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**
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** Copyright (C) 2019 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
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** This file is part of Qt Quick 3D.
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** accordance with the commercial license agreement provided with the
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** the Free Software Foundation and appearing in the file LICENSE.GPL3
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/* clang-format off */

#include <QtQuick3DUtils/private/qssgutils_p.h>

#include <QtQuick3DRuntimeRender/private/qssgrenderdefaultmaterialshadergenerator_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrendercontextcore_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrendershadercodegenerator_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrenderimage_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrenderlight_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrendercamera_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrendershadowmap_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrendercustommaterial_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrendershaderlibrarymanager_p.h>
#include <QtQuick3DRuntimeRender/private/qssgrendershaderkeys_p.h>
#include <QtQuick3DRuntimeRender/private/qssgshadermaterialadapter_p.h>

#include <QtCore/QByteArray>

QT_BEGIN_NAMESPACE

namespace  {
using Type = QSSGRenderableImage::Type;
template<Type> struct ImageStrings {};
#define DefineImageStrings(V) template<> struct ImageStrings<Type::V> \
{\
    static constexpr const char* sampler() { return "qt_"#V"Map_sampler"; }\
    static constexpr const char* offsets() { return "qt_"#V"Map_offsets"; }\
    static constexpr const char* rotations() { return "qt_"#V"Map_rotations"; }\
    static constexpr const char* fragCoords1() { return "qt_"#V"Map_uv_coords1"; }\
    static constexpr const char* fragCoords2() { return "qt_"#V"Map_uv_coords2"; }\
    static constexpr const char* samplerSize() { return "qt_"#V"Map_size"; }\
}

DefineImageStrings(Unknown);
DefineImageStrings(Diffuse);
DefineImageStrings(Opacity);
DefineImageStrings(Specular);
DefineImageStrings(Emissive);
DefineImageStrings(Bump);
DefineImageStrings(SpecularAmountMap);
DefineImageStrings(Normal);
DefineImageStrings(Translucency);
DefineImageStrings(Roughness);
DefineImageStrings(BaseColor);
DefineImageStrings(Metalness);
DefineImageStrings(Occlusion);
DefineImageStrings(Height);

struct ImageStringSet
{
    const char *imageSampler;
    const char *imageFragCoords;
    const char *imageFragCoordsTemp;
    const char *imageOffsets;
    const char *imageRotations;
    const char *imageSamplerSize;
};

#define DefineImageStringTableEntry(V) \
    { ImageStrings<Type::V>::sampler(), ImageStrings<Type::V>::fragCoords1(), ImageStrings<Type::V>::fragCoords2(), \
      ImageStrings<Type::V>::offsets(), ImageStrings<Type::V>::rotations(), ImageStrings<Type::V>::samplerSize() }

constexpr ImageStringSet imageStringTable[] {
    DefineImageStringTableEntry(Unknown),
    DefineImageStringTableEntry(Diffuse),
    DefineImageStringTableEntry(Opacity),
    DefineImageStringTableEntry(Specular),
    DefineImageStringTableEntry(Emissive),
    DefineImageStringTableEntry(Bump),
    DefineImageStringTableEntry(SpecularAmountMap),
    DefineImageStringTableEntry(Normal),
    DefineImageStringTableEntry(Translucency),
    DefineImageStringTableEntry(Roughness),
    DefineImageStringTableEntry(BaseColor),
    DefineImageStringTableEntry(Metalness),
    DefineImageStringTableEntry(Occlusion),
    DefineImageStringTableEntry(Height)
};

const int TEXCOORD_VAR_LEN = 16;

void textureCoordVaryingName(char (&outString)[TEXCOORD_VAR_LEN], quint8 uvSet)
{
    // For now, uvSet will be less than 2.
    // But this value will be verified in the setProperty function.
    Q_ASSERT(uvSet < 9);
    qstrncpy(outString, "qt_varTexCoordX", TEXCOORD_VAR_LEN);
    outString[14] = '0' + uvSet;
}

void textureCoordVariableName(char (&outString)[TEXCOORD_VAR_LEN], quint8 uvSet)
{
    // For now, uvSet will be less than 2.
    // But this value will be verified in the setProperty function.
    Q_ASSERT(uvSet < 9);
    qstrncpy(outString, "qt_texCoordX", TEXCOORD_VAR_LEN);
    outString[11] = '0' + uvSet;
}

}

const char *QSSGMaterialShaderGenerator::getSamplerName(QSSGRenderableImage::Type type)
{
    return imageStringTable[int(type)].imageSampler;
}

static void addLocalVariable(QSSGStageGeneratorBase &inGenerator, const QByteArray &inName, const QByteArray &inType)
{
    inGenerator << "    " << inType << " " << inName << ";\n";
}

static QByteArray uvTransform(const QByteArray& imageRotations, const QByteArray& imageOffsets)
{
    QByteArray transform;
    transform = "    qt_uTransform = vec3(" + imageRotations + ".x, " + imageRotations + ".y, " + imageOffsets + ".x);\n";
    transform += "    qt_vTransform = vec3(" + imageRotations + ".z, " + imageRotations + ".w, " + imageOffsets + ".y);\n";
    return transform;
}

static void generateImageUVCoordinates(QSSGMaterialVertexPipeline &vertexShader,
                                       QSSGStageGeneratorBase &fragmentShader,
                                       const QSSGShaderDefaultMaterialKey &key,
                                       QSSGRenderableImage &image,
                                       bool forceFragmentShader = false,
                                       quint32 uvSet = 0)
{
    if (image.uvCoordsGenerated)
        return;

    const auto &names = imageStringTable[int(image.m_mapType)];
    char textureCoordName[TEXCOORD_VAR_LEN];
    fragmentShader.addUniform(names.imageSampler, "sampler2D");
    if (!forceFragmentShader) {
        vertexShader.addUniform(names.imageOffsets, "vec3");
        vertexShader.addUniform(names.imageRotations, "vec4");
    } else {
        fragmentShader.addUniform(names.imageOffsets, "vec3");
        fragmentShader.addUniform(names.imageRotations, "vec4");
    }
    QByteArray uvTrans = uvTransform(names.imageRotations, names.imageOffsets);
    if (image.m_imageNode.m_mappingMode == QSSGRenderImage::MappingModes::Normal) {
        if (!forceFragmentShader) {
            vertexShader << uvTrans;
            vertexShader.addOutgoing(names.imageFragCoords, "vec2");
            vertexShader.addFunction("getTransformedUVCoords");
        } else {
            fragmentShader << uvTrans;
            fragmentShader.addFunction("getTransformedUVCoords");
        }
        vertexShader.generateUVCoords(uvSet, key);
        if (!forceFragmentShader) {
            textureCoordVaryingName(textureCoordName, uvSet);
            vertexShader << "    vec2 " << names.imageFragCoordsTemp << " = qt_getTransformedUVCoords(vec3(" << textureCoordName << ", 1.0), qt_uTransform, qt_vTransform);\n";
            vertexShader.assignOutput(names.imageFragCoords, names.imageFragCoordsTemp);
        } else {
            textureCoordVariableName(textureCoordName, uvSet);
            fragmentShader << "    vec2 " << names.imageFragCoords << " = qt_getTransformedUVCoords(vec3(" << textureCoordName << ", 1.0), qt_uTransform, qt_vTransform);\n";
        }
    } else {
        fragmentShader.addUniform(names.imageOffsets, "vec3");
        fragmentShader.addUniform(names.imageRotations, "vec4");
        fragmentShader << uvTrans;
        vertexShader.generateEnvMapReflection(key);
        fragmentShader.addFunction("getTransformedUVCoords");
        fragmentShader << "    vec2 " << names.imageFragCoords << " = qt_getTransformedUVCoords(environment_map_reflection, qt_uTransform, qt_vTransform);\n";
    }
    image.uvCoordsGenerated = true;
}

static void generateImageUVSampler(QSSGMaterialVertexPipeline &vertexGenerator,
                                   QSSGStageGeneratorBase &fragmentShader,
                                   const QSSGShaderDefaultMaterialKey &key,
                                   const QSSGRenderableImage &image,
                                   char (&outString)[TEXCOORD_VAR_LEN],
                                   quint8 uvSet = 0)
{
    const auto &names = imageStringTable[int(image.m_mapType)];
    fragmentShader.addUniform(names.imageSampler, "sampler2D");
    // NOTE: Actually update the uniform name here
    textureCoordVariableName(outString, uvSet);
    vertexGenerator.generateUVCoords(uvSet, key);
}

static void outputSpecularEquation(QSSGRenderDefaultMaterial::MaterialSpecularModel inSpecularModel,
                                   QSSGStageGeneratorBase &fragmentShader,
                                   const QByteArray &inLightDir,
                                   const QByteArray &inLightSpecColor)
{
    if (inSpecularModel == QSSGRenderDefaultMaterial::MaterialSpecularModel::KGGX) {
        fragmentShader.addInclude("physGlossyBSDF.glsllib");
        fragmentShader << "    global_specular_light += qt_lightAttenuation * qt_shadow_map_occl * qt_specularAmount"
                          " * qt_kggxGlossyDefaultMtl(qt_world_normal, qt_tangent, -" << inLightDir << ".xyz, qt_view_vector, " << inLightSpecColor << ".rgb, qt_specularTint, qt_roughnessAmount).rgb;\n";
    } else {
        fragmentShader.addFunction("specularBSDF");
        fragmentShader << "    global_specular_light += qt_lightAttenuation * qt_shadow_map_occl * qt_specularAmount"
                          " * qt_specularBSDF(qt_world_normal, -" << inLightDir << ".xyz, qt_view_vector, " << inLightSpecColor << ".rgb, 2.56 / (qt_roughnessAmount + 0.01)).rgb;\n";
    }
}

static void addTranslucencyIrradiance(QSSGStageGeneratorBase &infragmentShader,
                                      QSSGRenderableImage *image,
                                      const QSSGMaterialShaderGenerator::LightVariableNames &lightVarNames)
{
    if (image == nullptr)
        return;

    infragmentShader.addFunction("diffuseReflectionWrapBSDF");
    infragmentShader << "    tmp_light_color = " << lightVarNames.lightColor << ".rgb * (1.0 - qt_metalnessAmount);\n";
    infragmentShader << "    global_diffuse_light.rgb += qt_lightAttenuation * qt_shadow_map_occl * qt_translucent_thickness_exp * qt_diffuseReflectionWrapBSDF(-qt_world_normal, -"
                     << lightVarNames.normalizedDirection << ", tmp_light_color, qt_material_properties2.w).rgb;\n";
}

static QVarLengthArray<QSSGMaterialShaderGenerator::ShadowVariableNames, 16> q3ds_shadowMapVariableNames;

static QSSGMaterialShaderGenerator::ShadowVariableNames setupShadowMapVariableNames(qsizetype lightIdx)
{
    if (lightIdx >= q3ds_shadowMapVariableNames.count())
        q3ds_shadowMapVariableNames.resize(lightIdx + 1);

    QSSGMaterialShaderGenerator::ShadowVariableNames &names(q3ds_shadowMapVariableNames[lightIdx]);
    if (names.shadowMapStem.isEmpty()) {
        names.shadowMapStem = QByteArrayLiteral("qt_shadowmap");
        names.shadowCubeStem = QByteArrayLiteral("qt_shadowcube");
        char buf[16];
        qsnprintf(buf, 16, "%d", int(lightIdx));
        names.shadowCubeStem.append(buf);
        names.shadowMapStem.append(buf);
        names.shadowMatrixStem = names.shadowMapStem;
        names.shadowMatrixStem.append("_matrix");
        names.shadowCoordStem = names.shadowMapStem;
        names.shadowCoordStem.append("_coord");
        names.shadowControlStem = names.shadowMapStem;
        names.shadowControlStem.append("_control");
    }

    return names;
}

// this is for DefaultMaterial only
static void maybeAddMaterialFresnel(QSSGStageGeneratorBase &fragmentShader,
                                    const QSSGShaderDefaultMaterialKeyProperties &keyProps,
                                    QSSGDataView<quint32> inKey,
                                    bool hasMetalness)
{
    if (keyProps.m_fresnelEnabled.getValue(inKey)) {
        fragmentShader.addInclude("defaultMaterialFresnel.glsllib");
        fragmentShader << "    // Add fresnel ratio\n";
        if (hasMetalness) { // this won't be hit in practice since DefaultMaterial does not offer metalness as a property
            fragmentShader << "    qt_specularAmount *= qt_defaultMaterialSimpleFresnel(qt_specularBase, qt_metalnessAmount, qt_world_normal, qt_view_vector, "
                              "qt_dielectricSpecular(qt_material_specular.w), qt_material_properties2.x);\n";
        } else {
            fragmentShader << "    qt_specularAmount *= qt_defaultMaterialSimpleFresnelNoMetalness(qt_world_normal, qt_view_vector, "
                              "qt_dielectricSpecular(qt_material_specular.w), qt_material_properties2.x);\n";
        }
    }
}

static QSSGMaterialShaderGenerator::LightVariableNames setupLightVariableNames(qint32 lightIdx, QSSGRenderLight &inLight)
{
    Q_ASSERT(lightIdx > -1);
    QSSGMaterialShaderGenerator::LightVariableNames names;

    // See funcsampleLightVars.glsllib. Using an instance name (ubLights) is
    // intentional. The only uniform block that does not have an instance name
    // is cbMain (the main block with all default and custom material
    // uniforms). Any other uniform block must have an instance name in order
    // to avoid trouble with the OpenGL-targeted shaders generated by the
    // shader pipeline (as those do not use uniform blocks, and in absence of a
    // block instance name SPIR-Cross generates a struct uniform name based on
    // whatever SPIR-V ID glslang made up for the variable - this can lead to
    // clashes between the vertex and fragment shaders if there are blocks with
    // different names (but no instance names) that are only present in one of
    // the shaders). For cbMain the issue cannot happen since the exact same
    // block is present in both shaders. For cbLights it is simple enough to
    // use the correct prefix right here, so there is no reason not to use an
    // instance name.
    QByteArray lightStem = "ubLights.lights";
    char buf[16];
    qsnprintf(buf, 16, "[%d].", int(lightIdx));
    lightStem.append(buf);

    names.lightColor = lightStem;
    names.lightColor.append("diffuse");
    names.lightDirection = lightStem;
    names.lightDirection.append("direction");
    names.lightSpecularColor = lightStem;
    names.lightSpecularColor.append("specular");
    if (inLight.type == QSSGRenderLight::Type::PointLight) {
        names.lightPos = lightStem;
        names.lightPos.append("position");
        names.lightConstantAttenuation = lightStem;
        names.lightConstantAttenuation.append("constantAttenuation");
        names.lightLinearAttenuation = lightStem;
        names.lightLinearAttenuation.append("linearAttenuation");
        names.lightQuadraticAttenuation = lightStem;
        names.lightQuadraticAttenuation.append("quadraticAttenuation");
    } else if (inLight.type == QSSGRenderLight::Type::SpotLight) {
        names.lightPos = lightStem;
        names.lightPos.append("position");
        names.lightConstantAttenuation = lightStem;
        names.lightConstantAttenuation.append("constantAttenuation");
        names.lightLinearAttenuation = lightStem;
        names.lightLinearAttenuation.append("linearAttenuation");
        names.lightQuadraticAttenuation = lightStem;
        names.lightQuadraticAttenuation.append("quadraticAttenuation");
        names.lightConeAngle = lightStem;
        names.lightConeAngle.append("coneAngle");
        names.lightInnerConeAngle = lightStem;
        names.lightInnerConeAngle.append("innerConeAngle");
    }

    return names;
}

static void generateShadowMapOcclusion(QSSGStageGeneratorBase &fragmentShader,
                                       QSSGMaterialVertexPipeline &vertexShader,
                                       quint32 lightIdx,
                                       bool inShadowEnabled,
                                       QSSGRenderLight::Type inType,
                                       const QSSGMaterialShaderGenerator::LightVariableNames &lightVarNames,
                                       const QSSGShaderDefaultMaterialKey &inKey)
{
    if (inShadowEnabled) {
        vertexShader.generateWorldPosition(inKey);
        const auto names = setupShadowMapVariableNames(lightIdx);
        fragmentShader.addInclude("shadowMapping.glsllib");
        if (inType == QSSGRenderLight::Type::DirectionalLight) {
            fragmentShader.addUniform(names.shadowMapStem, "sampler2D");
        } else {
            fragmentShader.addUniform(names.shadowCubeStem, "samplerCube");
        }
        fragmentShader.addUniform(names.shadowControlStem, "vec4");
        fragmentShader.addUniform(names.shadowMatrixStem, "mat4");

        if (inType != QSSGRenderLight::Type::DirectionalLight) {
            fragmentShader << "    qt_shadow_map_occl = qt_sampleCubemap(" << names.shadowCubeStem << ", " << names.shadowControlStem << ", " << names.shadowMatrixStem << ", " << lightVarNames.lightPos << ".xyz, qt_varWorldPos, vec2(1.0, " << names.shadowControlStem << ".z));\n";
        } else {
            fragmentShader << "    qt_shadow_map_occl = qt_sampleOrthographic(" << names.shadowMapStem << ", " << names.shadowControlStem << ", " << names.shadowMatrixStem << ", qt_varWorldPos, vec2(1.0, " << names.shadowControlStem << ".z));\n";
        }
    } else {
        fragmentShader << "    qt_shadow_map_occl = 1.0;\n";
    }
}

static inline QSSGShaderMaterialAdapter *getMaterialAdapter(const QSSGRenderGraphObject &inMaterial)
{
    switch (inMaterial.type) {
    case QSSGRenderGraphObject::Type::DefaultMaterial:
    case QSSGRenderGraphObject::Type::PrincipledMaterial:
        return static_cast<const QSSGRenderDefaultMaterial &>(inMaterial).adapter;
    case QSSGRenderGraphObject::Type::CustomMaterial:
        return static_cast<const QSSGRenderCustomMaterial &>(inMaterial).adapter;
    default:
        break;
    }
    return nullptr;
}

const char *QSSGMaterialShaderGenerator::directionalLightProcessorArgumentList()
{
    return "inout vec3 DIFFUSE, in vec3 LIGHT_COLOR, in float SHADOW_CONTRIB, in vec3 TO_LIGHT_DIR, in vec3 NORMAL, in vec4 BASE_COLOR, in float METALNESS, in float ROUGHNESS, in vec3 VIEW_VECTOR";
}

const char *QSSGMaterialShaderGenerator::pointLightProcessorArgumentList()
{
    return "inout vec3 DIFFUSE, in vec3 LIGHT_COLOR, in float LIGHT_ATTENUATION, in float SHADOW_CONTRIB, in vec3 TO_LIGHT_DIR, in vec3 NORMAL, in vec4 BASE_COLOR, in float METALNESS, in float ROUGHNESS, in vec3 VIEW_VECTOR";
}

const char *QSSGMaterialShaderGenerator::spotLightProcessorArgumentList()
{
    return "inout vec3 DIFFUSE, in vec3 LIGHT_COLOR, in float LIGHT_ATTENUATION, float SPOT_FACTOR, in float SHADOW_CONTRIB, in vec3 TO_LIGHT_DIR, in vec3 NORMAL, in vec4 BASE_COLOR, in float METALNESS, in float ROUGHNESS, in vec3 VIEW_VECTOR";
}

const char *QSSGMaterialShaderGenerator::ambientLightProcessorArgumentList()
{
    return "inout vec3 DIFFUSE, in vec3 TOTAL_AMBIENT_COLOR, in vec3 NORMAL, in vec3 VIEW_VECTOR";
}

const char *QSSGMaterialShaderGenerator::specularLightProcessorArgumentList()
{
    return "inout vec3 SPECULAR, in vec3 LIGHT_COLOR, in float LIGHT_ATTENUATION, in float SHADOW_CONTRIB, in vec3 FRESNEL_CONTRIB, in vec3 TO_LIGHT_DIR, in vec3 NORMAL, in vec4 BASE_COLOR, in float METALNESS, in float ROUGHNESS, in float SPECULAR_AMOUNT, in vec3 VIEW_VECTOR";
}

const char *QSSGMaterialShaderGenerator::shadedFragmentMainArgumentList()
{
    return "inout vec4 BASE_COLOR, inout vec3 EMISSIVE_COLOR, inout float METALNESS, inout float ROUGHNESS, inout float SPECULAR_AMOUNT, inout float FRESNEL_POWER, inout vec3 NORMAL, inout vec3 TANGENT, inout vec3 BINORMAL, in vec2 UV0, in vec2 UV1, in vec3 VIEW_VECTOR";
}

const char *QSSGMaterialShaderGenerator::postProcessorArgumentList()
{
    return "inout vec4 COLOR_SUM, in vec4 DIFFUSE, in vec3 SPECULAR, in vec3 EMISSIVE, in vec2 UV0, in vec2 UV1";
}

const char *QSSGMaterialShaderGenerator::vertexMainArgumentList()
{
    return "inout vec3 VERTEX, inout vec3 NORMAL, inout vec2 UV0, inout vec2 UV1, inout vec3 TANGENT, inout vec3 BINORMAL, inout ivec4 JOINTS, inout vec4 WEIGHTS, inout vec4 COLOR";
}

const char *QSSGMaterialShaderGenerator::vertexInstancedMainArgumentList()
{
    return "inout vec3 VERTEX, inout vec3 NORMAL, inout vec2 UV0, inout vec2 UV1, inout vec3 TANGENT, inout vec3 BINORMAL, inout ivec4 JOINTS, inout vec4 WEIGHTS, inout vec4 COLOR, inout mat4 INSTANCE_MODEL_MATRIX, inout mat4 INSTANCE_MODELVIEWPROJECTION_MATRIX";
}

#define MAX_MORPH_TARGET 8

static void generateFragmentShader(QSSGStageGeneratorBase &fragmentShader,
                                   QSSGMaterialVertexPipeline &vertexShader,
                                   const QSSGShaderDefaultMaterialKey &inKey,
                                   const QSSGShaderDefaultMaterialKeyProperties &keyProps,
                                   const ShaderFeatureSetList &featureSet,
                                   const QSSGRenderGraphObject &inMaterial,
                                   const QSSGShaderLightList &lights,
                                   QSSGRenderableImage *firstImage,
                                   const QSSGRef<QSSGShaderLibraryManager> &shaderLibraryManager)
{
    QSSGShaderMaterialAdapter *materialAdapter = getMaterialAdapter(inMaterial);
    auto hasCustomFunction = [&shaderLibraryManager, materialAdapter](const QByteArray &funcName) {
        return materialAdapter->hasCustomShaderFunction(QSSGShaderCache::ShaderType::Fragment,
                                                 funcName,
                                                 shaderLibraryManager);
    };

    bool metalnessEnabled = materialAdapter->isMetalnessEnabled(); // always true for Custom, true if > 0 with Principled
    bool vertexColorsEnabled = materialAdapter->isVertexColorsEnabled();

    bool hasLighting = materialAdapter->hasLighting();
    bool isDoubleSided = keyProps.m_isDoubleSided.getValue(inKey);
    bool hasImage = firstImage != nullptr;

    bool hasIblProbe = keyProps.m_hasIbl.getValue(inKey);
    bool specularLightingEnabled = metalnessEnabled || materialAdapter->isSpecularEnabled() || hasIblProbe; // always true for Custom, depends for others
    quint32 numMorphTargets = keyProps.m_morphTargetCount.getValue(inKey);
    // Pull the bump out as
    QSSGRenderableImage *bumpImage = nullptr;
    quint32 imageIdx = 0;
    QSSGRenderableImage *specularAmountImage = nullptr;
    QSSGRenderableImage *roughnessImage = nullptr;
    QSSGRenderableImage *metalnessImage = nullptr;
    QSSGRenderableImage *occlusionImage = nullptr;
    // normal mapping
    QSSGRenderableImage *normalImage = nullptr;
    // translucency map
    QSSGRenderableImage *translucencyImage = nullptr;
    // opacity map
    QSSGRenderableImage *opacityImage = nullptr;
    // height map
    QSSGRenderableImage *heightImage = nullptr;

    QSSGRenderableImage *baseImage = nullptr;

    // Use shared texcoord when transforms are identity
    QVector<QSSGRenderableImage *> identityImages;
    char imageFragCoords[TEXCOORD_VAR_LEN];

    auto channelStr = [](const QSSGShaderKeyTextureChannel &chProp, const QSSGShaderDefaultMaterialKey &inKey) -> QByteArray {
        QByteArray ret;
        switch (chProp.getTextureChannel(inKey)) {
        case QSSGShaderKeyTextureChannel::R:
            ret.append(".r");
            break;
        case QSSGShaderKeyTextureChannel::G:
            ret.append(".g");
            break;
        case QSSGShaderKeyTextureChannel::B:
            ret.append(".b");
            break;
        case QSSGShaderKeyTextureChannel::A:
            ret.append(".a");
            break;
        }
        return ret;
    };

    for (QSSGRenderableImage *img = firstImage; img != nullptr; img = img->m_nextImage, ++imageIdx) {
        if (img->m_imageNode.isImageTransformIdentity())
            identityImages.push_back(img);
        if (img->m_mapType == QSSGRenderableImage::Type::BaseColor || img->m_mapType == QSSGRenderableImage::Type::Diffuse) {
            baseImage = img;
        } else if (img->m_mapType == QSSGRenderableImage::Type::Bump) {
            bumpImage = img;
        } else if (img->m_mapType == QSSGRenderableImage::Type::SpecularAmountMap) {
            specularAmountImage = img;
        } else if (img->m_mapType == QSSGRenderableImage::Type::Roughness) {
            roughnessImage = img;
        } else if (img->m_mapType == QSSGRenderableImage::Type::Metalness) {
            metalnessImage = img;
        } else if (img->m_mapType == QSSGRenderableImage::Type::Occlusion) {
            occlusionImage = img;
        } else if (img->m_mapType == QSSGRenderableImage::Type::Normal) {
            normalImage = img;
        } else if (img->m_mapType == QSSGRenderableImage::Type::Translucency) {
            translucencyImage = img;
        } else if (img->m_mapType == QSSGRenderableImage::Type::Opacity) {
            opacityImage = img;
        } else if (img->m_mapType == QSSGRenderableImage::Type::Height) {
            heightImage = img;
        }
    }

    bool enableSSAO = false;
    bool enableShadowMaps = false;
    bool isDepthPass = false;
    bool isOpaqueDepthPrePass = false;
    bool isOrthoShadowPass = false;
    bool isCubeShadowPass = false;
    bool enableBumpNormal = normalImage || bumpImage;
    bool enableParallaxMapping = heightImage != nullptr;
    specularLightingEnabled |= specularAmountImage != nullptr;

    for (qint32 idx = 0; idx < featureSet.size(); ++idx) {
        const auto &name = featureSet.at(idx).name;
        if (name == QSSGShaderDefines::asString(QSSGShaderDefines::Ssao))
            enableSSAO = featureSet.at(idx).enabled;
        else if (name == QSSGShaderDefines::asString(QSSGShaderDefines::Ssm))
            enableShadowMaps = featureSet.at(idx).enabled;
        else if (name == QSSGShaderDefines::asString(QSSGShaderDefines::DepthPass))
            isDepthPass = featureSet.at(idx).enabled;
        else if (name == QSSGShaderDefines::asString(QSSGShaderDefines::OrthoShadowPass))
            isOrthoShadowPass = featureSet.at(idx).enabled;
        else if (name == QSSGShaderDefines::asString(QSSGShaderDefines::CubeShadowPass))
            isCubeShadowPass = featureSet.at(idx).enabled;
        else if (name == QSSGShaderDefines::asString(QSSGShaderDefines::OpaqueDepthPrePass))
            isOpaqueDepthPrePass = featureSet.at(idx).enabled;
    }

    const bool hasCustomVert = materialAdapter->hasCustomShaderSnippet(QSSGShaderCache::ShaderType::Vertex);

    // Morphing
    if (numMorphTargets > 0 || hasCustomVert) {
        vertexShader.addDefinition(QByteArrayLiteral("QT_MORPH_MAX_COUNT"),
                QByteArray::number(keyProps.m_morphTargetCount.getValue(inKey)));
        const quint32 endIter = hasCustomVert ? MAX_MORPH_TARGET : numMorphTargets;
        for (quint32 i = 0; i < endIter; ++i) {
            quint32 attribs = keyProps.m_morphTargetAttributes[i].getValue(inKey);
            if (attribs & QSSGShaderKeyVertexAttribute::Position) {
                vertexShader.addDefinition(QByteArrayLiteral("QT_MORPH_IN_POSITION") + QByteArray::number(i));
                vertexShader.addIncoming(QByteArrayLiteral("attr_tpos") + QByteArray::number(i), "vec3");
            }
            if (attribs & QSSGShaderKeyVertexAttribute::Normal) {
                vertexShader.addDefinition(QByteArrayLiteral("QT_MORPH_IN_NORMAL") + QByteArray::number(i));
                vertexShader.addIncoming(QByteArrayLiteral("attr_tnorm") + QByteArray::number(i), "vec3");
            }
            if (attribs & QSSGShaderKeyVertexAttribute::Tangent) {
                vertexShader.addDefinition(QByteArrayLiteral("QT_MORPH_IN_TANGENT") + QByteArray::number(i));
                vertexShader.addIncoming(QByteArrayLiteral("attr_ttan") + QByteArray::number(i), "vec3");
            }
            if (attribs & QSSGShaderKeyVertexAttribute::Binormal) {
                vertexShader.addDefinition(QByteArrayLiteral("QT_MORPH_IN_BINORMAL") + QByteArray::number(i));
                vertexShader.addIncoming(QByteArrayLiteral("attr_tbinorm") + QByteArray::number(i), "vec3");
            }
        }
    }
    if (numMorphTargets > 0)
        vertexShader.addInclude("morphanim.glsllib");

    bool includeCustomFragmentMain = true;
    if (isDepthPass || isOrthoShadowPass || isCubeShadowPass) {
        hasLighting = false;
        enableSSAO = false;
        enableShadowMaps = false;

        metalnessEnabled = false;
        specularLightingEnabled = false;

        if (!isOpaqueDepthPrePass) {
            vertexColorsEnabled = false;
            baseImage = nullptr;
            includeCustomFragmentMain = false;
        }
    }

    bool includeSSAOVars = enableSSAO || enableShadowMaps;

    vertexShader.beginFragmentGeneration(shaderLibraryManager);

    // Unshaded custom materials need no code in main (apart from calling qt_customMain)
    const bool hasCustomFrag = materialAdapter->hasCustomShaderSnippet(QSSGShaderCache::ShaderType::Fragment);
    const bool usesSharedVar = materialAdapter->usesSharedVariables();
    if (hasCustomFrag && materialAdapter->isUnshaded())
        return;

    // hasCustomFrag == Shaded custom material from this point on, for Unshaded we returned above

    // The fragment or vertex shaders may not use the material_properties or diffuse
    // uniforms in all cases but it is simpler to just add them and let the linker strip them.
    fragmentShader.addUniform("qt_material_emissive_color", "vec3");
    fragmentShader.addUniform("qt_material_base_color", "vec4");
    fragmentShader.addUniform("qt_material_properties", "vec4");
    fragmentShader.addUniform("qt_material_properties2", "vec4");
    fragmentShader.addUniform("qt_material_properties3", "vec4");
    if (enableParallaxMapping)
        fragmentShader.addUniform("qt_material_properties4", "vec4");

    if (vertexColorsEnabled)
        vertexShader.generateVertexColor(inKey);
    else
        fragmentShader.append("    vec4 qt_vertColor = vec4(1.0);");

    if (hasLighting || hasCustomFrag) {
        // Do not move these three. These varyings are exposed to custom material shaders too.
        vertexShader.generateViewVector(inKey);
        if (keyProps.m_usesProjectionMatrix.getValue(inKey))
            fragmentShader.addUniform("qt_projectionMatrix", "mat4");
        if (keyProps.m_usesInverseProjectionMatrix.getValue(inKey))
            fragmentShader.addUniform("qt_inverseProjectionMatrix", "mat4");
        vertexShader.generateWorldNormal(inKey);
        vertexShader.generateWorldPosition(inKey);

        if (hasCustomFrag || includeSSAOVars || specularLightingEnabled || hasIblProbe || enableBumpNormal) {
            bool genTangent = false;
            bool genBinormal = false;
            vertexShader.generateVarTangentAndBinormal(inKey, genTangent, genBinormal);
            if (enableBumpNormal) {
                // It will not be generated for CustomMaterials.
                int id = (bumpImage != nullptr) ? int(QSSGRenderableImage::Type::Bump) : int(QSSGRenderableImage::Type::Normal);
                const auto &names = imageStringTable[id];
                if (!genTangent) {
                    fragmentShader << "    vec2 dUVdx = dFdx(" << names.imageFragCoords << ");\n"
                                   << "    vec2 dUVdy = dFdy(" << names.imageFragCoords << ");\n";
                    fragmentShader << "    qt_tangent = (dUVdy.y * dFdx(qt_varWorldPos) - dUVdx.y * dFdy(qt_varWorldPos)) / (dUVdx.x * dUVdy.y - dUVdx.y * dUVdy.x);\n"
                                   << "    qt_tangent = qt_tangent - dot(qt_world_normal, qt_tangent) * qt_world_normal;\n"
                                   << "    qt_tangent = normalize(qt_tangent);\n";
                }
            }
            if (!genBinormal)
                fragmentShader << "    qt_binormal = cross(qt_world_normal, qt_tangent);\n";

            if (isDoubleSided) {
                fragmentShader.append("    const float qt_facing = gl_FrontFacing ? 1.0 : -1.0;\n");
                fragmentShader.append("    qt_world_normal *= qt_facing;\n");
                fragmentShader.append("    qt_tangent *= qt_facing;");
                fragmentShader.append("    qt_binormal *= qt_facing;");
            }
        }
    }

    if (hasCustomFrag) {
        // A custom shaded material is effectively a principled material for
        // our purposes here. The defaults are different from a
        // PrincipledMaterial however, since this is more sensible here.
        // (because the shader has to state it to get things)

        if (usesSharedVar)
            fragmentShader << "    QT_SHARED_VARS qt_customShared;\n";
        // These should match the defaults of PrincipledMaterial.
        fragmentShader << "    float qt_customSpecularAmount = 0.5;\n"; // overrides qt_material_properties.x
        fragmentShader << "    float qt_customSpecularRoughness = 0.0;\n"; // overrides qt_material_properties.y
        fragmentShader << "    float qt_customMetalnessAmount = 0.0;\n"; // overrides qt_material_properties.z
        fragmentShader << "    float qt_customFresnelPower = 5.0;\n"; // overrides qt_material_properties2.x
        fragmentShader << "    vec4 qt_customBaseColor = vec4(1.0);\n"; // overrides qt_material_base_color
        fragmentShader << "    vec3 qt_customEmissiveColor = vec3(0.0);\n"; // overrides qt_material_emissive_color
        // Generate the varyings for UV0 and UV1 since customer materials don't use image
        // properties directly.
        vertexShader.generateUVCoords(0, inKey);
        vertexShader.generateUVCoords(1, inKey);
        if (includeCustomFragmentMain && hasCustomFunction(QByteArrayLiteral("qt_customMain"))) {
            fragmentShader << "    qt_customMain(qt_customBaseColor, qt_customEmissiveColor, qt_customMetalnessAmount, qt_customSpecularRoughness,"
                              " qt_customSpecularAmount, qt_customFresnelPower, qt_world_normal, qt_tangent, qt_binormal,"
                              " qt_texCoord0, qt_texCoord1, qt_view_vector";
            if (usesSharedVar)
                fragmentShader << ", qt_customShared);\n";
            else
                fragmentShader << ");\n";
        }
        fragmentShader << "    vec4 qt_diffuseColor = qt_customBaseColor * qt_vertColor;\n";
        fragmentShader << "    vec3 qt_global_emission = qt_customEmissiveColor;\n";
    } else {
        fragmentShader << "    vec4 qt_diffuseColor = qt_material_base_color * qt_vertColor;\n";
        fragmentShader << "    vec3 qt_global_emission = qt_material_emissive_color;\n";
    }

    if (isDepthPass)
        fragmentShader << "    vec4 fragOutput = vec4(0.0);\n";

    if (isOrthoShadowPass)
        vertexShader.generateDepth();

    if (isCubeShadowPass)
        vertexShader.generateShadowWorldPosition(inKey);

    if (hasImage && ((!isDepthPass && !isOrthoShadowPass && !isCubeShadowPass) || isOpaqueDepthPrePass)) {
        fragmentShader.append("    vec3 qt_uTransform;");
        fragmentShader.append("    vec3 qt_vTransform;");
    }

    // !hasLighting does not mean 'no light source'
    // it should be KHR_materials_unlit
    // https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
    if (hasLighting) {
        if (includeSSAOVars)
            fragmentShader.addInclude("ssao.glsllib");

        if (hasIblProbe)
            fragmentShader.addInclude("sampleProbe.glsllib");

        fragmentShader.addFunction("sampleLightVars");
        if (materialAdapter->isPrincipled())
            fragmentShader.addFunction("diffuseBurleyBSDF");
        else
            fragmentShader.addFunction("diffuseReflectionBSDF");

        if (enableParallaxMapping) {
            // Adjust UV coordinates to account for parallaxMapping before
            // reading any other texture.
            const bool hasIdentityMap = identityImages.contains(heightImage);
            if (hasIdentityMap)
                generateImageUVSampler(vertexShader, fragmentShader, inKey, *heightImage, imageFragCoords, heightImage->m_imageNode.m_indexUV);
            else
                generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *heightImage, true, heightImage->m_imageNode.m_indexUV);
            const auto &names = imageStringTable[int(QSSGRenderableImage::Type::Height)];
            fragmentShader.addInclude("parallaxMapping.glsllib");
            fragmentShader << "    qt_texCoord0 = qt_parallaxMapping(" << (hasIdentityMap ? imageFragCoords : names.imageFragCoords) << ", " << names.imageSampler <<", qt_tangent, qt_binormal, qt_world_normal, qt_varWorldPos, qt_cameraPosition, qt_material_properties4.x, qt_material_properties4.y, qt_material_properties4.z);\n";
        }

        if (bumpImage != nullptr) {
            generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *bumpImage, enableParallaxMapping, bumpImage->m_imageNode.m_indexUV);
            const auto &names = imageStringTable[int(QSSGRenderableImage::Type::Bump)];
            fragmentShader.addUniform(names.imageSamplerSize, "vec2");
            fragmentShader.append("    float bumpAmount = qt_material_properties2.y;\n");
            fragmentShader.addInclude("defaultMaterialBumpNoLod.glsllib");
            fragmentShader << "    qt_world_normal = qt_defaultMaterialBumpNoLod(" << names.imageSampler << ", bumpAmount, " << names.imageFragCoords << ", qt_tangent, qt_binormal, qt_world_normal, " << names.imageSamplerSize << ");\n";
        } else if (normalImage != nullptr) {
            generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *normalImage, enableParallaxMapping, normalImage->m_imageNode.m_indexUV);
            const auto &names = imageStringTable[int(QSSGRenderableImage::Type::Normal)];
            fragmentShader.append("    float normalStrength = qt_material_properties2.y;\n");
            fragmentShader.addFunction("sampleNormalTexture");
            fragmentShader << "    qt_world_normal = qt_sampleNormalTexture3(" << names.imageSampler << ", normalStrength, " << names.imageFragCoords << ", qt_tangent, qt_binormal, qt_world_normal);\n";
        }

        fragmentShader.append("    vec3 tmp_light_color;");
    }

    if (specularLightingEnabled || hasImage) {
        fragmentShader.append("    vec3 qt_specularBase;");
        fragmentShader.addUniform("qt_material_specular", "vec4");
        if (hasCustomFrag)
            fragmentShader.append("    vec3 qt_specularTint = vec3(1.0);");
        else
            fragmentShader.append("    vec3 qt_specularTint = qt_material_specular.rgb;");
    }

    if (baseImage) {
        QByteArray texSwizzle;
        QByteArray lookupSwizzle;

        const bool hasIdentityMap = identityImages.contains(baseImage);
        if (hasIdentityMap)
            generateImageUVSampler(vertexShader, fragmentShader, inKey, *baseImage, imageFragCoords, baseImage->m_imageNode.m_indexUV);
        else
            generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *baseImage, enableParallaxMapping, baseImage->m_imageNode.m_indexUV);

        // NOTE: The base image hande is used for both the diffuse map and the base color map, so we can't hard-code the type here...
        const auto &names = imageStringTable[int(baseImage->m_mapType)];
        // Diffuse and BaseColor maps need to converted to linear color space
        fragmentShader.addInclude("tonemapping.glsllib");
        fragmentShader << "    vec4 qt_base_texture_color" << texSwizzle << " = qt_sRGBToLinear(texture2D(" << names.imageSampler << ", " << (hasIdentityMap ? imageFragCoords : names.imageFragCoords) << "))" << lookupSwizzle << ";\n";
        fragmentShader << "    qt_diffuseColor *= qt_base_texture_color;\n";
    }

    // alpha cutoff
    if (materialAdapter->alphaMode() == QSSGRenderDefaultMaterial::MaterialAlphaMode::Mask) {
        // The Implementation Notes from
        // https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#alpha-coverage
        // must be met. Hence the discard.
        fragmentShader << "    if (qt_diffuseColor.a < qt_material_properties3.y) {\n"
                       << "        qt_diffuseColor = vec4(0.0);\n"
                       << "        discard;\n"
                       << "    } else {\n"
                       << "        qt_diffuseColor.a = 1.0;\n"
                       << "    }\n";
    } else if (materialAdapter->alphaMode() == QSSGRenderDefaultMaterial::MaterialAlphaMode::Opaque) {
        fragmentShader << "    qt_diffuseColor.a = 1.0;\n";
    }

    if (opacityImage) {
        const bool hasIdentityMap = identityImages.contains(opacityImage);
        if (hasIdentityMap)
            generateImageUVSampler(vertexShader, fragmentShader, inKey, *opacityImage, imageFragCoords, opacityImage->m_imageNode.m_indexUV);
        else
            generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *opacityImage, enableParallaxMapping, opacityImage->m_imageNode.m_indexUV);

        const auto &names = imageStringTable[int(QSSGRenderableImage::Type::Opacity)];
        const auto &channelProps = keyProps.m_textureChannels[QSSGShaderDefaultMaterialKeyProperties::OpacityChannel];
        fragmentShader << "    qt_objectOpacity *= texture2D(" << names.imageSampler << ", " << (hasIdentityMap ? imageFragCoords : names.imageFragCoords) << ")" << channelStr(channelProps, inKey) << ";\n";
    }

    if (hasLighting) {
        if (specularLightingEnabled) {
            vertexShader.generateViewVector(inKey);
            fragmentShader.addUniform("qt_material_properties", "vec4");

            if (materialAdapter->isPrincipled())
                fragmentShader << "    qt_specularBase = vec3(1.0);\n";
            else
                fragmentShader << "    qt_specularBase = qt_diffuseColor.rgb;\n";
            if (hasCustomFrag)
                fragmentShader << "    float qt_specularFactor = qt_customSpecularAmount;\n";
            else
                fragmentShader << "    float qt_specularFactor = qt_material_properties.x;\n";
        }

        // Metalness must be setup fairly earily since so many factors depend on the runtime value
        if (hasCustomFrag)
            fragmentShader << "    float qt_metalnessAmount = qt_customMetalnessAmount;\n";
        else
            fragmentShader << "    float qt_metalnessAmount = qt_material_properties.z;\n";

        if (specularLightingEnabled && metalnessImage) {
            const auto &channelProps = keyProps.m_textureChannels[QSSGShaderDefaultMaterialKeyProperties::MetalnessChannel];
            const bool hasIdentityMap = identityImages.contains(metalnessImage);
            if (hasIdentityMap)
                generateImageUVSampler(vertexShader, fragmentShader, inKey, *metalnessImage, imageFragCoords, metalnessImage->m_imageNode.m_indexUV);
            else
                generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *metalnessImage, enableParallaxMapping, metalnessImage->m_imageNode.m_indexUV);

            const auto &names = imageStringTable[int(QSSGRenderableImage::Type::Metalness)];
            fragmentShader << "    float qt_sampledMetalness = texture2D(" << names.imageSampler << ", "
                           << (hasIdentityMap ? imageFragCoords : names.imageFragCoords) << ")" << channelStr(channelProps, inKey) << ";\n";
            fragmentShader << "    qt_metalnessAmount = clamp(qt_metalnessAmount * qt_sampledMetalness, 0.0, 1.0);\n";
        }

        fragmentShader.addUniform("qt_light_ambient_total", "vec3");

        if (hasCustomFrag && hasCustomFunction(QByteArrayLiteral("qt_ambientLightProcessor"))) {
            // DIFFUSE, TOTAL_AMBIENT_COLOR, NORMAL, VIEW_VECTOR(, SHARED)
            fragmentShader.append("    vec4 global_diffuse_light = vec4(0.0);\n"
                                  "    qt_ambientLightProcessor(global_diffuse_light.rgb, qt_light_ambient_total.rgb * (1.0 - qt_metalnessAmount) * qt_diffuseColor.rgb, qt_world_normal, qt_view_vector");
            if (usesSharedVar)
                fragmentShader << ", qt_customShared);\n";
            else
                fragmentShader << ");\n";
        } else {
            fragmentShader.append("    vec4 global_diffuse_light = vec4(qt_light_ambient_total.rgb * (1.0 - qt_metalnessAmount) * qt_diffuseColor.rgb, 0.0);");
        }

        fragmentShader.append("    vec3 global_specular_light = vec3(0.0);");
        fragmentShader.append("    float qt_shadow_map_occl = 1.0;");

        // Fragment lighting means we can perhaps attenuate the specular amount by a texture
        // lookup.
        if (specularAmountImage) {
            const bool hasIdentityMap = identityImages.contains(specularAmountImage);
            if (hasIdentityMap)
                generateImageUVSampler(vertexShader, fragmentShader, inKey, *specularAmountImage, imageFragCoords, specularAmountImage->m_imageNode.m_indexUV);
            else
                generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *specularAmountImage, enableParallaxMapping, specularAmountImage->m_imageNode.m_indexUV);

            const auto &names = imageStringTable[int(QSSGRenderableImage::Type::SpecularAmountMap)];
            // TODO: This might need to be colorspace corrected to linear
            fragmentShader << "    qt_specularBase *= texture2D(" << names.imageSampler << ", " << (hasIdentityMap ? imageFragCoords : names.imageFragCoords) << ").rgb;\n";
        }

        if (specularLightingEnabled)
            fragmentShader << "    vec3 qt_specularAmount = qt_specularBase * vec3(qt_metalnessAmount + qt_specularFactor * (1.0 - qt_metalnessAmount));\n";

        if (translucencyImage != nullptr) {
            const bool hasIdentityMap = identityImages.contains(translucencyImage);
            if (hasIdentityMap)
                generateImageUVSampler(vertexShader, fragmentShader, inKey, *translucencyImage, imageFragCoords);
            else
                generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *translucencyImage, enableParallaxMapping);

            const auto &names = imageStringTable[int(QSSGRenderableImage::Type::Translucency)];
            const auto &channelProps = keyProps.m_textureChannels[QSSGShaderDefaultMaterialKeyProperties::TranslucencyChannel];
            fragmentShader << "    float qt_translucent_depth_range = texture2D(" << names.imageSampler
                           << ", " << (hasIdentityMap ? imageFragCoords : names.imageFragCoords) << ")" << channelStr(channelProps, inKey) << ";\n";
            fragmentShader << "    float qt_translucent_thickness = qt_translucent_depth_range * qt_translucent_depth_range;\n";
            fragmentShader << "    float qt_translucent_thickness_exp = exp(qt_translucent_thickness * qt_material_properties2.z);\n";
        }

        fragmentShader.append("    float qt_lightAttenuation = 1.0;");

        addLocalVariable(fragmentShader, "qt_aoFactor", "float");

        if (enableSSAO)
            fragmentShader.append("    qt_aoFactor = qt_screenSpaceAmbientOcclusionFactor();");
        else
            fragmentShader.append("    qt_aoFactor = 1.0;");

        if (hasCustomFrag)
            fragmentShader << "    float qt_roughnessAmount = qt_customSpecularRoughness;\n";
        else
            fragmentShader << "    float qt_roughnessAmount = qt_material_properties.y;\n";

        if (specularLightingEnabled && roughnessImage) {
            const auto &channelProps = keyProps.m_textureChannels[QSSGShaderDefaultMaterialKeyProperties::RoughnessChannel];
            const bool hasIdentityMap = identityImages.contains(roughnessImage);
            if (hasIdentityMap)
                generateImageUVSampler(vertexShader, fragmentShader, inKey, *roughnessImage, imageFragCoords, roughnessImage->m_imageNode.m_indexUV);
            else
                generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *roughnessImage, enableParallaxMapping, roughnessImage->m_imageNode.m_indexUV);

            const auto &names = imageStringTable[int(QSSGRenderableImage::Type::Roughness)];
            fragmentShader << "    qt_roughnessAmount *= texture2D(" << names.imageSampler << ", "
                           << (hasIdentityMap ? imageFragCoords : names.imageFragCoords) << ")" << channelStr(channelProps, inKey) << ";\n";
        }

        if (specularLightingEnabled) {
            if (materialAdapter->isPrincipled()) {
                fragmentShader.addInclude("principledMaterialFresnel.glsllib");
                if (hasCustomFrag)
                    fragmentShader << "    float qt_fresnelPower = qt_customFresnelPower;\n";
                else
                    fragmentShader << "    float qt_fresnelPower = qt_material_properties2.x;\n";
                fragmentShader << "    qt_specularAmount *= qt_principledMaterialFresnel(qt_world_normal, qt_view_vector, "
                               << "qt_metalnessAmount, qt_specularFactor, qt_diffuseColor.rgb, qt_roughnessAmount, qt_fresnelPower);\n";

                // Make sure that we scale the specularTint with repsect to metalness (no tint if qt_metalnessAmount == 1)
                // We actually need to do this here because we won't know the final metalness value until this point.
                fragmentShader << "    qt_specularTint = mix(vec3(1.0), qt_specularTint, 1.0 - qt_metalnessAmount);\n";
            } else {
                Q_ASSERT(!hasCustomFrag);
                fragmentShader.addInclude("defaultMaterialFresnel.glsllib");
                fragmentShader << "    qt_diffuseColor.rgb *= (1.0 - qt_dielectricSpecular(qt_material_specular.w)) * (1.0 - qt_metalnessAmount);\n";
                maybeAddMaterialFresnel(fragmentShader, keyProps, inKey, metalnessEnabled);
            }
        }


        // Iterate through all lights
        Q_ASSERT(lights.size() < INT32_MAX);
        int shadowMapCount = 0;
        for (qint32 lightIdx = 0; lightIdx < lights.size(); ++lightIdx) {
            auto &shaderLight = lights[lightIdx];
            QSSGRenderLight *lightNode = shaderLight.light;
            auto lightVarNames = setupLightVariableNames(lightIdx, *lightNode);

            const bool isDirectional = lightNode->type == QSSGRenderLight::Type::DirectionalLight;
            const bool isSpot = lightNode->type == QSSGRenderLight::Type::SpotLight;
            bool castsShadow = enableShadowMaps && lightNode->m_castShadow && shadowMapCount < QSSG_MAX_NUM_SHADOW_MAPS;
            if (castsShadow)
                ++shadowMapCount;

            fragmentShader.append("");
            char lightIdxStr[11];
            snprintf(lightIdxStr, 11, "%d", lightIdx);

            QByteArray lightVarPrefix = "light";
            lightVarPrefix.append(lightIdxStr);

            fragmentShader << "    //Light " << lightIdxStr << (isDirectional ? " [directional]" : isSpot ? " [spot]" : " [point]") << "\n";
            fragmentShader << "    qt_lightAttenuation = 1.0;\n";

            if (isDirectional) {
                generateShadowMapOcclusion(fragmentShader, vertexShader, lightIdx, castsShadow, lightNode->type, lightVarNames, inKey);
                fragmentShader << "    tmp_light_color = " << lightVarNames.lightColor << ".rgb * (1.0 - qt_metalnessAmount);\n";

                if (hasCustomFrag && hasCustomFunction(QByteArrayLiteral("qt_directionalLightProcessor"))) {
                    // DIFFUSE, LIGHT_COLOR, SHADOW_CONTRIB, TO_LIGHT_DIR, NORMAL, BASE_COLOR, METALNESS, ROUGHNESS, VIEW_VECTOR(, SHARED)
                    fragmentShader << "    qt_directionalLightProcessor(global_diffuse_light.rgb, tmp_light_color, qt_shadow_map_occl, -"
                                   << lightVarNames.lightDirection << ".xyz, qt_world_normal, qt_customBaseColor, "
                                   << "qt_metalnessAmount, qt_roughnessAmount, qt_view_vector";
                    if (usesSharedVar)
                        fragmentShader << ", qt_customShared);\n";
                    else
                        fragmentShader << ");\n";
                } else {
                    if (materialAdapter->isPrincipled()) {
                        fragmentShader << "    global_diffuse_light.rgb += qt_diffuseColor.rgb * qt_shadow_map_occl * "
                                       << "qt_diffuseBurleyBSDF(qt_world_normal, -" << lightVarNames.lightDirection << ".xyz, "
                                       << "qt_view_vector, tmp_light_color, qt_roughnessAmount).rgb;\n";
                    } else {
                        fragmentShader << "    global_diffuse_light.rgb += qt_diffuseColor.rgb * qt_shadow_map_occl * qt_diffuseReflectionBSDF(qt_world_normal, -"
                                       << lightVarNames.lightDirection << ".xyz, tmp_light_color).rgb;\n";
                    }
                }

                if (hasCustomFrag && hasCustomFunction(QByteArrayLiteral("qt_specularLightProcessor"))) {
                    // SPECULAR, LIGHT_COLOR, LIGHT_ATTENUATION, SHADOW_CONTRIB, FRESNEL_CONTRIB, TO_LIGHT_DIR, NORMAL, BASE_COLOR, METALNESS, ROUGHNESS, SPECULAR_AMOUNT, VIEW_VECTOR(, SHARED)
                    fragmentShader << "    qt_specularLightProcessor(global_specular_light, " << lightVarNames.lightSpecularColor << ".rgb, 1.0, qt_shadow_map_occl, "
                                   << "qt_specularAmount, -" << lightVarNames.lightDirection << ".xyz, qt_world_normal, qt_customBaseColor, "
                                   << "qt_metalnessAmount, qt_roughnessAmount, qt_customSpecularAmount, qt_view_vector";
                    if (usesSharedVar)
                        fragmentShader << ", qt_customShared);\n";
                    else
                        fragmentShader << ");\n";
                } else {
                    if (specularLightingEnabled) {
                        if (materialAdapter->isPrincipled()) {
                            // Principled materials (and Custom without a specular processor function) always use GGX SpecularModel
                            fragmentShader.addFunction("specularGGXBSDF");
                            fragmentShader << "    global_specular_light += qt_lightAttenuation * qt_shadow_map_occl * qt_specularTint"
                                              " * qt_specularGGXBSDF(qt_world_normal, -" << lightVarNames.lightDirection << ".xyz, qt_view_vector, "
                                           << lightVarNames.lightSpecularColor << ".rgb, qt_specularFactor, qt_roughnessAmount, qt_metalnessAmount, qt_diffuseColor.rgb).rgb;\n";
                        } else {
                            outputSpecularEquation(materialAdapter->specularModel(), fragmentShader, lightVarNames.lightDirection, lightVarNames.lightSpecularColor);
                        }
                    }
                }
            } else {
                vertexShader.generateWorldPosition(inKey);

                lightVarNames.relativeDirection = lightVarPrefix;
                lightVarNames.relativeDirection.append("_relativeDirection");

                lightVarNames.normalizedDirection = lightVarNames.relativeDirection;
                lightVarNames.normalizedDirection.append("_normalized");

                lightVarNames.relativeDistance = lightVarPrefix;
                lightVarNames.relativeDistance.append("_distance");

                fragmentShader << "    vec3 " << lightVarNames.relativeDirection << " = qt_varWorldPos - " << lightVarNames.lightPos << ".xyz;\n"
                               << "    float " << lightVarNames.relativeDistance << " = length(" << lightVarNames.relativeDirection << ");\n"
                               << "    vec3 " << lightVarNames.normalizedDirection << " = " << lightVarNames.relativeDirection << " / " << lightVarNames.relativeDistance << ";\n";

                if (isSpot) {
                    lightVarNames.spotAngle = lightVarPrefix;
                    lightVarNames.spotAngle.append("_spotAngle");

                    fragmentShader << "    float " << lightVarNames.spotAngle << " = dot(" << lightVarNames.normalizedDirection
                                   << ", normalize(vec3(" << lightVarNames.lightDirection << ")));\n";
                    fragmentShader << "    if (" << lightVarNames.spotAngle << " > " << lightVarNames.lightConeAngle << ") {\n";
                }

                generateShadowMapOcclusion(fragmentShader, vertexShader, lightIdx, castsShadow, lightNode->type, lightVarNames, inKey);

                fragmentShader.addFunction("calculatePointLightAttenuation");

                fragmentShader << "    qt_lightAttenuation = qt_calculatePointLightAttenuation(vec3("
                               << lightVarNames.lightConstantAttenuation << ", " << lightVarNames.lightLinearAttenuation << ", "
                               << lightVarNames.lightQuadraticAttenuation << "), " << lightVarNames.relativeDistance << ");\n";

                addTranslucencyIrradiance(fragmentShader, translucencyImage, lightVarNames);
                fragmentShader << "    tmp_light_color = " << lightVarNames.lightColor << ".rgb * (1.0 - qt_metalnessAmount);\n";

                if (isSpot) {
                    fragmentShader << "    float spotFactor = smoothstep(" << lightVarNames.lightConeAngle
                                   << ", " << lightVarNames.lightInnerConeAngle << ", " << lightVarNames.spotAngle
                                   << ");\n";
                    if (hasCustomFrag && hasCustomFunction(QByteArrayLiteral("qt_spotLightProcessor"))) {
                        // DIFFUSE, LIGHT_COLOR, LIGHT_ATTENUATION, SPOT_FACTOR, SHADOW_CONTRIB, TO_LIGHT_DIR, NORMAL, BASE_COLOR, METALNESS, ROUGHNESS, VIEW_VECTOR(, SHARED)
                        fragmentShader << "    qt_spotLightProcessor(global_diffuse_light.rgb, tmp_light_color, qt_lightAttenuation, spotFactor, qt_shadow_map_occl, -"
                                       << lightVarNames.normalizedDirection << ".xyz, qt_world_normal, qt_customBaseColor, "
                                       << "qt_metalnessAmount, qt_roughnessAmount, qt_view_vector";
                        if (usesSharedVar)
                            fragmentShader << ", qt_customShared);\n";
                        else
                            fragmentShader << ");\n";
                    } else {
                        if (materialAdapter->isPrincipled()) {
                            fragmentShader << "    global_diffuse_light.rgb += qt_diffuseColor.rgb * spotFactor * qt_lightAttenuation * qt_shadow_map_occl * "
                                           << "qt_diffuseBurleyBSDF(qt_world_normal, -" << lightVarNames.normalizedDirection << ".xyz, qt_view_vector, "
                                           << "tmp_light_color, qt_roughnessAmount).rgb;\n";
                        } else {
                            fragmentShader << "    global_diffuse_light.rgb += qt_diffuseColor.rgb * spotFactor * qt_lightAttenuation * qt_shadow_map_occl * "
                                           << "qt_diffuseReflectionBSDF(qt_world_normal, -" << lightVarNames.normalizedDirection << ".xyz, tmp_light_color).rgb;\n";
                        }
                    }
                    // spotFactor is multipled to qt_lightAttenuation and have an effect on the specularLight.
                    fragmentShader << "    qt_lightAttenuation *= spotFactor;\n";
                } else {
                    // point light
                    if (hasCustomFrag && hasCustomFunction(QByteArrayLiteral("qt_pointLightProcessor"))) {
                        // DIFFUSE, LIGHT_COLOR, LIGHT_ATTENUATION, SHADOW_CONTRIB, TO_LIGHT_DIR, NORMAL, BASE_COLOR, METALNESS, ROUGHNESS, VIEW_VECTOR(, SHARED)
                        fragmentShader << "    qt_pointLightProcessor(global_diffuse_light.rgb, tmp_light_color, qt_lightAttenuation, qt_shadow_map_occl, -"
                                       << lightVarNames.normalizedDirection << ".xyz, qt_world_normal, qt_customBaseColor, "
                                       << "qt_metalnessAmount, qt_roughnessAmount, qt_view_vector";
                        if (usesSharedVar)
                            fragmentShader << ", qt_customShared);\n";
                        else
                            fragmentShader << ");\n";
                    } else {
                        if (materialAdapter->isPrincipled()) {
                            fragmentShader << "    global_diffuse_light.rgb += qt_diffuseColor.rgb * qt_lightAttenuation * qt_shadow_map_occl * "
                                           << "qt_diffuseBurleyBSDF(qt_world_normal, -" << lightVarNames.normalizedDirection << ".xyz, qt_view_vector, "
                                           << "tmp_light_color, qt_roughnessAmount).rgb;\n";
                        } else {
                            fragmentShader << "    global_diffuse_light.rgb += qt_diffuseColor.rgb * qt_lightAttenuation * qt_shadow_map_occl * "
                                           << "qt_diffuseReflectionBSDF(qt_world_normal, -" << lightVarNames.normalizedDirection << ".xyz, tmp_light_color).rgb;\n";
                        }
                    }
                }

                if (hasCustomFrag && hasCustomFunction(QByteArrayLiteral("qt_specularLightProcessor"))) {
                    // SPECULAR, LIGHT_COLOR, LIGHT_ATTENUATION, SHADOW_CONTRIB, FRESNEL_CONTRIB, TO_LIGHT_DIR, NORMAL, BASE_COLOR, METALNESS, ROUGHNESS, SPECULAR_AMOUNT, VIEW_VECTOR(, SHARED)
                    fragmentShader << "    qt_specularLightProcessor(global_specular_light, " << lightVarNames.lightSpecularColor << ".rgb, qt_lightAttenuation, qt_shadow_map_occl, "
                                   << "qt_specularAmount, -" << lightVarNames.normalizedDirection << ".xyz, qt_world_normal, qt_customBaseColor, "
                                   << "qt_metalnessAmount, qt_roughnessAmount, qt_customSpecularAmount, qt_view_vector";
                    if (usesSharedVar)
                        fragmentShader << ", qt_customShared);\n";
                    else
                        fragmentShader << ");\n";
                } else {
                    if (specularLightingEnabled) {
                        if (materialAdapter->isPrincipled()) {
                            // Principled materials (and Custom without a specular processor function) always use GGX SpecularModel
                            fragmentShader.addFunction("specularGGXBSDF");
                            fragmentShader << "    global_specular_light += qt_lightAttenuation * qt_shadow_map_occl * qt_specularTint"
                                              " * qt_specularGGXBSDF(qt_world_normal, -" << lightVarNames.normalizedDirection << ".xyz, qt_view_vector, "
                                           << lightVarNames.lightSpecularColor << ".rgb, qt_specularFactor, qt_roughnessAmount, qt_metalnessAmount, qt_diffuseColor.rgb).rgb;\n";
                        } else {
                            outputSpecularEquation(materialAdapter->specularModel(), fragmentShader, lightVarNames.normalizedDirection, lightVarNames.lightSpecularColor);
                        }
                    }
                }

                if (isSpot)
                    fragmentShader << "    }\n";
            }
        }
        if (!lights.isEmpty())
            fragmentShader.append("");

        // The color in rgb is ready, including shadowing, just need to apply
        // the ambient occlusion factor. The alpha is the model opacity
        // multiplied by the alpha from the material color and/or the vertex colors.
        fragmentShader << "    global_diffuse_light = vec4(global_diffuse_light.rgb * qt_aoFactor, qt_objectOpacity * qt_diffuseColor.a);\n";

        if (hasIblProbe) {
            vertexShader.generateWorldNormal(inKey);
            if (materialAdapter->isPrincipled()) {
                fragmentShader << "    vec3 qt_iblDiffuse = qt_diffuseColor.rgb * qt_aoFactor * (1.0 - qt_specularAmount) * qt_sampleDiffuse(qt_world_normal).rgb;\n";
            } else {
                fragmentShader << "    vec3 qt_iblDiffuse = qt_diffuseColor.rgb * qt_aoFactor * qt_sampleDiffuse(qt_world_normal).rgb;\n";
            }
            if (specularLightingEnabled) {
                if (materialAdapter->isPrincipled()) {
                    fragmentShader << "    vec3 qt_iblSpecular = "
                                   << "qt_specularTint * qt_sampleGlossyPrincipled(qt_world_normal, qt_view_vector, qt_specularAmount, qt_roughnessAmount).rgb;\n";
                } else {
                    fragmentShader << "    vec3 qt_iblSpecular = qt_specularAmount * "
                                   << "qt_specularTint * qt_sampleGlossy(qt_world_normal, qt_view_vector, qt_roughnessAmount).rgb;\n";
                }
            }

            // Occlusion Map
            if (occlusionImage) {
                const auto &channelProps = keyProps.m_textureChannels[QSSGShaderDefaultMaterialKeyProperties::OcclusionChannel];
                const bool hasIdentityMap = identityImages.contains(occlusionImage);
                if (hasIdentityMap)
                    generateImageUVSampler(vertexShader, fragmentShader, inKey, *occlusionImage, imageFragCoords, occlusionImage->m_imageNode.m_indexUV);
                else
                    generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *occlusionImage, enableParallaxMapping, occlusionImage->m_imageNode.m_indexUV);
                const auto &names = imageStringTable[int(QSSGRenderableImage::Type::Occlusion)];
                fragmentShader << "    float qt_ao = texture2D(" << names.imageSampler << ", "
                               << (hasIdentityMap ? imageFragCoords : names.imageFragCoords) << ")" << channelStr(channelProps, inKey) << ";\n";
                fragmentShader << "    qt_iblDiffuse = mix(qt_iblDiffuse, qt_iblDiffuse * qt_ao, qt_material_properties3.x);\n";
                fragmentShader << "    qt_iblSpecular = mix(qt_iblSpecular, qt_iblSpecular * qt_ao, qt_material_properties3.x);\n";
            }

            fragmentShader << "    global_diffuse_light.rgb += qt_iblDiffuse;\n";
            if (specularLightingEnabled)
                fragmentShader << "    global_specular_light += qt_iblSpecular;\n";
        }

        if (hasImage) {
            bool texColorDeclared = false;
            for (QSSGRenderableImage *image = firstImage; image; image = image->m_nextImage) {
                // map types other than these 2 are handled elsewhere
                if (image->m_mapType != QSSGRenderableImage::Type::Specular
                        && image->m_mapType != QSSGRenderableImage::Type::Emissive)
                {
                    continue;
                }

                if (!texColorDeclared) {
                    fragmentShader.append("    vec4 qt_texture_color;");
                    texColorDeclared = true;
                }

                QByteArray texSwizzle;
                QByteArray lookupSwizzle;

                const bool hasIdentityMap = identityImages.contains(image);
                if (hasIdentityMap)
                    generateImageUVSampler(vertexShader, fragmentShader, inKey, *image, imageFragCoords, image->m_imageNode.m_indexUV);
                else
                    generateImageUVCoordinates(vertexShader, fragmentShader, inKey, *image, enableParallaxMapping, image->m_imageNode.m_indexUV);

                const auto &names = imageStringTable[int(image->m_mapType)];
                fragmentShader << "    qt_texture_color" << texSwizzle << " = texture2D(" << names.imageSampler
                               << ", " << (hasIdentityMap ? imageFragCoords : names.imageFragCoords) << ")" << lookupSwizzle << ";\n";

                switch (image->m_mapType) {
                case QSSGRenderableImage::Type::Specular:
                    fragmentShader.addInclude("tonemapping.glsllib");
                    fragmentShader.append("    global_specular_light += qt_sRGBToLinear(qt_texture_color.rgb) * qt_specularTint;");
                    fragmentShader.append("    global_diffuse_light.a *= qt_texture_color.a;");
                    break;
                case QSSGRenderableImage::Type::Emissive:
                    fragmentShader.addInclude("tonemapping.glsllib");
                    fragmentShader.append("    qt_global_emission *= qt_sRGBToLinear(qt_texture_color.rgb);");
                    break;
                default:
                    Q_ASSERT(false);
                    break;
                }
            }
        }

        if (materialAdapter->isPrincipled()) {
            fragmentShader << "    global_diffuse_light.rgb *= 1.0 - qt_metalnessAmount;\n";
        }

        fragmentShader << "    vec4 qt_color_sum = vec4(global_diffuse_light.rgb + global_specular_light + qt_global_emission, global_diffuse_light.a);\n";
        if (hasCustomFrag && hasCustomFunction(QByteArrayLiteral("qt_customPostProcessor"))) {
            // COLOR_SUM, DIFFUSE, SPECULAR, EMISSIVE, UV0, UV1(, SHARED)
            fragmentShader << "    qt_customPostProcessor(qt_color_sum, global_diffuse_light, global_specular_light, qt_global_emission, qt_texCoord0, qt_texCoord1";
            if (usesSharedVar)
                fragmentShader << ", qt_customShared);\n";
            else
                fragmentShader << ");\n";
        }

        Q_ASSERT(!isDepthPass && !isOrthoShadowPass && !isCubeShadowPass);
        fragmentShader.addInclude("tonemapping.glsllib");
        fragmentShader.append("    fragOutput = vec4(qt_tonemap(qt_color_sum));");


#if 0
        // ### Debug Code for viewing various parts of the shading process
        fragmentShader.append("    vec3 debugOutput = vec3(0.0);\n");
        // Base Color
        //fragmentShader.append("    debugOutput += qt_diffuseColor.rgb;\n");
        //fragmentShader.append("    debugOutput += qt_tonemap(qt_diffuseColor.rgb);\n");
        // Roughness
        //fragmentShader.append("    debugOutput += vec3(qt_roughnessAmount);\n");
        // Metalness
        //fragmentShader.append("    debugOutput += vec3(qt_metalnessAmount);\n");
        // Specular
        fragmentShader.append("    debugOutput += global_specular_light;\n");
        // Fresnel
        //fragmentShader.append("    debugOutput += vec3(qt_specularAmount);\n");
        //fragmentShader.append("    vec2 brdf = qt_brdfApproximation(qt_world_normal, qt_view_vector, qt_roughnessAmount);\n");
        //fragmentShader.append("    debugOutput += vec3(qt_specularAmount * brdf.x);\n");
        //fragmentShader.append("    debugOutput += vec3(qt_specularAmount * brdf.x + brdf.y);\n");
        // F0
        //fragmentShader.append("    debugOutput += qt_F0(qt_metalnessAmount, qt_specularFactor, qt_diffuseColor.rgb);");
        // Diffuse
        //fragmentShader.append("    debugOutput += global_diffuse_light.rgb;\n");
        //fragmentShader.append("    debugOutput += qt_tonemap(global_diffuse_light.rgb);\n");
        // Emission
        //fragmentShader.append("    debugOutput += qt_global_emission;\n");
        // Occlusion
        //if (occlusionImage) {
        //    fragmentShader.append("    debugOtuput += vec3(qt_ao);\n");
        // Normal
        //fragmentShader.append("    debugOutput += qt_world_normal * 0.5 + 0.5;\n");
        // Tangent
        //fragmentShader.append("    debugOutput += qt_tangent * 0.5 + 0.5;\n");
        // Binormal
        //fragmentShader.append("    debugOutput += qt_binormal * 0.5 + 0.5;\n");

        fragmentShader.append("    fragOutput = vec4(debugOutput, 1.0);\n");
#endif

    } else {
        if ((isOrthoShadowPass || isCubeShadowPass || isDepthPass) && isOpaqueDepthPrePass) {
            fragmentShader << "    if ((qt_diffuseColor.a * qt_objectOpacity) < 1.0)\n";
            fragmentShader << "        discard;\n";
        }

        if (isOrthoShadowPass) {
            fragmentShader.addUniform("qt_shadowDepthAdjust", "vec2");
            fragmentShader << "    // directional shadow pass\n"
                           << "    float qt_shadowDepth = (qt_varDepth + qt_shadowDepthAdjust.x) * qt_shadowDepthAdjust.y;\n"
                           << "    fragOutput = vec4(qt_shadowDepth);\n";
        } else if (isCubeShadowPass) {
            fragmentShader.addUniform("qt_cameraPosition", "vec3");
            fragmentShader.addUniform("qt_cameraProperties", "vec2");
            fragmentShader << "    // omnidirectional shadow pass\n"
                           << "    vec3 qt_shadowCamPos = vec3(qt_cameraPosition.x, qt_cameraPosition.y, qt_cameraPosition.z);\n"
                           << "    float qt_shadowDist = length(qt_varShadowWorldPos - qt_shadowCamPos);\n"
                           << "    qt_shadowDist = (qt_shadowDist - qt_cameraProperties.x) / (qt_cameraProperties.y - qt_cameraProperties.x);\n"
                           << "    fragOutput = vec4(qt_shadowDist, qt_shadowDist, qt_shadowDist, 1.0);\n";
        } else {
            fragmentShader.addInclude("tonemapping.glsllib");
            fragmentShader.append("    fragOutput = vec4(qt_tonemap(qt_diffuseColor.rgb), qt_diffuseColor.a * qt_objectOpacity);");
        }
    }
}

QSSGRef<QSSGRhiShaderPipeline> QSSGMaterialShaderGenerator::generateMaterialRhiShader(const QByteArray &inShaderKeyPrefix,
                                                                                      QSSGMaterialVertexPipeline &vertexPipeline,
                                                                                      const QSSGShaderDefaultMaterialKey &key,
                                                                                      QSSGShaderDefaultMaterialKeyProperties &inProperties,
                                                                                      const ShaderFeatureSetList &inFeatureSet,
                                                                                      const QSSGRenderGraphObject &inMaterial,
                                                                                      const QSSGShaderLightList &inLights,
                                                                                      QSSGRenderableImage *inFirstImage,
                                                                                      const QSSGRef<QSSGShaderLibraryManager> &shaderLibraryManager,
                                                                                      const QSSGRef<QSSGShaderCache> &theCache)
{
    QByteArray materialInfoString; // also serves as the key for the cache in compileGeneratedRhiShader
    // inShaderKeyPrefix can be a static string for default materials, but must
    // be unique for different sets of shaders in custom materials.
    materialInfoString = inShaderKeyPrefix;
    key.toString(materialInfoString, inProperties);

    // the call order is: beginVertex, beginFragment, endVertex, endFragment
    vertexPipeline.beginVertexGeneration(key, inFeatureSet, shaderLibraryManager);
    generateFragmentShader(vertexPipeline.fragment(), vertexPipeline, key, inProperties, inFeatureSet, inMaterial, inLights, inFirstImage, shaderLibraryManager);
    vertexPipeline.endVertexGeneration();
    vertexPipeline.endFragmentGeneration();

    return vertexPipeline.programGenerator()->compileGeneratedRhiShader(materialInfoString, inFeatureSet, shaderLibraryManager, theCache, {});
}

static float ZERO_MATRIX[16] = {};

void QSSGMaterialShaderGenerator::setRhiMaterialProperties(const QSSGRenderContextInterface &renderContext,
                                                           QSSGRef<QSSGRhiShaderPipeline> &shaders,
                                                           char *ubufData,
                                                           QSSGRhiGraphicsPipelineState *inPipelineState,
                                                           const QSSGRenderGraphObject &inMaterial,
                                                           const QSSGShaderDefaultMaterialKey &inKey,
                                                           QSSGShaderDefaultMaterialKeyProperties &inProperties,
                                                           QSSGRenderCamera &inCamera,
                                                           const QMatrix4x4 &inModelViewProjection,
                                                           const QMatrix3x3 &inNormalMatrix,
                                                           const QMatrix4x4 &inGlobalTransform,
                                                           const QMatrix4x4 &clipSpaceCorrMatrix,
                                                           const QMatrix4x4 &localInstanceTransform,
                                                           const QMatrix4x4 &globalInstanceTransform,
                                                           const QSSGDataView<QMatrix4x4> &inBoneGlobals,
                                                           const QSSGDataView<QMatrix3x3> &inBoneNormals,
                                                           const QSSGDataView<float> &inMorphWeights,
                                                           QSSGRenderableImage *inFirstImage,
                                                           float inOpacity,
                                                           const QSSGLayerGlobalRenderProperties &inRenderProperties,
                                                           const QSSGShaderLightList &inLights,
                                                           bool receivesShadows,
                                                           const QVector2D *shadowDepthAdjust)
{
    QSSGShaderMaterialAdapter *materialAdapter = getMaterialAdapter(inMaterial);
    QSSGRhiShaderPipeline::CommonUniformIndices &cui = shaders->commonUniformIndices;

    materialAdapter->setCustomPropertyUniforms(ubufData, shaders, renderContext);

    const QVector3D camGlobalPos = inCamera.getGlobalPos();
    const QVector2D camProperties(inCamera.clipNear, inCamera.clipFar);

    shaders->setUniform(ubufData, "qt_cameraPosition", &camGlobalPos, 3 * sizeof(float), &cui.cameraPositionIdx);
    shaders->setUniform(ubufData, "qt_cameraDirection", &inRenderProperties.cameraDirection, 3 * sizeof(float), &cui.cameraDirectionIdx);
    shaders->setUniform(ubufData, "qt_cameraProperties", &camProperties, 2 * sizeof(float), &cui.cameraPropertiesIdx);

    // Projection and view matrices are only needed by CustomMaterial shaders
    if (inMaterial.type == QSSGRenderGraphObject::Type::CustomMaterial) {
        const auto *customMaterial = static_cast<const QSSGRenderCustomMaterial *>(&inMaterial);
        const bool usesProjectionMatrix = customMaterial->m_renderFlags.testFlag(QSSGRenderCustomMaterial::RenderFlag::ProjectionMatrix);
        const bool usesInvProjectionMatrix = customMaterial->m_renderFlags.testFlag(QSSGRenderCustomMaterial::RenderFlag::InverseProjectionMatrix);

        if (usesProjectionMatrix || usesInvProjectionMatrix) {
            const QMatrix4x4 projection = clipSpaceCorrMatrix * inCamera.projection;
            if (usesProjectionMatrix)
                shaders->setUniform(ubufData, "qt_projectionMatrix", projection.constData(), 16 * sizeof(float), &cui.projectionMatrixIdx);
            if (usesInvProjectionMatrix)
                shaders->setUniform(ubufData, "qt_inverseProjectionMatrix", projection.inverted().constData(), 16 * sizeof (float), &cui.inverseProjectionMatrixIdx);
        }

        // ### these should use flags like the above two
        QMatrix4x4 viewProj;
        inCamera.calculateViewProjectionMatrix(viewProj);
        viewProj = clipSpaceCorrMatrix * viewProj;
        shaders->setUniform(ubufData, "qt_viewProjectionMatrix", viewProj.constData(), 16 * sizeof(float), &cui.viewProjectionMatrixIdx);
        const QMatrix4x4 viewMatrix = inCamera.globalTransform.inverted();
        shaders->setUniform(ubufData, "qt_viewMatrix", viewMatrix.constData(), 16 * sizeof(float), &cui.viewMatrixIdx);
    }

    const bool usesInstancing = inProperties.m_usesInstancing.getValue(inKey);
    if (!usesInstancing) {
        const QMatrix4x4 mvp = clipSpaceCorrMatrix * inModelViewProjection;
        shaders->setUniform(ubufData, "qt_modelViewProjection", mvp.constData(), 16 * sizeof(float), &cui.modelViewProjectionIdx);

        shaders->setUniform(ubufData, "qt_normalMatrix", inNormalMatrix.constData(), 12 * sizeof(float), &cui.normalMatrixIdx,
                            QSSGRhiShaderPipeline::UniformFlag::Mat3); // real size will be 12 floats, setUniform repacks as needed
        shaders->setUniform(ubufData, "qt_modelMatrix", inGlobalTransform.constData(), 16 * sizeof(float), &cui.modelMatrixIdx);
    } else {
        // Instanced calls have to calculate MVP and normalMatrix in the vertex shader
        QMatrix4x4 viewProj;
        inCamera.calculateViewProjectionMatrix(viewProj);
        viewProj = clipSpaceCorrMatrix * viewProj;
        shaders->setUniform(ubufData, "qt_viewProjectionMatrix", viewProj.constData(), 16 * sizeof(float), &cui.viewProjectionMatrixIdx);
        shaders->setUniform(ubufData, "qt_modelMatrix", localInstanceTransform.constData(), 16 * sizeof(float), &cui.modelMatrixIdx);
        shaders->setUniform(ubufData, "qt_parentMatrix", globalInstanceTransform.constData(), 16 * sizeof(float));
    }

    // Skinning
    const bool hasCustomVert = materialAdapter->hasCustomShaderSnippet(QSSGShaderCache::ShaderType::Vertex);
    const bool hasSkinningInputs = inProperties.m_vertexAttributes.getBitValue(QSSGShaderKeyVertexAttribute::JointAndWeight, inKey);
    const bool hasSkinning = inBoneGlobals.size() > 0 && (hasSkinningInputs || hasCustomVert);
    if (hasSkinning) {
        shaders->setUniformArray(ubufData, "qt_boneTransforms", inBoneGlobals.mData, inBoneGlobals.mSize,
                                 QSSGRenderShaderDataType::Matrix4x4, &cui.boneTransformsIdx);
        shaders->setUniformArray(ubufData, "qt_boneNormalTransforms", inBoneNormals.mData, inBoneNormals.mSize,
                                 QSSGRenderShaderDataType::Matrix3x3, &cui.boneNormalTransformsIdx);
    }

    // Morphing
    if (inMorphWeights.mSize > 0)
        shaders->setUniformArray(ubufData, "qt_morphWeights",inMorphWeights.mData, inMorphWeights.mSize,
                                 QSSGRenderShaderDataType::Float, &cui.morphWeightsIdx);

    QVector3D theLightAmbientTotal;
    shaders->resetShadowMaps();
    float lightColor[QSSG_MAX_NUM_LIGHTS][3];
    QSSGShaderLightsUniformData &lightsUniformData(shaders->lightsUniformData());
    lightsUniformData.count = 0;

    for (quint32 lightIdx = 0, shadowMapCount = 0, lightEnd = inLights.size();
         lightIdx < lightEnd && lightIdx < QSSG_MAX_NUM_LIGHTS; ++lightIdx)
    {
        QSSGRenderLight *theLight(inLights[lightIdx].light);
        // For all disabled lights, the shader code will be generated as the same as enabled.
        // but the light color will be zero, and shadows will not be affected
        const bool lightEnabled = inLights[lightIdx].enabled;
        const bool lightShadows = inLights[lightIdx].shadows;
        const float brightness = lightEnabled ? theLight->m_brightness : 0.0f;
        lightColor[lightIdx][0] = theLight->m_diffuseColor.x() * brightness;
        lightColor[lightIdx][1] = theLight->m_diffuseColor.y() * brightness;
        lightColor[lightIdx][2] = theLight->m_diffuseColor.z() * brightness;
        lightsUniformData.count += 1;
        QSSGShaderLightData &lightData(lightsUniformData.lightData[lightIdx]);
        const QVector3D &lightSpecular(theLight->m_specularColor);
        lightData.specular[0] = lightSpecular.x() * brightness;
        lightData.specular[1] = lightSpecular.y() * brightness;
        lightData.specular[2] = lightSpecular.z() * brightness;
        lightData.specular[3] = 1.0f;
        const QVector3D &lightDirection(inLights[lightIdx].direction);
        lightData.direction[0] = lightDirection.x();
        lightData.direction[1] = lightDirection.y();
        lightData.direction[2] = lightDirection.z();
        lightData.direction[3] = 1.0f;

        // When it comes to receivesShadows, it is a bit tricky: to stay
        // compatible with the old, direct OpenGL rendering path (and the
        // generated shader code), we will need to ensure the texture
        // (shadowmap0, shadowmap1, ...) and sampler bindings are present.
        // So receivesShadows must not be included in the following
        // condition. Instead, it is the other shadow-related uniforms that
        // get an all-zero value, which then ensures no shadow contribution
        // for the object in question.

        if (lightEnabled && lightShadows && shadowMapCount < QSSG_MAX_NUM_SHADOW_MAPS) {
            QSSGRhiShadowMapProperties &theShadowMapProperties(shaders->addShadowMap());
            ++shadowMapCount;

            QSSGShadowMapEntry *pEntry = inRenderProperties.shadowMapManager->shadowMapEntry(lightIdx);
            Q_ASSERT(pEntry);

            const auto names = setupShadowMapVariableNames(lightIdx);

            if (theLight->type != QSSGRenderLight::Type::DirectionalLight) {
                theShadowMapProperties.shadowMapTexture = pEntry->m_rhiDepthCube;
                theShadowMapProperties.shadowMapTextureUniformName = names.shadowCubeStem;
                if (receivesShadows)
                    shaders->setUniform(ubufData, names.shadowMatrixStem, pEntry->m_lightView.constData(), 16 * sizeof(float));
                else
                    shaders->setUniform(ubufData, names.shadowMatrixStem, ZERO_MATRIX, 16 * sizeof(float));
            } else {
                theShadowMapProperties.shadowMapTexture = pEntry->m_rhiDepthMap;
                theShadowMapProperties.shadowMapTextureUniformName = names.shadowMapStem;
                if (receivesShadows) {
                    // add fixed scale bias matrix
                    const QMatrix4x4 bias = {
                        0.5, 0.0, 0.0, 0.5,
                        0.0, 0.5, 0.0, 0.5,
                        0.0, 0.0, 0.5, 0.5,
                        0.0, 0.0, 0.0, 1.0 };
                    const QMatrix4x4 m = bias * pEntry->m_lightVP;
                    shaders->setUniform(ubufData, names.shadowMatrixStem, m.constData(), 16 * sizeof(float));
                } else {
                    shaders->setUniform(ubufData, names.shadowMatrixStem, ZERO_MATRIX, 16 * sizeof(float));
                }
            }

            if (receivesShadows) {
                const QVector4D shadowControl(theLight->m_shadowBias,
                                              theLight->m_shadowFactor,
                                              theLight->m_shadowMapFar,
                                              inRenderProperties.isYUpInFramebuffer ? 0.0f : 1.0f);
                shaders->setUniform(ubufData, names.shadowControlStem, &shadowControl, 4 * sizeof(float));
            } else {
                shaders->setUniform(ubufData, names.shadowControlStem, ZERO_MATRIX, 4 * sizeof(float));
            }
        }

        if (theLight->type == QSSGRenderLight::Type::PointLight
                || theLight->type == QSSGRenderLight::Type::SpotLight) {
            const QVector3D globalPos = theLight->getGlobalPos();
            lightData.position[0] = globalPos.x();
            lightData.position[1] = globalPos.y();
            lightData.position[2] = globalPos.z();
            lightData.position[3] = 1.0f;
            lightData.constantAttenuation = aux::translateConstantAttenuation(theLight->m_constantFade);
            lightData.linearAttenuation = aux::translateLinearAttenuation(theLight->m_linearFade);
            lightData.quadraticAttenuation = aux::translateQuadraticAttenuation(theLight->m_quadraticFade);
            lightData.coneAngle = 180.0f;
            if (theLight->type == QSSGRenderLight::Type::SpotLight) {
                const float coneAngle = theLight->m_coneAngle;
                const float innerConeAngle = (theLight->m_innerConeAngle > coneAngle) ?
                                                coneAngle : theLight->m_innerConeAngle;
                lightData.coneAngle = qCos(qDegreesToRadians(coneAngle));
                lightData.innerConeAngle = qCos(qDegreesToRadians(innerConeAngle));
            }
        }

        if (lightEnabled)
            theLightAmbientTotal += theLight->m_ambientColor;
    }

    shaders->setDepthTexture(inRenderProperties.rhiDepthTexture);
    shaders->setSsaoTexture(inRenderProperties.rhiSsaoTexture);
    shaders->setScreenTexture(inRenderProperties.rhiScreenTexture);

    QSSGRenderImage *theLightProbe = inRenderProperties.lightProbe;

    // If the material has its own IBL Override, we should use that image instead.
    QSSGRenderImage *materialIblProbe = materialAdapter->iblProbe();
    if (materialIblProbe)
        theLightProbe = materialIblProbe;
    QSSGRenderImageTexture lightProbeTexture;
    if (theLightProbe)
        lightProbeTexture = renderContext.bufferManager()->loadRenderImage(theLightProbe, QSSGBufferManager::MipModeBsdf);
    if (theLightProbe && lightProbeTexture.m_texture) {
        QSSGRenderTextureCoordOp theHorzLightProbeTilingMode = theLightProbe->m_horizontalTilingMode;
        QSSGRenderTextureCoordOp theVertLightProbeTilingMode = theLightProbe->m_verticalTilingMode;
        const int maxMipLevel = lightProbeTexture.m_mipmapCount - 1;

        if (!materialIblProbe && !inRenderProperties.probeOrientation.isIdentity())
            shaders->setUniform(ubufData, "qt_lightProbeOrientation", inRenderProperties.probeOrientation.constData(), 16 * sizeof(float), &cui.lightProbeOrientationIdx);

        const float props[4] = { 0.0f, float(maxMipLevel), inRenderProperties.probeHorizon, inRenderProperties.probeExposure };
        shaders->setUniform(ubufData, "qt_lightProbeProperties", props, 4 * sizeof(float), &cui.lightProbePropertiesIdx);

        shaders->setLightProbeTexture(lightProbeTexture.m_texture, theHorzLightProbeTilingMode, theVertLightProbeTilingMode);
    } else {
        // no lightprobe
        const float emptyProps[4] = { 0.0f, 0.0f, -1.0f, 0.0f };
        shaders->setUniform(ubufData, "qt_lightProbeProperties", emptyProps, 4 * sizeof(float), &cui.lightProbePropertiesIdx);

        shaders->setLightProbeTexture(nullptr);
    }

    const QVector3D emissiveColor = materialAdapter->emissiveColor();
    shaders->setUniform(ubufData, "qt_material_emissive_color", &emissiveColor, 3 * sizeof(float), &cui.material_emissiveColorIdx);

    const auto qMix = [](float x, float y, float a) {
        return (x * (1.0f - a) + (y * a));
    };

    const auto qMix3 = [&qMix](const QVector3D &x, const QVector3D &y, float a) {
        return QVector3D{qMix(x.x(), y.x(), a), qMix(x.y(), y.y(), a), qMix(x.z(), y.z(), a)};
    };

    const QVector4D color = materialAdapter->color();
    const QVector3D materialSpecularTint = materialAdapter->specularTint();
    const QVector3D specularTint = materialAdapter->isPrincipled() ? qMix3(QVector3D(1.0f, 1.0f, 1.0f), color.toVector3D(), materialSpecularTint.x())
                                                                   : materialSpecularTint;
    shaders->setUniform(ubufData, "qt_material_base_color", &color, 4 * sizeof(float), &cui.material_baseColorIdx);

    const float ior = materialAdapter->ior();
    QVector4D specularColor(specularTint, ior);
    shaders->setUniform(ubufData, "qt_material_specular", &specularColor, 4 * sizeof(float), &cui.material_specularIdx);

     // metalnessAmount cannot be multiplied in here yet due to custom materials
    const bool hasLighting = materialAdapter->hasLighting();
    shaders->setLightsEnabled(hasLighting);
    if (hasLighting) {
        for (int lightIdx = 0; lightIdx < lightsUniformData.count; ++lightIdx) {
            QSSGShaderLightData &lightData(lightsUniformData.lightData[lightIdx]);
            lightData.diffuse[0] = lightColor[lightIdx][0];
            lightData.diffuse[1] = lightColor[lightIdx][1];
            lightData.diffuse[2] = lightColor[lightIdx][2];
            lightData.diffuse[3] = 1.0f;
        }
        memcpy(ubufData + shaders->ub0LightDataOffset(), &lightsUniformData, shaders->ub0LightDataSize());
    }

    shaders->setUniform(ubufData, "qt_light_ambient_total", &theLightAmbientTotal, 3 * sizeof(float), &cui.light_ambient_totalIdx);

    const float materialProperties[4] = {
        materialAdapter->specularAmount(),
        materialAdapter->specularRoughness(),
        materialAdapter->metalnessAmount(),
        inOpacity
    };
    shaders->setUniform(ubufData, "qt_material_properties", materialProperties, 4 * sizeof(float), &cui.material_propertiesIdx);

    const float materialProperties2[4] = {
        materialAdapter->fresnelPower(),
        materialAdapter->bumpAmount(),
        materialAdapter->translucentFallOff(),
        materialAdapter->diffuseLightWrap()
    };
    shaders->setUniform(ubufData, "qt_material_properties2", materialProperties2, 4 * sizeof(float), &cui.material_properties2Idx);

    const float materialProperties3[4] = {
        materialAdapter->occlusionAmount(),
        materialAdapter->alphaCutOff(),
        0.0f, // unused
        0.0f  // unused
    };
    shaders->setUniform(ubufData, "qt_material_properties3", materialProperties3, 4 * sizeof(float), &cui.material_properties3Idx);

    const float materialProperties4[4] = {
        materialAdapter->heightAmount(),
        materialAdapter->minHeightSamples(),
        materialAdapter->maxHeightSamples(),
        0.0f  // unused
    };
    shaders->setUniform(ubufData, "qt_material_properties4", materialProperties4, 4 * sizeof(float), &cui.material_properties4Idx);

    const float rhiProperties[4] = {
        inRenderProperties.isYUpInFramebuffer ? 1.0f : -1.0f,
        inRenderProperties.isYUpInNDC ? 1.0f : -1.0f,
        inRenderProperties.isClipDepthZeroToOne ? 0.0f : -1.0f,
        0.0f // unused
    };
    shaders->setUniform(ubufData, "qt_rhi_properties", rhiProperties, 4 * sizeof(float), &cui.rhiPropertiesIdx);

    qsizetype imageIdx = 0;
    for (QSSGRenderableImage *theImage = inFirstImage; theImage; theImage = theImage->m_nextImage, ++imageIdx) {
        // we need to map image to uniform name: "image0_rotations", "image0_offsets", etc...
        const auto &names = imageStringTable[int(theImage->m_mapType)];
        if (imageIdx == cui.imageIndices.size())
            cui.imageIndices.append(QSSGRhiShaderPipeline::CommonUniformIndices::ImageIndices());
        auto &indices = cui.imageIndices[imageIdx];

        const QMatrix4x4 &textureTransform = theImage->m_imageNode.m_textureTransform;
        // We separate rotational information from offset information so that just maybe the shader
        // will attempt to push less information to the card.
        const float *dataPtr(textureTransform.constData());
        // The third member of the offsets contains a flag indicating if the texture was
        // premultiplied or not.
        // We use this to mix the texture alpha.
        const float offsets[3] = { dataPtr[12], dataPtr[13], 0.0f /* non-premultiplied */ };
        shaders->setUniform(ubufData, names.imageOffsets, offsets, sizeof(offsets), &indices.imageOffsetsUniformIndex);
        // Grab just the upper 2x2 rotation matrix from the larger matrix.
        const float rotations[4] = { dataPtr[0], dataPtr[4], dataPtr[1], dataPtr[5] };
        shaders->setUniform(ubufData, names.imageRotations, rotations, sizeof(rotations), &indices.imageRotationsUniformIndex);
    }

    if (shadowDepthAdjust)
        shaders->setUniform(ubufData, "qt_shadowDepthAdjust", shadowDepthAdjust, 2 * sizeof(float), &cui.shadowDepthAdjustIdx);

    const bool usesPointsTopology = inProperties.m_usesPointsTopology.getValue(inKey);
    if (usesPointsTopology) {
        const float pointSize = materialAdapter->pointSize();
        shaders->setUniform(ubufData, "qt_materialPointSize", &pointSize, sizeof(float), &cui.pointSizeIdx);
    }

    inPipelineState->lineWidth = materialAdapter->lineWidth();
}

QT_END_NAMESPACE
