Simple URP Dithering Shader

DitheringShader.shader

Shader "Custom/DitheringShader"
{
    Properties
    {
        _BaseMap("Base Map", 2D) = "white"
    }

    SubShader
    {
        Tags { "RenderType" = "Opaque" "RenderPipeline" = "UniversalPipeline" "Queue" = "Geometry" }

        Pass
        {
            Name "ForwardLitLike"
            Tags { "LightMode" = "UniversalForward" }

            ZWrite On
            Cull Back

            HLSLPROGRAM

            #pragma vertex vert
            #pragma fragment frag

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

            TEXTURE2D(_BaseMap);
            SAMPLER(sampler_BaseMap);

            TEXTURE2D(_DitherPattern);
            SAMPLER(sampler_DitherPattern);

            CBUFFER_START(UnityPerMaterial)
                float4 _BaseMap_ST;
            CBUFFER_END

            struct Attributes
            {
                float4 positionOS : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct Varyings {
                float4 positionCS : SV_POSITION;
                float2 uv : TEXCOORD0;
            };

            // 8x8 베이어 행렬 (Bayer Matrix)
            // 픽셀을 그릴지 말지를 결정하는 임계값(Threshold) 패턴입니다.
            // 값들은 0~63 범위이며, 64로 나누어 0~1 범위로 정규화해서 사용합니다.
            static const float dither_matrix[64] =
            {
                 0, 32,  8, 40,  2, 34, 10, 42,
                48, 16, 56, 24, 50, 18, 58, 26,
                12, 44,  4, 36, 14, 46,  6, 38,
                60, 28, 52, 20, 62, 30, 54, 22,
                 3, 35, 11, 43,  1, 33,  9, 41,
                51, 19, 59, 27, 49, 17, 57, 25,
                15, 47,  7, 39, 13, 45,  5, 37,
                63, 31, 55, 23, 61, 29, 53, 21
            };


            Varyings vert(Attributes IN)
            {
                Varyings OUT;

                OUT.positionCS = TransformObjectToHClip(IN.positionOS);
                OUT.uv = TRANSFORM_TEX(IN.uv, _BaseMap);
            
                return OUT;
            }

            half4 frag(Varyings IN) : SV_Target
            {
               float4 baseColor = SAMPLE_TEXTURE2D(_BaseMap, sampler_BaseMap, IN.uv);

                float2 screenUV = IN.positionCS.xy / IN.positionCS.w;
                screenUV = screenUV * 0.5 + 0.5;
                int2 pixelPos = int2(screenUV * _ScreenParams.xy);
                int x = pixelPos.x % 8;
                int y = pixelPos.y % 8;
                int index = y * 8 + x;
                float ditherValue = dither_matrix[index] / 64.0;


               if(baseColor.a - ditherValue <= 0)
               {
                   discard;
               }

               return baseColor;
            }

            ENDHLSL
        }
    }
}