Shader "Custom/ScreenOffset"
{
    Properties
    {
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
        _ScreenNo ("ScreenNo", Int) = 0
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 200

        CGPROGRAM
        // Physically based Standard lighting model, and enable shadows on all light types
        #pragma surface surf Standard fullforwardshadows

        // Use shader model 3.0 target, to get nicer looking lighting
        #pragma target 3.0

        sampler2D _MainTex;

        struct Input
        {
            float2 uv_MainTex;
        };

        half _Glossiness;
        half _Metallic;
        int _ScreenNo;

        // Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
        // See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
        // #pragma instancing_options assumeuniformscaling
        UNITY_INSTANCING_BUFFER_START(Props)
            // put more per-instance properties here
        UNITY_INSTANCING_BUFFER_END(Props)

        void surf (Input IN, inout SurfaceOutputStandard o)
        {
            float u = IN.uv_MainTex.x;
            float su = (fmod(_ScreenNo, 3.0) + u) / 3.0;
            float v = IN.uv_MainTex.y;
            float sv = (floor(_ScreenNo / 3.0) + v) / 2.0;

            fixed4 c = tex2D(_MainTex, float2(su, sv));
            o.Albedo = c.rgb;
            o.Emission = c.rgb;
            o.Metallic = 0;
            o.Smoothness = 0;
            o.Alpha = 1;
        }
        ENDCG
    }
    FallBack "Diffuse"
}