Unity shader学习之高光反射光照模型

高光反射光照模型的公式如下：

　　C_specular = C_light * m_specular * max(0, dot(v, r))^gloss

要计算高光反射需要知道4个参数：入射光线颜色C_specular，材质高光反射系数gloss，视角方向v和反射方向r。

其中r可由cg函数reflect(i, n)求得。

转载请注明出处：http://www.cnblogs.com/jietian331/p/7088297.html

逐顶点高光反射shader如下：

 Shader "Custom/Specular Vertex-Level"
 {
     Properties
     {
         _Diffuse ("Diffuse Color", Color) = (,,,)
         _Specular ("Specular Color", Color) = (,,,)
         _Gloss ("Gloss", Range(, )) =
     }
     SubShader
     {
         Tags { "RenderType"="Opaque" }
         LOD 

         Pass
         {
             Tags { "LightMode"="ForwardBase" }

             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag

             #include "UnityCG.cginc"
             #include "Lighting.cginc"

             struct appdata
             {
                 float4 vertex : POSITION;
                 float3 normal : NORMAL;
             };

             struct v2f
             {
                 float4 vertex : SV_POSITION;
                 fixed4 color : COLOR;
             };

             fixed4 _Diffuse;
             fixed4 _Specular;
             float _Gloss;

             v2f vert (appdata v)
             {
                 v2f o;
                 o.vertex = UnityObjectToClipPos(v.vertex);

                 // specular
                 float3 lightDir = ObjSpaceLightDir(v.vertex);
                 lightDir = normalize(lightDir);
                 float3 nor = normalize(v.normal);
                 float3 refLightDir = reflect(-lightDir, nor);
                 refLightDir = normalize(refLightDir);
                 float3 viewDir = ObjSpaceViewDir(v.vertex);
                 viewDir = normalize(viewDir);
                 float d = max(, dot(refLightDir, viewDir));
                 float3 specColor = _LightColor0.rgb * _Specular.rgb * pow(d, _Gloss);

                 // diffuse
                 float3 diffuseColor = _LightColor0.rgb * _Diffuse.rgb * max(, dot(lightDir, nor));

                 float3 c = specColor + diffuseColor + UNITY_LIGHTMODEL_AMBIENT.rgb;

                 o.color = float4(c, );

                 return o;
             }

             fixed4 frag (v2f i) : SV_Target
             {
                 return i.color;
             }
             ENDCG
         }
     }
 }

Custom/Specular Vertex-Level

逐像素高光反射shader如下：

 Shader "Custom/Specular Fragment-Level"
 {
     Properties
     {
         _Diffuse ("Diffuse Color", Color) = (,,,)
         _Specular ("Specular Color", Color) = (,,,)
         _Gloss ("Gloss", Range(, )) =
     }
     SubShader
     {
         Tags { "RenderType"="Opaque" }
         LOD 

         Pass
         {
             Tags { "LightMode"="ForwardBase" }

             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag

             #include "UnityCG.cginc"
             #include "Lighting.cginc"

             struct appdata
             {
                 float4 vertex : POSITION;
                 float3 normal : NORMAL;
             };

             struct v2f
             {
                 float4 vertex : SV_POSITION;
                 float3 worldPos : TEXCOORD0;
                 float3 worldNormal : TEXCOORD1;
             };

             fixed4 _Diffuse;
             fixed4 _Specular;
             float _Gloss;

             v2f vert (appdata v)
             {
                 v2f o;
                 o.vertex = UnityObjectToClipPos(v.vertex);
                 o.worldNormal = UnityObjectToWorldNormal(v.normal);
                 o.worldPos = mul(unity_ObjectToWorld, v.vertex);
                 return o;
             }

             fixed4 frag (v2f i) : SV_Target
             {
                 // specular
                 float3 worldNormal = normalize(i.worldNormal);
                 float3 lightDir = UnityWorldSpaceLightDir(i.worldPos);
                 lightDir = normalize(lightDir);
                 float3 refLightDir = reflect(-lightDir, worldNormal);
                 refLightDir = normalize(refLightDir);
                 float3 viewDir = UnityWorldSpaceViewDir(i.worldPos);
                 viewDir = normalize(viewDir);
                 float d = max(, dot(refLightDir, viewDir));
                 float3 spec = _LightColor0.rgb * _Specular.rgb * pow(d, _Gloss);

                 // diffuse
                 float3 diff = _LightColor0.rgb * _Diffuse.rgb * max(, dot(lightDir, worldNormal));

                 float3 c = spec + diff + UNITY_LIGHTMODEL_AMBIENT.rgb;
                 return fixed4(c, );
             }
             ENDCG
         }
     }
 }

Custom/Specular Fragment-Level

效果分别如下：