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


#include "Common.usf"
#include "PostProcessCommon.usf"

#if MSAA_SAMPLE_COUNT > 1
Texture2DMS<float4, MSAA_SAMPLE_COUNT> EditorPrimitivesColor;
Texture2DMS<float, MSAA_SAMPLE_COUNT> EditorPrimitivesDepth;
#else
Texture2D EditorPrimitivesColor;
//SamplerState EditorPrimitivesColorSampler;
Texture2D<float> EditorPrimitivesDepth;
#endif

// depth in the red channel in DeviceZ
Texture2D		FilteredSceneDepthTexture;
SamplerState	FilteredSceneDepthTextureSampler;

// r. value of r.Editor.OpaqueGizmo .g:r.Editor.MovingPattern ba: unused
float4 EditorRenderParams;

float4 GetScrColorAt(int2 PixelPos, out float OutDeviceZ)
{
	// furthest device Z or 0 if there is no
	OutDeviceZ = 0;

	float4 Ret = 0;
	
#if MSAA_SAMPLE_COUNT > 1

	{
		float SumWeight = 0.00001f;

		for( uint SampleIndex = 0; SampleIndex < MSAA_SAMPLE_COUNT; ++SampleIndex )
		{
			float4 Sample = EditorPrimitivesColor.Load( PixelPos, SampleIndex );
			float SampleDeviceZ = EditorPrimitivesDepth.Load( PixelPos, SampleIndex ).r;

			// Check if any color was applied to this pixel.  Note  this prevents actual black pixels from being visible
			float Weight = Sample.a;

			// if not far plane (we use inverted z)
			if(Weight == 0 && SampleDeviceZ > 0.0f)
			{
				// We want MSAA wireframe rendering but the basepass outputs 0 as alpha value so we fix that here
				Weight = 1;
			}

			FLATTEN if(Weight)
			{
				OutDeviceZ = max(OutDeviceZ, SampleDeviceZ);
				
				// fix gamma (better quality)
	//			Sample.rgb = pow(Sample.rgb, 2.2f);

//				Ret += float4(Sample.rgb, 1) * Weight;	// input is converted to premultipled alpha (transparent layer has a color) good
				Ret += float4(Sample.rgb, Weight);		// input is already premultipled alpha (transparent layer is black)

				SumWeight += Weight;
			}
		}

		Ret.rgb /= MSAA_SAMPLE_COUNT;
		Ret.a /= MSAA_SAMPLE_COUNT;

		// fix gamma (better quality)
//		Ret.rgb = pow( Ret.rgb, 1.0f / 2.2f );
	}

#else
//	Ret = Texture2DSample(EditorPrimitivesColor, EditorPrimitivesColorSampler, UV);
	Ret = EditorPrimitivesColor.Load(int3(PixelPos, 0));

	OutDeviceZ = EditorPrimitivesDepth.Load(int3(PixelPos, 0)).r;

	if(Ret.a == 0 && OutDeviceZ > 0.0f)
	{
		// We want MSAA wireframe rendering but the basepass outputs 0 as alpha value so we fix that here
		Ret.a = 1;
	}

	// make premultiplied alpha (if input isn't yet)
//	Ret.rgb *= Ret.a;

#endif

	// bring out of premultiplied
	Ret.rgb /= max(Ret.a, 0.0001f);		
	// fix gamma
	Ret.rgb = pow( Ret.rgb, 1.0f / 2.2f );
	// bring back to premultiplied
	Ret.rgb *= Ret.a;

	return Ret;
}

void MainPS(float4 UVAndScreenPos : TEXCOORD0, out float4 OutColor : SV_Target0)
{
	float2 UV = UVAndScreenPos.xy;
	float2 PixelPosF = UVAndScreenPos.zw * ScreenPosToPixel.xy + ScreenPosToPixel.zw + 0.5f;
	int2 PixelPos = int2(PixelPosF);

	float4 DestColor = Texture2DSample(PostprocessInput0, PostprocessInput0Sampler, UV);

	// furthest device Z or 0 if there is no
	float MaxDeviceZ;

	float4 SrcColor = GetScrColorAt(PixelPos, MaxDeviceZ);

/* disabled for now

	// UE3 wireframe style outline (non MSAA and slower)
	float Opacity = 1.0f;

	UNROLL for(int dy = -1; dy <= 1; ++dy)
	{
		UNROLL for(int dx = -1; dx <= 1; ++dx)
		{
			float LocalDeviceZ;
			GetScrColorAt(PixelPos + int2(dx, dy), LocalDeviceZ);
			
			// get the difference between the current pixel and the neighbor
			float DepthDistanceDelta = ConvertFromDeviceZ(MaxDeviceZ) - ConvertFromDeviceZ(LocalDeviceZ);
//			float DepthDistanceDelta = -(MaxDeviceZ - LocalDeviceZ);

			// if the neighboring pixel is closer to the camera than the current pixel
			if (DepthDistanceDelta > 0)
			{
				const float FadeStartDistance = 100.0f;
				const float FadeGradientDistance = 0.2f;

				// find percent along the domain of "StartFadeDistance - CompleteFadeDistance", (x - start)/distance
				float RawTransparency = (DepthDistanceDelta - FadeStartDistance) / FadeGradientDistance;
				
				// clamp that value to 0.0 - 1.0f and invert
				float TempOpacity = 1.0f - saturate(RawTransparency);
				
				// take the minimum so far
				Opacity = min(Opacity, TempOpacity);
			}
		}
	}
	
	SrcColor.a *= Opacity;
*/

	// debugging functionality 
//	OutColor = float4(SrcColor.aaa*0.18f,0) + float4(0.13,0.13,0.13,0) * (1-SrcColor.a);	return;
//	OutColor = float4(SrcColor.rgb,0) + float4(0.13,0.13,0.13,0) * (1-SrcColor.a);	return;
//	OutColor = SrcColor  / (0.001f+SrcColor.a);	return;
//	OutColor = SrcColor.a;	return;

	// dejitter the sample position and make a filtered lookup - for planes this allows to reconstruct a much less jittery depth comparison function, it however doesn't fix silhuetes
	float DeviceZ = Texture2DSampleLevel(FilteredSceneDepthTexture, FilteredSceneDepthTextureSampler, (PixelPosF - View.TemporalAAParams.zw) * View.BufferSizeAndInvSize.zw, 0).r;

	// Soft Bias with DeviceZ for best quality
	const float DeviceDepthFade = 0.00005f;
	float DepthMask = saturate(1.0f - (DeviceZ - MaxDeviceZ) / DeviceDepthFade);

	// moving diagonal lines
//	float PatternMask = saturate(sin((PixelPos.x + PixelPos.y) * 0.8f + 8.0f * View.RealTime * EditorRenderParams.g));
	// non moving high frequency pattern
//	float PatternMask = ((PixelPos.x + PixelPos.y) % 2) * 0.7f;
	float PatternMask = ((PixelPos.x/2 + PixelPos.y/2) % 2) * 0.7f;

	// the contants express the two opacity values we see when the primitive is hidden
	float LowContrastPatternMask = lerp(0.2, 1, PatternMask);

	// temporary
	LowContrastPatternMask = saturate(lerp(LowContrastPatternMask, 1, EditorRenderParams.r));

	//
	float HiddenMask = lerp(0.7f, 1.0f, DepthMask);
	float DarkenMask = lerp(LowContrastPatternMask, 1.0f, DepthMask);

	// Dest color has gamma applied so we need to remove it before applying linear color
//	DestColor.rgb = pow( DestColor.rgb, 2.2f );

	// fade if occluded
//	OutColor.rgb = lerp(DestColor.rgb, DarkenMask * SrcColor.rgb / max(0.001f, SrcColor.a), SrcColor.a * HiddenMask );
	// darken if occluded
//	OutColor.rgb = lerp(DestColor.rgb, DarkenMask * SrcColor.rgb * HiddenMask, SrcColor.a );

	// SrcColor is in premultipied alpha
	OutColor.rgb = DestColor.rgb * (1 - SrcColor.a) + DarkenMask * SrcColor.rgb * HiddenMask;

	// Re-apply gamma corrrection
//	OutColor.rgb = pow( OutColor.rgb, 1/2.2f );

	OutColor.a = 0;
}