[Unity] Unity中实现羽化功能的shader

GLSL->ShaderLab,原GLSL代码来自http://blog.csdn.net/panda1234lee/article/details/52199296，

由于shaderLab的一些特性，shaderLab代码显得要简洁很多。

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Custom/eclosion" {
    Properties {
        _MainTex ("Main Tex", 2D) = "white" {}
        _Diff("Diff", Range(0, 1)) = 0.5
    }
    SubShader {     
        Pass { 
            Tags { "LightMode"="ForwardBase" }

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag

            fixed4 _Color;
            sampler2D _MainTex;
            float4 _MainTex_ST;
            float _Diff;

            struct a2v {
                float4 vertex : POSITION;
                float4 texcoord : TEXCOORD0;
            };

            struct v2f {
                float4 pos : SV_POSITION;
                float2 uv : TEXCOORD1;
            };

            v2f vert(a2v v) {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;

                return o;
            }

            fixed4 frag(v2f i) : SV_Target {
                fixed3 srcColor = tex2D(_MainTex, i.uv).rgb;
                float dx = i.uv.x - 0.5;  
                float dy = i.uv.y - 0.5;  
                float dstSq = pow(dx, 2.0) + pow(dy, 2.0); 
                float v = (dstSq / _Diff); 
                float r = clamp(srcColor.r + v, 0.0, 1.0);  
                float g = clamp(srcColor.g + v, 0.0, 1.0);  
                float b = clamp(srcColor.b + v, 0.0, 1.0);

                return fixed4(r,g,b,1.0);
            }

            ENDCG
        }
    } 
    FallBack "Specular"
}