[渲染向]毛发-各向异性高光

unity，选择默认渲染管线

效果图：

 原理：

通过副切线和对半方向（即视线方向+光照方向）进行点乘计算高光，从而代替blinn-Phong中法线和对半方向的点乘

代码：

   Properties{_MainTex("MainTex", 2D) = "white"{}_SpecularTex("_SpecularTex", 2D) = "black"{}_exp("Exp", Range(0.0, 20.0)) = 1.0_scale("HightLightScale", Range(0.5, 5.0)) = 1.0_shiftControl("shiftControl", Range(-1.0, 1.0)) = 0.0_SpecularCol("SpecularCol", color) = (1.0, 1.0, 1.0, 1.0)}SubShader{Tags { "RenderType"="Opaque" }Cull OffPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"uniform sampler2D _MainTex;uniform sampler2D _SpecularTex;uniform float _exp;uniform float _scale;uniform float _shiftControl;uniform float3 _SpecularCol;struct VertexInput{float4 vertex : POSITION;float4 tangent : TANGENT;float4 normal : NORMAL;float2 uv : TEXCOORD0;};struct VertexOutput{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;float3 posWS : TEXCOORD1;float3 nDir : TEXCOORD2;float3 tDir : TEXCOORD3;float3 bDir : TEXCOORD4;};VertexOutput vert (VertexInput v){VertexOutput o;o.vertex = UnityObjectToClipPos(v.vertex);o.posWS = mul(unity_ObjectToWorld, v.vertex);o.nDir = UnityObjectToWorldNormal(v.normal);o.tDir = UnityObjectToWorldDir(v.tangent.xyz);o.bDir = cross(o.tDir, o.nDir);o.uv = v.uv;return o;}fixed4 frag (VertexOutput i) : SV_Target{//mainTexfloat3 var_MainTex = tex2D(_MainTex, i.uv);//数据准备float3 lDir = _WorldSpaceLightPos0.xyz;float3 vDir = _WorldSpaceCameraPos.xyz - i.posWS;float3 nDir = i.nDir;float3 tDir = i.tDir;float3 bDir = i.bDir;float3 hDir = normalize(lDir + vDir);//偏移bDirfloat var_SpecularTex = tex2D(_SpecularTex, i.uv) - 0.5;  //控制高光以及偏移量bDir = normalize(bDir + (var_SpecularTex + _shiftControl) * nDir);   //偏移后的结果//点积准备float ndotl = dot(nDir, lDir);float bdoth = dot(bDir, hDir);//光照模型//half-Lambertfloat diffusion = ndotl * 0.5 + 0.5;//Kajiya-Kayfloat sinBH = sqrt(1 - bdoth * bdoth);float dirAtten = smoothstep(-1.0, 0.0, bdoth);  //控制衰减float3 specular = dirAtten * pow(sinBH, _exp) * 0.3 * _SpecularCol;//返回最终值float finalLight = diffusion + specular;float3 finalCol = var_MainTex * diffusion + specular;return float4(finalCol, 1.0);}ENDCG}}

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