highlight only the border of an object

Questions & Answers
1

iam new to unity....... i would like to know how can i highlight just the borders of an object

3 
Shader "Outlined Diffuse" 
{ 
   Properties 
   { 
      _Color ("Main Color", Color) = (.5,.5,.5,1) 
      _OutlineColor ("Outline Color", Color) = (0,1,0,1) 
      _Outline ("Outline width", Range (0.002, 0.03)) = 0.01 
      _MainTex ("Base (RGBA)", 2D) = "white" { } 
      //Not needed 
      //_ToonShade ("ToonShader Cubemap(RGB)", CUBE) = "" { Texgen CubeNormal } 
   } 

   SubShader 
   { 
      Tags {"Queue"="Transparent" "RenderType"="Transparent"} 

      //Minor switch 
      //UsePass "Toon/Basic/BASE" 

      CGPROGRAM
        #pragma surface surf Lambert

        sampler2D _MainTex;
        float4 _Color;

        struct Input {
            float2 uv_MainTex;
        };

        void surf (Input IN, inout SurfaceOutput o) {
            half4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
            o.Albedo = c.rgb;
            o.Alpha = c.a;
        }
        ENDCG

      Pass 
      { 
         Name "OUTLINE" 
         Tags { "LightMode" = "Always" } 

         Blend SrcAlpha OneMinusSrcAlpha

         CGPROGRAM 
#pragma exclude_renderers gles
#pragma exclude_renderers xbox360
         #pragma vertex vert 

         struct appdata { 
             float4 vertex; 
             float3 normal; 
         }; 

         struct v2f { 
            float4 pos : POSITION; 
            float4 color : COLOR; 
            float fog : FOGC; 
         }; 
         uniform float _Outline; 
         uniform float4 _OutlineColor; 

         v2f vert(appdata v) { 
            v2f o; 
            o.pos = mul(UNITY_MATRIX_MVP, v.vertex); 
            float3 norm = mul ((float3x3)UNITY_MATRIX_MV, v.normal); 
            norm.x *= UNITY_MATRIX_P[0][0]; 
            norm.y *= UNITY_MATRIX_P[1][1]; 
            o.pos.xy += norm.xy * o.pos.z * _Outline; 

            o.fog = o.pos.z; 
            o.color = _OutlineColor; 
            return o; 
         } 

         ENDCG 

         Cull Front
         ZWrite On
         ColorMask RGBA
         Blend SrcAlpha OneMinusSrcAlpha
         //? -Note: I don't remember why I put a "?" here 
         SetTexture [_MainTex] { combine primary } 
      } 
   } 

   Fallback "Diffuse" 
}
2

Try using the ToonShading.unityPackage