关于shader的学习

教程地址：https://onevcat.com/2013/07/shader-tutorial-1

因为想做一些特效，所以想稍微了解一下shader的代码,一下是一些笔记

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

Shader "Custom/Edge"  
{  
    Properties  
    {  
    //name （"客户端显示名字",可调节的值）=默认值
        _Edge ("Edge", Range(0, 0.2)) = 0.043  
        _EdgeColor ("EdgeColor", Color) = (1, 1, 1, 1)  
        _MainTex ("MainTex", 2D) = "white" {}  
    }  
    SubShader  
    {  
        Pass  
        {  
        //开始标记，表明这里开始是一段CG程序，与之匹配是下面的ENDCG
            CGPROGRAM 
            //编译指令 声明我们要写个啥样的着色器 着色器的名字
            #pragma vertex vert  
            #pragma fragment frag  
            #include "UnityCG.cginc"  
  
  //链接上面的_声明 ，因为这是一段CG程序，和上面是两个独立的块
            fixed _Edge;  
            fixed4 _EdgeColor; 
            sampler2D _MainTex;  
  
            struct appdata  
            {  
                float4 vertex : POSITION;  
                fixed2 uv : TEXCOORD0;  
            };  
  
            struct v2f  
            {  
                float4 vertex : SV_POSITION;  
                float4 objVertex : TEXCOORD0;  
                fixed2 uv : TEXCOORD1;  
            };  
  
            v2f vert (appdata v)  
            {  
                v2f o;  
                o.vertex = UnityObjectToClipPos(v.vertex);  
                o.objVertex = v.vertex;  
                o.uv = v.uv;  
  
                return o;  
            }  
              
            fixed4 frag (v2f i) : SV_Target  
            {     
                fixed x = i.uv.x;  
                fixed y = i.uv.y;  
                      
                if((x < _Edge) || (abs(1 - x) < _Edge) || (y < _Edge) || (abs(1 - y) < _Edge))   
                {  
                    return _EdgeColor * abs(cos(_Time.y));  
                }  
                else   
                {  
                    fixed4 color = tex2D(_MainTex, i.uv);  
                    return color;  
                }  
  
                //return i.objVertex;  
                //return fixed4(i.uv, 0, 1);  
            }  
            ENDCG  
        }  
    }  
}