o3de/Gems/Atom/Feature/Common/Assets/Shaders/Materials/Skin/Skin_PixelGeometryEval.azsli

/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */

#pragma once

// This #define magic lets you use the EvaluatePixelGeometry function in this file without making it the final EvaluatePixelGeometry
// used in your shader. Simply #define EvaluatePixelGeometry to your custom definition before including this file
//
#ifndef EvaluatePixelGeometry
#define EvaluatePixelGeometry EvaluatePixelGeometry_Skin
#endif

#include "../BasePBR/BasePBR_PixelGeometryEval.azsli"

PixelGeometryData EvaluatePixelGeometry_Skin(
    VsSystemValues SV,
    const MaterialParameters params,
    float3 positionWS,
    real3 normalWS,
    real3 tangentWS,
    real3 bitangentWS,
    float2 uvs[UvSetCount],
    float2 detailUvs[UvSetCount],
    real4 wrinkleBlendFactors,
    bool isFrontFace)
{
    // Base PBR Geo Data
    PixelGeometryData geoData = EvaluatePixelGeometry_BasePBR(SV, params, positionWS, normalWS, tangentWS, bitangentWS, uvs, isFrontFace);

    // Skin specifics
    // skin only has one detail UV channel
    geoData.detailUv = detailUvs[0];
    geoData.wrinkleBlendFactors = wrinkleBlendFactors;

    return geoData;
}

PixelGeometryData EvaluatePixelGeometry_Skin(VsOutput IN, VsSystemValues SV, bool isFrontFace, const MaterialParameters params)
{
    real4x4 objectToWorld = real4x4(GetObjectToWorldMatrix(SV));
    real3x3 objectToWorldIT = real3x3(GetObjectToWorldMatrixInverseTranspose(SV));

    real3 normalWS, tangentWS, bitangentWS;
    ConstructTBN(real3(IN.normal), real4(IN.tangent), objectToWorld, objectToWorldIT, normalWS, tangentWS, bitangentWS);

    return EvaluatePixelGeometry_Skin(
        SV,
        params,
        IN.worldPosition,
        normalWS,
        tangentWS,
        bitangentWS,
        IN.uvs,
        IN.detailUvs,
        real4(IN.blendFactors),
        isFrontFace);
}