Shader "Unlit/deph"
{
    Properties
    {
        _MainTexL ("Texture L", 2D) = "white" {}
        _MainTexR ("Texture R", 2D) = "white" {}
        _Size ("Texture Size", Vector) = (256,256,0,0)
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            // make fog work
            #pragma multi_compile_fog

            #include "UnityCG.cginc"

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

            struct v2f
            {
                float2 uv : TEXCOORD0;
                UNITY_FOG_COORDS(1)
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTexL;
            sampler2D _MainTexR;
            fixed4 _Size;

            float4 _MainTex_ST;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
                o.uv = v.uv;
                //UNITY_TRANSFER_FOG(o,o.vertex);
                return o;
            }

            fixed4 frag (v2f inp) : SV_Target
            {

                //fixed4 col = tex2D(_MainTexL, i.uv)*0.5 + tex2D(_MainTexR, i.uv)*0.5;
                fixed3 col=0;
                fixed dpX = 1/_Size.x;
                fixed dpY = 1/_Size.y;

                fixed3 minW = fixed3(100,100,100);
                fixed d = 0;
                fixed3 wght = 0;

                for(int i=0; i < int(_Size.z); i++) {
                    wght = 0;
                        int y=0;
                    for(int y = -2; y <= 2; y++) {
                        for(int x=-2; x <= 2; x++) {
                            float4 lw = tex2D(_MainTexL, inp.uv + float2(x * dpX,y * dpY)) - tex2D(_MainTexR, inp.uv + float2((x+i) * dpX,y * dpY));
                            wght += (lw*lw).rgb;
                        }
                    }
                    if(wght.r < minW.r && wght.g < minW.g && wght.b < minW.b) {
                        minW = wght;
                        d = float(i) / _Size.z;
                    }
                }

                return fixed4(d,d,d,1);
            }
            ENDCG
        }
    }
}