shader眼球效果

（1）眼睛，眼球，

相关介绍：
眼睛介绍

效果图：

其中用到的知识点： 视差，漫反射，环境反射
直接贴上代码：
里面有注释：

Shader "Eye"
{
	Properties
	{
		_BaseMap ("_BaseMap", 2D) = "white" {}
		_NormalMap ("_NormalMap", 2D) = "bump" {}
		_Parallax("_Parallax",float) = -0.1	
		_DecalMap ("_DecalMap", 2D) = "white" {}		
		// 光滑度
		_Roughness("_Roughness",range(0,1)) = 0.5
		_EnvMap("_EnvMap",Cube) = "_Skybox"{}
		_EnvRotate("眼球的旋转_EnvRotate",Range(0,360)) = 0
		_EnvIntensity("_EnvIntensity",range(0,5)) = 1

	}
	SubShader
	{
		Tags { "RenderType"="Opaque" "LightMode"="ForwardBase"}
	

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#pragma multi_compile_fwdbase
			#include "UnityCG.cginc"
			#include "AutoLight.cginc"
			struct appdata
			{
				float4 vertex : POSITION;
				float2 texcoord0 : TEXCOORD0;
				float3 normal : NORMAL;
				float4 tangent : TANGENT;
				// 顶点色 颜色   可以用作遮罩
				float4 color : COLOR;

			};

			struct v2f
			{
				float4 pos : SV_POSITION;
				float2 uv : TEXCOORD0;
				float3 posWorld : TEXCOORD1;
				float3 normalDir : TEXCOORD2;
				float3 tangentDir : TEXCOORD3;
				float3 binormalDir : TEXCOORD4;
				
			};

			sampler2D _BaseMap,_NormalMap;
			//贴花的图
			sampler2D _DecalMap;
		
			float _Roughness;
			samplerCUBE _EnvMap;
			float4 _EnvMap_HDR;
			float _EnvIntensity;
			float _EnvRotate;
			float _Parallax;
			//旋转
			float3 RotateAround(float degree,float3 target)
			{
				float rad = degree * UNITY_PI / 180;
				float2x2 m_rotate = float2x2(cos(rad),-sin(rad),
				sin(rad),cos(rad));
				float2 dir_rotate = mul(m_rotate,target.xyz);
				target = float3(dir_rotate.x,target.y,dir_rotate.y);
				return target;
			}
			/// aces  高转低
			inline float3 ACESFilm(float3 x)
			{
				float a = 2.51f;
				float b = 0.03f;
				float c = 2.43f;
				float d = 0.59f;
				float e = 0.14f;
				return saturate((x * (a * x+ b)) / (x*(c*x+d)+e));
			}


			v2f vert (appdata v)
			{
				v2f o;
				o.pos = UnityObjectToClipPos(v.vertex);
				o.uv = v.texcoord0;
				// 法线三剑客
				o.normalDir = UnityObjectToWorldNormal(v.normal);
				o.tangentDir = normalize(mul(unity_ObjectToWorld,float4(v.tangent.xyz,0.0))).xyz;
				o.binormalDir = normalize(cross(o.normalDir,o.tangentDir) * v.tangent.w);
				o.posWorld = mul(unity_ObjectToWorld,v.vertex).xyz;
				
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{

				// 
				half3 normalDir = normalize(i.normalDir);
				half3 tangentDir = normalize(i.tangentDir);
				half3 binormalDir = normalize(i.binormalDir);

				half3 lightDir = normalize(UnityWorldSpaceLightDir(i.posWorld));
				half3 viewDir = normalize(UnityWorldSpaceViewDir(i.posWorld));

				// 法线贴图
				float3x3 TBN = float3x3(tangentDir,binormalDir,normalDir);
				float4 normal_Map = tex2D(_NormalMap,i.uv);
				float3 normal_Data = UnpackNormal(normal_Map);
				normalDir = normalize(mul(normal_Data,TBN));


				// 视差效果 从侧面看，模拟眼球是凸出的
				//float parallax_depth =  1.0 - saturate(distance(i.uv,float2(0.5,0.5)) / 0.2);
				// 和上面是一样的效果，但是写法更高端一点，，用作遮罩
				float parallax_depth =  smoothstep(1.0,0.5,distance(i.uv,float2(0.5,0.5)) / 0.2);
				float3 tanViewDir = normalize(mul(TBN,viewDir));
				float2 parallax_Offset = parallax_depth * tanViewDir.xy / (tanViewDir.z + 0.42) * _Parallax; 
				half3 base_Color = tex2D(_BaseMap, i.uv + parallax_Offset);
				half3 decal_color = tex2D(_DecalMap, i.uv).rgb;


				// 眼球最外层是凸出的 ，内层是凹陷的，所以法线反向求出内陷的法线效果
				normal_Data.xy = - normal_Data.xy;
				float3 normalDir_Iris = normalize(mul(normal_Data,TBN));
				// 漫反射
				half NdotL = max(0.0,dot(normalDir_Iris,lightDir));
				half half_lambert = (NdotL + 1) * 0.5;
				half3 final_diffuse =  pow(half_lambert * base_Color,2.2);		


				/// 环境反射 、  边缘光，  最外层的外层的计算 用正常的normal				
				float3 reflectDir = reflect(-viewDir,normalDir);
				reflectDir =  RotateAround(_EnvRotate,reflectDir);
				float roughtness = lerp(0.0,0.95,saturate(_Roughness));
				roughtness = roughtness * (1.7 - 0.7 * roughtness);
				float mip_level = roughtness * 6.0;
				float4 color_CubeMap = texCUBElod(_EnvMap,float4(reflectDir,mip_level));
				float3 evn_Color = DecodeHDR(color_CubeMap,_EnvMap_HDR);
				float3 final_evn = evn_Color * _EnvIntensity;
				// 求出明度值 用明度  会让眼球的对比度更见明显
				float evn_lumin = dot(final_evn,float3(0.299f,0.587f,0.114f));
				final_evn = final_evn * evn_lumin;
				half3 finalColor = final_diffuse +( final_diffuse  *  pow(final_evn,2.2) ) + decal_color;
				half3 enconde_color = pow(ACESFilm(finalColor), 1 / 2.2);
				return float4(enconde_color,1.0);
			}
			ENDCG
		}
	}
}