ScriptableRenderPipeline/ScriptableRenderPipeline/HDRenderPipeline/ShaderPass/ShaderPassLightTransport.hlsl

#if SHADERPASS != SHADERPASS_LIGHT_TRANSPORT
#error SHADERPASS_is_not_correctly_define
#endif

#include "../../Core/ShaderLibrary/Color.hlsl"

CBUFFER_START(UnityMetaPass)
// x = use uv1 as raster position
// y = use uv2 as raster position
bool4 unity_MetaVertexControl;

// x = return albedo
// y = return normal
bool4 unity_MetaFragmentControl;
CBUFFER_END


// This was not in constant buffer in original unity, so keep outiside. But should be in as ShaderRenderPass frequency
float unity_OneOverOutputBoost;
float unity_MaxOutputValue;

#include "VertMesh.hlsl"

PackedVaryingsToPS Vert(AttributesMesh inputMesh)
{
    VaryingsToPS output;

    // Output UV coordinate in vertex shader
    float2 uv;

    if (unity_MetaVertexControl.x)
    {
        uv = inputMesh.uv1 * unity_LightmapST.xy + unity_LightmapST.zw;
    }
    else if (unity_MetaVertexControl.y)
    {
        uv = inputMesh.uv2 * unity_DynamicLightmapST.xy + unity_DynamicLightmapST.zw;
    }

    // OpenGL right now needs to actually use the incoming vertex position
    // so we create a fake dependency on it here that haven't any impact.
    output.vmesh.positionCS = float4(uv * 2.0 - 1.0, inputMesh.positionOS.z > 0 ? 1.0e-4 : 0.0, 1.0);
    output.vmesh.texCoord0  = inputMesh.uv0;
    output.vmesh.texCoord1  = inputMesh.uv1;

#if defined(VARYINGS_NEED_COLOR)
    output.vmesh.color = inputMesh.color;
#endif

    return PackVaryingsToPS(output);
}

float4 Frag(PackedVaryingsToPS packedInput) : SV_Target
{
    FragInputs input = UnpackVaryingsMeshToFragInputs(packedInput.vmesh);

    // input.unPositionSS is SV_Position
    PositionInputs posInput = GetPositionInput(input.unPositionSS.xy, _ScreenSize.zw);
    // No position and depth in case of light transport
    float3 V = float3(0.0, 0.0, 1.0); // No vector view in case of light transport

    SurfaceData surfaceData;
    BuiltinData builtinData;
    GetSurfaceAndBuiltinData(input, V, posInput, surfaceData, builtinData);

    BSDFData bsdfData = ConvertSurfaceDataToBSDFData(surfaceData);
    LightTransportData lightTransportData = GetLightTransportData(surfaceData, builtinData, bsdfData);

    // This shader is call two times. Once for getting emissiveColor, the other time to get diffuseColor
    // We use unity_MetaFragmentControl to make the distinction.
    float4 res = float4(0.0, 0.0, 0.0, 1.0);

    if (unity_MetaFragmentControl.x)
    {
        // Apply diffuseColor Boost from LightmapSettings.
        // put abs here to silent a warning, no cost, no impact as color is assume to be positive.
        res.rgb = Clamp(pow(abs(lightTransportData.diffuseColor), saturate(unity_OneOverOutputBoost)), 0, unity_MaxOutputValue);
    }

    if (unity_MetaFragmentControl.y)
    {
        // emissive use HDR format
        res.rgb = lightTransportData.emissiveColor;
    }

    return res;
}