表面着色器的一些问题

#pragma surface surf Lambert vertex:vert
/***********/
void vert(inout appdata_full v, out Input o)  
{
    UNITY_INITIALIZE_OUTPUT(Input, o);  
    /**********/
} 

struct Input 
{
    float2 uv_MainTex;
    float2 secondUV;
};
void vert(inout appdata_full v, out Input o)  
{
    UNITY_INITIALIZE_OUTPUT(Input, o);  
    secondUV = v.texcoord1.xy;
    /**********/
}