Shader "Hidden/HDRP/PreIntegratedFGD_Marschner"
{
    SubShader
    {
        Tags{ "RenderPipeline" = "HDRenderPipeline" }
        Pass
        {
            ZTest Always Cull Off ZWrite Off

            HLSLPROGRAM

            #pragma editor_sync_compilation

            #pragma vertex Vert
            #pragma fragment Frag
            #pragma target 4.5
            #pragma only_renderers d3d11 playstation xboxone xboxseries vulkan metal switch
            #define PREFER_HALF 0
            #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl"
            #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/ImageBasedLighting.hlsl"
            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariables.hlsl"

            // ----------------------------------------------------------------------------
            // Pre-Integration
            // ----------------------------------------------------------------------------

            struct Attributes
            {
                uint vertexID : SV_VertexID;
            };

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

            Varyings Vert(Attributes input)
            {
                Varyings output;

                output.positionCS = GetFullScreenTriangleVertexPosition(input.vertexID);
                output.texCoord   = GetFullScreenTriangleTexCoord(input.vertexID);

                return output;
            }

            float4 Frag(Varyings input) : SV_Target
            {
                // Currently, we do not implement the pre-integration of Marschner for two reason:
                // 1) Area Light support for anisotropic LTC is not supported, and we fall back to GGX.
                // 2) Environment lighting is evaluated with the BSDF directly.

                float4 preFGD = 0;

                return float4(preFGD.xyz, 1.0);
            }

            ENDHLSL
        }
    }
    Fallback Off
}