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

/*=============================================================================
	PostProcessGBufferHints.cpp: Post processing GBufferHints implementation.
=============================================================================*/

#include "PostProcess/PostProcessGBufferHints.h"
#include "EngineGlobals.h"
#include "StaticBoundShaderState.h"
#include "CanvasTypes.h"
#include "UnrealEngine.h"
#include "RenderTargetTemp.h"
#include "SceneUtils.h"
#include "PostProcess/SceneRenderTargets.h"
#include "PostProcess/SceneFilterRendering.h"
#include "SceneRenderTargetParameters.h"
#include "PostProcess/PostProcessing.h"
#include "PostProcess/PostProcessEyeAdaptation.h"
#include "PipelineStateCache.h"

/** Encapsulates the post processing eye adaptation pixel shader. */
class FPostProcessGBufferHintsPS : public FGlobalShader
{
	DECLARE_SHADER_TYPE(FPostProcessGBufferHintsPS, Global);

	static bool ShouldCache(EShaderPlatform Platform)
	{
		return IsFeatureLevelSupported(Platform, ERHIFeatureLevel::SM4);
	}

	static void ModifyCompilationEnvironment(EShaderPlatform Platform, FShaderCompilerEnvironment& OutEnvironment)
	{
		FGlobalShader::ModifyCompilationEnvironment(Platform,OutEnvironment);
	}

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

public:
	FPostProcessPassParameters PostprocessParameter;
	FDeferredPixelShaderParameters DeferredParameters;
	FShaderParameter EyeAdaptationParams;
	FShaderResourceParameter MiniFontTexture;

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

	void SetPS(const FRenderingCompositePassContext& Context)
	{
		const FPixelShaderRHIParamRef ShaderRHI = GetPixelShader();

		FGlobalShader::SetParameters<FViewUniformShaderParameters>(Context.RHICmdList, ShaderRHI, Context.View.ViewUniformBuffer);

		PostprocessParameter.SetPS(ShaderRHI, Context, TStaticSamplerState<SF_Point,AM_Clamp,AM_Clamp,AM_Clamp>::GetRHI());
		DeferredParameters.Set(Context.RHICmdList, ShaderRHI, Context.View);

		{
			FVector4 Temp[3];

			FRCPassPostProcessEyeAdaptation::ComputeEyeAdaptationParamsValue(Context.View, Temp);
			SetShaderValueArray(Context.RHICmdList, ShaderRHI, EyeAdaptationParams, Temp, 3);
		}

		SetTextureParameter(Context.RHICmdList, ShaderRHI, MiniFontTexture, GEngine->MiniFontTexture ? GEngine->MiniFontTexture->Resource->TextureRHI : GSystemTextures.WhiteDummy->GetRenderTargetItem().TargetableTexture);
	}
	
	// FShader interface.
	virtual bool Serialize(FArchive& Ar) override
	{
		bool bShaderHasOutdatedParameters = FGlobalShader::Serialize(Ar);
		Ar << PostprocessParameter << DeferredParameters << EyeAdaptationParams << MiniFontTexture;
		return bShaderHasOutdatedParameters;
	}
};

IMPLEMENT_SHADER_TYPE(,FPostProcessGBufferHintsPS,TEXT("PostProcessGBufferHints"),TEXT("MainPS"),SF_Pixel);


FRCPassPostProcessGBufferHints::FRCPassPostProcessGBufferHints(FRHICommandList& RHICmdList)
{
	// AdjustGBufferRefCount(-1) call is done when the pass gets executed
	FSceneRenderTargets::Get(RHICmdList).AdjustGBufferRefCount(RHICmdList, 1);
}


void FRCPassPostProcessGBufferHints::Process(FRenderingCompositePassContext& Context)
{
	SCOPED_DRAW_EVENT(Context.RHICmdList, GBufferHints);
	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);
	
	FIntRect SrcRect = View.ViewRect;
	FIntRect DestRect = View.ViewRect;
	FIntPoint SrcSize = InputDesc->Extent;

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

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

	FGraphicsPipelineStateInitializer GraphicsPSOInit;
	Context.RHICmdList.ApplyCachedRenderTargets(GraphicsPSOInit);
	GraphicsPSOInit.BlendState = TStaticBlendState<>::GetRHI();
	GraphicsPSOInit.RasterizerState = TStaticRasterizerState<>::GetRHI();
	GraphicsPSOInit.DepthStencilState = TStaticDepthStencilState<false, CF_Always>::GetRHI();

	TShaderMapRef<FPostProcessVS> VertexShader(Context.GetShaderMap());
	TShaderMapRef<FPostProcessGBufferHintsPS> PixelShader(Context.GetShaderMap());

	GraphicsPSOInit.BoundShaderState.VertexDeclarationRHI = GFilterVertexDeclaration.VertexDeclarationRHI;
	GraphicsPSOInit.BoundShaderState.VertexShaderRHI = GETSAFERHISHADER_VERTEX(*VertexShader);
	GraphicsPSOInit.BoundShaderState.PixelShaderRHI = GETSAFERHISHADER_PIXEL(*PixelShader);
	GraphicsPSOInit.PrimitiveType = PT_TriangleList;

	SetGraphicsPipelineState(Context.RHICmdList, GraphicsPSOInit);

	PixelShader->SetPS(Context);

	// Draw a quad mapping scene color to the view's render target
	DrawRectangle(
		Context.RHICmdList,
		0, 0,
		DestRect.Width(), DestRect.Height(),
		SrcRect.Min.X, SrcRect.Min.Y,
		SrcRect.Width(), SrcRect.Height(),
		DestRect.Size(),
		SrcSize,
		*VertexShader,
		EDRF_UseTriangleOptimization);


	FRenderTargetTemp TempRenderTarget(View, (const FTexture2DRHIRef&)DestRenderTarget.TargetableTexture);
	FCanvas Canvas(&TempRenderTarget, NULL, ViewFamily.CurrentRealTime, ViewFamily.CurrentWorldTime, ViewFamily.DeltaWorldTime, View.GetFeatureLevel());

	float X = 30;
	float Y = 8;
	const float YStep = 14;
	const float ColumnWidth = 250;

	FString Line;

	Line = FString::Printf(TEXT("GBufferHints"));
	Canvas.DrawShadowedString( X, Y += YStep, *Line, GetStatsFont(), FLinearColor(1, 1, 1));

	Y += YStep;
	
	Line = FString::Printf(TEXT("Yellow: Unrealistic material (In nature even black materials reflect a small amount of light)"));
	Canvas.DrawShadowedString( X, Y += YStep, *Line, GetStatsFont(), FLinearColor(0.8f, 0.8f, 0));

	Line = FString::Printf(TEXT("Red: Impossible material (This material emits more light than it receives)"));
	Canvas.DrawShadowedString( X, Y += YStep, *Line, GetStatsFont(), FLinearColor(1, 0, 0));

	Canvas.Flush_RenderThread(Context.RHICmdList);

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

	// AdjustGBufferRefCount(1) call is done in constructor
	FSceneRenderTargets::Get(Context.RHICmdList).AdjustGBufferRefCount(Context.RHICmdList, -1);
}

FPooledRenderTargetDesc FRCPassPostProcessGBufferHints::ComputeOutputDesc(EPassOutputId InPassOutputId) const
{
	FPooledRenderTargetDesc Ret = GetInput(ePId_Input0)->GetOutput()->RenderTargetDesc;

	Ret.Reset();
	Ret.DebugName = TEXT("GBufferHints");

	return Ret;
}