-- Created clean D3D12-native RHI interfaces in `Ghost.Graphics\RHI\`
-- Interfaces include: `IRenderDevice`, `ICommandBuffer`, `ICommandQueue`, `ISwapChain`, `IRenderTarget`, `IDescriptorAllocator`
-
-✅ **2. Move all D3D12-specific code into D3D12 implementations**
-- All D3D12 implementations moved to `Ghost.Graphics\D3D12\`
-- Clean separation between interface and implementation
-
-✅ **3. Delete the current Renderer class and rewrite it to use interfaces**
-- ❌ Removed legacy `Renderer.cs` (was tightly coupled to D3D12)
-- ✅ Created new `D3D12Renderer` that implements `IRenderer` interface
-
-✅ **4. Extract SwapChain logic from Renderer into its own class**
-- ✅ Created `D3D12SwapChain` implementing `ISwapChain`
-- SwapChain now manages presentation independently of rendering
-
-✅ **5. Remove renderer management from GraphicsDevice - make it a pure device factory**
-- ❌ Marked legacy `GraphicsDevice` as obsolete
-- ✅ Created new `D3D12RenderDevice` as clean factory for D3D12 resources
-
-✅ **6. Create separate CommandQueue classes for Graphics/Compute/Copy queues**
-- ✅ Created `D3D12CommandQueue` supporting all three queue types
-- `D3D12RenderDevice` exposes separate queues via properties
-
-✅ **7. Abstract descriptor allocation behind an interface**
-- ✅ Created `IDescriptorAllocator` interface
-- ✅ Implemented `D3D12DescriptorAllocator`
-
-✅ **8. Move frame synchronization to application level, not RHI level**
-- ✅ Created `RenderSystem` class for application-level frame management
-- ❌ Marked legacy `GraphicsPipeline` as obsolete
-- Frame synchronization now handled by `RenderSystem`, not buried in graphics device
-
-## 🏗️ New Architecture
-
-### Core RHI Interfaces
-```
-Ghost.Graphics\RHI\
-├── IRenderDevice.cs      # Device factory for creating resources
-├── ICommandBuffer.cs     # Command recording interface
-├── ICommandQueue.cs      # Command submission interface  
-├── ISwapChain.cs         # Presentation interface
-├── IRenderTarget.cs      # Render target interface (color OR depth only)
-├── IRenderer.cs          # High-level renderer interface
-├── IDescriptorAllocator.cs # Descriptor management
-└── IResource.cs          # Base resource interfaces
-```
-
-### D3D12 Implementations
-```
-Ghost.Graphics\D3D12\
-├── D3D12RenderDevice.cs     # Main device factory
-├── D3D12CommandBuffer.cs    # Command list wrapper
-├── D3D12CommandQueue.cs     # Command queue wrapper
-├── D3D12SwapChain.cs        # Swap chain management
-├── D3D12RenderTarget.cs     # Render target (single type: color OR depth)
-├── D3D12Renderer.cs         # High-level renderer implementation
-├── D3D12DescriptorAllocator.cs # Descriptor heap management
-├── D3D12Texture.cs          # Texture implementation
-└── D3D12Buffer.cs           # Buffer implementation
-```
-
-### Application Level
-```
-Ghost.Graphics\
-├── RenderSystem.cs          # Frame synchronization & renderer management
-└── Examples\
-    └── ModernRenderingExample.cs # Usage examples
-```
-
-## 🎯 Key Improvements
-
-### **1. Clean Separation of Concerns**
-- **SwapChain**: Only handles presentation
-- **Renderer**: Only handles rendering logic
-- **RenderDevice**: Only creates resources
-- **RenderSystem**: Only manages frame synchronization
-
-### **2. Simplified Render Target Design**
-- Render targets now support **either color OR depth**, not both
-- Use `RenderTargetDesc.Color()` or `RenderTargetDesc.Depth()` factory methods
-- Cleaner API, less complex state management
-
-### **3. D3D12-Native RHI Design**
-- No abstraction overhead - direct mapping to D3D12 concepts
-- Command buffers, resource states, pipeline state objects
-- Descriptor heaps and bindless rendering support
-- Access to all D3D12 features without compromise
-
-### **4. Application-Level Frame Management**
-```csharp
-// OLD: Frame sync buried in GraphicsPipeline
-GraphicsPipeline.SignalCPUReady();
-GraphicsPipeline.WaitForGPUReady();
-
-// NEW: Clear application-level control
-renderSystem.SignalCPUReady();
-renderSystem.WaitForGPUReady();
-```
-
-### **5. Multiple Renderer Support**
-```csharp
-var renderSystem = new RenderSystem(device);
-
-// Add multiple renderers
-renderSystem.AddRenderer(forwardRenderer);   // Main scene
-renderSystem.AddRenderer(shadowRenderer);    // Shadow maps  
-renderSystem.AddRenderer(postProcessRenderer); // Post effects
-
-renderSystem.Start(); // Manages all renderers
-```
-
-## 📖 Usage Examples
-
-### **Modern Approach**
-```csharp
-// Create device and render system
-var device = new D3D12RenderDevice();
-var renderSystem = new RenderSystem(device);
-
-// Create renderer with swap chain
-var renderer = new D3D12Renderer(device);
-var swapChain = device.CreateSwapChain(swapChainDesc);
-renderer.SetSwapChain(swapChain);
-
-// Or render to off-screen target
-var colorTarget = device.CreateRenderTarget(
-    RenderTargetDesc.Color(1024, 1024, TextureFormat.R8G8B8A8_UNorm));
-renderer.SetRenderTarget(colorTarget);
-
-// Start rendering
-renderSystem.AddRenderer(renderer);
-renderSystem.Start();
-```
-
-### **Legacy Compatibility**
-```csharp
-// Legacy code still works (with obsolete warnings)
-GraphicsPipeline.Initialize(); // ⚠️ Obsolete
-GraphicsPipeline.Start();      // ⚠️ Obsolete
-
-// But modern API is preferred
-var device = GraphicsPipeline.RenderDevice;      // ✅ New
-var renderSystem = GraphicsPipeline.RenderSystem; // ✅ New
-```
-
-## 🎯 Benefits Achieved
-
-1. **Cleaner Code**: High-level rendering code no longer knows about D3D12 specifics
-2. **Better Testing**: All components can be mocked via interfaces  
-3. **Flexible Rendering**: Easy to support multiple renderers and render targets
-4. **Future-Proof**: Clean abstraction allows adding Vulkan/Metal later
-5. **Performance**: Zero abstraction overhead with D3D12-native design
-6. **Maintainability**: Clear separation of concerns and responsibilities
-
-The refactoring successfully transforms a monolithic, tightly-coupled graphics system into a clean, modular, and flexible RHI architecture while maintaining backward compatibility and achieving all the stated goals.

Ghost.Graphics/RHI/IRenderDevice.cs

@@ -8,17 +8,34 @@ public interface IRenderDevice : IDisposable
     /// <summary>
     /// Graphics command queue for rendering operations
     /// </summary>
-    ICommandQueue GraphicsQueue { get; }
+    ICommandQueue GraphicsQueue
+    {
+        get;
+    }
 
     /// <summary>
     /// Compute command queue for compute shader operations
     /// </summary>
-    ICommandQueue ComputeQueue { get; }
+    ICommandQueue ComputeQueue
+    {
+        get;
+    }
 
     /// <summary>
     /// Copy command queue for data transfer operations
     /// </summary>
-    ICommandQueue CopyQueue { get; }
+    ICommandQueue CopyQueue
+    {
+        get;
+    }
+
+    /// <summary>
+    /// Gets the descriptor allocator for managing descriptors
+    /// </summary>
+    IDescriptorAllocator DescriptorAllocator
+    {
+        get;
+    }
 
     /// <summary>
     /// Creates a command buffer for recording rendering commands
@@ -33,32 +50,6 @@ public interface IRenderDevice : IDisposable
     /// <param name="desc">Swap chain description</param>
     /// <returns>A new swap chain instance</returns>
     ISwapChain CreateSwapChain(SwapChainDesc desc);
-
-    /// <summary>
-    /// Creates a render target for off-screen rendering
-    /// </summary>
-    /// <param name="desc">Render target description</param>
-    /// <returns>A new render target instance</returns>
-    IRenderTarget CreateRenderTarget(RenderTargetDesc desc);
-
-    /// <summary>
-    /// Creates a texture resource
-    /// </summary>
-    /// <param name="desc">Texture description</param>
-    /// <returns>A new texture instance</returns>
-    ITexture CreateTexture(TextureDesc desc);
-
-    /// <summary>
-    /// Creates a buffer resource
-    /// </summary>
-    /// <param name="desc">Buffer description</param>
-    /// <returns>A new buffer instance</returns>
-    IBuffer CreateBuffer(BufferDesc desc);
-
-    /// <summary>
-    /// Gets the descriptor allocator for managing descriptors
-    /// </summary>
-    IDescriptorAllocator DescriptorAllocator { get; }
 }
 
 /// <summary>

Ghost.Graphics/RHI/IRenderTypes.cs

@@ -71,6 +71,21 @@ public struct RenderTargetDesc
     /// </summary>
     public TextureFormat Format;
 
+    /// <summary>
+    /// Texture dimension
+    /// </summary>
+    public TextureDimension Dimension;
+
+    /// <summary>
+    /// Creation flags for the render target
+    /// </summary>
+    public RenderTargetCreationFlags CreationFlags;
+
+    /// <summary>
+    /// Number of mip levels. 0 to generate full mip chain
+    /// </summary>
+    public uint MipLevels;
+
     /// <summary>
     /// Number of samples for MSAA
     /// </summary>
@@ -79,7 +94,10 @@ public struct RenderTargetDesc
     /// <summary>
     /// Creates a color render target
     /// </summary>
-    public static RenderTargetDesc Color(uint width, uint height, TextureFormat format, uint sampleCount = 1)
+    public static RenderTargetDesc Color(uint width, uint height,
+        TextureFormat format, TextureDimension dimension = TextureDimension.Texture2D,
+        RenderTargetCreationFlags creationFlags = RenderTargetCreationFlags.AllowUAV | RenderTargetCreationFlags.DynamicallyScalable | RenderTargetCreationFlags.GenerateMips,
+        uint mipLevels = 0u, uint sampleCount = 1)
     {
         return new RenderTargetDesc
         {
@@ -87,6 +105,9 @@ public struct RenderTargetDesc
             Height = height,
             Type = RenderTargetType.Color,
             Format = format,
+            Dimension = dimension,
+            CreationFlags = creationFlags,
+            MipLevels = mipLevels,
             SampleCount = sampleCount
         };
     }
@@ -94,7 +115,10 @@ public struct RenderTargetDesc
     /// <summary>
     /// Creates a depth render target
     /// </summary>
-    public static RenderTargetDesc Depth(uint width, uint height, TextureFormat format = TextureFormat.D24_UNorm_S8_UInt, uint sampleCount = 1)
+    public static RenderTargetDesc Depth(uint width, uint height,
+        TextureFormat format = TextureFormat.D24_UNorm_S8_UInt, TextureDimension dimension = TextureDimension.Texture2D,
+        RenderTargetCreationFlags creationFlags = RenderTargetCreationFlags.AllowUAV | RenderTargetCreationFlags.DynamicallyScalable,
+        uint mipLevels = 0u, uint sampleCount = 1)
     {
         return new RenderTargetDesc
         {
@@ -102,6 +126,9 @@ public struct RenderTargetDesc
             Height = height,
             Type = RenderTargetType.Depth,
             Format = format,
+            Dimension = dimension,
+            CreationFlags = creationFlags,
+            MipLevels = mipLevels,
             SampleCount = sampleCount
         };
     }
@@ -128,7 +155,12 @@ public struct TextureDesc
     public TextureFormat Format;
 
     /// <summary>
-    /// Number of mip levels
+    /// Texture dimension
+    /// </summary>
+    public TextureDimension Dimension;
+
+    /// <summary>
+    /// Number of mip levels. 0 to generate full mip chain
     /// </summary>
     public uint MipLevels;
 
@@ -137,11 +169,12 @@ public struct TextureDesc
     /// </summary>
     public TextureUsage Usage;
 
-    public TextureDesc(uint width, uint height, TextureFormat format, uint mipLevels = 1, TextureUsage usage = TextureUsage.ShaderResource)
+    public TextureDesc(uint width, uint height, TextureFormat format, TextureDimension dimension = TextureDimension.Texture2D, uint mipLevels = 0u, TextureUsage usage = TextureUsage.ShaderResource)
     {
         Width = width;
         Height = height;
         Format = format;
+        Dimension = dimension;
         MipLevels = mipLevels;
         Usage = usage;
     }
@@ -188,6 +221,33 @@ public enum TextureUsage
     UnorderedAccess = 1 << 3
 }
 
+/// <summary>
+/// Dimensions of the texture
+/// </summary>
+public enum TextureDimension
+{
+    Unknown = -1,
+    None = 0,
+    Texture2D = 1,
+    Texture3D = 2,
+    TextureCube = 3,
+    Texture2DArray = 4,
+    TextureCubeArray = 5
+}
+
+/// <summary>
+/// Render target creation flags
+/// </summary>
+[Flags]
+public enum RenderTargetCreationFlags
+{
+    None = 0,
+    AllowUAV = 1 << 0,
+    AllowMSAA = 1 << 1,
+    DynamicallyScalable = 1 << 2,
+    GenerateMips = 1 << 3
+}
+
 /// <summary>
 /// Memory types for resources
 /// </summary>

Ghost.Graphics/RHI/IResourceFactory.cs

@@ -0,0 +1,41 @@
+using Ghost.Graphics.Data;
+
+namespace Ghost.Graphics.RHI;
+
+public interface IResourceFactory
+{
+    /// <summary>
+    /// Creates a render target for off-screen rendering
+    /// </summary>
+    /// <param name="desc">Render target description</param>
+    /// <returns>A new render target instance</returns>
+    public IRenderTarget CreateRenderTarget(ref readonly RenderTargetDesc desc);
+
+    /// <summary>
+    /// Creates a texture resource
+    /// </summary>
+    /// <param name="desc">Texture description</param>
+    /// <returns>A new texture handle point to the resource</returns>
+    public TextureHandle CreateTextureHandle(ref readonly TextureDesc desc);
+
+    /// <summary>
+    /// Creates a texture resource
+    /// </summary>
+    /// <param name="desc">Texture description</param>
+    /// <returns>A new texture instance</returns>
+    public ITexture CreateTexture(ref readonly TextureDesc desc);
+
+    /// <summary>
+    /// Creates a buffer resource
+    /// </summary>
+    /// <param name="desc">Buffer description</param>
+    /// <returns>A new buffer handle point to the resource</returns>
+    public BufferHandle CreateBufferHandle(ref readonly BufferDesc desc);
+
+    /// <summary>
+    /// Creates a buffer resource
+    /// </summary>
+    /// <param name="desc">Buffer description</param>
+    /// <returns>A new buffer instance</returns>
+    public IBuffer CreateBuffer(ref readonly BufferDesc desc);
+}

Ghost.Graphics/RHI/ISwapChain.cs

@@ -28,6 +28,12 @@ public interface ISwapChain : IDisposable
     /// <returns>Current back buffer texture</returns>
     ITexture GetCurrentBackBuffer();
 
+    /// <summary>
+    /// Gets the current back buffer as a render target
+    /// </summary>
+    /// <returns>Current back buffer render target</returns>
+    IRenderTarget GetCurrentBackBufferRenderTarget();
+
     /// <summary>
     /// Presents the rendered frame
     /// </summary>