UE4 RHI(2)

/** 
 * only set if RHI has the information (after init of the RHI and only if RHI has that information, never changes after that)
 * e.g. "NVIDIA GeForce GTX 670"
 */
extern RHI_API FString GRHIAdapterName;
extern RHI_API FString GRHIAdapterInternalDriverVersion;
extern RHI_API FString GRHIAdapterUserDriverVersion;
extern RHI_API FString GRHIAdapterDriverDate;
extern RHI_API uint32 GRHIDeviceId;
extern RHI_API uint32 GRHIDeviceRevision;

// 0 means not defined yet, use functions like IsRHIDeviceAMD() to access
extern RHI_API uint32 GRHIVendorId;

// to trigger GPU specific optimizations and fallbacks
RHI_API bool IsRHIDeviceAMD();

// to trigger GPU specific optimizations and fallbacks
RHI_API bool IsRHIDeviceIntel();

// to trigger GPU specific optimizations and fallbacks
RHI_API bool IsRHIDeviceNVIDIA();

/** The interface which is implemented by the dynamically bound RHI. */
class RHI_API FDynamicRHI
{
public:

    ....
}

// FlushType: Wait RHI Thread
    virtual FPixelShaderRHIRef RHICreatePixelShader(FRHIShaderLibraryParamRef Library, FSHAHash Hash)
    {
        return nullptr;
    }

    // FlushType: Wait RHI Thread
    virtual FVertexShaderRHIRef RHICreateVertexShader(const TArray<uint8>& Code) = 0;
    
    // FlushType: Wait RHI Thread
    virtual FVertexShaderRHIRef RHICreateVertexShader(FRHIShaderLibraryParamRef Library, FSHAHash Hash)
    {
        return nullptr;
    }

/**
 * A rendering resource which is owned by the rendering thread.
 */
class RENDERCORE_API FRenderResource
{
public:
    /** @return The global initialized resource list. */
    static TLinkedList<FRenderResource*>*& GetResourceList();
        ...
        /**
     * Initializes the RHI resources used by this resource.
     * Called when entering the state where both the resource and the RHI have been initialized.
     * This is only called by the rendering thread.
     */
    virtual void InitRHI() {}

    /**
     * Releases the RHI resources used by this resource.
     * Called when leaving the state where both the resource and the RHI have been initialized.
     * This is only called by the rendering thread.
     */
    virtual void ReleaseRHI() {}
        ...
}

/** An index buffer resource. */
class FIndexBuffer : public FRenderResource
{
public:
    FIndexBufferRHIRef IndexBufferRHI;

    /** Destructor. */
    virtual ~FIndexBuffer() {}

    // FRenderResource interface.
    virtual void ReleaseRHI() override
    {
        IndexBufferRHI.SafeRelease();
    }
    virtual FString GetFriendlyName() const override { return TEXT("FIndexBuffer"); }
};

/* Index Buffer */
class FMyMeshIndexBuffer : public FIndexBuffer
{
public:
    int32 NumIndices;
    virtual void InitRHI() override
    {
        FRHIResourceCreateInfo CreateInfo;
        IndexBufferRHI = RHICreateIndexBuffer(sizeof(int32), NumIndices * sizeof(int32), BUF_Dynamic, CreateInfo);
    }
};

struct FRHICommandBase
{
    FRHICommandBase* Next = nullptr;
    virtual void ExecuteAndDestruct(FRHICommandListBase& CmdList, FRHICommandListDebugContext& DebugContext) = 0;
};

template<typename TCmd>
struct FRHICommand : public FRHICommandBase
{
    void ExecuteAndDestruct(FRHICommandListBase& CmdList, FRHICommandListDebugContext& Context) override final
    {
        TCmd *ThisCmd = static_cast<TCmd*>(this);
#if RHI_COMMAND_LIST_DEBUG_TRACES
        ThisCmd->StoreDebugInfo(Context);
#endif
        ThisCmd->Execute(CmdList);
        ThisCmd->~TCmd();
    }

    virtual void StoreDebugInfo(FRHICommandListDebugContext& Context) {};
};