Unity的灰阶公式

 Shader "Unlit/NewUnlitShader"
{
  Properties
  {
    _MainTex ("Texture", 2D) = "white" {}
    _DesatValue("DesatValue",Range(0,1)) = 0.5
  }
  SubShader
  {
    Tags { "RenderType"="Opaque" }
    LOD 100

    CGPROGRAM
    #pragma surface surf Lambert
    
    sampler2D _MainTex;
    fixed _DesatValue;

    struct Input
{
      float2 uv_MainTex;
    };

    void surf(Input IN,inout SurfaceOutput o)
    {
      float4 c = tex2D(_MainTex,IN.uv_MainTex);
      c.rgb = lerp(c.rgb,Luminance(c.rgb),_DesatValue);
      o.Albedo = c.rgb;
      o.Alpha = c.a;
    }


    ENDCG
  }
}

 // Converts color to luminance (grayscale)
float Luminance( vec3 c )
{
	return dot( c, vec3(0.22, 0.707, 0.071) );
}