shader知识：
http://imgtec.eetrend.com/blogs/%E5%A2%A8%E5%8D%8A%E6%88%90%E9%9C%9C

最终效果

Shader "Learning Unity Shader/Lecture 14/Surface Rim Shader" 
{  
    //-----------------------------------【属性 || Properties】------------------------------------------   
    Properties  
    {  
        //主颜色 || Main Color  
        _MainColor("【主颜色】Main Color", Color) = (0.5,0.5,0.5,1)  
        //漫反射纹理 || Diffuse Texture  
        _MainTex("【纹理】Texture", 2D) = "white" {}  
        //凹凸纹理 || Bump Texture  
        _BumpMap("【凹凸纹理】Bumpmap", 2D) = "bump" {}  
        //边缘发光颜色 || Rim Color  
        _RimColor("【边缘发光颜色】Rim Color", Color) = (0.17,0.36,0.81,0.0)  
        //边缘发光强度 ||Rim Power  
        _RimPower("【边缘颜色强度】Rim Power", Range(0.6,36.0)) = 8.0  
        //边缘发光强度系数 || Rim Intensity Factor  
        _RimIntensity("【边缘颜色强度系数】Rim Intensity", Range(0.0,100.0)) = 1.0  
    }  
   
    //----------------------------------【子着色器 || SubShader】---------------------------------------   
    SubShader  
    {  
        //渲染类型为Opaque，不透明 || RenderType Opaque  
        Tags  
        {  
            "RenderType" = "Opaque"  
        }  
   
        //-------------------------开启CG着色器编程语言段 || Begin CG Programming Part----------------------   
        CGPROGRAM  
   
            //【1】声明使用兰伯特光照模式 ||Using the Lambert light mode  
            #pragma surface surf Lambert   
   
            //【2】定义输入结构 ||  Input Struct  
            struct Input  
            {  
                //纹理贴图 || Texture  
                float2 uv_MainTex;  
                //法线贴图 || Bump Texture  
                float2 uv_BumpMap;  
                //观察方向 || Observation direction  
                float3 viewDir;   
            };  
   
            //【3】变量声明 || Variable Declaration  
            //边缘颜色  
            float4 _MainColor;  
            //主纹理  
            sampler2D _MainTex;   
            //凹凸纹理   
            sampler2D _BumpMap;  
            //边缘颜色  
            float4 _RimColor;  
            //边缘颜色强度  
            float _RimPower;  
            //边缘颜色强度  
            float _RimIntensity;  
   
            //【4】表面着色函数的编写 || Writing the surface shader function  
            void surf(Input IN, inout SurfaceOutput o)  
            {  
                //表面反射颜色为纹理颜色   
                o.Albedo = tex2D(_MainTex, IN.uv_MainTex).rgb*_MainColor.rgb;  
                //表面法线为凹凸纹理的颜色   
                o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));  
                //边缘颜色   
                half rim = 1.0 - saturate(dot(normalize(IN.viewDir), o.Normal));  
                //计算出边缘颜色强度系数   
                o.Emission = _RimColor.rgb * pow(rim, _RimPower)*_RimIntensity;  
            }  
   
        //-------------------结束CG着色器编程语言段 || End CG Programming Part------------------   
        ENDCG  
    }  
   
        //后备着色器为普通漫反射 || Fallback use Diffuse  
        Fallback "Diffuse" 
}