// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.

/*=============================================================================
	PostProcessNoiseBlur.cpp: Post processing down sample implementation.
=============================================================================*/

#include "RendererPrivate.h"
#include "ScenePrivate.h"
#include "SceneFilterRendering.h"
#include "PostProcessNoiseBlur.h"
#include "PostProcessing.h"
#include "SceneUtils.h"

/** Encapsulates the post processing noise blur shader. */
template <uint32 Method>
class FPostProcessNoiseBlurPS : public FGlobalShader
{
	DECLARE_SHADER_TYPE(FPostProcessNoiseBlurPS, Global);

	static bool ShouldCache(EShaderPlatform Platform)
	{
		return true;
	}

	static void ModifyCompilationEnvironment(EShaderPlatform Platform, FShaderCompilerEnvironment& OutEnvironment)
	{
		FGlobalShader::ModifyCompilationEnvironment(Platform,OutEnvironment);
		OutEnvironment.SetDefine(TEXT("METHOD"), Method);
	}

	/** Default constructor. */
	FPostProcessNoiseBlurPS() {}

public:
	FPostProcessPassParameters PostprocessParameter;
	FDeferredPixelShaderParameters DeferredParameters;
	FShaderParameter NoiseParams;

	/** Initialization constructor. */
	FPostProcessNoiseBlurPS(const ShaderMetaType::CompiledShaderInitializerType& Initializer)
		: FGlobalShader(Initializer)
	{
		PostprocessParameter.Bind(Initializer.ParameterMap);
		DeferredParameters.Bind(Initializer.ParameterMap);
		NoiseParams.Bind(Initializer.ParameterMap, TEXT("NoiseParams"));
	}

	// FShader interface.
	virtual bool Serialize(FArchive& Ar) override
	{
		bool bShaderHasOutdatedParameters = FGlobalShader::Serialize(Ar);
		Ar << PostprocessParameter << DeferredParameters << NoiseParams;
		return bShaderHasOutdatedParameters;
	}

	void SetParameters(const FRenderingCompositePassContext& Context, float InRadius)
	{
		const FPixelShaderRHIParamRef ShaderRHI = GetPixelShader();

		FGlobalShader::SetParameters(Context.RHICmdList, ShaderRHI, Context.View);
		DeferredParameters.Set(Context.RHICmdList, ShaderRHI, Context.View);
		PostprocessParameter.SetPS(ShaderRHI, Context, TStaticSamplerState<SF_Bilinear,AM_Border,AM_Border,AM_Border>::GetRHI());

		{
			FVector4 ColorScale(InRadius, 0, 0, 0);
			SetShaderValue(Context.RHICmdList, ShaderRHI, NoiseParams, ColorScale);
		}
	}

	static const TCHAR* GetSourceFilename()
	{
		return TEXT("PostProcessNoiseBlur");
	}

	static const TCHAR* GetFunctionName()
	{
		return TEXT("MainPS");
	}
};

// #define avoids a lot of code duplication
#define VARIATION1(A) typedef FPostProcessNoiseBlurPS<A> FPostProcessNoiseBlurPS##A; \
	IMPLEMENT_SHADER_TYPE2(FPostProcessNoiseBlurPS##A, SF_Pixel);

VARIATION1(0)			VARIATION1(1)			VARIATION1(2)
#undef VARIATION1


FRCPassPostProcessNoiseBlur::FRCPassPostProcessNoiseBlur(float InRadius, EPixelFormat InOverrideFormat, uint32 InQuality)
	: Radius(InRadius)
	, Quality(InQuality)
	, OverrideFormat(InOverrideFormat)
{
}


template <uint32 Method>
void SetNoiseBlurShader(const FRenderingCompositePassContext& Context, float InRadius)
{
	TShaderMapRef<FPostProcessVS> VertexShader(Context.GetShaderMap());
	TShaderMapRef<FPostProcessNoiseBlurPS<Method> > PixelShader(Context.GetShaderMap());

	static FGlobalBoundShaderState BoundShaderState;
	

	SetGlobalBoundShaderState(Context.RHICmdList, Context.GetFeatureLevel(), BoundShaderState, GFilterVertexDeclaration.VertexDeclarationRHI, *VertexShader, *PixelShader);

	PixelShader->SetParameters(Context, InRadius);
	VertexShader->SetParameters(Context);
}


void FRCPassPostProcessNoiseBlur::Process(FRenderingCompositePassContext& Context)
{
	SCOPED_DRAW_EVENT(Context.RHICmdList, NoiseBlur);

	const FPooledRenderTargetDesc* InputDesc = GetInputDesc(ePId_Input0);

	if(!InputDesc)
	{
		// input is not hooked up correctly
		return;
	}

	const FSceneView& View = Context.View;
	const FSceneViewFamily& ViewFamily = *(View.Family);

	FIntPoint SrcSize = InputDesc->Extent;
	FIntPoint DestSize = PassOutputs[0].RenderTargetDesc.Extent;

	// e.g. 4 means the input texture is 4x smaller than the buffer size
	uint32 ScaleFactor = GSceneRenderTargets.GetBufferSizeXY().X / SrcSize.X;

	FIntRect SrcRect = View.ViewRect / ScaleFactor;
	FIntRect DestRect = SrcRect;

	const FSceneRenderTargetItem& DestRenderTarget = PassOutputs[0].RequestSurface(Context);

	// Set the view family's render target/viewport.
	SetRenderTarget(Context.RHICmdList, DestRenderTarget.TargetableTexture, FTextureRHIRef());

	// is optimized away if possible (RT size=view size, )
	Context.RHICmdList.Clear(true, FLinearColor(0, 0, 0, 0), false, 1.0f, false, 0, DestRect);

	Context.SetViewportAndCallRHI(0, 0, 0.0f, DestSize.X, DestSize.Y, 1.0f );

	// set the state
	Context.RHICmdList.SetBlendState(TStaticBlendState<>::GetRHI());
	Context.RHICmdList.SetRasterizerState(TStaticRasterizerState<>::GetRHI());
	Context.RHICmdList.SetDepthStencilState(TStaticDepthStencilState<false, CF_Always>::GetRHI());
	
	if(Quality == 0)
	{
		SetNoiseBlurShader<0>(Context, Radius);
	}
	else if(Quality == 1)
	{
		SetNoiseBlurShader<1>(Context, Radius);
	}
	else
	{
		SetNoiseBlurShader<2>(Context, Radius);
	}

	// Draw a quad mapping scene color to the view's render target
	TShaderMapRef<FPostProcessVS> VertexShader(Context.GetShaderMap());
	DrawRectangle(
		Context.RHICmdList,
		DestRect.Min.X, DestRect.Min.Y,
		DestRect.Width(), DestRect.Height(),
		SrcRect.Min.X, SrcRect.Min.Y,
		SrcRect.Width(), SrcRect.Height(),
		DestSize,
		SrcSize,
		*VertexShader,
		EDRF_UseTriangleOptimization);

	Context.RHICmdList.CopyToResolveTarget(DestRenderTarget.TargetableTexture, DestRenderTarget.ShaderResourceTexture, false, FResolveParams());
}


FPooledRenderTargetDesc FRCPassPostProcessNoiseBlur::ComputeOutputDesc(EPassOutputId InPassOutputId) const
{
	FPooledRenderTargetDesc Ret = PassInputs[0].GetOutput()->RenderTargetDesc;

	Ret.Reset();

	if(OverrideFormat != PF_Unknown)
	{
		Ret.Format = OverrideFormat;
	}

	Ret.TargetableFlags &= ~TexCreate_UAV;
	Ret.TargetableFlags |= TexCreate_RenderTargetable;
	Ret.DebugName = TEXT("NoiseBlur");

	return Ret;
}