一些shader的基本规则

变灰

<1>

fixed4 frag(v2f IN) : SV_Target
{    
    fixed4 c = tex2D(_MainTex, IN.texcoord) * IN.color;
    c.rgb *= c.a;
    float gray = dot(c.xyz, float3(0.299, 0.587, 0.114));
    c.xyz = float3(gray, gray, gray);
    return c;
}

<2>
half4 frag (v2f IN) : COLOR
{
  half4 col = tex2D(_MainTex, IN.texcoord) * IN.color;
  float c = 0.299*col.r + 0.587*col.g + 0.184*col.b;
  col.rgb = float3(c, c, c);

   return col;
}