RHICoreTransitions.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "RHITransition.h"
#include "RHIContext.h"
 
namespace UE::RHICore
{
 
struct FResourceState
{
    FResourceState(IRHIComputeContext& Context, ERHIPipeline InSrcPipelines, ERHIPipeline InDstPipelines, const FRHITransitionInfo& Info)
        : AccessBefore(Info.AccessBefore)
        , AccessAfter(Info.AccessAfter)
        , SrcPipelines(InSrcPipelines)
        , DstPipelines(InDstPipelines)
    {
        if (FRHIViewableResource* ViewableResource = GetViewableResource(Info))
        {
            if (NeedToReplaceBeforeInfo())
            {
                SrcPipelines = Context.GetTrackedPipelines(ViewableResource);
                AccessBefore = Context.GetTrackedAccess(ViewableResource);
            }
 
            if (AccessAfter == ERHIAccess::Unknown)
            {
                AccessAfter = Context.GetTrackedAccess(ViewableResource);
            }
 
            check(AccessBefore != ERHIAccess::Unknown);
            check(AccessAfter != ERHIAccess::Unknown);
        }
    }
 
    ERHIAccess AccessBefore;
    ERHIAccess AccessAfter;
 
    // SrcPipeline may differ from the declared RHI SrcPipeline when CollapseToSinglePipeline is used, in which case this will be ERHIPipeline::All.
    ERHIPipeline SrcPipelines;
    ERHIPipeline DstPipelines;
 
private:
    bool NeedToReplaceBeforeInfo() const
    {
        if (AccessBefore == ERHIAccess::Unknown)
        {
            return true;
        }
        if (AccessBefore == ERHIAccess::Discard
            && GRHIGlobals.NeedsTransientDiscardStateTracking)
        {
            return true;
        }
        return false;
    }
};
 
}