Blinn-Phong模型

最近在看基础光照模型，比较感兴趣的是高光反射模型，有下列两种：

1.Phong模型

　　

R = 2*N(dot(N, L)) - L

specular = lightColor * SpecularColor*(max(V· R, 0)) ^shininess；

2.Blinn-Phong模型

引入了H，Blinn模型不仅在速度上更快，而且更符合实际。

H = normalize（L+V）

specular = lightColor * SpecularColor*(max(N· H, 0)) ^shininess；

下面上Shader代码

 Shader "基础光照/BlinnPhongShader"
 {
     Properties
     {
         _MainTex ("Texture", 2D) = "white" {}
         _SpecularColor("SpecColor",Color) = (,,,)
         _DiffuseColor("DiffuseColor",Color) = (,,,)
         _Gloss("Gloss",Range(,)) =
     }
     SubShader
     {
         Tags{"RenderType"="Opaque"}
         //Cull Off ZWrite Off ZTest Always

         Pass
         {
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #include "Lighting.cginc"
             #include "UnityCG.cginc"

             struct appdata
             {
                 float4 pos : POSITION;
                 float3 normal : NORMAL;
                 float2 uv: TEXCOORD0;

             };

             struct v2f
             {

                 float4 pos: SV_POSITION;

                 float2 uv :TEXCOORD0;

                 float3 normal : TEXCOORD1;

                 float4 worldPos : TEXCOORD2;
             };

             v2f vert (appdata v)
             {
                 v2f o;
                 o.pos = mul(UNITY_MATRIX_MVP,v.pos);
                 o.worldPos= mul(_Object2World,v.pos);
                 o.normal = normalize( mul(v.normal,(float3x3)_World2Object));
                 o.uv = v.uv;
                 return o;
             }

             sampler2D _MainTex;
             fixed4 _DiffuseColor;
             fixed4 _SpecularColor;
             float _Gloss;

             fixed4 frag(v2f i): SV_Target
             {
                 //计算环境光
                 fixed3 ambient  = UNITY_LIGHTMODEL_AMBIENT.xyz;

                 float3 worldNormal = i.normal;

                 float3 worldLightDir = -normalize(_WorldSpaceLightPos0.xyz);

                 //计算漫反射
                 fixed3 diffuse = _LightColor0.rgb*_DiffuseColor*saturate(dot(worldNormal,worldLightDir));

                 //计算高光反射

                 float3 viewDir = normalize(_WorldSpaceCameraPos.xyz - i.worldPos.xyz);

                 fixed3 h = normalize(worldLightDir+viewDir);

                 fixed3 specular = _LightColor0.rgb*_SpecularColor*(pow(saturate(dot(h,worldNormal)),_Gloss));
                 fixed4 col = tex2D(_MainTex,i.uv);
                 return col*fixed4(ambient+diffuse+specular,1.0);
             }

             ENDCG
         }
     }
     FallBack "Specular"
 }

效果展示