InvertColors.shader

Shader "Hidden/InvertColors"
{
    Properties
    {
        _MainTex("Texture", 2D) = "white" {}
    }
        SubShader
    {
        // No culling or depth
        Cull Off ZWrite Off ZTest Always

        Pass
        {
        Stencil{
            Ref 1
            ReadMask 1
            Comp NotEqual
            Pass Keep
        }
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            v2f vert(appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            sampler2D _MainTex;

            fixed4 frag(v2f i) : SV_Target
            {
                fixed4 col = tex2D(_MainTex, i.uv);
            // inverted colors
            col.rgb = 1 - col.rgb;
            return col;
        }
        ENDCG
    }
    }
}