Shader "MyShaders/Image Effects/My Grayscale Image Effect"{
    Properties{
        _MainTex("Texture", 2D) = "white"{}
        _NoiseTex("Noise Texture", 2D) = "white"{}
        _Intensity("Intensity",Range(0,1)) = 0
    }
        SubShader{
            Cull Off
            ZWrite Off
            ZTest Always
            Pass{
                HLSLPROGRAM
                #pragma vertex MyVertexProgram
                #pragma fragment MyFragmentProgram
                #include "UnityCG.cginc"
                struct VertexData {
                    float4 position : POSITION;
                    float2 uv : TEXCOORD0;
                };
                struct VertexToFragment {
                    float4 position : SV_POSITION;
                    float2 uv : TEXCOORD0;
                };
                sampler2D _MainTex;
                float4 _MainTex_ST;
                float _Intensity;
                VertexToFragment MyVertexProgram(VertexData vertex)
                {
                    VertexToFragment v2f;
                    v2f.position = UnityObjectToClipPos(vertex.position);
                    v2f.uv = vertex.uv * _MainTex_ST.xy + _MainTex_ST.zw;
                    return v2f;
                }
                float4 MyFragmentProgram(VertexToFragment v2f) : SV_TARGET
                {
                    float4 color = tex2D(_MainTex, v2f.uv);
                    float avgColor = (color.r + color.g + color.b) / 3;
                    float4 c = lerp(color, avgColor, _Intensity);
                    return c;
                }
            ENDHLSL
        }
    }
}