Shader "Custom/DepthOnly"
{
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            struct v2f
            {
                float4 pos : SV_POSITION;
                float depth : TEXCOORD0;
                float4 pos2 : TEXCOORD2;
            };

            v2f vert(appdata_base v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                // o.depth = (o.pos.z + 1.) / 2. / o.pos.w;
                // o.depth = (o.pos.z + 1.) / 2.;
                // o.depth = o.pos.z;

                // o.pos.x = o.pos.x / o.pos.w;
                // o.pos.y = o.pos.y / o.pos.w;
                // o.pos.z = o.pos.z / o.pos.w;
                o.depth = o.pos.z / o.pos.w;
                //o.depth = mul(UNITY_MATRIX_M, v.vertex).x;
                // o.pos2 = o.pos;
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {


                // Outputs depth in RGB (2^24 precision)
                // ****We had to change Unity's color space to Gamma such that it doesn't add its own gamma correction,
                //     for this to work *******
                // uint depth24b = (i.depth * ((1<<24)-1)); // maps depth to be from 0 --- 2^24

                // uint rEncode = 0;
                // uint gEncode = 0;
                // uint bEncode = 0;
                // // This loop encodes depth into a 24 bit value split across all three color channels.
                // // The least significant digit is the last blue value.
                // // The most significant digit is the first red value.
                // for (int i = 0; i < 8; i++){
                //     bEncode |= ((depth24b) & 1) << i;
                //     depth24b >>= 1;

                //     gEncode |= ((depth24b) & 1) << i;
                //     depth24b >>= 1;

                //     rEncode |= ((depth24b) & 1) << i;
                //     depth24b >>= 1;
                // }
                // return fixed4(
                //     rEncode/255.,
                //     gEncode/255.,
                //     bEncode/255.,
                //     1.0
                // );

                // Output depth as grayscale (2^8 precision)
                return fixed4((i.depth), (i.depth), (i.depth), 1.0);

                // return fixed4(
                //     (i.pos2.x) * .5 + .5, 
                //     (i.pos2.x) * .5 + .5, 
                //     (i.pos2.x) * .5 + .5, 1.0);
            }
            ENDCG
        }
    }
    FallBack "Diffuse"
}