// Copyright 1998-2014 Epic Games, Inc. All Rights Reserved.

/*=============================================================================
	SimpleElementPixelShader.hlsl: Pixel shader for drawing simple elements.
=============================================================================*/

#include "Common.usf"
#include "ColorUtils.usf"

#define USE_IES_PROFILE 1
#include "IESLightProfilesCommon.usf"


Texture2D InTexture;
SamplerState InTextureSampler;

half4 TextureComponentReplicate;
half4 TextureComponentReplicateAlpha;

void ReplicateChannelSimpleElementShader(inout float4 BaseColor)
{
	ReplicateChannel(BaseColor, TextureComponentReplicate, TextureComponentReplicateAlpha);
}

bool bEnableEditorPrimitiveDepthTest;
float4 ScreenToPixel;

#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4

void PerformEditorCompositingDepthTest(float4 SvPosition)
{
	bool bIsPerspective = (View.ViewToClip._m33 < 1.0f);
	// Using SV_Position because manual interpolation fails in precision for the editor grid.
	float SceneDepthDeviceZ = SceneDepthTextureNonMS.Load(int3(SvPosition.xy, 0)).r;

	float InterpolatedDeviceZ = SvPosition.z;

	// This is for a reversed Z depth buffer.
	clip(InterpolatedDeviceZ - SceneDepthDeviceZ);
}

#endif

void Main(
	in float2 TextureCoordinate : TEXCOORD0,
	in float4 Color : TEXCOORD1,
	in float4 HitProxyId : TEXCOORD2,
	out float4 OutColor : SV_Target0
#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	,out float4 OutWorldNormal : SV_Target1 
	,in float4 SvPosition : SV_Position
#endif
	)
{
#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	// depth test manually if compositing editor primitives
	FLATTEN
	if (bEnableEditorPrimitiveDepthTest)
	{
		PerformEditorCompositingDepthTest(SvPosition);
	}
#endif
	 
	float4 BaseColor = Texture2DSample(InTexture, InTextureSampler,TextureCoordinate);
	ReplicateChannelSimpleElementShader(BaseColor);
	OutColor = RETURN_COLOR(BaseColor * Color);	

#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	// Set the G buffer bits that indicate unlit
	OutWorldNormal = 0;
#endif
}

#if METAL_PROFILE
static const half Gamma = 1.0f;
#else
half Gamma;
#endif

void GammaMain(
	in float2 TextureCoordinate : TEXCOORD0,
	in float4 Color : TEXCOORD1,
	in float4 InHitProxyId : TEXCOORD2,			// needed to have d3ddebug warning supressed (VS and PS signatures with SV_Position
	out float4 OutColor : SV_Target0
#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	,in float4 SvPosition : SV_Position
	,out float4 OutWorldNormal : SV_Target1
#endif
	)
{
#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	// depth test manually if compositing editor primitives
	FLATTEN
	if (bEnableEditorPrimitiveDepthTest)
	{
		PerformEditorCompositingDepthTest(SvPosition);
	}
#endif

	float4 BaseColor = Texture2DSample(InTexture, InTextureSampler,TextureCoordinate);
	ReplicateChannelSimpleElementShader(BaseColor);
	OutColor = BaseColor * Color;
	if( Gamma != 1.0 )
	{
		// Gamma correct the output color.
		OutColor.rgb = pow(saturate(OutColor.rgb),Gamma);	
	}
	OutColor = RETURN_COLOR(OutColor);

#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	// Set the G buffer bits that indicate unlit
	OutWorldNormal = 0;
#endif
}

float ClipRef;

void GammaMaskedMain(
	in float2 TextureCoordinate : TEXCOORD0,
	in float4 Color : TEXCOORD1,
	in float4 HitProxyId : TEXCOORD2,
	out float4 OutColor : SV_Target0
#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	,in float4 SvPosition : SV_Position
	,out float4 OutWorldNormal : SV_Target1
#endif
	)
{
#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	// depth test manually if compositing editor primitives
	FLATTEN
	if (bEnableEditorPrimitiveDepthTest)
	{
		PerformEditorCompositingDepthTest(SvPosition);
	}
#endif

	float4 BaseColor = Texture2DSample(InTexture, InTextureSampler,TextureCoordinate);
	ReplicateChannelSimpleElementShader(BaseColor);
	clip(BaseColor.a - ClipRef);
	OutColor.rgba = BaseColor * Color;
	if( Gamma != 1.0 )
	{
		// Gamma correct the output color.
		OutColor.rgb = pow(saturate(OutColor.rgb),Gamma);	
	}
	OutColor = RETURN_COLOR(OutColor);

#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	// Set the G buffer bits that indicate unlit
	OutWorldNormal = 0;
#endif
}


/** the width to smooth the edge the texture */
float SmoothWidth;
/** toggles drop shadow rendering */
bool EnableShadow;
/** 2d vector specifying the direction of shadow */
float2 ShadowDirection;
/** Color of the shadowed pixels */
float4 ShadowColor;
/** the width to smooth the edge the shadow of the texture */
float ShadowSmoothWidth;
/** toggles glow rendering */
bool EnableGlow;
/** base color to use for the glow */
float4 GlowColor;
/** outline glow outer radius */
float2 GlowOuterRadius;
/** outline glow inner radius */
float2 GlowInnerRadius;

/**
* Distance field rendering of textured tile.
* Alpha value represents distance to silhouette edge. A value of 0.5 is exactly on the edge.
*
* Based on the following paper:
* http://www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf
*/
void GammaDistanceFieldMain(
	in float2 TextureCoordinate : TEXCOORD0,
	in float4 Color : TEXCOORD1,
	out float4 OutColor : SV_Target0
	)
{
	float4 BaseTexture = Texture2DSample(InTexture, InTextureSampler,TextureCoordinate);
	ReplicateChannelSimpleElementShader(BaseTexture);
	float BaseDist = BaseTexture.a;
	// smooth range between SmoothWidth texels around edge
	// We want to control font edge smoothness in screen space, but the distance field is stored in texture space.
	// Using ddx scales the smoothstep steepness based on texel-to-pixel scaling.
	float TextureToScreenCompensation = ddx(TextureCoordinate.x);
	float SmoothstepWidth = SmoothWidth * TextureToScreenCompensation;
	float4 BaseColor = float4(Color.rgb, smoothstep(0.5-SmoothstepWidth, 0.5+SmoothstepWidth, BaseDist));
	
// @todo-mobile: bool doesn't work on ES2
#if !ES2_PROFILE
	if( EnableShadow )
	{
		// sample texture with shadow direction offset
		float4 ShadowTexture = Texture2DSample(InTexture, InTextureSampler,TextureCoordinate + ShadowDirection);
		ReplicateChannelSimpleElementShader(ShadowTexture);
		float ShadowDist = ShadowTexture.a;
		// smooth range between ShadowSmoothWidth texels around edge
		float4 ShadowResult = ShadowColor * smoothstep(0.5-ShadowSmoothWidth, 0.5+ShadowSmoothWidth, ShadowDist);
		BaseColor = lerp(ShadowResult,BaseColor,BaseColor.a);
	}

	if (EnableGlow)
	{
		// testing glow rendering
		//GlowOuterRadius = float2(0.3,0.45);
		//GlowInnerRadius = float2(0.45,0.5);	

		if (BaseDist >= GlowOuterRadius[0] && BaseDist <= GlowInnerRadius[1])
		{
			float OutlineFactor=0.0;
			if (BaseDist <= GlowOuterRadius[1])
			{
				OutlineFactor = smoothstep(GlowOuterRadius[0],GlowOuterRadius[1],BaseDist);
			}
			else
			{
				OutlineFactor = smoothstep(GlowInnerRadius[1],GlowInnerRadius[0],BaseDist);			
			}
			BaseColor = lerp(BaseColor,GlowColor,OutlineFactor);
		}
	}
 #endif
 	
	clip(BaseColor.a - ClipRef);
	OutColor = BaseColor;
	OutColor.a *= Color.a;
	if( Gamma != 1.0 )
	{
		// Gamma correct the output color.
		OutColor.rgb = pow(saturate(OutColor.rgb),Gamma);	
	}	
	OutColor = RETURN_COLOR(OutColor);
}

TextureCube CubeTexture;
SamplerState CubeTextureSampler;

// .x:MipLevel, .yzw:unused
float4 PackedProperties0;
float4x4 ColorWeights;

// used in the Texture info dialog when looking at a cubemap texture
void CubemapTextureProperties(
	in float2 TextureCoordinate : TEXCOORD0,
	in float4 InterpolatedColor : TEXCOORD1,
	out float4 OutColor : SV_Target0
#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	,out float4 OutWorldNormal : SV_Target1 
#endif
	)
{
	float2 Angles = float2(2 * PI * (TextureCoordinate.x + 0.5f), PI * TextureCoordinate.y);
	
	float s = sin(Angles.y);
	float3 Direction = float3(s * sin(Angles.x), cos(Angles.y), -s * cos(Angles.x));

	float MipLevel = PackedProperties0.x;

	// show specified mip level
	float4 BaseColor = TextureCubeSampleLevel(CubeTexture, CubeTextureSampler, Direction.xzy, MipLevel);

	float4 FinalColor;

	// Seperate the Color weights and use against the Base colour to detrmine the actual colour from our filter
	FinalColor.r = dot(BaseColor, ColorWeights[0]);
	FinalColor.g = dot(BaseColor, ColorWeights[1]);
	FinalColor.b = dot(BaseColor, ColorWeights[2]);
	FinalColor.a = dot(BaseColor, ColorWeights[3]);

	FinalColor *= InterpolatedColor;

#if HDR_OUTPUT == 1
	FinalColor.rgb =max(float3(0,0,0),FinalColor.rgb);	
#else
	// Gamma correct the output color.
	FinalColor.rgb = pow(saturate(FinalColor.rgb), Gamma);	
#endif
	
	OutColor = RETURN_COLOR(FinalColor);	

#if FEATURE_LEVEL >= FEATURE_LEVEL_SM4
	// Set the G buffer bits that indicate unlit
	OutWorldNormal = 0;
#endif
}

float3 ExtractLargestComponent(float3 v)
{
	float3 a = abs(v);

	if(a.x > a.y)
	{
		if(a.x > a.z)
		{
			return float3(v.x > 0 ? 1 : -1, 0, 0);
		}
	}
	else
	{
		if(a.y > a.z)
		{
			return float3(0, v.y > 0 ? 1 : -1, 0);
		}
	}

	return float3(0, 0, v.z > 0 ? 1 : -1);
}

// from the IES profile
float BrightnessInLumens;

void IESLightProfileMain(
	in float2 TextureCoordinate : TEXCOORD0,
	out float4 OutColor : SV_Target0
	)
{
	float3 BoxExtent = float3(2, 1.0f, 1);

	float TiltAngle = 0.3f;
	// y is downwards
	// z is pointing into the screen
	float3 EyePos = float3(0, 0.8f, 0.3f);
	float3 EyeDirection = float3(TextureCoordinate.xy * 2 - 1, 1) * 20;

	{
		float s = sin(TiltAngle);
		float c = cos(TiltAngle);
		EyeDirection = float3(EyeDirection.x, EyeDirection.y * c - EyeDirection.z * s, EyeDirection.y  * s + EyeDirection.z * c);
	}

	float2 Intersection = LineBoxIntersect(EyePos, EyePos + EyeDirection, -BoxExtent, BoxExtent);
	float3 Position = EyePos + EyeDirection * Intersection.y;
	float3 Normal = ExtractLargestComponent(Position / BoxExtent);

	float3 LightPos = float3(0, -0.25f, 0.85f);

	float LightProfileMultiplier = ComputeLightProfileMultiplier(Position, LightPos, float3(0, -1, 0));

	// Inverse square falloff
	float Attenuation = 0.01f / max( 0.01f, length(Position - LightPos));

	// don't preview brightness in thumbnail, arbitrary scale factor for the test scene
	float3 LinearColor = 100.0f * LightProfileMultiplier * Attenuation * saturate(dot(Normal, normalize(Position - LightPos)));

	// preview with actual brightness (some are too dark, others are too bright), arbitrary scale factor to preview light brightness without eye adaptation
//	LinearColor *= 0.0002f * IESMultiplier;

	// simple tonemapper without toe adjustment
	float3 GammaColor;
	{
		half TonemapperRange = 20;
		half TonemapperScaleClamped = 1;
		half A = 0.22 / TonemapperScaleClamped;
		half B = (TonemapperRange + A) / TonemapperRange;
		GammaColor = LinearColor / abs(LinearColor + A) * B;
	}

	OutColor = RETURN_COLOR(float4(GammaColor, 0));
}