Shader "zzwater/FSBlur"
{


    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _DepthThreshold ("Depth Threshold", Range(0, 200)) = 50 
        //_BlurRadius ("Blur Radius", Range(1, 10)) = 3
    }

    SubShader
    {
        Tags { "RenderType"="Opaque" "RenderPipeline" = "UniversalPipeline"}
        LOD 100
        ZWrite Off Cull Off
        Pass
        {
            Name "FSBlur"

            HLSLPROGRAM
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            
            // The Blit.hlsl file provides the vertex shader (Vert),
            // the input structure (Attributes) and the output structure (Varyings)
            #include "Packages/com.unity.render-pipelines.core/Runtime/Utilities/Blit.hlsl"
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DeclareDepthTexture.hlsl"

            #pragma vertex Vert
            #pragma fragment frag


            float _DepthThreshold;
            SAMPLER(sampler_BlitTexture);
            float4 _BlitTexture_TexelSize;


            half4 frag (Varyings input) : SV_Target
            {
                // Sample depth
                float deviceDepth = SampleSceneDepth(input.texcoord);
                float linearDepth = LinearEyeDepth(deviceDepth, _ZBufferParams);
                float _BlurRadius = 5;

                // Original color
                half4 originalColor = SAMPLE_TEXTURE2D(_BlitTexture, sampler_BlitTexture, input.texcoord);

                // If depth is less than threshold, return original color
                if (linearDepth < _DepthThreshold)
                    return originalColor;
                
                // Simple box blur (much faster than Gaussian)
                half4 blurredColor = half4(0, 0, 0, 0);
                int samples = 0;
                
                // Use fixed radius for simplicity
                for (int x = -_BlurRadius; x <= _BlurRadius; x++)
                {
                    for (int y = -_BlurRadius; y <= _BlurRadius; y++)
                    {
                        float2 offset = float2(x, y) * _BlitTexture_TexelSize;
                        blurredColor += SAMPLE_TEXTURE2D(_BlitTexture, sampler_BlitTexture, input.texcoord + offset);
                        samples++;
                    }
                }
                
                // Average the samples
                return blurredColor / samples;

            }
            ENDHLSL
        }
    }
}