D3D11ConstantBuffer.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
    D3D11ConstantBuffer.h: Public D3D Constant Buffer definitions.
=============================================================================*/
 
#pragma once
 
#include "RenderResource.h"
#include "Stats/Stats.h"
 
class FD3D11DynamicRHI;
 
#define MAX_GLOBAL_CONSTANT_BUFFER_BYTE_SIZE        (16*4096)
#define MIN_GLOBAL_CONSTANT_BUFFER_BYTE_SIZE        128
 
// !!! These offsets must match the cbuffer register definitions in Common.usf !!!
enum ED3D11ShaderOffsetBuffer
{
    GLOBAL_CONSTANT_BUFFER_INDEX = 0,
    MAX_CONSTANT_BUFFER_SLOTS
};
 
class FD3D11ConstantBuffer : public FRenderResource, public FRefCountedObject
{
public:
    // New circular buffer system for faster constant uploads.  Avoids CopyResource and speeds things up considerably
    FD3D11ConstantBuffer(FD3D11DynamicRHI* InD3DRHI);
    virtual ~FD3D11ConstantBuffer();
 
    // FRenderResource interface.
    virtual void    InitRHI(FRHICommandListBase& RHICmdList) override;
    virtual void    ReleaseRHI() override;
 
    static inline constexpr uint32 GetMaxSize() { return (uint32)Align(MAX_GLOBAL_CONSTANT_BUFFER_BYTE_SIZE, 16); }
 
    void UpdateConstant(const uint8* Data, uint16 Offset, uint16 InSize)
    {
        // Check that the data we are shadowing fits in the allocated shadow data
        check((uint32)Offset + (uint32)InSize <= GetMaxSize());
        FMemory::Memcpy(ShadowData+Offset, Data, InSize);
        CurrentUpdateSize = FMath::Max((uint32)(Offset + InSize), CurrentUpdateSize);
    }
 
protected:
    FD3D11DynamicRHI* D3DRHI;
    uint8*  ShadowData = nullptr;
 
    uint32  CurrentUpdateSize = 0;
};
 
DECLARE_CYCLE_STAT_EXTERN(TEXT("Global Constant buffer update time"),STAT_D3D11GlobalConstantBufferUpdateTime,STATGROUP_D3D11RHI, );