// Copyright 1998-2017 Epic Games, Inc. All Rights Reserved.

/*=============================================================================
	PostProcessDownsample.h: Post processing down sample implementation.
=============================================================================*/

#pragma once

#include "CoreMinimal.h"
#include "RendererInterface.h"
#include "PostProcess/RenderingCompositionGraph.h"

// derives from TRenderingCompositePassBase<InputCount, OutputCount>
// ePId_Input0: Color input
// ePId_Input1: optional depth input (then quality is ignores and it uses the a 4 sample unfiltered samples method)
class FRCPassPostProcessDownsample : public TRenderingCompositePassBase<2, 1>
{
public:
	// constructor
	// @param InDebugName we store the pointer so don't release this string
	// @param Quality only used if ePId_Input1 is not set, 0:one filtered sample, 1:four filtered samples
	FRCPassPostProcessDownsample(EPixelFormat InOverrideFormat = PF_Unknown,
			uint32 InQuality = 1,
			bool bInIsComputePass = false, 
			const TCHAR *InDebugName = TEXT("Downsample"));

	// interface FRenderingCompositePass ---------

	virtual void Process(FRenderingCompositePassContext& Context) override;
	virtual void Release() override { delete this; }
	virtual FPooledRenderTargetDesc ComputeOutputDesc(EPassOutputId InPassOutputId) const override;

	virtual FComputeFenceRHIParamRef GetComputePassEndFence() const override { return AsyncEndFence; }

private:
	template <uint32 Method>
	void SetShader(const FRenderingCompositePassContext& Context, const FPooledRenderTargetDesc* InputDesc);

	template <uint32 Method, typename TRHICmdList>
	void DispatchCS(TRHICmdList& RHICmdList, FRenderingCompositePassContext& Context, const FIntPoint& SrcSize, const FIntRect& DestRect, FUnorderedAccessViewRHIParamRef DestUAV);

	FComputeFenceRHIRef AsyncEndFence;

	EPixelFormat OverrideFormat;
	// explained in constructor
	uint32 Quality;
	// must be a valid pointer
	const TCHAR* DebugName;
};