Shader "Hidden/VolumetricFog"
{
    SubShader
    {
        Tags
        { 
            "RenderPipeline" = "UniversalPipeline"
        }

        Pass
        {
            Name "VolumetricFogRender"

            ZTest Always
            ZWrite Off
            Cull Off
            Blend Off

            HLSLPROGRAM

            #include "./VolumetricFog.hlsl"

            #pragma multi_compile _ _FORWARD_PLUS

            #pragma multi_compile _ _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MAIN_LIGHT_SHADOWS_SCREEN
            #pragma multi_compile _ _ADDITIONAL_LIGHTS
            #pragma multi_compile _ _ADDITIONAL_LIGHT_SHADOWS
            #pragma multi_compile_fragment _ _LIGHT_COOKIES
#if UNITY_VERSION >= 202310
            #pragma multi_compile_fragment _ PROBE_VOLUMES_L1 PROBE_VOLUMES_L2
#endif

            #pragma multi_compile_local_fragment _ _MAIN_LIGHT_CONTRIBUTION_DISABLED
            #pragma multi_compile_local_fragment _ _ADDITIONAL_LIGHTS_CONTRIBUTION_DISABLED
            #pragma multi_compile_local_fragment _ _APV_CONTRIBUTION_ENABLED

            #pragma vertex Vert
            #pragma fragment Frag

            float4 Frag(Varyings input) : SV_Target
            {
                UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);

                return VolumetricFog(input.texcoord, input.positionCS.xy);
            }

            ENDHLSL
        }

        Pass
        {
            Name "VolumetricFogHorizontalBlur"
            
            ZTest Always
            ZWrite Off
            Cull Off
            Blend Off

            HLSLPROGRAM

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.core/Runtime/Utilities/Blit.hlsl"
            #include "./DepthAwareGaussianBlur.hlsl"

            #pragma vertex Vert
            #pragma fragment Frag

#if UNITY_VERSION < 202320
            float4 _BlitTexture_TexelSize;
#endif

            float4 Frag(Varyings input) : SV_Target
            {
                UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);

                return DepthAwareGaussianBlur(input.texcoord, float2(1.0, 0.0), _BlitTexture, sampler_PointClamp, _BlitTexture_TexelSize.xy);
            }

            ENDHLSL
        }

        Pass
        {
            Name "VolumetricFogVerticalBlur"
            
            ZTest Always
            ZWrite Off
            Cull Off
            Blend Off

            HLSLPROGRAM

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.core/Runtime/Utilities/Blit.hlsl"
            #include "./DepthAwareGaussianBlur.hlsl"

            #pragma vertex Vert
            #pragma fragment Frag

#if UNITY_VERSION < 202320
            float4 _BlitTexture_TexelSize;
#endif

            float4 Frag(Varyings input) : SV_Target
            {
                UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);

                return DepthAwareGaussianBlur(input.texcoord, float2(0.0, 1.0), _BlitTexture, sampler_PointClamp, _BlitTexture_TexelSize.xy);
            }

            ENDHLSL
        }

        Pass
        {
            Name "VolumetricFogUpsampleComposition"
            
            ZTest Always
            ZWrite Off
            Cull Off
            Blend Off

            HLSLPROGRAM

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.core/Runtime/Utilities/Blit.hlsl"
            #include "./DepthAwareUpsample.hlsl"

            #pragma target 4.5

            #pragma vertex Vert
            #pragma fragment Frag

            TEXTURE2D_X(_VolumetricFogTexture);
            SAMPLER(sampler_BlitTexture);

            float4 Frag(Varyings input) : SV_Target
            {
                UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);

                float4 volumetricFog = DepthAwareUpsample(input.texcoord, _VolumetricFogTexture);
                float4 cameraColor = SAMPLE_TEXTURE2D_X(_BlitTexture, sampler_BlitTexture, input.texcoord);

                return float4(cameraColor.rgb * volumetricFog.a + volumetricFog.rgb, cameraColor.a);
            }

            ENDHLSL
        }
    }

    SubShader
    {
        Tags
        { 
            "RenderPipeline" = "UniversalPipeline"
        }

        UsePass "Hidden/VolumetricFog/VOLUMETRICFOGRENDER"

        UsePass "Hidden/VolumetricFog/VOLUMETRICFOGHORIZONTALBLUR"
            
        UsePass "Hidden/VolumetricFog/VOLUMETRICFOGVERTICALBLUR"

        Pass
        {
            Name "VolumetricFogUpsampleComposition"
            
            ZTest Always
            ZWrite Off
            Cull Off
            Blend Off

            HLSLPROGRAM

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.core/Runtime/Utilities/Blit.hlsl"
            #include "./DepthAwareUpsample.hlsl"

            #pragma vertex Vert
            #pragma fragment Frag

            TEXTURE2D_X(_VolumetricFogTexture);
            SAMPLER(sampler_BlitTexture);

            float4 Frag(Varyings input) : SV_Target
            {
                UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);

                float4 volumetricFog = DepthAwareUpsample(input.texcoord, _VolumetricFogTexture);
                float4 cameraColor = SAMPLE_TEXTURE2D_X(_BlitTexture, sampler_BlitTexture, input.texcoord);

                return float4(cameraColor.rgb * volumetricFog.a + volumetricFog.rgb, cameraColor.a);
            }

            ENDHLSL
        }
    }

    Fallback Off
}