// Copyright 1998-2019 Epic Games, Inc. All Rights Reserved.

#include "RenderGraphPass.h"

void FRDGPassParameterStruct::ClearUniformBuffers() const
{
	/** The pass parameter struct is mostly POD, with the exception of uniform buffers.
	 *  Since the explicit type of the struct is unknown, the method traverses and destructs
	 *  all uniform buffer references manually.
	 */
	const auto& Resources = Layout->Resources;

	for (int32 ResourceIndex = 0; ResourceIndex < Resources.Num(); ++ResourceIndex)
	{
		const EUniformBufferBaseType MemberType = Resources[ResourceIndex].MemberType;

		if (MemberType == UBMT_REFERENCED_STRUCT)
		{
			const uint16 MemberOffset = Resources[ResourceIndex].MemberOffset;

			FUniformBufferRHIRef* UniformBufferPtr = reinterpret_cast<FUniformBufferRHIRef*>(Contents + MemberOffset);
			*UniformBufferPtr = FUniformBufferRHIRef();
		}
	}
}

FRDGPass::FRDGPass(
	FRDGEventName&& InName,
	FRDGPassParameterStruct InParameterStruct,
	ERDGPassFlags InPassFlags)
	: Name(static_cast<FRDGEventName&&>(InName))
	, ParameterStruct(InParameterStruct)
	, PassFlags(InPassFlags)
{
	if (IsCompute())
	{
		ensureMsgf(ParameterStruct.GetLayout().NumRenderTargets() == 0, TEXT("Pass %s was declared as ERDGPassFlags::Compute yet has RenderTargets in its ResourceTable"), GetName());
	}
}

void FRDGPass::Execute(FRHICommandListImmediate& RHICmdList) const
{
	ExecuteImpl(RHICmdList);

	ParameterStruct.ClearUniformBuffers();
}