feat(RHI): 添加 RHIDescriptorPool 抽象类

- 新增 RHIDescriptorPool 抽象基类，定义描述符池统一接口
- D3D12DescriptorHeap 现在继承自 RHIDescriptorPool
- 添加 DescriptorPoolDesc 结构体，包含设备指针、类型、数量等信息
- 添加 Initialize(const DescriptorPoolDesc&) 统一初始化方法

engine/include/XCEngine/RHI/D3D12/D3D12DescriptorHeap.h

@@ -5,6 +5,7 @@
 
 #include "../RHIEnums.h"
 #include "../RHITypes.h"
+#include "../RHIDescriptorPool.h"
 #include "D3D12Enum.h"
 
 using Microsoft::WRL::ComPtr;
@@ -12,25 +13,29 @@ using Microsoft::WRL::ComPtr;
 namespace XCEngine {
 namespace RHI {
 
-class D3D12DescriptorHeap {
+class D3D12DescriptorHeap : public RHIDescriptorPool {
 public:
     D3D12DescriptorHeap();
-    ~D3D12DescriptorHeap();
+    ~D3D12DescriptorHeap() override;
 
     bool Initialize(ID3D12Device* device, DescriptorHeapType type, uint32_t numDescriptors, bool shaderVisible = false);
-    void Shutdown();
+    void Shutdown() override;
+
+    bool Initialize(const DescriptorPoolDesc& desc) override;
 
     ID3D12DescriptorHeap* GetDescriptorHeap() const { return m_descriptorHeap.Get(); }
 
     CPUDescriptorHandle GetCPUDescriptorHandle(uint32_t index);
     GPUDescriptorHandle GetGPUDescriptorHandle(uint32_t index);
-    uint32_t GetDescriptorCount() const;
-    DescriptorType GetType() const;
+    uint32_t GetDescriptorCount() const override;
+    DescriptorHeapType GetType() const override;
 
     uint32_t GetDescriptorSize() const { return m_descriptorSize; }
     D3D12_CPU_DESCRIPTOR_HANDLE GetCPUDescriptorHandleForHeapStart() const;
     D3D12_GPU_DESCRIPTOR_HANDLE GetGPUDescriptorHandleForHeapStart() const;
 
+    void* GetNativeHandle() override { return m_descriptorHeap.Get(); }
+
     static D3D12_DESCRIPTOR_HEAP_DESC CreateDesc(DescriptorHeapType type, uint32_t numDescriptors, bool shaderVisible = false);
 
 private:

engine/include/XCEngine/RHI/RHIDescriptorPool.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include "RHIEnums.h"
+#include <cstdint>
+
+namespace XCEngine {
+namespace RHI {
+
+struct DescriptorPoolDesc {
+    void* device;
+    DescriptorHeapType type;
+    uint32_t descriptorCount;
+    bool shaderVisible;
+};
+
+class RHIDescriptorPool {
+public:
+    virtual ~RHIDescriptorPool() = default;
+
+    virtual bool Initialize(const DescriptorPoolDesc& desc) = 0;
+    virtual void Shutdown() = 0;
+
+    virtual void* GetNativeHandle() = 0;
+
+    virtual uint32_t GetDescriptorCount() const = 0;
+    virtual DescriptorHeapType GetType() const = 0;
+};
+
+} // namespace RHI
+} // namespace XCEngine