// ***********************************************************************
// Author           : Kimch
// Created          : 2018-7-1
// Description      : 角色Shader
// Last Modified By : Kimch
// Last Modified On : 2019-7-1
// ***********************************************************************
// <copyright file= "MY/Skin" company="kk"></copyright>
// ***********************************************************************
Shader "MY/Skin(SSS)"
{
	Properties
	{
		_Color("Main Color", Color) = (1,1,1,1)
		_MainTex("Albedo", 2D) = "white" {}
		[Toggle]NORMAL("法线开关",Float) = 0
		_BumpMap("Normalmap", 2D) = "bump" {}

		[Toggle]Spec("Specular Mode",Float) = 1
		_Glossiness("Smoothness", Range(0.0, 5.0)) = 0.5

		[Toggle]SSS("SSS 开关",Float) = 0
		_BRDFTex("BRDF Lookup (RGB)", 2D) = "white" {}
		_SubColor("Subsurface Color", Color) = (1, .4, .25, 1)
		_SubFactor("Subsurface Factor",Range(0,5)) = 1

		[KeywordEnum(Const,Calc,Tex)] Curve("Curve Mode",Float) = 1
		_CurveTex("CurveTex", 2D) = "white" {}
		_CurveFactor("CurveFactor",Range(0,5)) = 1

			//[KeywordEnum(None, Curve, Specular)] Debug("Debug Mode", Float) = 0
	}

		SubShader
		{
			Tags{"RenderType" = "Opaque"}
			Pass
			{
				Tags { "LightMode" = "ForwardBase"}
				CGPROGRAM
				#pragma target 3.0
				#pragma vertex myvert
				#pragma fragment myfrag
				#pragma multi_compile_fwdbase
				#pragma shader_feature NORMAL_ON
				#pragma shader_feature SSS_ON
				#pragma shader_feature SPEC_ON
				#pragma shader_feature CURVE_CONST CURVE_CALC CURVE_TEX
			//#pragma multi_compile DEBUG_NONE DEBUG_CURVE DEBUG_SPECULAR

			#include "UnityCG.cginc"
			#include "AutoLight.cginc"		

			sampler2D _MainTex;
			fixed4 _MainTex_ST;
			fixed4 _Color;

			sampler2D _BumpMap;
			fixed4 _BumpMap_ST;

			fixed _Glossiness;

			sampler2D _CurveTex;
			fixed _CurveFactor;

			sampler2D _BRDFTex;
			fixed _SubFactor;
			fixed3 _SubColor;

			fixed4 _LightColor0;

			struct v2f_my
			{
				float4 pos : SV_POSITION;
				float4 uv : TEXCOORD0;
				float4 T2W0 :TEXCOORD1;
				float4 T2W1 :TEXCOORD2;
				float4 T2W2 :TEXCOORD3;
				LIGHTING_COORDS(4, 5)
			};

			v2f_my myvert(appdata_full v)
			{
				v2f_my o;
				o.pos = UnityObjectToClipPos(v.vertex);
				o.uv.xy = TRANSFORM_TEX(v.texcoord, _MainTex);
				o.uv.zw = TRANSFORM_TEX(v.texcoord,_BumpMap);

				float3 worldPos = mul(unity_ObjectToWorld,v.vertex);
				float3 worldNormal = UnityObjectToWorldNormal(v.normal);
				float3 worldTangent = UnityObjectToWorldDir(v.tangent);
				float3 worldBitangent = cross(worldNormal ,worldTangent) * v.tangent.w;

				o.T2W0 = float4 (worldTangent.x,worldBitangent.x,worldNormal.x,worldPos.x);
				o.T2W1 = float4 (worldTangent.y,worldBitangent.y,worldNormal.y,worldPos.y);
				o.T2W2 = float4 (worldTangent.z,worldBitangent.z,worldNormal.z,worldPos.z);

				TRANSFER_VERTEX_TO_FRAGMENT(o);

				return o;
			}

			//			inline float fresnelReflectance( float3 H, float3 V, float F0 )
			//			{
			//				float base = 1.0 - dot( V, H );
			//				float exponential = pow( base, 5.0 );
			//				return exponential + F0 * ( 1.0 - exponential );
			//			}

						half4 myfrag(v2f_my i) : SV_Target
						{
							float3 albedo = tex2D(_MainTex,i.uv.xy).rgb * _Color;

							fixed4 ambient = UNITY_LIGHTMODEL_AMBIENT;//环境光
							fixed attenuation = LIGHT_ATTENUATION(i);//投影

							float3 worldPos = float3(i.T2W0.w,i.T2W1.w,i.T2W2.w);
							fixed3 lightDir = normalize(UnityWorldSpaceLightDir(worldPos));
							fixed3 viewDir = normalize(UnityWorldSpaceViewDir(worldPos));

#if defined(NORMAL_ON)
								fixed4 tangentNormal = tex2D(_BumpMap,i.uv.zw);
								fixed3 bump = UnpackNormal(tangentNormal);
								fixed3 worldBump = normalize(half3(dot(i.T2W0.zzz,bump),
																	dot(i.T2W1.zzz,bump),
																	dot(i.T2W2.zzz,bump)));
#else
								fixed3 worldBump = normalize(half3(i.T2W0.z, i.T2W1.z, i.T2W2.z));
#endif

								#if defined(CURVE_CONST)
									fixed curvature = _CurveFactor;
								#elif defined(CURVE_TEX)
									fixed curvature = tex2D(_CurveTex,i.uv.zw);
								#else
									fixed3 worldShapeBump = normalize(float3(i.T2W0.z,i.T2W1.z,i.T2W2.z));
									fixed curvature = saturate(_CurveFactor * 0.01 * (length(fwidth(worldShapeBump)) / length(fwidth(worldPos))));
								#endif

									fixed dotNL = dot(worldBump,lightDir);
									half3 H = normalize(lightDir + viewDir);
									fixed dotNH = dot(worldBump, H);

#if defined(SPEC_ON)
									fixed3 specular = pow(max(0, dotNH), 10.0) * _Glossiness;
#else
									fixed3 specular = 0;
#endif

								#if defined(SSS_ON)
									//	Skin Lighting
									float2 brdfUV;
									// Half-Lambert lighting value based on blurred normals.
									brdfUV.x = dotNL * 0.5 + 0.5;
									// Curvature amount. Multiplied by light's luminosity so brighter light = more scattering.
									// Pleae note: gi.light.color already contains light attenuation
									brdfUV.y = curvature;// *dot(_LightColor0.rgb, fixed3(0.22, 0.707, 0.071));
									fixed3 diffuse = tex2D(_BRDFTex, brdfUV) +  (dotNH * _SubFactor)*_SubColor.rgb;

								#else					
									fixed3 diffuse = max(0, dotNL);
								#endif



							fixed3 finalColor = (ambient + (diffuse + specular) * _LightColor0.rgb * attenuation) * albedo;

							#if defined(DEBUG_CURVE)
								return fixed4(curvature, curvature, curvature,1);
							#elif defined (DEBUG_SPECULAR)
								return fixed4(specular,1);
							#else
								return fixed4(finalColor,1);
							#endif
							}
							ENDCG
						}
		}
			FallBack "Diffuse"
}