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/** @file  FBXConverter.cpp
 *  @brief Implementation of the FBX DOM -> aiScene converter
 */

#ifndef ASSIMP_BUILD_NO_FBX_IMPORTER

#include "FBXConverter.h"
#include "FBXDocument.h"
#include "FBXImporter.h"
#include "FBXMeshGeometry.h"
#include "FBXParser.h"
#include "FBXProperties.h"
#include "FBXUtil.h"

#include <assimp/MathFunctions.h>
#include <assimp/StringComparison.h>
#include <assimp/scene.h>
#include <assimp/CreateAnimMesh.h>
#include <assimp/StringUtils.h>
#include <assimp/commonMetaData.h>

#include <stdlib.h>
#include <cstdint>
#include <iomanip>
#include <iterator>
#include <memory>
#include <sstream>

namespace Assimp {
namespace FBX {

using namespace Util;

#define MAGIC_NODE_TAG "_$AssimpFbx$"

#define CONVERT_FBX_TIME(time) static_cast<double>(time) / 46186158000LL

static void correctRootTransform(const aiScene *scene) {
    if (scene == nullptr) {
        return;
    }

    if (scene->mMetaData == nullptr) {
        return;
    }

    int32_t UpAxis = 1, UpAxisSign = 1, FrontAxis = 2, FrontAxisSign = 1, CoordAxis = 0, CoordAxisSign = 1;
    double UnitScaleFactor = 1.0;
    for (unsigned MetadataIndex = 0; MetadataIndex < scene->mMetaData->mNumProperties; ++MetadataIndex) {
        if (strcmp(scene->mMetaData->mKeys[MetadataIndex].C_Str(), "UpAxis") == 0) {
            scene->mMetaData->Get<int32_t>(MetadataIndex, UpAxis);
        }
        if (strcmp(scene->mMetaData->mKeys[MetadataIndex].C_Str(), "UpAxisSign") == 0) {
            scene->mMetaData->Get<int32_t>(MetadataIndex, UpAxisSign);
        }
        if (strcmp(scene->mMetaData->mKeys[MetadataIndex].C_Str(), "FrontAxis") == 0) {
            scene->mMetaData->Get<int32_t>(MetadataIndex, FrontAxis);
        }
        if (strcmp(scene->mMetaData->mKeys[MetadataIndex].C_Str(), "FrontAxisSign") == 0) {
            scene->mMetaData->Get<int32_t>(MetadataIndex, FrontAxisSign);
        }
        if (strcmp(scene->mMetaData->mKeys[MetadataIndex].C_Str(), "CoordAxis") == 0) {
            scene->mMetaData->Get<int32_t>(MetadataIndex, CoordAxis);
        }
        if (strcmp(scene->mMetaData->mKeys[MetadataIndex].C_Str(), "CoordAxisSign") == 0) {
            scene->mMetaData->Get<int32_t>(MetadataIndex, CoordAxisSign);
        }
        if (strcmp(scene->mMetaData->mKeys[MetadataIndex].C_Str(), "UnitScaleFactor") == 0) {
            scene->mMetaData->Get<double>(MetadataIndex, UnitScaleFactor);
        }
    }

    aiVector3D upVec, forwardVec, rightVec;
    upVec[UpAxis] = UpAxisSign * static_cast<float>(UnitScaleFactor);
    forwardVec[FrontAxis] = FrontAxisSign * static_cast<float>(UnitScaleFactor);
    rightVec[CoordAxis] = CoordAxisSign * (float)UnitScaleFactor;

    aiMatrix4x4 mat(rightVec.x, rightVec.y, rightVec.z, 0.0f,
                    upVec.x, upVec.y, upVec.z, 0.0f,
                    forwardVec.x, forwardVec.y, forwardVec.z, 0.0f,
                    0.0f, 0.0f, 0.0f, 1.0f);
    scene->mRootNode->mTransformation *= mat;
}

FBXConverter::FBXConverter(aiScene *out, const Document &doc, bool removeEmptyBones) :
        defaultMaterialIndex(),
        mMeshes(),
        lights(),
        cameras(),
        textures(),
        materials_converted(),
        textures_converted(),
        meshes_converted(),
        node_anim_chain_bits(),
        mNodeNames(),
        anim_fps(),
        mSceneOut(out),
        doc(doc),
        mRemoveEmptyBones(removeEmptyBones) {


    // animations need to be converted first since this will
    // populate the node_anim_chain_bits map, which is needed
    // to determine which nodes need to be generated.
    ConvertAnimations();
    // Embedded textures in FBX could be connected to nothing but to itself,
    // for instance Texture -> Video connection only but not to the main graph,
    // The idea here is to traverse all objects to find these Textures and convert them,
    // so later during material conversion it will find converted texture in the textures_converted array.
    if (doc.Settings().readTextures) {
        ConvertOrphanedEmbeddedTextures();
    }
    ConvertRootNode();

    if (doc.Settings().readAllMaterials) {
        // unfortunately this means we have to evaluate all objects
        for (const ObjectMap::value_type &v : doc.Objects()) {

            const Object *ob = v.second->Get();
            if (!ob) {
                continue;
            }

            const Material *mat = dynamic_cast<const Material *>(ob);
            if (mat) {

                if (materials_converted.find(mat) == materials_converted.end()) {
                    ConvertMaterial(*mat, nullptr);
                }
            }
        }
    }

    ConvertGlobalSettings();
    TransferDataToScene();

    // if we didn't read any meshes set the AI_SCENE_FLAGS_INCOMPLETE
    // to make sure the scene passes assimp's validation. FBX files
    // need not contain geometry (i.e. camera animations, raw armatures).
    if (out->mNumMeshes == 0) {
        out->mFlags |= AI_SCENE_FLAGS_INCOMPLETE;
    } else {
        correctRootTransform(mSceneOut);
    }
}

FBXConverter::~FBXConverter() {
    std::for_each(mMeshes.begin(), mMeshes.end(), Util::delete_fun<aiMesh>());
    std::for_each(materials.begin(), materials.end(), Util::delete_fun<aiMaterial>());
    std::for_each(animations.begin(), animations.end(), Util::delete_fun<aiAnimation>());
    std::for_each(lights.begin(), lights.end(), Util::delete_fun<aiLight>());
    std::for_each(cameras.begin(), cameras.end(), Util::delete_fun<aiCamera>());
    std::for_each(textures.begin(), textures.end(), Util::delete_fun<aiTexture>());
}

void FBXConverter::ConvertRootNode() {
    mSceneOut->mRootNode = new aiNode();
    std::string unique_name;
    GetUniqueName("RootNode", unique_name);
    mSceneOut->mRootNode->mName.Set(unique_name);

    // root has ID 0
    ConvertNodes(0L, mSceneOut->mRootNode, mSceneOut->mRootNode);
}

static std::string getAncestorBaseName(const aiNode *node) {
    const char *nodeName = nullptr;
    size_t length = 0;
    while (node && (!nodeName || length == 0)) {
        nodeName = node->mName.C_Str();
        length = node->mName.length;
        node = node->mParent;
    }

    if (!nodeName || length == 0) {
        return {};
    }
    // could be std::string_view if c++17 available
    return std::string(nodeName, length);
}

// Make unique name
std::string FBXConverter::MakeUniqueNodeName(const Model *const model, const aiNode &parent) {
    std::string original_name = FixNodeName(model->Name());
    if (original_name.empty()) {
        original_name = getAncestorBaseName(&parent);
    }
    std::string unique_name;
    GetUniqueName(original_name, unique_name);
    return unique_name;
}

/// This struct manages nodes which may or may not end up in the node hierarchy.
/// When a node becomes a child of another node, that node becomes its owner and mOwnership should be released.
struct FBXConverter::PotentialNode {
    PotentialNode() : mOwnership(new aiNode), mNode(mOwnership.get()) {}
    PotentialNode(const std::string& name) : mOwnership(new aiNode(name)), mNode(mOwnership.get()) {}
    aiNode* operator->() { return mNode; }
    std::unique_ptr<aiNode> mOwnership;
    aiNode* mNode;
};

/// todo: pre-build node hierarchy
/// todo: get bone from stack
/// todo: make map of aiBone* to aiNode*
/// then update convert clusters to the new format
void FBXConverter::ConvertNodes(uint64_t id, aiNode *parent, aiNode *root_node) {
    const std::vector<const Connection *> &conns = doc.GetConnectionsByDestinationSequenced(id, "Model");

    std::vector<PotentialNode> nodes;
    nodes.reserve(conns.size());

    std::vector<PotentialNode> nodes_chain;
    std::vector<PotentialNode> post_nodes_chain;

    for (const Connection *con : conns) {
        // ignore object-property links
        if (con->PropertyName().length()) {
            // really important we document why this is ignored.
            FBXImporter::LogInfo("ignoring property link - no docs on why this is ignored");
            continue; //?
        }

        // convert connection source object into Object base class
        const Object *const object = con->SourceObject();
        if (nullptr == object) {
            FBXImporter::LogError("failed to convert source object for Model link");
            continue;
        }

        // FBX Model::Cube, Model::Bone001, etc elements
        // This detects if we can cast the object into this model structure.
        const Model *const model = dynamic_cast<const Model *>(object);

        if (nullptr != model) {
            nodes_chain.clear();
            post_nodes_chain.clear();
            aiMatrix4x4 new_abs_transform = parent->mTransformation;
            std::string node_name = FixNodeName(model->Name());
            // even though there is only a single input node, the design of
            // assimp (or rather: the complicated transformation chain that
            // is employed by fbx) means that we may need multiple aiNode's
            // to represent a fbx node's transformation.

            // generate node transforms - this includes pivot data
            // if need_additional_node is true then you t
            const bool need_additional_node = GenerateTransformationNodeChain(*model, node_name, nodes_chain, post_nodes_chain);

            // assert that for the current node we must have at least a single transform
            ai_assert(nodes_chain.size());

            if (need_additional_node) {
                nodes_chain.emplace_back(node_name);
            }

            //setup metadata on newest node
            SetupNodeMetadata(*model, *nodes_chain.back().mNode);

            // link all nodes in a row
            aiNode *last_parent = parent;
            for (PotentialNode& child : nodes_chain) {
                ai_assert(child.mNode);

                if (last_parent != parent) {
                    last_parent->mNumChildren = 1;
                    last_parent->mChildren = new aiNode *[1];
                    last_parent->mChildren[0] = child.mOwnership.release();
                }

                child->mParent = last_parent;
                last_parent = child.mNode;
            }

            // attach geometry
            ConvertModel(*model, nodes_chain.back().mNode, root_node, new_abs_transform);

            // check if there will be any child nodes
            const std::vector<const Connection *> &child_conns = doc.GetConnectionsByDestinationSequenced(model->ID(), "Model");

            // if so, link the geometric transform inverse nodes
            // before we attach any child nodes
            if (child_conns.size()) {
                for (PotentialNode& postnode : post_nodes_chain) {
                    ai_assert(postnode.mNode);

                    if (last_parent != parent) {
                        last_parent->mNumChildren = 1;
                        last_parent->mChildren = new aiNode *[1];
                        last_parent->mChildren[0] = postnode.mOwnership.release();
                    }

                    postnode->mParent = last_parent;
                    last_parent = postnode.mNode;
                }
            } else {
                // free the nodes we allocated as we don't need them
                post_nodes_chain.clear();
            }

            // recursion call - child nodes
            ConvertNodes(model->ID(), last_parent, root_node);

            if (doc.Settings().readLights) {
                ConvertLights(*model, node_name);
            }

            if (doc.Settings().readCameras) {
                ConvertCameras(*model, node_name);
            }

            nodes.push_back(std::move(nodes_chain.front()));
            nodes_chain.clear();
        }
    }

    if (nodes.empty()) {
        parent->mNumChildren = 0;
        parent->mChildren = nullptr;
    }

    parent->mChildren = new aiNode *[nodes.size()]();
    parent->mNumChildren = static_cast<unsigned int>(nodes.size());
    for (unsigned int i = 0; i < nodes.size(); ++i) {
        parent->mChildren[i] = nodes[i].mOwnership.release();
    }
}

void FBXConverter::ConvertLights(const Model &model, const std::string &orig_name) {
    const std::vector<const NodeAttribute *> &node_attrs = model.GetAttributes();
    for (const NodeAttribute *attr : node_attrs) {
        const Light *const light = dynamic_cast<const Light *>(attr);
        if (light) {
            ConvertLight(*light, orig_name);
        }
    }
}

void FBXConverter::ConvertCameras(const Model &model, const std::string &orig_name) {
    const std::vector<const NodeAttribute *> &node_attrs = model.GetAttributes();
    for (const NodeAttribute *attr : node_attrs) {
        const Camera *const cam = dynamic_cast<const Camera *>(attr);
        if (cam) {
            ConvertCamera(*cam, orig_name);
        }
    }
}

void FBXConverter::ConvertLight(const Light &light, const std::string &orig_name) {
    lights.push_back(new aiLight());
    aiLight *const out_light = lights.back();

    out_light->mName.Set(orig_name);

    const float intensity = light.Intensity() / 100.0f;
    const aiVector3D &col = light.Color();

    out_light->mColorDiffuse = aiColor3D(col.x, col.y, col.z);
    out_light->mColorDiffuse.r *= intensity;
    out_light->mColorDiffuse.g *= intensity;
    out_light->mColorDiffuse.b *= intensity;

    out_light->mColorSpecular = out_light->mColorDiffuse;

    //lights are defined along negative y direction
    out_light->mPosition = aiVector3D(0.0f);
    out_light->mDirection = aiVector3D(0.0f, -1.0f, 0.0f);
    out_light->mUp = aiVector3D(0.0f, 0.0f, -1.0f);

    switch (light.LightType()) {
        case Light::Type_Point:
            out_light->mType = aiLightSource_POINT;
            break;

        case Light::Type_Directional:
            out_light->mType = aiLightSource_DIRECTIONAL;
            break;

        case Light::Type_Spot:
            out_light->mType = aiLightSource_SPOT;
            out_light->mAngleOuterCone = AI_DEG_TO_RAD(light.OuterAngle());
            out_light->mAngleInnerCone = AI_DEG_TO_RAD(light.InnerAngle());
            break;

        case Light::Type_Area:
            FBXImporter::LogWarn("cannot represent area light, set to UNDEFINED");
            out_light->mType = aiLightSource_UNDEFINED;
            break;

        case Light::Type_Volume:
            FBXImporter::LogWarn("cannot represent volume light, set to UNDEFINED");
            out_light->mType = aiLightSource_UNDEFINED;
            break;
        default:
            ai_assert(false);
    }

    float decay = light.DecayStart();
    switch (light.DecayType()) {
        case Light::Decay_None:
            out_light->mAttenuationConstant = decay;
            out_light->mAttenuationLinear = 0.0f;
            out_light->mAttenuationQuadratic = 0.0f;
            break;
        case Light::Decay_Linear:
            out_light->mAttenuationConstant = 0.0f;
            out_light->mAttenuationLinear = 2.0f / decay;
            out_light->mAttenuationQuadratic = 0.0f;
            break;
        case Light::Decay_Quadratic:
            out_light->mAttenuationConstant = 0.0f;
            out_light->mAttenuationLinear = 0.0f;
            out_light->mAttenuationQuadratic = 2.0f / (decay * decay);
            break;
        case Light::Decay_Cubic:
            FBXImporter::LogWarn("cannot represent cubic attenuation, set to Quadratic");
            out_light->mAttenuationQuadratic = 1.0f;
            break;
        default:
            ai_assert(false);
            break;
    }
}

void FBXConverter::ConvertCamera(const Camera &cam, const std::string &orig_name) {
    cameras.push_back(new aiCamera());
    aiCamera *const out_camera = cameras.back();

    out_camera->mName.Set(orig_name);

    out_camera->mAspect = cam.AspectWidth() / cam.AspectHeight();

    // NOTE: Camera mPosition, mLookAt and mUp must be set to default here.
    // All transformations to the camera will be handled by its node in the scenegraph.
    out_camera->mPosition = aiVector3D(0.0f);
    out_camera->mLookAt = aiVector3D(1.0f, 0.0f, 0.0f);
    out_camera->mUp = aiVector3D(0.0f, 1.0f, 0.0f);

    // NOTE: Some software (maya) does not put FieldOfView in FBX, so we compute
    // mHorizontalFOV from FocalLength and FilmWidth with unit conversion.

    // TODO: This is not a complete solution for how FBX cameras can be stored.
    // TODO: Incorporate non-square pixel aspect ratio.
    // TODO: FBX aperture mode might be storing vertical FOV in need of conversion with aspect ratio.

    float fov_deg = cam.FieldOfView();
    // If FOV not specified in file, compute using FilmWidth and FocalLength.
    if (fov_deg == kFovUnknown) {
        float film_width_inches = cam.FilmWidth();
        float focal_length_mm = cam.FocalLength();
        ASSIMP_LOG_VERBOSE_DEBUG("FBX FOV unspecified. Computing from FilmWidth (", film_width_inches, "inches) and FocalLength (", focal_length_mm, "mm).");
        double half_fov_rad = std::atan2(film_width_inches * 25.4 * 0.5, focal_length_mm);
        out_camera->mHorizontalFOV = static_cast<float>(half_fov_rad);
    } else {
        // FBX fov is full-view degrees. We want half-view radians.
        out_camera->mHorizontalFOV = AI_DEG_TO_RAD(fov_deg) * 0.5f;
    }

    out_camera->mClipPlaneNear = cam.NearPlane();
    out_camera->mClipPlaneFar = cam.FarPlane();
}

void FBXConverter::GetUniqueName(const std::string &name, std::string &uniqueName) {
    uniqueName = name;
    auto it_pair = mNodeNames.insert({ name, 0 }); // duplicate node name instance count
    unsigned int &i = it_pair.first->second;
    while (!it_pair.second) {
        ++i;
        std::ostringstream ext;
        ext << name << std::setfill('0') << std::setw(3) << i;
        uniqueName = ext.str();
        it_pair = mNodeNames.insert({ uniqueName, 0 });
    }
}

const char *FBXConverter::NameTransformationComp(TransformationComp comp) {
    switch (comp) {
        case TransformationComp_Translation:
            return "Translation";
        case TransformationComp_RotationOffset:
            return "RotationOffset";
        case TransformationComp_RotationPivot:
            return "RotationPivot";
        case TransformationComp_PreRotation:
            return "PreRotation";
        case TransformationComp_Rotation:
            return "Rotation";
        case TransformationComp_PostRotation:
            return "PostRotation";
        case TransformationComp_RotationPivotInverse:
            return "RotationPivotInverse";
        case TransformationComp_ScalingOffset:
            return "ScalingOffset";
        case TransformationComp_ScalingPivot:
            return "ScalingPivot";
        case TransformationComp_Scaling:
            return "Scaling";
        case TransformationComp_ScalingPivotInverse:
            return "ScalingPivotInverse";
        case TransformationComp_GeometricScaling:
            return "GeometricScaling";
        case TransformationComp_GeometricRotation:
            return "GeometricRotation";
        case TransformationComp_GeometricTranslation:
            return "GeometricTranslation";
        case TransformationComp_GeometricScalingInverse:
            return "GeometricScalingInverse";
        case TransformationComp_GeometricRotationInverse:
            return "GeometricRotationInverse";
        case TransformationComp_GeometricTranslationInverse:
            return "GeometricTranslationInverse";
        case TransformationComp_MAXIMUM: // this is to silence compiler warnings
        default:
            break;
    }

    ai_assert(false);

    return nullptr;
}

const char *FBXConverter::NameTransformationCompProperty(TransformationComp comp) {
    switch (comp) {
        case TransformationComp_Translation:
            return "Lcl Translation";
        case TransformationComp_RotationOffset:
            return "RotationOffset";
        case TransformationComp_RotationPivot:
            return "RotationPivot";
        case TransformationComp_PreRotation:
            return "PreRotation";
        case TransformationComp_Rotation:
            return "Lcl Rotation";
        case TransformationComp_PostRotation:
            return "PostRotation";
        case TransformationComp_RotationPivotInverse:
            return "RotationPivotInverse";
        case TransformationComp_ScalingOffset:
            return "ScalingOffset";
        case TransformationComp_ScalingPivot:
            return "ScalingPivot";
        case TransformationComp_Scaling:
            return "Lcl Scaling";
        case TransformationComp_ScalingPivotInverse:
            return "ScalingPivotInverse";
        case TransformationComp_GeometricScaling:
            return "GeometricScaling";
        case TransformationComp_GeometricRotation:
            return "GeometricRotation";
        case TransformationComp_GeometricTranslation:
            return "GeometricTranslation";
        case TransformationComp_GeometricScalingInverse:
            return "GeometricScalingInverse";
        case TransformationComp_GeometricRotationInverse:
            return "GeometricRotationInverse";
        case TransformationComp_GeometricTranslationInverse:
            return "GeometricTranslationInverse";
        case TransformationComp_MAXIMUM: // this is to silence compiler warnings
            break;
    }

    ai_assert(false);

    return nullptr;
}

aiVector3D FBXConverter::TransformationCompDefaultValue(TransformationComp comp) {
    // XXX a neat way to solve the never-ending special cases for scaling
    // would be to do everything in log space!
    return comp == TransformationComp_Scaling ? aiVector3D(1.f, 1.f, 1.f) : aiVector3D();
}

void FBXConverter::GetRotationMatrix(Model::RotOrder mode, const aiVector3D &rotation, aiMatrix4x4 &out) {
    if (mode == Model::RotOrder_SphericXYZ) {
        FBXImporter::LogError("Unsupported RotationMode: SphericXYZ");
        out = aiMatrix4x4();
        return;
    }

    const float angle_epsilon = Math::getEpsilon<float>();

    out = aiMatrix4x4();

    bool is_id[3] = { true, true, true };

    aiMatrix4x4 temp[3];
    const auto rot = AI_DEG_TO_RAD(rotation);
    if (std::fabs(rot.z) > angle_epsilon) {
        aiMatrix4x4::RotationZ(rot.z, temp[2]);
        is_id[2] = false;
    }
    if (std::fabs(rot.y) > angle_epsilon) {
        aiMatrix4x4::RotationY(rot.y, temp[1]);
        is_id[1] = false;
    }
    if (std::fabs(rot.x) > angle_epsilon) {
        aiMatrix4x4::RotationX(rot.x, temp[0]);
        is_id[0] = false;
    }

    int order[3] = { -1, -1, -1 };

    // note: rotation order is inverted since we're left multiplying as is usual in assimp
    switch (mode) {
        case Model::RotOrder_EulerXYZ:
            order[0] = 2;
            order[1] = 1;
            order[2] = 0;
            break;

        case Model::RotOrder_EulerXZY:
            order[0] = 1;
            order[1] = 2;
            order[2] = 0;
            break;

        case Model::RotOrder_EulerYZX:
            order[0] = 0;
            order[1] = 2;
            order[2] = 1;
            break;

        case Model::RotOrder_EulerYXZ:
            order[0] = 2;
            order[1] = 0;
            order[2] = 1;
            break;

        case Model::RotOrder_EulerZXY:
            order[0] = 1;
            order[1] = 0;
            order[2] = 2;
            break;

        case Model::RotOrder_EulerZYX:
            order[0] = 0;
            order[1] = 1;
            order[2] = 2;
            break;

        default:
            ai_assert(false);
            break;
    }

    ai_assert(order[0] >= 0);
    ai_assert(order[0] <= 2);
    ai_assert(order[1] >= 0);
    ai_assert(order[1] <= 2);
    ai_assert(order[2] >= 0);
    ai_assert(order[2] <= 2);

    if (!is_id[order[0]]) {
        out = temp[order[0]];
    }

    if (!is_id[order[1]]) {
        out = out * temp[order[1]];
    }

    if (!is_id[order[2]]) {
        out = out * temp[order[2]];
    }
}

bool FBXConverter::NeedsComplexTransformationChain(const Model &model) {
    const PropertyTable &props = model.Props();

    const auto zero_epsilon = Math::getEpsilon<ai_real>();
    const aiVector3D all_ones(1.0f, 1.0f, 1.0f);
    for (size_t i = 0; i < TransformationComp_MAXIMUM; ++i) {
        const TransformationComp comp = static_cast<TransformationComp>(i);

        if (comp == TransformationComp_Rotation || comp == TransformationComp_Scaling || comp == TransformationComp_Translation ||
            comp == TransformationComp_PreRotation || comp == TransformationComp_PostRotation) {
            continue;
        }

        bool scale_compare = (comp == TransformationComp_GeometricScaling || comp == TransformationComp_Scaling);

        bool ok = true;
        const aiVector3D &v = PropertyGet<aiVector3D>(props, NameTransformationCompProperty(comp), ok);
        if (ok && scale_compare) {
            if ((v - all_ones).SquareLength() > zero_epsilon) {
                return true;
            }
        } else if (ok) {
            if (v.SquareLength() > zero_epsilon) {
                return true;
            }
        }
    }

    return false;
}

std::string FBXConverter::NameTransformationChainNode(const std::string &name, TransformationComp comp) {
    return name + std::string(MAGIC_NODE_TAG) + "_" + NameTransformationComp(comp);
}

bool FBXConverter::GenerateTransformationNodeChain(const Model &model, const std::string &name, std::vector<PotentialNode> &output_nodes,
        std::vector<PotentialNode> &post_output_nodes) {
    const PropertyTable &props = model.Props();
    const Model::RotOrder rot = model.RotationOrder();

    bool ok;

    aiMatrix4x4 chain[TransformationComp_MAXIMUM];

    ai_assert(TransformationComp_MAXIMUM < 32);
    std::uint32_t chainBits = 0;
    // A node won't need a node chain if it only has these.
    const std::uint32_t chainMaskSimple = (1 << TransformationComp_Translation) + (1 << TransformationComp_Scaling) + (1 << TransformationComp_Rotation);
    // A node will need a node chain if it has any of these.
    const std::uint32_t chainMaskComplex = ((1 << (TransformationComp_MAXIMUM)) - 1) - chainMaskSimple;

    std::fill_n(chain, static_cast<unsigned int>(TransformationComp_MAXIMUM), aiMatrix4x4());

    // generate transformation matrices for all the different transformation components
    const float zero_epsilon = Math::getEpsilon<float>();
    const aiVector3D all_ones(1.0f, 1.0f, 1.0f);

    const aiVector3D &PreRotation = PropertyGet<aiVector3D>(props, "PreRotation", ok);
    if (ok && PreRotation.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_PreRotation);

        GetRotationMatrix(Model::RotOrder::RotOrder_EulerXYZ, PreRotation, chain[TransformationComp_PreRotation]);
    }

    const aiVector3D &PostRotation = PropertyGet<aiVector3D>(props, "PostRotation", ok);
    if (ok && PostRotation.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_PostRotation);

        GetRotationMatrix(Model::RotOrder::RotOrder_EulerXYZ, PostRotation, chain[TransformationComp_PostRotation]);
    }

    const aiVector3D &RotationPivot = PropertyGet<aiVector3D>(props, "RotationPivot", ok);
    if (ok && RotationPivot.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_RotationPivot) | (1 << TransformationComp_RotationPivotInverse);

        aiMatrix4x4::Translation(RotationPivot, chain[TransformationComp_RotationPivot]);
        aiMatrix4x4::Translation(-RotationPivot, chain[TransformationComp_RotationPivotInverse]);
    }

    const aiVector3D &RotationOffset = PropertyGet<aiVector3D>(props, "RotationOffset", ok);
    if (ok && RotationOffset.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_RotationOffset);

        aiMatrix4x4::Translation(RotationOffset, chain[TransformationComp_RotationOffset]);
    }

    const aiVector3D &ScalingOffset = PropertyGet<aiVector3D>(props, "ScalingOffset", ok);
    if (ok && ScalingOffset.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_ScalingOffset);

        aiMatrix4x4::Translation(ScalingOffset, chain[TransformationComp_ScalingOffset]);
    }

    const aiVector3D &ScalingPivot = PropertyGet<aiVector3D>(props, "ScalingPivot", ok);
    if (ok && ScalingPivot.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_ScalingPivot) | (1 << TransformationComp_ScalingPivotInverse);

        aiMatrix4x4::Translation(ScalingPivot, chain[TransformationComp_ScalingPivot]);
        aiMatrix4x4::Translation(-ScalingPivot, chain[TransformationComp_ScalingPivotInverse]);
    }

    const aiVector3D &Translation = PropertyGet<aiVector3D>(props, "Lcl Translation", ok);
    if (ok && Translation.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_Translation);

        aiMatrix4x4::Translation(Translation, chain[TransformationComp_Translation]);
    }

    const aiVector3D &Scaling = PropertyGet<aiVector3D>(props, "Lcl Scaling", ok);
    if (ok && (Scaling - all_ones).SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_Scaling);

        aiMatrix4x4::Scaling(Scaling, chain[TransformationComp_Scaling]);
    }

    const aiVector3D &Rotation = PropertyGet<aiVector3D>(props, "Lcl Rotation", ok);
    if (ok && Rotation.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_Rotation);

        GetRotationMatrix(rot, Rotation, chain[TransformationComp_Rotation]);
    }

    const aiVector3D &GeometricScaling = PropertyGet<aiVector3D>(props, "GeometricScaling", ok);
    if (ok && (GeometricScaling - all_ones).SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_GeometricScaling);
        aiMatrix4x4::Scaling(GeometricScaling, chain[TransformationComp_GeometricScaling]);
        aiVector3D GeometricScalingInverse = GeometricScaling;
        bool canscale = true;
        for (unsigned int i = 0; i < 3; ++i) {
            if (std::fabs(GeometricScalingInverse[i]) > zero_epsilon) {
                GeometricScalingInverse[i] = 1.0f / GeometricScaling[i];
            } else {
                FBXImporter::LogError("cannot invert geometric scaling matrix with a 0.0 scale component");
                canscale = false;
                break;
            }
        }
        if (canscale) {
            chainBits = chainBits | (1 << TransformationComp_GeometricScalingInverse);
            aiMatrix4x4::Scaling(GeometricScalingInverse, chain[TransformationComp_GeometricScalingInverse]);
        }
    }

    const aiVector3D &GeometricRotation = PropertyGet<aiVector3D>(props, "GeometricRotation", ok);
    if (ok && GeometricRotation.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_GeometricRotation) | (1 << TransformationComp_GeometricRotationInverse);
        GetRotationMatrix(rot, GeometricRotation, chain[TransformationComp_GeometricRotation]);
        GetRotationMatrix(rot, GeometricRotation, chain[TransformationComp_GeometricRotationInverse]);
        chain[TransformationComp_GeometricRotationInverse].Inverse();
    }

    const aiVector3D &GeometricTranslation = PropertyGet<aiVector3D>(props, "GeometricTranslation", ok);
    if (ok && GeometricTranslation.SquareLength() > zero_epsilon) {
        chainBits = chainBits | (1 << TransformationComp_GeometricTranslation) | (1 << TransformationComp_GeometricTranslationInverse);
        aiMatrix4x4::Translation(GeometricTranslation, chain[TransformationComp_GeometricTranslation]);
        aiMatrix4x4::Translation(-GeometricTranslation, chain[TransformationComp_GeometricTranslationInverse]);
    }

    // now, if we have more than just Translation, Scaling and Rotation,
    // we need to generate a full node chain to accommodate for assimp's
    // lack to express pivots and offsets.
    if ((chainBits & chainMaskComplex) && doc.Settings().preservePivots) {
        FBXImporter::LogInfo("generating full transformation chain for node: ", name);

        // query the anim_chain_bits dictionary to find out which chain elements
        // have associated node animation channels. These can not be dropped
        // even if they have identity transform in bind pose.
        NodeAnimBitMap::const_iterator it = node_anim_chain_bits.find(name);
        const unsigned int anim_chain_bitmask = (it == node_anim_chain_bits.end() ? 0 : (*it).second);

        unsigned int bit = 0x1;
        for (size_t i = 0; i < TransformationComp_MAXIMUM; ++i, bit <<= 1) {
            const TransformationComp comp = static_cast<TransformationComp>(i);

            if ((chainBits & bit) == 0 && (anim_chain_bitmask & bit) == 0) {
                continue;
            }

            if (comp == TransformationComp_PostRotation) {
                chain[i] = chain[i].Inverse();
            }

            PotentialNode nd;
            nd->mName.Set(NameTransformationChainNode(name, comp));
            nd->mTransformation = chain[i];

            // geometric inverses go in a post-node chain
            if (comp == TransformationComp_GeometricScalingInverse ||
                    comp == TransformationComp_GeometricRotationInverse ||
                    comp == TransformationComp_GeometricTranslationInverse) {
                post_output_nodes.emplace_back(std::move(nd));
            } else {
                output_nodes.emplace_back(std::move(nd));
            }
        }

        ai_assert(output_nodes.size());
        return true;
    }

    // else, we can just multiply the matrices together
    PotentialNode nd;

    // name passed to the method is already unique
    nd->mName.Set(name);
    // for (const auto &transform : chain) {
    // skip inverse chain for no preservePivots
    for (unsigned int i = TransformationComp_Translation; i < TransformationComp_MAXIMUM; i++) {
      nd->mTransformation = nd->mTransformation * chain[i];
    }
    output_nodes.push_back(std::move(nd));
    return false;
}

void FBXConverter::SetupNodeMetadata(const Model &model, aiNode &nd) {
    const PropertyTable &props = model.Props();
    DirectPropertyMap unparsedProperties = props.GetUnparsedProperties();

    // create metadata on node
    const std::size_t numStaticMetaData = 2;
    aiMetadata *data = aiMetadata::Alloc(static_cast<unsigned int>(unparsedProperties.size() + numStaticMetaData));
    nd.mMetaData = data;
    int index = 0;

    // find user defined properties (3ds Max)
    data->Set(index++, "UserProperties", aiString(PropertyGet<std::string>(props, "UDP3DSMAX", "")));
    // preserve the info that a node was marked as Null node in the original file.
    data->Set(index++, "IsNull", model.IsNull() ? true : false);

    // add unparsed properties to the node's metadata
    for (const DirectPropertyMap::value_type &prop : unparsedProperties) {
        // Interpret the property as a concrete type
        if (const TypedProperty<bool> *interpretedBool = prop.second->As<TypedProperty<bool>>()) {
            data->Set(index++, prop.first, interpretedBool->Value());
        } else if (const TypedProperty<int> *interpretedInt = prop.second->As<TypedProperty<int>>()) {
            data->Set(index++, prop.first, interpretedInt->Value());
        } else if (const TypedProperty<uint32_t> *interpretedUInt = prop.second->As<TypedProperty<uint32_t>>()) {
            data->Set(index++, prop.first, interpretedUInt->Value());
        } else if (const TypedProperty<uint64_t> *interpretedUint64 = prop.second->As<TypedProperty<uint64_t>>()) {
            data->Set(index++, prop.first, interpretedUint64->Value());
        } else if (const TypedProperty<int64_t> *interpretedint64 = prop.second->As<TypedProperty<int64_t>>()) {
            data->Set(index++, prop.first, interpretedint64->Value());
        } else if (const TypedProperty<float> *interpretedFloat = prop.second->As<TypedProperty<float>>()) {
            data->Set(index++, prop.first, interpretedFloat->Value());
        } else if (const TypedProperty<std::string> *interpretedString = prop.second->As<TypedProperty<std::string>>()) {
            data->Set(index++, prop.first, aiString(interpretedString->Value()));
        } else if (const TypedProperty<aiVector3D> *interpretedVec3 = prop.second->As<TypedProperty<aiVector3D>>()) {
            data->Set(index++, prop.first, interpretedVec3->Value());
        } else {
            ai_assert(false);
        }
    }
}

void FBXConverter::ConvertModel(const Model &model, aiNode *parent, aiNode *root_node, const aiMatrix4x4 &absolute_transform) {
    const std::vector<const Geometry *> &geos = model.GetGeometry();

    std::vector<unsigned int> meshes;
    meshes.reserve(geos.size());

    for (const Geometry *geo : geos) {
        const MeshGeometry *const mesh = dynamic_cast<const MeshGeometry *>(geo);
        const LineGeometry *const line = dynamic_cast<const LineGeometry *>(geo);
        if (mesh) {
            const std::vector<unsigned int> &indices = ConvertMesh(*mesh, model, parent, root_node, absolute_transform);
            std::copy(indices.begin(), indices.end(), std::back_inserter(meshes));
        } else if (line) {
            const std::vector<unsigned int> &indices = ConvertLine(*line, root_node);
            std::copy(indices.begin(), indices.end(), std::back_inserter(meshes));
        } else if (geo) {
            FBXImporter::LogWarn("ignoring unrecognized geometry: ", geo->Name());
        } else {
            FBXImporter::LogWarn("skipping null geometry");
        }
    }

    if (meshes.size()) {
        parent->mMeshes = new unsigned int[meshes.size()]();
        parent->mNumMeshes = static_cast<unsigned int>(meshes.size());

        std::swap_ranges(meshes.begin(), meshes.end(), parent->mMeshes);
    }
}

std::vector<unsigned int>
FBXConverter::ConvertMesh(const MeshGeometry &mesh, const Model &model, aiNode *parent, aiNode *root_node, const aiMatrix4x4 &absolute_transform) {
    std::vector<unsigned int> temp;

    MeshMap::const_iterator it = meshes_converted.find(&mesh);
    if (it != meshes_converted.end()) {
        std::copy((*it).second.begin(), (*it).second.end(), std::back_inserter(temp));
        return temp;
    }

    const std::vector<aiVector3D> &vertices = mesh.GetVertices();
    const std::vector<unsigned int> &faces = mesh.GetFaceIndexCounts();
    if (vertices.empty() || faces.empty()) {
        FBXImporter::LogWarn("ignoring empty geometry: ", mesh.Name());
        return temp;
    }

    // one material per mesh maps easily to aiMesh. Multiple material
    // meshes need to be split.
    const MatIndexArray &mindices = mesh.GetMaterialIndices();
    if (doc.Settings().readMaterials && !mindices.empty()) {
        const MatIndexArray::value_type base = mindices[0];
        for (MatIndexArray::value_type index : mindices) {
            if (index != base) {
                return ConvertMeshMultiMaterial(mesh, model, absolute_transform, parent, root_node);
            }
        }
    }

    // faster code-path, just copy the data
    temp.push_back(ConvertMeshSingleMaterial(mesh, model, absolute_transform, parent, root_node));
    return temp;
}

std::vector<unsigned int> FBXConverter::ConvertLine(const LineGeometry &line, aiNode *root_node) {
    std::vector<unsigned int> temp;

    const std::vector<aiVector3D> &vertices = line.GetVertices();
    const std::vector<int> &indices = line.GetIndices();
    if (vertices.empty() || indices.empty()) {
        FBXImporter::LogWarn("ignoring empty line: ", line.Name());
        return temp;
    }

    aiMesh *const out_mesh = SetupEmptyMesh(line, root_node);
    out_mesh->mPrimitiveTypes |= aiPrimitiveType_LINE;

    // copy vertices
    out_mesh->mNumVertices = static_cast<unsigned int>(vertices.size());
    out_mesh->mVertices = new aiVector3D[out_mesh->mNumVertices];
    std::copy(vertices.begin(), vertices.end(), out_mesh->mVertices);

    //Number of line segments (faces) is "Number of Points - Number of Endpoints"
    //N.B.: Endpoints in FbxLine are denoted by negative indices.
    //If such an Index is encountered, add 1 and multiply by -1 to get the real index.
    unsigned int epcount = 0;
    for (unsigned i = 0; i < indices.size(); i++) {
        if (indices[i] < 0) {
            epcount++;
        }
    }
    unsigned int pcount = static_cast<unsigned int>(indices.size());
    unsigned int scount = out_mesh->mNumFaces = pcount - epcount;

    aiFace *fac = out_mesh->mFaces = new aiFace[scount]();
    for (unsigned int i = 0; i < pcount; ++i) {
        if (indices[i] < 0) continue;
        aiFace &f = *fac++;
        f.mNumIndices = 2; //2 == aiPrimitiveType_LINE
        f.mIndices = new unsigned int[2];
        f.mIndices[0] = indices[i];
        int segid = indices[(i + 1 == pcount ? 0 : i + 1)]; //If we have reached he last point, wrap around
        f.mIndices[1] = (segid < 0 ? (segid + 1) * -1 : segid); //Convert EndPoint Index to normal Index
    }
    temp.push_back(static_cast<unsigned int>(mMeshes.size() - 1));
    return temp;
}

aiMesh *FBXConverter::SetupEmptyMesh(const Geometry &mesh, aiNode *parent) {
    aiMesh *const out_mesh = new aiMesh();
    mMeshes.push_back(out_mesh);
    meshes_converted[&mesh].push_back(static_cast<unsigned int>(mMeshes.size() - 1));

    // set name
    std::string name = mesh.Name();
    if (name.substr(0, 10) == "Geometry::") {
        name = name.substr(10);
    }

    if (name.length()) {
        out_mesh->mName.Set(name);
    } else {
        out_mesh->mName = parent->mName;
    }

    return out_mesh;
}

static aiSkeleton *createAiSkeleton(SkeletonBoneContainer &sbc) {
    if (sbc.MeshArray.empty() || sbc.SkeletonBoneToMeshLookup.empty()) {
        return nullptr;
    }

    aiSkeleton *skeleton = new aiSkeleton;
    for (auto *mesh : sbc.MeshArray) {
        auto it = sbc.SkeletonBoneToMeshLookup.find(mesh);
        if (it == sbc.SkeletonBoneToMeshLookup.end()) {
            continue;
        }
        SkeletonBoneArray *ba = it->second;
        if (ba == nullptr) {
            continue;
        }

        skeleton->mNumBones = static_cast<unsigned int>(ba->size());
        skeleton->mBones = new aiSkeletonBone*[skeleton->mNumBones];
        size_t index = 0;
        for (auto bone : (* ba)) {
            skeleton->mBones[index] = bone;
            ++index;
        }
    }

    return skeleton;
}

unsigned int FBXConverter::ConvertMeshSingleMaterial(const MeshGeometry &mesh, const Model &model, const aiMatrix4x4 &absolute_transform,
        aiNode *parent, aiNode *) {
    const MatIndexArray &mindices = mesh.GetMaterialIndices();
    aiMesh *const out_mesh = SetupEmptyMesh(mesh, parent);

    const std::vector<aiVector3D> &vertices = mesh.GetVertices();
    const std::vector<unsigned int> &faces = mesh.GetFaceIndexCounts();

    // copy vertices
    out_mesh->mNumVertices = static_cast<unsigned int>(vertices.size());
    out_mesh->mVertices = new aiVector3D[vertices.size()];

    std::copy(vertices.begin(), vertices.end(), out_mesh->mVertices);

    // generate dummy faces
    out_mesh->mNumFaces = static_cast<unsigned int>(faces.size());
    aiFace *fac = out_mesh->mFaces = new aiFace[faces.size()]();

    unsigned int cursor = 0;
    for (unsigned int pcount : faces) {
        aiFace &f = *fac++;
        f.mNumIndices = pcount;
        f.mIndices = new unsigned int[pcount];
        switch (pcount) {
            case 1:
                out_mesh->mPrimitiveTypes |= aiPrimitiveType_POINT;
                break;
            case 2:
                out_mesh->mPrimitiveTypes |= aiPrimitiveType_LINE;
                break;
            case 3:
                out_mesh->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
                break;
            default:
                out_mesh->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
                break;
        }
        for (unsigned int i = 0; i < pcount; ++i) {
            f.mIndices[i] = cursor++;
        }
    }

    // copy normals
    const std::vector<aiVector3D> &normals = mesh.GetNormals();
    if (normals.size()) {
        ai_assert(normals.size() == vertices.size());

        out_mesh->mNormals = new aiVector3D[vertices.size()];
        std::copy(normals.begin(), normals.end(), out_mesh->mNormals);
    }

    // copy tangents - assimp requires both tangents and bitangents (binormals)
    // to be present, or neither of them. Compute binormals from normals
    // and tangents if needed.
    const std::vector<aiVector3D> &tangents = mesh.GetTangents();
    const std::vector<aiVector3D> *binormals = &mesh.GetBinormals();

    if (tangents.size()) {
        std::vector<aiVector3D> tempBinormals;
        if (!binormals->size()) {
            if (normals.size()) {
                tempBinormals.resize(normals.size());
                for (unsigned int i = 0; i < tangents.size(); ++i) {
                    tempBinormals[i] = normals[i] ^ tangents[i];
                }

                binormals = &tempBinormals;
            } else {
                binormals = nullptr;
            }
        }

        if (binormals) {
            ai_assert(tangents.size() == vertices.size());
            ai_assert(binormals->size() == vertices.size());

            out_mesh->mTangents = new aiVector3D[vertices.size()];
            std::copy(tangents.begin(), tangents.end(), out_mesh->mTangents);

            out_mesh->mBitangents = new aiVector3D[vertices.size()];
            std::copy(binormals->begin(), binormals->end(), out_mesh->mBitangents);
        }
    }

    // copy texture coords
    for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i) {
        const std::vector<aiVector2D> &uvs = mesh.GetTextureCoords(i);
        if (uvs.empty()) {
            break;
        }

        aiVector3D *out_uv = out_mesh->mTextureCoords[i] = new aiVector3D[vertices.size()];
        for (const aiVector2D &v : uvs) {
            *out_uv++ = aiVector3D(v.x, v.y, 0.0f);
        }

        out_mesh->SetTextureCoordsName(i, aiString(mesh.GetTextureCoordChannelName(i)));

        out_mesh->mNumUVComponents[i] = 2;
    }

    // copy vertex colors
    for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_COLOR_SETS; ++i) {
        const std::vector<aiColor4D> &colors = mesh.GetVertexColors(i);
        if (colors.empty()) {
            break;
        }

        out_mesh->mColors[i] = new aiColor4D[vertices.size()];
        std::copy(colors.begin(), colors.end(), out_mesh->mColors[i]);
    }

    if (!doc.Settings().readMaterials || mindices.empty()) {
        FBXImporter::LogError("no material assigned to mesh, setting default material");
        out_mesh->mMaterialIndex = GetDefaultMaterial();
    } else {
        ConvertMaterialForMesh(out_mesh, model, mesh, mindices[0]);
    }

    if (doc.Settings().readWeights && mesh.DeformerSkin() != nullptr && !doc.Settings().useSkeleton) {
        ConvertWeights(out_mesh, mesh, absolute_transform, parent, NO_MATERIAL_SEPARATION, nullptr);
    } else if (doc.Settings().readWeights && mesh.DeformerSkin() != nullptr && doc.Settings().useSkeleton) {
        SkeletonBoneContainer sbc;
        ConvertWeightsToSkeleton(out_mesh, mesh, absolute_transform, parent, NO_MATERIAL_SEPARATION, nullptr, sbc);
        aiSkeleton *skeleton = createAiSkeleton(sbc);
        if (skeleton != nullptr) {
            mSkeletons.emplace_back(skeleton);
        }
    }

    std::vector<aiAnimMesh *> animMeshes;
    for (const BlendShape *blendShape : mesh.GetBlendShapes()) {
        for (const BlendShapeChannel *blendShapeChannel : blendShape->BlendShapeChannels()) {
            const auto& shapeGeometries = blendShapeChannel->GetShapeGeometries();
            for (const ShapeGeometry *shapeGeometry : shapeGeometries) {
                aiAnimMesh *animMesh = aiCreateAnimMesh(out_mesh);
                const auto &curVertices = shapeGeometry->GetVertices();
                const auto &curNormals = shapeGeometry->GetNormals();
                const auto &curIndices = shapeGeometry->GetIndices();
                //losing channel name if using shapeGeometry->Name()
                // if blendShapeChannel Name is empty or doesn't have a ".", add geoMetryName;
                auto aniName = FixAnimMeshName(blendShapeChannel->Name());
                auto geoMetryName = FixAnimMeshName(shapeGeometry->Name());
                if (aniName.empty()) {
                    aniName = geoMetryName;
                }
                else if (aniName.find('.') == aniName.npos) {
                    aniName += "." + geoMetryName;
                }
                animMesh->mName.Set(aniName);
                for (size_t j = 0; j < curIndices.size(); j++) {
                    const unsigned int curIndex = curIndices.at(j);
                    aiVector3D vertex = curVertices.at(j);
                    aiVector3D normal = curNormals.at(j);
                    unsigned int count = 0;
                    const unsigned int *outIndices = mesh.ToOutputVertexIndex(curIndex, count);
                    for (unsigned int k = 0; k < count; k++) {
                        unsigned int index = outIndices[k];
                        animMesh->mVertices[index] += vertex;
                        if (animMesh->mNormals != nullptr) {
                            animMesh->mNormals[index] += normal;
                            animMesh->mNormals[index].NormalizeSafe();
                        }
                    }
                }
                animMesh->mWeight = shapeGeometries.size() > 1 ? blendShapeChannel->DeformPercent() / 100.0f : 1.0f;
                animMeshes.push_back(animMesh);
            }
        }
    }
    const size_t numAnimMeshes = animMeshes.size();
    if (numAnimMeshes > 0) {
        out_mesh->mNumAnimMeshes = static_cast<unsigned int>(numAnimMeshes);
        out_mesh->mAnimMeshes = new aiAnimMesh *[numAnimMeshes];
        for (size_t i = 0; i < numAnimMeshes; i++) {
            out_mesh->mAnimMeshes[i] = animMeshes.at(i);
        }
    }
    return static_cast<unsigned int>(mMeshes.size() - 1);
}

std::vector<unsigned int>
FBXConverter::ConvertMeshMultiMaterial(const MeshGeometry &mesh, const Model &model, const aiMatrix4x4 &absolute_transform, aiNode *parent,
        aiNode *root_node) {
    const MatIndexArray &mindices = mesh.GetMaterialIndices();
    ai_assert(mindices.size());

    std::set<MatIndexArray::value_type> had;
    std::vector<unsigned int> indices;

    for (MatIndexArray::value_type index : mindices) {
        if (had.find(index) == had.end()) {

            indices.push_back(ConvertMeshMultiMaterial(mesh, model, absolute_transform, index, parent, root_node));
            had.insert(index);
        }
    }

    return indices;
}

unsigned int FBXConverter::ConvertMeshMultiMaterial(const MeshGeometry &mesh, const Model &model, const aiMatrix4x4 &absolute_transform,
        MatIndexArray::value_type index, aiNode *parent, aiNode *) {
    aiMesh *const out_mesh = SetupEmptyMesh(mesh, parent);

    const MatIndexArray &mindices = mesh.GetMaterialIndices();
    const std::vector<aiVector3D> &vertices = mesh.GetVertices();
    const std::vector<unsigned int> &faces = mesh.GetFaceIndexCounts();

    const bool process_weights = doc.Settings().readWeights && mesh.DeformerSkin() != nullptr;

    unsigned int count_faces = 0;
    unsigned int count_vertices = 0;

    // count faces
    std::vector<unsigned int>::const_iterator itf = faces.begin();
    for (MatIndexArray::const_iterator it = mindices.begin(),
                                       end = mindices.end();
            it != end; ++it, ++itf) {
        if ((*it) != index) {
            continue;
        }
        ++count_faces;
        count_vertices += *itf;
    }

    ai_assert(count_faces);
    ai_assert(count_vertices);

    // mapping from output indices to DOM indexing, needed to resolve weights or blendshapes
    std::vector<unsigned int> reverseMapping;
    std::map<unsigned int, unsigned int> translateIndexMap;
    if (process_weights || mesh.GetBlendShapes().size() > 0) {
        reverseMapping.resize(count_vertices);
    }

    // allocate output data arrays, but don't fill them yet
    out_mesh->mNumVertices = count_vertices;
    out_mesh->mVertices = new aiVector3D[count_vertices];

    out_mesh->mNumFaces = count_faces;
    aiFace *fac = out_mesh->mFaces = new aiFace[count_faces]();

    // allocate normals
    const std::vector<aiVector3D> &normals = mesh.GetNormals();
    if (normals.size()) {
        ai_assert(normals.size() == vertices.size());
        out_mesh->mNormals = new aiVector3D[count_vertices];
    }

    // allocate tangents, binormals.
    const std::vector<aiVector3D> &tangents = mesh.GetTangents();
    const std::vector<aiVector3D> *binormals = &mesh.GetBinormals();
    std::vector<aiVector3D> tempBinormals;

    if (tangents.size()) {
        if (!binormals->size()) {
            if (normals.size()) {
                // XXX this computes the binormals for the entire mesh, not only
                // the part for which we need them.
                tempBinormals.resize(normals.size());
                for (unsigned int i = 0; i < tangents.size(); ++i) {
                    tempBinormals[i] = normals[i] ^ tangents[i];
                }

                binormals = &tempBinormals;
            } else {
                binormals = nullptr;
            }
        }

        if (binormals) {
            ai_assert(tangents.size() == vertices.size());
            ai_assert(binormals->size() == vertices.size());

            out_mesh->mTangents = new aiVector3D[count_vertices];
            out_mesh->mBitangents = new aiVector3D[count_vertices];
        }
    }

    // allocate texture coords
    unsigned int num_uvs = 0;
    for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i, ++num_uvs) {
        const std::vector<aiVector2D> &uvs = mesh.GetTextureCoords(i);
        if (uvs.empty()) {
            break;
        }

        out_mesh->mTextureCoords[i] = new aiVector3D[count_vertices];
        out_mesh->mNumUVComponents[i] = 2;
    }

    // allocate vertex colors
    unsigned int num_vcs = 0;
    for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_COLOR_SETS; ++i, ++num_vcs) {
        const std::vector<aiColor4D> &colors = mesh.GetVertexColors(i);
        if (colors.empty()) {
            break;
        }

        out_mesh->mColors[i] = new aiColor4D[count_vertices];
    }

    unsigned int cursor = 0, in_cursor = 0;

    itf = faces.begin();
    for (MatIndexArray::const_iterator it = mindices.begin(), end = mindices.end(); it != end; ++it, ++itf) {
        const unsigned int pcount = *itf;
        if ((*it) != index) {
            in_cursor += pcount;
            continue;
        }

        aiFace &f = *fac++;

        f.mNumIndices = pcount;
        f.mIndices = new unsigned int[pcount];
        switch (pcount) {
            case 1:
                out_mesh->mPrimitiveTypes |= aiPrimitiveType_POINT;
                break;
            case 2:
                out_mesh->mPrimitiveTypes |= aiPrimitiveType_LINE;
                break;
            case 3:
                out_mesh->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
                break;
            default:
                out_mesh->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
                break;
        }
        for (unsigned int i = 0; i < pcount; ++i, ++cursor, ++in_cursor) {
            f.mIndices[i] = cursor;

            if (reverseMapping.size()) {
                reverseMapping[cursor] = in_cursor;
                translateIndexMap[in_cursor] = cursor;
            }

            out_mesh->mVertices[cursor] = vertices[in_cursor];

            if (out_mesh->mNormals) {
                out_mesh->mNormals[cursor] = normals[in_cursor];
            }

            if (out_mesh->mTangents) {
                out_mesh->mTangents[cursor] = tangents[in_cursor];
                out_mesh->mBitangents[cursor] = (*binormals)[in_cursor];
            }

            for (unsigned int j = 0; j < num_uvs; ++j) {
                const std::vector<aiVector2D> &uvs = mesh.GetTextureCoords(j);
                out_mesh->mTextureCoords[j][cursor] = aiVector3D(uvs[in_cursor].x, uvs[in_cursor].y, 0.0f);
            }

            for (unsigned int j = 0; j < num_vcs; ++j) {
                const std::vector<aiColor4D> &cols = mesh.GetVertexColors(j);
                out_mesh->mColors[j][cursor] = cols[in_cursor];
            }
        }
    }

    ConvertMaterialForMesh(out_mesh, model, mesh, index);

    if (process_weights) {
        ConvertWeights(out_mesh, mesh, absolute_transform, parent, index, &reverseMapping);
    }

    std::vector<aiAnimMesh *> animMeshes;
    for (const BlendShape *blendShape : mesh.GetBlendShapes()) {
        for (const BlendShapeChannel *blendShapeChannel : blendShape->BlendShapeChannels()) {
            const auto& shapeGeometries = blendShapeChannel->GetShapeGeometries();
            for (const ShapeGeometry *shapeGeometry : shapeGeometries) {
                aiAnimMesh *animMesh = aiCreateAnimMesh(out_mesh);
                const auto& curVertices = shapeGeometry->GetVertices();
                const auto& curNormals = shapeGeometry->GetNormals();
                const auto& curIndices = shapeGeometry->GetIndices();
                animMesh->mName.Set(FixAnimMeshName(shapeGeometry->Name()));
                for (size_t j = 0; j < curIndices.size(); j++) {
                    unsigned int curIndex = curIndices.at(j);
                    aiVector3D vertex = curVertices.at(j);
                    aiVector3D normal = curNormals.at(j);
                    unsigned int count = 0;
                    const unsigned int *outIndices = mesh.ToOutputVertexIndex(curIndex, count);
                    for (unsigned int k = 0; k < count; k++) {
                        unsigned int outIndex = outIndices[k];
                        if (translateIndexMap.find(outIndex) == translateIndexMap.end())
                            continue;
                        unsigned int transIndex = translateIndexMap[outIndex];
                        animMesh->mVertices[transIndex] += vertex;
                        if (animMesh->mNormals != nullptr) {
                            animMesh->mNormals[transIndex] += normal;
                            animMesh->mNormals[transIndex].NormalizeSafe();
                        }
                    }
                }
                animMesh->mWeight = shapeGeometries.size() > 1 ? blendShapeChannel->DeformPercent() / 100.0f : 1.0f;
                animMeshes.push_back(animMesh);
            }
        }
    }

    const size_t numAnimMeshes = animMeshes.size();
    if (numAnimMeshes > 0) {
        out_mesh->mNumAnimMeshes = static_cast<unsigned int>(numAnimMeshes);
        out_mesh->mAnimMeshes = new aiAnimMesh *[numAnimMeshes];
        for (size_t i = 0; i < numAnimMeshes; i++) {
            out_mesh->mAnimMeshes[i] = animMeshes.at(i);
        }
    }

    return static_cast<unsigned int>(mMeshes.size() - 1);
}

static void copyBoneToSkeletonBone(aiMesh *mesh, aiBone *bone, aiSkeletonBone *skeletonBone ) {
    skeletonBone->mNumnWeights = bone->mNumWeights;
    skeletonBone->mWeights = bone->mWeights;
    skeletonBone->mOffsetMatrix = bone->mOffsetMatrix;
    skeletonBone->mMeshId = mesh;
#ifndef ASSIMP_BUILD_NO_ARMATUREPOPULATE_PROCESS
    skeletonBone->mNode = bone->mNode;
#endif
    skeletonBone->mParent = -1;
}

void FBXConverter::ConvertWeightsToSkeleton(aiMesh *out, const MeshGeometry &geo, const aiMatrix4x4 &absolute_transform, aiNode *parent, unsigned int materialIndex,
        std::vector<unsigned int> *outputVertStartIndices, SkeletonBoneContainer &skeletonContainer) {

    if (skeletonContainer.SkeletonBoneToMeshLookup.find(out) != skeletonContainer.SkeletonBoneToMeshLookup.end()) {
        return;
    }

    ConvertWeights(out, geo, absolute_transform, parent, materialIndex, outputVertStartIndices);
    skeletonContainer.MeshArray.emplace_back(out);
    SkeletonBoneArray *ba = new SkeletonBoneArray;
    for (size_t i = 0; i < out->mNumBones; ++i) {
        aiBone *bone = out->mBones[i];
        if (bone == nullptr) {
            continue;
        }
        aiSkeletonBone *skeletonBone = new aiSkeletonBone;
        copyBoneToSkeletonBone(out, bone, skeletonBone);
        ba->emplace_back(skeletonBone);
    }
    skeletonContainer.SkeletonBoneToMeshLookup[out] = ba;
}

void FBXConverter::ConvertWeights(aiMesh *out, const MeshGeometry &geo, const aiMatrix4x4 &absolute_transform,
        aiNode *parent, unsigned int materialIndex,
        std::vector<unsigned int> *outputVertStartIndices) {
    ai_assert(geo.DeformerSkin());

    std::vector<size_t> out_indices, index_out_indices, count_out_indices;

    const Skin &sk = *geo.DeformerSkin();

    std::vector<aiBone*> bones;
    const bool no_mat_check = materialIndex == NO_MATERIAL_SEPARATION;
    ai_assert(no_mat_check || outputVertStartIndices);

    try {
        // iterate over the sub deformers
        for (const Cluster *cluster : sk.Clusters()) {
            ai_assert(cluster);

            const WeightIndexArray &indices = cluster->GetIndices();

            const MatIndexArray &mats = geo.GetMaterialIndices();

            const size_t no_index_sentinel = std::numeric_limits<size_t>::max();

            count_out_indices.clear();
            index_out_indices.clear();
            out_indices.clear();

            // now check if *any* of these weights is contained in the output mesh,
            // taking notes so we don't need to do it twice.
            for (WeightIndexArray::value_type index : indices) {

                unsigned int count = 0;
                const unsigned int *const out_idx = geo.ToOutputVertexIndex(index, count);
                // ToOutputVertexIndex only returns nullptr if index is out of bounds
                // which should never happen
                ai_assert(out_idx != nullptr);

                index_out_indices.push_back(no_index_sentinel);
                count_out_indices.push_back(0);

                for (unsigned int i = 0; i < count; ++i) {
                    if (no_mat_check || static_cast<size_t>(mats[geo.FaceForVertexIndex(out_idx[i])]) == materialIndex) {

                        if (index_out_indices.back() == no_index_sentinel) {
                            index_out_indices.back() = out_indices.size();
                        }

                        if (no_mat_check) {
                            out_indices.push_back(out_idx[i]);
                        } else {
                            // this extra lookup is in O(logn), so the entire algorithm becomes O(nlogn)
                            const std::vector<unsigned int>::iterator it = std::lower_bound(
                                    outputVertStartIndices->begin(),
                                    outputVertStartIndices->end(),
                                    out_idx[i]);

                            out_indices.push_back(std::distance(outputVertStartIndices->begin(), it));
                        }

                        ++count_out_indices.back();
                    }
                }
            }

            // if we found at least one, generate the output bones
            // XXX this could be heavily simplified by collecting the bone
            // data in a single step.
            ConvertCluster(bones, cluster, out_indices, index_out_indices,
                    count_out_indices, absolute_transform, parent);
        }

        bone_map.clear();
    } catch (std::exception &) {
        std::for_each(bones.begin(), bones.end(), Util::delete_fun<aiBone>());
        throw;
    }

    if (bones.empty()) {
        out->mBones = nullptr;
        out->mNumBones = 0;
        return;
    }

    out->mBones = new aiBone *[bones.size()]();
    out->mNumBones = static_cast<unsigned int>(bones.size());
    std::swap_ranges(bones.begin(), bones.end(), out->mBones);
}

void FBXConverter::ConvertCluster(std::vector<aiBone*> &local_mesh_bones, const Cluster *cluster,
        std::vector<size_t> &out_indices, std::vector<size_t> &index_out_indices,
        std::vector<size_t> &count_out_indices, const aiMatrix4x4 &absolute_transform,
        aiNode *) {
    ai_assert(cluster != nullptr); // make sure cluster valid

    std::string deformer_name = cluster->TargetNode()->Name();
    aiString bone_name = aiString(FixNodeName(deformer_name));

    aiBone *bone = nullptr;

    if (bone_map.count(deformer_name)) {
        ASSIMP_LOG_VERBOSE_DEBUG("retrieved bone from lookup ", bone_name.C_Str(), ". Deformer:", deformer_name);
        bone = bone_map[deformer_name];
    } else {
        ASSIMP_LOG_VERBOSE_DEBUG("created new bone ", bone_name.C_Str(), ". Deformer: ", deformer_name);
        bone = new aiBone();
        bone->mName = bone_name;

        //bone->mOffsetMatrix = cluster->Transform();
        // store local transform link for post processing
        
        bone->mOffsetMatrix = cluster->TransformLink();
        bone->mOffsetMatrix.Inverse();

        const aiMatrix4x4 matrix = (aiMatrix4x4)absolute_transform;

        bone->mOffsetMatrix = bone->mOffsetMatrix * matrix; // * mesh_offset
        
        //
        // Now calculate the aiVertexWeights
        //

        aiVertexWeight *cursor = nullptr;

        bone->mNumWeights = static_cast<unsigned int>(out_indices.size());
        cursor = bone->mWeights = new aiVertexWeight[out_indices.size()];

        const size_t no_index_sentinel = std::numeric_limits<size_t>::max();
        const WeightArray &weights = cluster->GetWeights();

        const size_t c = index_out_indices.size();
        for (size_t i = 0; i < c; ++i) {
            const size_t index_index = index_out_indices[i];

            if (index_index == no_index_sentinel) {
                continue;
            }

            const size_t cc = count_out_indices[i];
            for (size_t j = 0; j < cc; ++j) {
                // cursor runs from first element relative to the start
                // or relative to the start of the next indexes.
                aiVertexWeight &out_weight = *cursor++;

                out_weight.mVertexId = static_cast<unsigned int>(out_indices[index_index + j]);
                out_weight.mWeight = weights[i];
            }
        }

        bone_map.insert(std::pair<const std::string, aiBone *>(deformer_name, bone));
    }

    ASSIMP_LOG_DEBUG("bone research: Indices size: ", out_indices.size());

    // lookup must be populated in case something goes wrong
    // this also allocates bones to mesh instance outside
    local_mesh_bones.push_back(bone);
}

void FBXConverter::ConvertMaterialForMesh(aiMesh *out, const Model &model, const MeshGeometry &geo,
        MatIndexArray::value_type materialIndex) {
    // locate source materials for this mesh
    const std::vector<const Material *> &mats = model.GetMaterials();
    if (static_cast<unsigned int>(materialIndex) >= mats.size() || materialIndex < 0) {
        FBXImporter::LogError("material index out of bounds, setting default material");
        out->mMaterialIndex = GetDefaultMaterial();
        return;
    }

    const Material *const mat = mats[materialIndex];
    MaterialMap::const_iterator it = materials_converted.find(mat);
    if (it != materials_converted.end()) {
        out->mMaterialIndex = (*it).second;
        return;
    }

    out->mMaterialIndex = ConvertMaterial(*mat, &geo);
    materials_converted[mat] = out->mMaterialIndex;
}

unsigned int FBXConverter::GetDefaultMaterial() {
    if (defaultMaterialIndex) {
        return defaultMaterialIndex - 1;
    }

    aiMaterial *out_mat = new aiMaterial();
    materials.push_back(out_mat);

    const aiColor3D diffuse = aiColor3D(0.8f, 0.8f, 0.8f);
    out_mat->AddProperty(&diffuse, 1, AI_MATKEY_COLOR_DIFFUSE);

    aiString s;
    s.Set(AI_DEFAULT_MATERIAL_NAME);

    out_mat->AddProperty(&s, AI_MATKEY_NAME);

    defaultMaterialIndex = static_cast<unsigned int>(materials.size());
    return defaultMaterialIndex - 1;
}

unsigned int FBXConverter::ConvertMaterial(const Material &material, const MeshGeometry *const mesh) {
    const PropertyTable &props = material.Props();

    // generate empty output material
    aiMaterial *out_mat = new aiMaterial();
    materials_converted[&material] = static_cast<unsigned int>(materials.size());

    materials.push_back(out_mat);

    aiString str;

    // strip Material:: prefix
    std::string name = material.Name();
    if (name.substr(0, 10) == "Material::") {
        name = name.substr(10);
    }

    // set material name if not empty - this could happen
    // and there should be no key for it in this case.
    if (name.length()) {
        str.Set(name);
        out_mat->AddProperty(&str, AI_MATKEY_NAME);
    }

    // Set the shading mode as best we can: The FBX specification only mentions Lambert and Phong, and only Phong is mentioned in Assimp's aiShadingMode enum.
    if (material.GetShadingModel() == "phong") {
        aiShadingMode shadingMode = aiShadingMode_Phong;
        out_mat->AddProperty<aiShadingMode>(&shadingMode, 1, AI_MATKEY_SHADING_MODEL);
    }

    // shading stuff and colors
    SetShadingPropertiesCommon(out_mat, props);
    SetShadingPropertiesRaw(out_mat, props, material.Textures(), mesh);

    // texture assignments
    SetTextureProperties(out_mat, material.Textures(), mesh);
    SetTextureProperties(out_mat, material.LayeredTextures(), mesh);

    return static_cast<unsigned int>(materials.size() - 1);
}

unsigned int FBXConverter::ConvertVideo(const Video &video) {
    // generate empty output texture
    aiTexture *out_tex = new aiTexture();
    textures.push_back(out_tex);

    // assuming the texture is compressed
    out_tex->mWidth = static_cast<unsigned int>(video.ContentLength()); // total data size
    out_tex->mHeight = 0; // fixed to 0

    // steal the data from the Video to avoid an additional copy
    out_tex->pcData = reinterpret_cast<aiTexel *>(const_cast<Video &>(video).RelinquishContent());

    // try to extract a hint from the file extension
    const std::string &filename = video.RelativeFilename().empty() ? video.FileName() : video.RelativeFilename();
    std::string ext = BaseImporter::GetExtension(filename);

    if (ext == "jpeg") {
        ext = "jpg";
    }

    if (ext.size() <= 3) {
        memcpy(out_tex->achFormatHint, ext.c_str(), ext.size());
    }

    out_tex->mFilename.Set(filename.c_str());

    return static_cast<unsigned int>(textures.size() - 1);
}

aiString FBXConverter::GetTexturePath(const Texture *tex) {
    aiString path;
    path.Set(tex->RelativeFilename());

    const Video *media = tex->Media();
    if (media != nullptr) {
        bool textureReady = false; //tells if our texture is ready (if it was loaded or if it was found)
        unsigned int index=0;

        VideoMap::const_iterator it = textures_converted.find(media);
        if (it != textures_converted.end()) {
            index = (*it).second;
            textureReady = true;
        } else {
            if (media->ContentLength() > 0) {
                index = ConvertVideo(*media);
                textures_converted[media] = index;
                textureReady = true;
            }
        }

        // setup texture reference string (copied from ColladaLoader::FindFilenameForEffectTexture), if the texture is ready
        if (doc.Settings().useLegacyEmbeddedTextureNaming) {
            if (textureReady) {
                // TODO: check the possibility of using the flag "AI_CONFIG_IMPORT_FBX_EMBEDDED_TEXTURES_LEGACY_NAMING"
                // In FBX files textures are now stored internally by Assimp with their filename included
                // Now Assimp can lookup through the loaded textures after all data is processed
                // We need to load all textures before referencing them, as FBX file format order may reference a texture before loading it
                // This may occur on this case too, it has to be studied
                path.data[0] = '*';
                path.length = 1 + ASSIMP_itoa10(path.data + 1, AI_MAXLEN - 1, index);
            }
        }
    }

    return path;
}

void FBXConverter::TrySetTextureProperties(aiMaterial *out_mat, const TextureMap &_textures,
        const std::string &propName,
        aiTextureType target, const MeshGeometry *const mesh) {
    TextureMap::const_iterator it = _textures.find(propName);
    if (it == _textures.end()) {
        return;
    }

    const Texture *const tex = (*it).second;
    if (tex != nullptr) {
        aiString path = GetTexturePath(tex);
        out_mat->AddProperty(&path, _AI_MATKEY_TEXTURE_BASE, target, 0);

        aiUVTransform uvTrafo;
        // XXX handle all kinds of UV transformations
        uvTrafo.mScaling = tex->UVScaling();
        uvTrafo.mTranslation = tex->UVTranslation();
        uvTrafo.mRotation = tex->UVRotation();
        out_mat->AddProperty(&uvTrafo, 1, _AI_MATKEY_UVTRANSFORM_BASE, target, 0);

        const PropertyTable &props = tex->Props();

        int uvIndex = 0;

        bool ok;
        const std::string &uvSet = PropertyGet<std::string>(props, "UVSet", ok);
        if (ok) {
            // "default" is the name which usually appears in the FbxFileTexture template
            if (uvSet != "default" && uvSet.length()) {
                // this is a bit awkward - we need to find a mesh that uses this
                // material and scan its UV channels for the given UV name because
                // assimp references UV channels by index, not by name.

                // XXX: the case that UV channels may appear in different orders
                // in meshes is unhandled. A possible solution would be to sort
                // the UV channels alphabetically, but this would have the side
                // effect that the primary (first) UV channel would sometimes
                // be moved, causing trouble when users read only the first
                // UV channel and ignore UV channel assignments altogether.

                const unsigned int matIndex = static_cast<unsigned int>(std::distance(materials.begin(),
                        std::find(materials.begin(), materials.end(), out_mat)));

                uvIndex = -1;
                if (!mesh) {
                    for (const MeshMap::value_type &v : meshes_converted) {
                        const MeshGeometry *const meshGeom = dynamic_cast<const MeshGeometry *>(v.first);
                        if (!meshGeom) {
                            continue;
                        }

                        const MatIndexArray &mats = meshGeom->GetMaterialIndices();
                        MatIndexArray::const_iterator curIt = std::find(mats.begin(), mats.end(), (int) matIndex);
                        if (curIt == mats.end()) {
                            continue;
                        }

                        int index = -1;
                        for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i) {
                            if (meshGeom->GetTextureCoords(i).empty()) {
                                break;
                            }
                            const std::string &name = meshGeom->GetTextureCoordChannelName(i);
                            if (name == uvSet) {
                                index = static_cast<int>(i);
                                break;
                            }
                        }
                        if (index == -1) {
                            FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                            continue;
                        }

                        if (uvIndex == -1) {
                            uvIndex = index;
                        } else {
                            FBXImporter::LogWarn("the UV channel named ", uvSet,
                                                 " appears at different positions in meshes, results will be wrong");
                        }
                    }
                } else {
                    int index = -1;
                    for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i) {
                        if (mesh->GetTextureCoords(i).empty()) {
                            break;
                        }
                        const std::string &name = mesh->GetTextureCoordChannelName(i);
                        if (name == uvSet) {
                            index = static_cast<int>(i);
                            break;
                        }
                    }
                    if (index == -1) {
                        FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                    }

                    if (uvIndex == -1) {
                        uvIndex = index;
                    }
                }

                if (uvIndex == -1) {
                    FBXImporter::LogWarn("failed to resolve UV channel ", uvSet, ", using first UV channel");
                    uvIndex = 0;
                }
            }
        }

        out_mat->AddProperty(&uvIndex, 1, _AI_MATKEY_UVWSRC_BASE, target, 0);
    }
}

void FBXConverter::TrySetTextureProperties(aiMaterial *out_mat, const LayeredTextureMap &layeredTextures,
        const std::string &propName,
        aiTextureType target, const MeshGeometry *const mesh) {
    LayeredTextureMap::const_iterator it = layeredTextures.find(propName);
    if (it == layeredTextures.end()) {
        return;
    }

    int texCount = (*it).second->textureCount();

    // Set the blend mode for layered textures
    int blendmode = (*it).second->GetBlendMode();
    out_mat->AddProperty(&blendmode, 1, _AI_MATKEY_TEXOP_BASE, target, 0);

    for (int texIndex = 0; texIndex < texCount; texIndex++) {

        const Texture *const tex = (*it).second->getTexture(texIndex);

        aiString path = GetTexturePath(tex);
        out_mat->AddProperty(&path, _AI_MATKEY_TEXTURE_BASE, target, texIndex);

        aiUVTransform uvTrafo;
        // XXX handle all kinds of UV transformations
        uvTrafo.mScaling = tex->UVScaling();
        uvTrafo.mTranslation = tex->UVTranslation();
        uvTrafo.mRotation = tex->UVRotation();
        out_mat->AddProperty(&uvTrafo, 1, _AI_MATKEY_UVTRANSFORM_BASE, target, texIndex);

        const PropertyTable &props = tex->Props();

        int uvIndex = 0;

        bool ok;
        const std::string &uvSet = PropertyGet<std::string>(props, "UVSet", ok);
        if (ok) {
            // "default" is the name which usually appears in the FbxFileTexture template
            if (uvSet != "default" && uvSet.length()) {
                // this is a bit awkward - we need to find a mesh that uses this
                // material and scan its UV channels for the given UV name because
                // assimp references UV channels by index, not by name.

                // XXX: the case that UV channels may appear in different orders
                // in meshes is unhandled. A possible solution would be to sort
                // the UV channels alphabetically, but this would have the side
                // effect that the primary (first) UV channel would sometimes
                // be moved, causing trouble when users read only the first
                // UV channel and ignore UV channel assignments altogether.

                const unsigned int matIndex = static_cast<unsigned int>(std::distance(materials.begin(),
                        std::find(materials.begin(), materials.end(), out_mat)));

                uvIndex = -1;
                if (!mesh) {
                    for (const MeshMap::value_type &v : meshes_converted) {
                        const MeshGeometry *const meshGeom = dynamic_cast<const MeshGeometry *>(v.first);
                        if (!meshGeom) {
                            continue;
                        }

                        const MatIndexArray &mats = meshGeom->GetMaterialIndices();
                        MatIndexArray::const_iterator curIt = std::find(mats.begin(), mats.end(), (int) matIndex);
                        if ( curIt == mats.end()) {
                            continue;
                        }

                        int index = -1;
                        for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i) {
                            if (meshGeom->GetTextureCoords(i).empty()) {
                                break;
                            }
                            const std::string &name = meshGeom->GetTextureCoordChannelName(i);
                            if (name == uvSet) {
                                index = static_cast<int>(i);
                                break;
                            }
                        }
                        if (index == -1) {
                            FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                            continue;
                        }

                        if (uvIndex == -1) {
                            uvIndex = index;
                        } else {
                            FBXImporter::LogWarn("the UV channel named ", uvSet,
                                                 " appears at different positions in meshes, results will be wrong");
                        }
                    }
                } else {
                    int index = -1;
                    for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i) {
                        if (mesh->GetTextureCoords(i).empty()) {
                            break;
                        }
                        const std::string &name = mesh->GetTextureCoordChannelName(i);
                        if (name == uvSet) {
                            index = static_cast<int>(i);
                            break;
                        }
                    }
                    if (index == -1) {
                        FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                    }

                    if (uvIndex == -1) {
                        uvIndex = index;
                    }
                }

                if (uvIndex == -1) {
                    FBXImporter::LogWarn("failed to resolve UV channel ", uvSet, ", using first UV channel");
                    uvIndex = 0;
                }
            }
        }

        out_mat->AddProperty(&uvIndex, 1, _AI_MATKEY_UVWSRC_BASE, target, texIndex);
    }
}

void FBXConverter::SetTextureProperties(aiMaterial *out_mat, const TextureMap &_textures, const MeshGeometry *const mesh) {
    TrySetTextureProperties(out_mat, _textures, "DiffuseColor", aiTextureType_DIFFUSE, mesh);
    TrySetTextureProperties(out_mat, _textures, "AmbientColor", aiTextureType_AMBIENT, mesh);
    TrySetTextureProperties(out_mat, _textures, "EmissiveColor", aiTextureType_EMISSIVE, mesh);
    TrySetTextureProperties(out_mat, _textures, "SpecularColor", aiTextureType_SPECULAR, mesh);
    TrySetTextureProperties(out_mat, _textures, "SpecularFactor", aiTextureType_SPECULAR, mesh);
    TrySetTextureProperties(out_mat, _textures, "TransparentColor", aiTextureType_OPACITY, mesh);
    TrySetTextureProperties(out_mat, _textures, "ReflectionColor", aiTextureType_REFLECTION, mesh);
    TrySetTextureProperties(out_mat, _textures, "DisplacementColor", aiTextureType_DISPLACEMENT, mesh);
    TrySetTextureProperties(out_mat, _textures, "NormalMap", aiTextureType_NORMALS, mesh);
    TrySetTextureProperties(out_mat, _textures, "Bump", aiTextureType_HEIGHT, mesh);
    TrySetTextureProperties(out_mat, _textures, "ShininessExponent", aiTextureType_SHININESS, mesh);
    TrySetTextureProperties(out_mat, _textures, "TransparencyFactor", aiTextureType_OPACITY, mesh);
    TrySetTextureProperties(out_mat, _textures, "EmissiveFactor", aiTextureType_EMISSIVE, mesh);
    TrySetTextureProperties(out_mat, _textures, "ReflectionFactor", aiTextureType_METALNESS, mesh);
    //Maya counterparts
    TrySetTextureProperties(out_mat, _textures, "Maya|DiffuseTexture", aiTextureType_DIFFUSE, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|NormalTexture", aiTextureType_NORMALS, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|SpecularTexture", aiTextureType_SPECULAR, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|FalloffTexture", aiTextureType_OPACITY, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|ReflectionMapTexture", aiTextureType_REFLECTION, mesh);

    // Maya PBR
    TrySetTextureProperties(out_mat, _textures, "Maya|baseColor", aiTextureType_BASE_COLOR, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|normalCamera", aiTextureType_NORMAL_CAMERA, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|emissionColor", aiTextureType_EMISSION_COLOR, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|metalness", aiTextureType_METALNESS, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|diffuseRoughness", aiTextureType_DIFFUSE_ROUGHNESS, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|base", aiTextureType_MAYA_BASE, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|specular", aiTextureType_MAYA_SPECULAR, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|specularColor", aiTextureType_MAYA_SPECULAR_COLOR, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|specularRoughness", aiTextureType_MAYA_SPECULAR_ROUGHNESS, mesh);

    // Maya stingray
    TrySetTextureProperties(out_mat, _textures, "Maya|TEX_color_map", aiTextureType_BASE_COLOR, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|TEX_normal_map", aiTextureType_NORMAL_CAMERA, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|TEX_emissive_map", aiTextureType_EMISSION_COLOR, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|TEX_metallic_map", aiTextureType_METALNESS, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|TEX_roughness_map", aiTextureType_DIFFUSE_ROUGHNESS, mesh);
    TrySetTextureProperties(out_mat, _textures, "Maya|TEX_ao_map", aiTextureType_AMBIENT_OCCLUSION, mesh);

    // 3DSMax Physical material
    TrySetTextureProperties(out_mat, _textures, "3dsMax|Parameters|base_color_map", aiTextureType_BASE_COLOR, mesh);
    TrySetTextureProperties(out_mat, _textures, "3dsMax|Parameters|bump_map", aiTextureType_NORMAL_CAMERA, mesh);
    TrySetTextureProperties(out_mat, _textures, "3dsMax|Parameters|emission_map", aiTextureType_EMISSION_COLOR, mesh);
    TrySetTextureProperties(out_mat, _textures, "3dsMax|Parameters|metalness_map", aiTextureType_METALNESS, mesh);
    TrySetTextureProperties(out_mat, _textures, "3dsMax|Parameters|roughness_map", aiTextureType_DIFFUSE_ROUGHNESS, mesh);

    // 3DSMax PBR materials
    TrySetTextureProperties(out_mat, _textures, "3dsMax|main|base_color_map", aiTextureType_BASE_COLOR, mesh);
    TrySetTextureProperties(out_mat, _textures, "3dsMax|main|norm_map", aiTextureType_NORMAL_CAMERA, mesh);
    TrySetTextureProperties(out_mat, _textures, "3dsMax|main|emit_color_map", aiTextureType_EMISSION_COLOR, mesh);
    TrySetTextureProperties(out_mat, _textures, "3dsMax|main|ao_map", aiTextureType_AMBIENT_OCCLUSION, mesh);
    TrySetTextureProperties(out_mat, _textures, "3dsMax|main|opacity_map", aiTextureType_OPACITY, mesh);
    // Metalness/Roughness material type
    TrySetTextureProperties(out_mat, _textures, "3dsMax|main|metalness_map", aiTextureType_METALNESS, mesh);
    // Specular/Gloss material type
    TrySetTextureProperties(out_mat, _textures, "3dsMax|main|specular_map", aiTextureType_SPECULAR, mesh);

    // Glossiness vs roughness in 3ds Max Pbr Materials
    int useGlossiness;
    if (out_mat->Get("$raw.3dsMax|main|useGlossiness", aiTextureType_NONE, 0, useGlossiness) == aiReturn_SUCCESS) {
        // These textures swap meaning if ((useGlossiness == 1) != (material type is Specular/Gloss))
        if (useGlossiness == 1) {
            TrySetTextureProperties(out_mat, _textures, "3dsMax|main|roughness_map", aiTextureType_SHININESS, mesh);
            TrySetTextureProperties(out_mat, _textures, "3dsMax|main|glossiness_map", aiTextureType_SHININESS, mesh);
        }
        else if (useGlossiness == 2) {
            TrySetTextureProperties(out_mat, _textures, "3dsMax|main|roughness_map", aiTextureType_DIFFUSE_ROUGHNESS, mesh);
            TrySetTextureProperties(out_mat, _textures, "3dsMax|main|glossiness_map", aiTextureType_DIFFUSE_ROUGHNESS, mesh);
        }
        else {
            FBXImporter::LogWarn("A 3dsMax Pbr Material must have a useGlossiness value to correctly interpret roughness and glossiness textures.");
        }
    }
}

void FBXConverter::SetTextureProperties(aiMaterial *out_mat, const LayeredTextureMap &layeredTextures, const MeshGeometry *const mesh) {
    TrySetTextureProperties(out_mat, layeredTextures, "DiffuseColor", aiTextureType_DIFFUSE, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "AmbientColor", aiTextureType_AMBIENT, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "EmissiveColor", aiTextureType_EMISSIVE, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "SpecularColor", aiTextureType_SPECULAR, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "SpecularFactor", aiTextureType_SPECULAR, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "TransparentColor", aiTextureType_OPACITY, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "ReflectionColor", aiTextureType_REFLECTION, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "DisplacementColor", aiTextureType_DISPLACEMENT, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "NormalMap", aiTextureType_NORMALS, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "Bump", aiTextureType_HEIGHT, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "ShininessExponent", aiTextureType_SHININESS, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "EmissiveFactor", aiTextureType_EMISSIVE, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "TransparencyFactor", aiTextureType_OPACITY, mesh);
    TrySetTextureProperties(out_mat, layeredTextures, "ReflectionFactor", aiTextureType_METALNESS, mesh);
}

aiColor3D FBXConverter::GetColorPropertyFactored(const PropertyTable &props, const std::string &colorName,
        const std::string &factorName, bool &result, bool useTemplate) {
    result = true;

    bool ok;
    aiVector3D BaseColor = PropertyGet<aiVector3D>(props, colorName, ok, useTemplate);
    if (!ok) {
        result = false;
        return aiColor3D(0.0f, 0.0f, 0.0f);
    }

    // if no factor name, return the colour as is
    if (factorName.empty()) {
        return aiColor3D(BaseColor.x, BaseColor.y, BaseColor.z);
    }

    // otherwise it should be multiplied by the factor, if found.
    float factor = PropertyGet<float>(props, factorName, ok, useTemplate);
    if (ok) {
        BaseColor *= factor;
    }
    return aiColor3D(BaseColor.x, BaseColor.y, BaseColor.z);
}

aiColor3D FBXConverter::GetColorPropertyFromMaterial(const PropertyTable &props, const std::string &baseName,
        bool &result) {
    return GetColorPropertyFactored(props, baseName + "Color", baseName + "Factor", result, true);
}

aiColor3D FBXConverter::GetColorProperty(const PropertyTable &props, const std::string &colorName,
        bool &result, bool useTemplate) {
    result = true;
    bool ok;
    const aiVector3D &ColorVec = PropertyGet<aiVector3D>(props, colorName, ok, useTemplate);
    if (!ok) {
        result = false;
        return aiColor3D(0.0f, 0.0f, 0.0f);
    }
    return aiColor3D(ColorVec.x, ColorVec.y, ColorVec.z);
}

void FBXConverter::SetShadingPropertiesCommon(aiMaterial *out_mat, const PropertyTable &props) {
    // Set shading properties.
    // Modern FBX Files have two separate systems for defining these,
    // with only the more comprehensive one described in the property template.
    // Likely the other values are a legacy system,
    // which is still always exported by the official FBX SDK.
    //
    // Blender's FBX import and export mostly ignore this legacy system,
    // and as we only support recent versions of FBX anyway, we can do the same.
    bool ok;

    const aiColor3D &Diffuse = GetColorPropertyFromMaterial(props, "Diffuse", ok);
    if (ok) {
        out_mat->AddProperty(&Diffuse, 1, AI_MATKEY_COLOR_DIFFUSE);
    }

    const aiColor3D &Emissive = GetColorPropertyFromMaterial(props, "Emissive", ok);
    if (ok) {
        out_mat->AddProperty(&Emissive, 1, AI_MATKEY_COLOR_EMISSIVE);
    } else {
        const aiColor3D &emissiveColor = GetColorProperty(props, "Maya|emissive", ok);
        if (ok) {
            out_mat->AddProperty(&emissiveColor, 1, AI_MATKEY_COLOR_EMISSIVE);
        }
     }

    const aiColor3D &Ambient = GetColorPropertyFromMaterial(props, "Ambient", ok);
    if (ok) {
        out_mat->AddProperty(&Ambient, 1, AI_MATKEY_COLOR_AMBIENT);
    }

    // we store specular factor as SHININESS_STRENGTH, so just get the color
    const aiColor3D &Specular = GetColorProperty(props, "SpecularColor", ok, true);
    if (ok) {
        out_mat->AddProperty(&Specular, 1, AI_MATKEY_COLOR_SPECULAR);
    }

    // and also try to get SHININESS_STRENGTH
    const float SpecularFactor = PropertyGet<float>(props, "SpecularFactor", ok, true);
    if (ok) {
        out_mat->AddProperty(&SpecularFactor, 1, AI_MATKEY_SHININESS_STRENGTH);
    }

    // and the specular exponent
    const float ShininessExponent = PropertyGet<float>(props, "ShininessExponent", ok);
    if (ok) {
        out_mat->AddProperty(&ShininessExponent, 1, AI_MATKEY_SHININESS);
         // Match Blender behavior to extract roughness when only shininess is present
        const float roughness = 1.0f - (sqrt(ShininessExponent) / 10.0f);
        out_mat->AddProperty(&roughness, 1, AI_MATKEY_ROUGHNESS_FACTOR);
    }

    // TransparentColor / TransparencyFactor... gee thanks FBX :rolleyes:
    const aiColor3D &Transparent = GetColorPropertyFactored(props, "TransparentColor", "TransparencyFactor", ok);
    float CalculatedOpacity = 1.0f;
    if (ok) {
        out_mat->AddProperty(&Transparent, 1, AI_MATKEY_COLOR_TRANSPARENT);
        // as calculated by FBX SDK 2017:
        CalculatedOpacity = 1.0f - ((Transparent.r + Transparent.g + Transparent.b) / 3.0f);
    }

    // try to get the transparency factor
    const float TransparencyFactor = PropertyGet<float>(props, "TransparencyFactor", ok);
    if (ok) {
        out_mat->AddProperty(&TransparencyFactor, 1, AI_MATKEY_TRANSPARENCYFACTOR);
    }

    // use of TransparencyFactor is inconsistent.
    // Maya always stores it as 1.0,
    // so we can't use it to set AI_MATKEY_OPACITY.
    // Blender is more sensible and stores it as the alpha value.
    // However both the FBX SDK and Blender always write an additional
    // legacy "Opacity" field, so we can try to use that.
    //
    // If we can't find it,
    // we can fall back to the value which the FBX SDK calculates
    // from transparency colour (RGB) and factor (F) as
    // 1.0 - F*((R+G+B)/3).
    //
    // There's no consistent way to interpret this opacity value,
    // so it's up to clients to do the correct thing.
    const float Opacity = PropertyGet<float>(props, "Opacity", ok);
    if (ok) {
        out_mat->AddProperty(&Opacity, 1, AI_MATKEY_OPACITY);
    } else if (CalculatedOpacity != 1.0) {
        out_mat->AddProperty(&CalculatedOpacity, 1, AI_MATKEY_OPACITY);
    }

    // reflection color and factor are stored separately
    const aiColor3D &Reflection = GetColorProperty(props, "ReflectionColor", ok, true);
    if (ok) {
        out_mat->AddProperty(&Reflection, 1, AI_MATKEY_COLOR_REFLECTIVE);
    }

    float ReflectionFactor = PropertyGet<float>(props, "ReflectionFactor", ok, true);
    if (ok) {
        out_mat->AddProperty(&ReflectionFactor, 1, AI_MATKEY_REFLECTIVITY);
    }

    const float BumpFactor = PropertyGet<float>(props, "BumpFactor", ok);
    if (ok) {
        out_mat->AddProperty(&BumpFactor, 1, AI_MATKEY_BUMPSCALING);
    }

    const float DispFactor = PropertyGet<float>(props, "DisplacementFactor", ok);
    if (ok) {
        out_mat->AddProperty(&DispFactor, 1, "$mat.displacementscaling", 0, 0);
    }

    // PBR material information
    const aiColor3D &baseColor = GetColorProperty(props, "Maya|base_color", ok);
    if (ok) {
        out_mat->AddProperty(&baseColor, 1, AI_MATKEY_BASE_COLOR);
    }

    const float useColorMap = PropertyGet<float>(props, "Maya|use_color_map", ok);
    if (ok) {
        out_mat->AddProperty(&useColorMap, 1, AI_MATKEY_USE_COLOR_MAP);
    }

    const float useMetallicMap = PropertyGet<float>(props, "Maya|use_metallic_map", ok);
    if (ok) {
        out_mat->AddProperty(&useMetallicMap, 1, AI_MATKEY_USE_METALLIC_MAP);
    }

    const float metallicFactor = PropertyGet<float>(props, "Maya|metallic", ok);
    if (ok) {
        out_mat->AddProperty(&metallicFactor, 1, AI_MATKEY_METALLIC_FACTOR);
    }

    const float useRoughnessMap = PropertyGet<float>(props, "Maya|use_roughness_map", ok);
    if (ok) {
        out_mat->AddProperty(&useRoughnessMap, 1, AI_MATKEY_USE_ROUGHNESS_MAP);
    }

    const float roughnessFactor = PropertyGet<float>(props, "Maya|roughness", ok);
    if (ok) {
        out_mat->AddProperty(&roughnessFactor, 1, AI_MATKEY_ROUGHNESS_FACTOR);
    }

    const float useEmissiveMap = PropertyGet<float>(props, "Maya|use_emissive_map", ok);
    if (ok) {
        out_mat->AddProperty(&useEmissiveMap, 1, AI_MATKEY_USE_EMISSIVE_MAP);
    }

    const float emissiveIntensity = PropertyGet<float>(props, "Maya|emissive_intensity", ok);
    if (ok) {
        out_mat->AddProperty(&emissiveIntensity, 1, AI_MATKEY_EMISSIVE_INTENSITY);
    }

    const float useAOMap = PropertyGet<float>(props, "Maya|use_ao_map", ok);
    if (ok) {
        out_mat->AddProperty(&useAOMap, 1, AI_MATKEY_USE_AO_MAP);
    }
}

void FBXConverter::SetShadingPropertiesRaw(aiMaterial *out_mat, const PropertyTable &props, const TextureMap &_textures, const MeshGeometry *const mesh) {
    // Add all the unparsed properties with a "$raw." prefix

    const std::string prefix = "$raw.";

    for (const DirectPropertyMap::value_type &prop : props.GetUnparsedProperties()) {

        std::string name = prefix + prop.first;

        if (const TypedProperty<aiVector3D> *interpretedVec3 = prop.second->As<TypedProperty<aiVector3D>>()) {
            out_mat->AddProperty(&interpretedVec3->Value(), 1, name.c_str(), 0, 0);
        } else if (const TypedProperty<aiColor3D> *interpretedCol3 = prop.second->As<TypedProperty<aiColor3D>>()) {
            out_mat->AddProperty(&interpretedCol3->Value(), 1, name.c_str(), 0, 0);
        } else if (const TypedProperty<aiColor4D> *interpretedCol4 = prop.second->As<TypedProperty<aiColor4D>>()) {
            out_mat->AddProperty(&interpretedCol4->Value(), 1, name.c_str(), 0, 0);
        } else if (const TypedProperty<float> *interpretedFloat = prop.second->As<TypedProperty<float>>()) {
            out_mat->AddProperty(&interpretedFloat->Value(), 1, name.c_str(), 0, 0);
        } else if (const TypedProperty<int> *interpretedInt = prop.second->As<TypedProperty<int>>()) {
            out_mat->AddProperty(&interpretedInt->Value(), 1, name.c_str(), 0, 0);
        } else if (const TypedProperty<bool> *interpretedBool = prop.second->As<TypedProperty<bool>>()) {
            int value = interpretedBool->Value() ? 1 : 0;
            out_mat->AddProperty(&value, 1, name.c_str(), 0, 0);
        } else if (const TypedProperty<std::string> *interpretedString = prop.second->As<TypedProperty<std::string>>()) {
            const aiString value = aiString(interpretedString->Value());
            out_mat->AddProperty(&value, name.c_str(), 0, 0);
        }
    }

    // Add the textures' properties

    for (TextureMap::const_iterator it = _textures.begin(); it != _textures.end(); ++it) {

        std::string name = prefix + it->first;

        const Texture *const tex = it->second;
        if (tex != nullptr) {
            aiString path;
            path.Set(tex->RelativeFilename());

            const Video *media = tex->Media();
            if (media != nullptr && media->ContentLength() > 0) {
                unsigned int index;

                VideoMap::const_iterator videoIt = textures_converted.find(media);
                if (videoIt != textures_converted.end()) {
                    index = videoIt->second;
                } else {
                    index = ConvertVideo(*media);
                    textures_converted[media] = index;
                }

                // setup texture reference string (copied from ColladaLoader::FindFilenameForEffectTexture)
                path.data[0] = '*';
                path.length = 1 + ASSIMP_itoa10(path.data + 1, AI_MAXLEN - 1, index);
            }

            out_mat->AddProperty(&path, (name + "|file").c_str(), aiTextureType_UNKNOWN, 0);

            aiUVTransform uvTrafo;
            // XXX handle all kinds of UV transformations
            uvTrafo.mScaling = tex->UVScaling();
            uvTrafo.mTranslation = tex->UVTranslation();
            uvTrafo.mRotation = tex->UVRotation();
            out_mat->AddProperty(&uvTrafo, 1, (name + "|uvtrafo").c_str(), aiTextureType_UNKNOWN, 0);

            int uvIndex = 0;

            bool uvFound = false;
            const std::string &uvSet = PropertyGet<std::string>(tex->Props(), "UVSet", uvFound);
            if (uvFound) {
                // "default" is the name which usually appears in the FbxFileTexture template
                if (uvSet != "default" && uvSet.length()) {
                    // this is a bit awkward - we need to find a mesh that uses this
                    // material and scan its UV channels for the given UV name because
                    // assimp references UV channels by index, not by name.

                    // XXX: the case that UV channels may appear in different orders
                    // in meshes is unhandled. A possible solution would be to sort
                    // the UV channels alphabetically, but this would have the side
                    // effect that the primary (first) UV channel would sometimes
                    // be moved, causing trouble when users read only the first
                    // UV channel and ignore UV channel assignments altogether.

                    std::vector<aiMaterial *>::iterator materialIt = std::find(materials.begin(), materials.end(), out_mat);
                    const unsigned int matIndex = static_cast<unsigned int>(std::distance(materials.begin(), materialIt));

                    uvIndex = -1;
                    if (!mesh) {
                        for (const MeshMap::value_type &v : meshes_converted) {
                            const MeshGeometry *const meshGeom = dynamic_cast<const MeshGeometry *>(v.first);
                            if (!meshGeom) {
                                continue;
                            }

                            const MatIndexArray &mats = meshGeom->GetMaterialIndices();
                            if (std::find(mats.begin(), mats.end(), (int)matIndex) == mats.end()) {
                                continue;
                            }

                            int index = -1;
                            for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i) {
                                if (meshGeom->GetTextureCoords(i).empty()) {
                                    break;
                                }
                                const std::string &curName = meshGeom->GetTextureCoordChannelName(i);
                                if (curName == uvSet) {
                                    index = static_cast<int>(i);
                                    break;
                                }
                            }
                            if (index == -1) {
                                FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                                continue;
                            }

                            if (uvIndex == -1) {
                                uvIndex = index;
                            } else {
                                FBXImporter::LogWarn("the UV channel named ", uvSet, " appears at different positions in meshes, results will be wrong");
                            }
                        }
                    } else {
                        int index = -1;
                        for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i) {
                            if (mesh->GetTextureCoords(i).empty()) {
                                break;
                            }
                            const std::string &curName = mesh->GetTextureCoordChannelName(i);
                            if (curName == uvSet) {
                                index = static_cast<int>(i);
                                break;
                            }
                        }
                        if (index == -1) {
                            FBXImporter::LogWarn("did not find UV channel named ", uvSet, " in a mesh using this material");
                        }

                        if (uvIndex == -1) {
                            uvIndex = index;
                        }
                    }

                    if (uvIndex == -1) {
                        FBXImporter::LogWarn("failed to resolve UV channel ", uvSet, ", using first UV channel");
                        uvIndex = 0;
                    }
                }
            }

            out_mat->AddProperty(&uvIndex, 1, (name + "|uvwsrc").c_str(), aiTextureType_UNKNOWN, 0);
        }
    }
}

double FBXConverter::FrameRateToDouble(FileGlobalSettings::FrameRate fp, double customFPSVal) {
    switch (fp) {
        case FileGlobalSettings::FrameRate_DEFAULT:
            return 1.0;

        case FileGlobalSettings::FrameRate_120:
            return 120.0;

        case FileGlobalSettings::FrameRate_100:
            return 100.0;

        case FileGlobalSettings::FrameRate_60:
            return 60.0;

        case FileGlobalSettings::FrameRate_50:
            return 50.0;

        case FileGlobalSettings::FrameRate_48:
            return 48.0;

        case FileGlobalSettings::FrameRate_30:
        case FileGlobalSettings::FrameRate_30_DROP:
            return 30.0;

        case FileGlobalSettings::FrameRate_NTSC_DROP_FRAME:
        case FileGlobalSettings::FrameRate_NTSC_FULL_FRAME:
            return 29.9700262;

        case FileGlobalSettings::FrameRate_PAL:
            return 25.0;

        case FileGlobalSettings::FrameRate_CINEMA:
            return 24.0;

        case FileGlobalSettings::FrameRate_1000:
            return 1000.0;

        case FileGlobalSettings::FrameRate_CINEMA_ND:
            return 23.976;

        case FileGlobalSettings::FrameRate_CUSTOM:
            return customFPSVal;

        case FileGlobalSettings::FrameRate_MAX: // this is to silence compiler warnings
            break;
    }

    ai_assert(false);

    return -1.0f;
}

void FBXConverter::ConvertAnimations() {
    // first of all determine framerate
    const FileGlobalSettings::FrameRate fps = doc.GlobalSettings().TimeMode();
    const float custom = doc.GlobalSettings().CustomFrameRate();
    anim_fps = FrameRateToDouble(fps, custom);

    const std::vector<const AnimationStack *> &curAnimations = doc.AnimationStacks();
    for (const AnimationStack *stack : curAnimations) {
        ConvertAnimationStack(*stack);
    }
}

std::string FBXConverter::FixNodeName(const std::string &name) {
    // strip Model:: prefix, avoiding ambiguities (i.e. don't strip if
    // this causes ambiguities, well possible between empty identifiers,
    // such as "Model::" and ""). Make sure the behaviour is consistent
    // across multiple calls to FixNodeName().
    if (name.substr(0, 7) == "Model::") {
        std::string temp = name.substr(7);
        return temp;
    }

    return name;
}

std::string FBXConverter::FixAnimMeshName(const std::string &name) {
    if (name.length()) {
        size_t indexOf = name.find_first_of("::");
        if (indexOf != std::string::npos && indexOf < name.size() - 2) {
            return name.substr(indexOf + 2);
        }
    }
    return name.length() ? name : "AnimMesh";
}

void FBXConverter::ConvertAnimationStack(const AnimationStack &st) {
    const AnimationLayerList &layers = st.Layers();
    if (layers.empty()) {
        return;
    }

    aiAnimation *const anim = new aiAnimation();
    animations.push_back(anim);

    // strip AnimationStack:: prefix
    std::string name = st.Name();
    if (name.substr(0, 16) == "AnimationStack::") {
        name = name.substr(16);
    } else if (name.substr(0, 11) == "AnimStack::") {
        name = name.substr(11);
    }

    anim->mName.Set(name);

    // need to find all nodes for which we need to generate node animations -
    // it may happen that we need to merge multiple layers, though.
    NodeMap node_map;

    // reverse mapping from curves to layers, much faster than querying
    // the FBX DOM for it.
    LayerMap layer_map;

    const char *prop_whitelist[] = {
        "Lcl Scaling",
        "Lcl Rotation",
        "Lcl Translation",
        "DeformPercent"
    };

    std::map<std::string, morphAnimData *> morphAnimDatas;

    for (const AnimationLayer *layer : layers) {
        ai_assert(layer);
        const AnimationCurveNodeList &nodes = layer->Nodes(prop_whitelist, 4);
        for (const AnimationCurveNode *node : nodes) {
            ai_assert(node);
            const Model *const model = dynamic_cast<const Model *>(node->Target());
            if (model) {
                const std::string &curName = FixNodeName(model->Name());
                node_map[curName].push_back(node);
                layer_map[node] = layer;
                continue;
            }
            const BlendShapeChannel *const bsc = dynamic_cast<const BlendShapeChannel *>(node->Target());
            if (bsc) {
                ProcessMorphAnimDatas(&morphAnimDatas, bsc, node);
            }
        }
    }

    // generate node animations
    std::vector<aiNodeAnim *> node_anims;

    double min_time = 1e10;
    double max_time = -1e10;

    int64_t start_time = st.LocalStart();
    int64_t stop_time = st.LocalStop();
    bool has_local_startstop = start_time != 0 || stop_time != 0;
    if (!has_local_startstop) {
        // no time range given, so accept every keyframe and use the actual min/max time
        // the numbers are INT64_MIN/MAX, the 20000 is for safety because GenerateNodeAnimations uses an epsilon of 10000
        start_time = -9223372036854775807ll + 20000;
        stop_time = 9223372036854775807ll - 20000;
    }

    try {
        for (const NodeMap::value_type &kv : node_map) {
            GenerateNodeAnimations(node_anims,
                    kv.first,
                    kv.second,
                    layer_map,
                    start_time, stop_time,
                    max_time,
                    min_time);
        }
    } catch (std::exception &) {
        std::for_each(node_anims.begin(), node_anims.end(), Util::delete_fun<aiNodeAnim>());
        throw;
    }

    if (node_anims.size() || morphAnimDatas.size()) {
        if (node_anims.size()) {
            anim->mChannels = new aiNodeAnim *[node_anims.size()]();
            anim->mNumChannels = static_cast<unsigned int>(node_anims.size());
            std::swap_ranges(node_anims.begin(), node_anims.end(), anim->mChannels);
        }
        if (morphAnimDatas.size()) {
            unsigned int numMorphMeshChannels = static_cast<unsigned int>(morphAnimDatas.size());
            anim->mMorphMeshChannels = new aiMeshMorphAnim *[numMorphMeshChannels];
            anim->mNumMorphMeshChannels = numMorphMeshChannels;
            unsigned int i = 0;
            for (const auto &morphAnimIt : morphAnimDatas) {
                morphAnimData *animData = morphAnimIt.second;
                unsigned int numKeys = static_cast<unsigned int>(animData->size());
                aiMeshMorphAnim *meshMorphAnim = new aiMeshMorphAnim();
                meshMorphAnim->mName.Set(morphAnimIt.first);
                meshMorphAnim->mNumKeys = numKeys;
                meshMorphAnim->mKeys = new aiMeshMorphKey[numKeys];
                unsigned int j = 0;
                for (auto &animIt : *animData) {
                    morphKeyData *keyData = animIt.second;
                    unsigned int numValuesAndWeights = static_cast<unsigned int>(keyData->values.size());
                    meshMorphAnim->mKeys[j].mNumValuesAndWeights = numValuesAndWeights;
                    meshMorphAnim->mKeys[j].mValues = new unsigned int[numValuesAndWeights];
                    meshMorphAnim->mKeys[j].mWeights = new double[numValuesAndWeights];
                    meshMorphAnim->mKeys[j].mTime = CONVERT_FBX_TIME(animIt.first) * anim_fps;
                    for (unsigned int k = 0; k < numValuesAndWeights; k++) {
                        meshMorphAnim->mKeys[j].mValues[k] = keyData->values.at(k);
                        meshMorphAnim->mKeys[j].mWeights[k] = keyData->weights.at(k);
                    }
                    j++;
                }
                anim->mMorphMeshChannels[i++] = meshMorphAnim;
            }
        }
    } else {
        // empty animations would fail validation, so drop them
        delete anim;
        animations.pop_back();
        FBXImporter::LogInfo("ignoring empty AnimationStack (using IK?): ", name);
        return;
    }

    double start_time_fps = has_local_startstop ? (CONVERT_FBX_TIME(start_time) * anim_fps) : min_time;
    double stop_time_fps = has_local_startstop ? (CONVERT_FBX_TIME(stop_time) * anim_fps) : max_time;

    // adjust relative timing for animation
    for (unsigned int c = 0; c < anim->mNumChannels; c++) {
        aiNodeAnim *channel = anim->mChannels[c];
        for (uint32_t i = 0; i < channel->mNumPositionKeys; i++) {
            channel->mPositionKeys[i].mTime -= start_time_fps;
        }
        for (uint32_t i = 0; i < channel->mNumRotationKeys; i++) {
            channel->mRotationKeys[i].mTime -= start_time_fps;
        }
        for (uint32_t i = 0; i < channel->mNumScalingKeys; i++) {
            channel->mScalingKeys[i].mTime -= start_time_fps;
        }
    }
    for (unsigned int c = 0; c < anim->mNumMorphMeshChannels; c++) {
        aiMeshMorphAnim *channel = anim->mMorphMeshChannels[c];
        for (uint32_t i = 0; i < channel->mNumKeys; i++) {
            channel->mKeys[i].mTime -= start_time_fps;
        }
    }

    // for some mysterious reason, mDuration is simply the maximum key -- the
    // validator always assumes animations to start at zero.
    anim->mDuration = stop_time_fps - start_time_fps;
    anim->mTicksPerSecond = anim_fps;
}

// ------------------------------------------------------------------------------------------------
void FBXConverter::ProcessMorphAnimDatas(std::map<std::string, morphAnimData *> *morphAnimDatas, const BlendShapeChannel *bsc, const AnimationCurveNode *node) {
    std::vector<const Connection *> bscConnections = doc.GetConnectionsBySourceSequenced(bsc->ID(), "Deformer");
    for (const Connection *bscConnection : bscConnections) {
        auto bs = dynamic_cast<const BlendShape *>(bscConnection->DestinationObject());
        if (bs) {
            auto channelIt = std::find(bs->BlendShapeChannels().begin(), bs->BlendShapeChannels().end(), bsc);
            if (channelIt != bs->BlendShapeChannels().end()) {
                auto channelIndex = static_cast<unsigned int>(std::distance(bs->BlendShapeChannels().begin(), channelIt));
                std::vector<const Connection *> bsConnections = doc.GetConnectionsBySourceSequenced(bs->ID(), "Geometry");
                for (const Connection *bsConnection : bsConnections) {
                    auto geo = dynamic_cast<const Geometry *>(bsConnection->DestinationObject());
                    if (geo) {
                        std::vector<const Connection *> geoConnections = doc.GetConnectionsBySourceSequenced(geo->ID(), "Model");
                        for (const Connection *geoConnection : geoConnections) {
                            auto model = dynamic_cast<const Model *>(geoConnection->DestinationObject());
                            if (model) {
                                auto geoIt = std::find(model->GetGeometry().begin(), model->GetGeometry().end(), geo);
                                auto geoIndex = static_cast<unsigned int>(std::distance(model->GetGeometry().begin(), geoIt));
                                auto name = aiString(FixNodeName(model->Name() + "*"));
                                name.length = 1 + ASSIMP_itoa10(name.data + name.length, AI_MAXLEN - 1, geoIndex);
                                morphAnimData *animData;
                                auto animIt = morphAnimDatas->find(name.C_Str());
                                if (animIt == morphAnimDatas->end()) {
                                    animData = new morphAnimData();
                                    morphAnimDatas->insert(std::make_pair(name.C_Str(), animData));
                                } else {
                                    animData = animIt->second;
                                }
                                for (std::pair<std::string, const AnimationCurve *> curvesIt : node->Curves()) {
                                    if (curvesIt.first == "d|DeformPercent") {
                                        const AnimationCurve *animationCurve = curvesIt.second;
                                        const KeyTimeList &keys = animationCurve->GetKeys();
                                        const KeyValueList &values = animationCurve->GetValues();
                                        unsigned int k = 0;
                                        for (auto key : keys) {
                                            morphKeyData *keyData;
                                            auto keyIt = animData->find(key);
                                            if (keyIt == animData->end()) {
                                                keyData = new morphKeyData();
                                                animData->insert(std::make_pair(key, keyData));
                                            } else {
                                                keyData = keyIt->second;
                                            }
                                            keyData->values.push_back(channelIndex);
                                            keyData->weights.push_back(values.at(k) / 100.0f);
                                            k++;
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

// ------------------------------------------------------------------------------------------------
#ifdef ASSIMP_BUILD_DEBUG
// ------------------------------------------------------------------------------------------------
// sanity check whether the input is ok
static void validateAnimCurveNodes(const std::vector<const AnimationCurveNode *> &curves,
        bool strictMode) {
    const Object *target(nullptr);
    for (const AnimationCurveNode *node : curves) {
        if (!target) {
            target = node->Target();
        }
        if (node->Target() != target) {
            FBXImporter::LogWarn("Node target is nullptr type.");
        }
        if (strictMode) {
            ai_assert(node->Target() == target);
        }
    }
}
#endif // ASSIMP_BUILD_DEBUG

// ------------------------------------------------------------------------------------------------
void FBXConverter::GenerateNodeAnimations(std::vector<aiNodeAnim *> &node_anims,
        const std::string &fixed_name,
        const std::vector<const AnimationCurveNode *> &curves,
        const LayerMap &layer_map,
        int64_t start, int64_t stop,
        double &max_time,
        double &min_time) {

    NodeMap node_property_map;
    ai_assert(curves.size());

#ifdef ASSIMP_BUILD_DEBUG
    validateAnimCurveNodes(curves, doc.Settings().strictMode);
#endif
    const AnimationCurveNode *curve_node = nullptr;
    for (const AnimationCurveNode *node : curves) {
        ai_assert(node);

        if (node->TargetProperty().empty()) {
            FBXImporter::LogWarn("target property for animation curve not set: ", node->Name());
            continue;
        }

        curve_node = node;
        if (node->Curves().empty()) {
            FBXImporter::LogWarn("no animation curves assigned to AnimationCurveNode: ", node->Name());
            continue;
        }

        node_property_map[node->TargetProperty()].push_back(node);
    }

    ai_assert(curve_node);
    ai_assert(curve_node->TargetAsModel());

    const Model &target = *curve_node->TargetAsModel();

    // check for all possible transformation components
    NodeMap::const_iterator chain[TransformationComp_MAXIMUM];

    bool has_any = false;
    bool has_complex = false;

    for (size_t i = 0; i < TransformationComp_MAXIMUM; ++i) {
        const TransformationComp comp = static_cast<TransformationComp>(i);

        // inverse pivots don't exist in the input, we just generate them
        if (comp == TransformationComp_RotationPivotInverse || comp == TransformationComp_ScalingPivotInverse) {
            chain[i] = node_property_map.end();
            continue;
        }

        chain[i] = node_property_map.find(NameTransformationCompProperty(comp));
        if (chain[i] != node_property_map.end()) {

            // check if this curves contains redundant information by looking
            // up the corresponding node's transformation chain.
            if (doc.Settings().optimizeEmptyAnimationCurves &&
                    IsRedundantAnimationData(target, comp, (chain[i]->second))) {

                FBXImporter::LogVerboseDebug("dropping redundant animation channel for node ", target.Name());
                continue;
            }

            has_any = true;

            if (comp != TransformationComp_Rotation && comp != TransformationComp_Scaling && comp != TransformationComp_Translation) {
                has_complex = true;
            }
        }
    }

    if (!has_any) {
        FBXImporter::LogWarn("ignoring node animation, did not find any transformation key frames");
        return;
    }

    // this needs to play nicely with GenerateTransformationNodeChain() which will
    // be invoked _later_ (animations come first). If this node has only rotation,
    // scaling and translation _and_ there are no animated other components either,
    // we can use a single node and also a single node animation channel.
    if( !has_complex && !NeedsComplexTransformationChain(target)) {
        aiNodeAnim* const nd = GenerateSimpleNodeAnim(fixed_name, target, chain,
                node_property_map.end(),
                start, stop,
                max_time,
                min_time
        );

        ai_assert(nd);
        if (nd->mNumPositionKeys == 0 && nd->mNumRotationKeys == 0 && nd->mNumScalingKeys == 0) {
            delete nd;
        } else {
            node_anims.push_back(nd);
        }
        return;
    }

    // otherwise, things get gruesome and we need separate animation channels
    // for each part of the transformation chain. Remember which channels
    // we generated and pass this information to the node conversion
    // code to avoid nodes that have identity transform, but non-identity
    // animations, being dropped.
    unsigned int flags = 0, bit = 0x1;
    for (size_t i = 0; i < TransformationComp_MAXIMUM; ++i, bit <<= 1) {
        const TransformationComp comp = static_cast<TransformationComp>(i);

        if (chain[i] != node_property_map.end()) {
            flags |= bit;

            ai_assert(comp != TransformationComp_RotationPivotInverse);
            ai_assert(comp != TransformationComp_ScalingPivotInverse);

            const std::string &chain_name = NameTransformationChainNode(fixed_name, comp);

            aiNodeAnim *na = nullptr;
            switch (comp) {
                case TransformationComp_Rotation:
                case TransformationComp_PreRotation:
                case TransformationComp_PostRotation:
                case TransformationComp_GeometricRotation:
                    na = GenerateRotationNodeAnim(chain_name,
                            target,
                            (*chain[i]).second,
                            layer_map,
                            start, stop,
                            max_time,
                            min_time);

                    break;

                case TransformationComp_RotationOffset:
                case TransformationComp_RotationPivot:
                case TransformationComp_ScalingOffset:
                case TransformationComp_ScalingPivot:
                case TransformationComp_Translation:
                case TransformationComp_GeometricTranslation:
                    na = GenerateTranslationNodeAnim(chain_name,
                            target,
                            (*chain[i]).second,
                            layer_map,
                            start, stop,
                            max_time,
                            min_time);

                    // pivoting requires us to generate an implicit inverse channel to undo the pivot translation
                    if (comp == TransformationComp_RotationPivot) {
                        const std::string &invName = NameTransformationChainNode(fixed_name,
                                TransformationComp_RotationPivotInverse);

                        aiNodeAnim *const inv = GenerateTranslationNodeAnim(invName,
                                target,
                                (*chain[i]).second,
                                layer_map,
                                start, stop,
                                max_time,
                                min_time,
                                true);

                        ai_assert(inv);
                        if (inv->mNumPositionKeys == 0 && inv->mNumRotationKeys == 0 && inv->mNumScalingKeys == 0) {
                            delete inv;
                        } else {
                            node_anims.push_back(inv);
                        }

                        ai_assert(TransformationComp_RotationPivotInverse > i);
                        flags |= bit << (TransformationComp_RotationPivotInverse - i);
                    } else if (comp == TransformationComp_ScalingPivot) {
                        const std::string &invName = NameTransformationChainNode(fixed_name,
                                TransformationComp_ScalingPivotInverse);

                        aiNodeAnim *const inv = GenerateTranslationNodeAnim(invName,
                                target,
                                (*chain[i]).second,
                                layer_map,
                                start, stop,
                                max_time,
                                min_time,
                                true);

                        ai_assert(inv);
                        if (inv->mNumPositionKeys == 0 && inv->mNumRotationKeys == 0 && inv->mNumScalingKeys == 0) {
                            delete inv;
                        } else {
                            node_anims.push_back(inv);
                        }

                        ai_assert(TransformationComp_RotationPivotInverse > i);
                        flags |= bit << (TransformationComp_RotationPivotInverse - i);
                    }

                    break;

                case TransformationComp_Scaling:
                case TransformationComp_GeometricScaling:
                    na = GenerateScalingNodeAnim(chain_name,
                            target,
                            (*chain[i]).second,
                            layer_map,
                            start, stop,
                            max_time,
                            min_time);

                    break;

                default:
                    ai_assert(false);
            }

            ai_assert(na);
            if (na->mNumPositionKeys == 0 && na->mNumRotationKeys == 0 && na->mNumScalingKeys == 0) {
                delete na;
            } else {
                node_anims.push_back(na);
            }
            continue;
        }
    }

    node_anim_chain_bits[fixed_name] = flags;
}

bool FBXConverter::IsRedundantAnimationData(const Model &target,
        TransformationComp comp,
        const std::vector<const AnimationCurveNode *> &curves) {
    ai_assert(curves.size());

    // look for animation nodes with
    //  * sub channels for all relevant components set
    //  * one key/value pair per component
    //  * combined values match up the corresponding value in the bind pose node transformation
    // only such nodes are 'redundant' for this function.

    if (curves.size() > 1) {
        return false;
    }

    const AnimationCurveNode &nd = *curves.front();
    const AnimationCurveMap &sub_curves = nd.Curves();

    const AnimationCurveMap::const_iterator dx = sub_curves.find("d|X");
    const AnimationCurveMap::const_iterator dy = sub_curves.find("d|Y");
    const AnimationCurveMap::const_iterator dz = sub_curves.find("d|Z");

    if (dx == sub_curves.end() || dy == sub_curves.end() || dz == sub_curves.end()) {
        return false;
    }

    const KeyValueList &vx = (*dx).second->GetValues();
    const KeyValueList &vy = (*dy).second->GetValues();
    const KeyValueList &vz = (*dz).second->GetValues();

    if (vx.size() != 1 || vy.size() != 1 || vz.size() != 1) {
        return false;
    }

    const aiVector3D dyn_val = aiVector3D(vx[0], vy[0], vz[0]);
    const aiVector3D &static_val = PropertyGet<aiVector3D>(target.Props(),
            NameTransformationCompProperty(comp),
            TransformationCompDefaultValue(comp));

    const float epsilon = Math::getEpsilon<float>();
    return (dyn_val - static_val).SquareLength() < epsilon;
}

aiNodeAnim *FBXConverter::GenerateRotationNodeAnim(const std::string &name,
        const Model &target,
        const std::vector<const AnimationCurveNode *> &curves,
        const LayerMap &layer_map,
        int64_t start, int64_t stop,
        double &max_time,
        double &min_time) {
    std::unique_ptr<aiNodeAnim> na(new aiNodeAnim());
    na->mNodeName.Set(name);

    ConvertRotationKeys(na.get(), curves, layer_map, start, stop, max_time, min_time, target.RotationOrder());

    // dummy scaling key
    na->mScalingKeys = new aiVectorKey[1];
    na->mNumScalingKeys = 1;

    na->mScalingKeys[0].mTime = 0.;
    na->mScalingKeys[0].mValue = aiVector3D(1.0f, 1.0f, 1.0f);

    // dummy position key
    na->mPositionKeys = new aiVectorKey[1];
    na->mNumPositionKeys = 1;

    na->mPositionKeys[0].mTime = 0.;
    na->mPositionKeys[0].mValue = aiVector3D();

    return na.release();
}

aiNodeAnim *FBXConverter::GenerateScalingNodeAnim(const std::string &name,
        const Model & /*target*/,
        const std::vector<const AnimationCurveNode *> &curves,
        const LayerMap &layer_map,
        int64_t start, int64_t stop,
        double &max_time,
        double &min_time) {
    std::unique_ptr<aiNodeAnim> na(new aiNodeAnim());
    na->mNodeName.Set(name);

    ConvertScaleKeys(na.get(), curves, layer_map, start, stop, max_time, min_time);

    // dummy rotation key
    na->mRotationKeys = new aiQuatKey[1];
    na->mNumRotationKeys = 1;

    na->mRotationKeys[0].mTime = 0.;
    na->mRotationKeys[0].mValue = aiQuaternion();

    // dummy position key
    na->mPositionKeys = new aiVectorKey[1];
    na->mNumPositionKeys = 1;

    na->mPositionKeys[0].mTime = 0.;
    na->mPositionKeys[0].mValue = aiVector3D();

    return na.release();
}

aiNodeAnim *FBXConverter::GenerateTranslationNodeAnim(const std::string &name,
        const Model & /*target*/,
        const std::vector<const AnimationCurveNode *> &curves,
        const LayerMap &layer_map,
        int64_t start, int64_t stop,
        double &max_time,
        double &min_time,
        bool inverse) {
    std::unique_ptr<aiNodeAnim> na(new aiNodeAnim());
    na->mNodeName.Set(name);

    ConvertTranslationKeys(na.get(), curves, layer_map, start, stop, max_time, min_time);

    if (inverse) {
        for (unsigned int i = 0; i < na->mNumPositionKeys; ++i) {
            na->mPositionKeys[i].mValue *= -1.0f;
        }
    }

    // dummy scaling key
    na->mScalingKeys = new aiVectorKey[1];
    na->mNumScalingKeys = 1;

    na->mScalingKeys[0].mTime = 0.;
    na->mScalingKeys[0].mValue = aiVector3D(1.0f, 1.0f, 1.0f);

    // dummy rotation key
    na->mRotationKeys = new aiQuatKey[1];
    na->mNumRotationKeys = 1;

    na->mRotationKeys[0].mTime = 0.;
    na->mRotationKeys[0].mValue = aiQuaternion();

    return na.release();
}

aiNodeAnim* FBXConverter::GenerateSimpleNodeAnim(const std::string& name,
        const Model& target,
        NodeMap::const_iterator chain[TransformationComp_MAXIMUM],
        NodeMap::const_iterator iterEnd,
        int64_t start, int64_t stop,
        double& maxTime,
        double& minTime)
{
    std::unique_ptr<aiNodeAnim> na(new aiNodeAnim());
    na->mNodeName.Set(name);

    const PropertyTable &props = target.Props();

    // collect unique times and keyframe lists
    KeyFrameListList keyframeLists[TransformationComp_MAXIMUM];
    KeyTimeList keytimes;

    for (size_t i = 0; i < TransformationComp_MAXIMUM; ++i) {
        if (chain[i] == iterEnd)
            continue;

        if (i == TransformationComp_Rotation || i == TransformationComp_PreRotation
                || i == TransformationComp_PostRotation || i == TransformationComp_GeometricRotation) {
            keyframeLists[i] = GetRotationKeyframeList((*chain[i]).second, start, stop);
        } else {
            keyframeLists[i] = GetKeyframeList((*chain[i]).second, start, stop);
        }

        for (KeyFrameListList::const_iterator it = keyframeLists[i].begin(); it != keyframeLists[i].end(); ++it) {
            const KeyTimeList& times = *std::get<0>(*it);
            keytimes.insert(keytimes.end(), times.begin(), times.end());
        }

        // remove duplicates
        std::sort(keytimes.begin(), keytimes.end());

        auto last = std::unique(keytimes.begin(), keytimes.end());
        keytimes.erase(last, keytimes.end());
    }

    const Model::RotOrder rotOrder = target.RotationOrder();
    const size_t keyCount = keytimes.size();

    aiVector3D defTranslate = PropertyGet(props, "Lcl Translation", aiVector3D(0.f, 0.f, 0.f));
    aiVector3D defRotation = PropertyGet(props, "Lcl Rotation", aiVector3D(0.f, 0.f, 0.f));
    aiVector3D defScale = PropertyGet(props, "Lcl Scaling", aiVector3D(1.f, 1.f, 1.f));

    aiVectorKey* outTranslations = new aiVectorKey[keyCount];
    aiQuatKey* outRotations = new aiQuatKey[keyCount];
    aiVectorKey* outScales = new aiVectorKey[keyCount];

    if (keyframeLists[TransformationComp_Translation].size() > 0) {
        InterpolateKeys(outTranslations, keytimes, keyframeLists[TransformationComp_Translation], defTranslate, maxTime, minTime);
    } else {
        for (size_t i = 0; i < keyCount; ++i) {
            outTranslations[i].mTime = CONVERT_FBX_TIME(keytimes[i]) * anim_fps;
            outTranslations[i].mValue = defTranslate;
        }
    }

    if (keyframeLists[TransformationComp_Rotation].size() > 0) {
        InterpolateKeys(outRotations, keytimes, keyframeLists[TransformationComp_Rotation], defRotation, maxTime, minTime, rotOrder);
    } else {
        aiQuaternion defQuat = EulerToQuaternion(defRotation, rotOrder);
        for (size_t i = 0; i < keyCount; ++i) {
            outRotations[i].mTime = CONVERT_FBX_TIME(keytimes[i]) * anim_fps;
            outRotations[i].mValue = defQuat;
        }
    }

    if (keyframeLists[TransformationComp_Scaling].size() > 0) {
        InterpolateKeys(outScales, keytimes, keyframeLists[TransformationComp_Scaling], defScale, maxTime, minTime);
    } else {
        for (size_t i = 0; i < keyCount; ++i) {
            outScales[i].mTime = CONVERT_FBX_TIME(keytimes[i]) * anim_fps;
            outScales[i].mValue = defScale;
        }
    }

    bool ok = false;

    const auto zero_epsilon = ai_epsilon;

    const aiVector3D& preRotation = PropertyGet<aiVector3D>(props, "PreRotation", ok);
    if (ok && preRotation.SquareLength() > zero_epsilon) {
        const aiQuaternion preQuat = EulerToQuaternion(preRotation, Model::RotOrder_EulerXYZ);
        for (size_t i = 0; i < keyCount; ++i) {
            outRotations[i].mValue = preQuat * outRotations[i].mValue;
        }
    }

    const aiVector3D& postRotation = PropertyGet<aiVector3D>(props, "PostRotation", ok);
    if (ok && postRotation.SquareLength() > zero_epsilon) {
        const aiQuaternion postQuat = EulerToQuaternion(postRotation, Model::RotOrder_EulerXYZ);
        for (size_t i = 0; i < keyCount; ++i) {
            outRotations[i].mValue = outRotations[i].mValue * postQuat;
        }
    }

    // convert TRS to SRT
    for (size_t i = 0; i < keyCount; ++i) {
        aiQuaternion& r = outRotations[i].mValue;
        aiVector3D& s = outScales[i].mValue;
        aiVector3D& t = outTranslations[i].mValue;

        aiMatrix4x4 mat, temp;
        aiMatrix4x4::Translation(t, mat);
        mat *= aiMatrix4x4(r.GetMatrix());
        mat *= aiMatrix4x4::Scaling(s, temp);

        mat.Decompose(s, r, t);
    }

    na->mNumScalingKeys = static_cast<unsigned int>(keyCount);
    na->mNumRotationKeys = na->mNumScalingKeys;
    na->mNumPositionKeys = na->mNumScalingKeys;

    na->mScalingKeys = outScales;
    na->mRotationKeys = outRotations;
    na->mPositionKeys = outTranslations;

    return na.release();
}

FBXConverter::KeyFrameListList FBXConverter::GetKeyframeList(const std::vector<const AnimationCurveNode *> &nodes, int64_t start, int64_t stop) {
    KeyFrameListList inputs;
    inputs.reserve(nodes.size() * 3);

    //give some breathing room for rounding errors
    int64_t adj_start = start - 10000;
    int64_t adj_stop = stop + 10000;

    for (const AnimationCurveNode *node : nodes) {
        ai_assert(node);

        const AnimationCurveMap &curves = node->Curves();
        for (const AnimationCurveMap::value_type &kv : curves) {

            unsigned int mapto;
            if (kv.first == "d|X") {
                mapto = 0;
            } else if (kv.first == "d|Y") {
                mapto = 1;
            } else if (kv.first == "d|Z") {
                mapto = 2;
            } else {
                FBXImporter::LogWarn("ignoring scale animation curve, did not recognize target component");
                continue;
            }

            const AnimationCurve *const curve = kv.second;
            ai_assert(curve->GetKeys().size() == curve->GetValues().size());
            ai_assert(curve->GetKeys().size());

            //get values within the start/stop time window
            std::shared_ptr<KeyTimeList> Keys(new KeyTimeList());
            std::shared_ptr<KeyValueList> Values(new KeyValueList());
            const size_t count = curve->GetKeys().size();
            Keys->reserve(count);
            Values->reserve(count);
            for (size_t n = 0; n < count; n++) {
                int64_t k = curve->GetKeys().at(n);
                if (k >= adj_start && k <= adj_stop) {
                    Keys->push_back(k);
                    Values->push_back(curve->GetValues().at(n));
                }
            }

            inputs.emplace_back(Keys, Values, mapto);
        }
    }
    return inputs; // pray for NRVO :-)
}

FBXConverter::KeyFrameListList FBXConverter::GetRotationKeyframeList(const std::vector<const AnimationCurveNode *> &nodes,
                                                                     int64_t start, int64_t stop) {
    KeyFrameListList inputs;
    inputs.reserve(nodes.size() * 3);

    //give some breathing room for rounding errors
    const int64_t adj_start = start - 10000;
    const int64_t adj_stop = stop + 10000;

    for (const AnimationCurveNode *node : nodes) {
        ai_assert(node);

        const AnimationCurveMap &curves = node->Curves();
        for (const AnimationCurveMap::value_type &kv : curves) {

            unsigned int mapto;
            if (kv.first == "d|X") {
                mapto = 0;
            } else if (kv.first == "d|Y") {
                mapto = 1;
            } else if (kv.first == "d|Z") {
                mapto = 2;
            } else {
                FBXImporter::LogWarn("ignoring scale animation curve, did not recognize target component");
                continue;
            }

            const AnimationCurve *const curve = kv.second;
            ai_assert(curve->GetKeys().size() == curve->GetValues().size());
            ai_assert(curve->GetKeys().size());

            //get values within the start/stop time window
            std::shared_ptr<KeyTimeList> Keys(new KeyTimeList());
            std::shared_ptr<KeyValueList> Values(new KeyValueList());
            const size_t count = curve->GetKeys().size();

            int64_t tp = curve->GetKeys().at(0);
            float vp = curve->GetValues().at(0);
            Keys->push_back(tp);
            Values->push_back(vp);
            if (count > 1) {
                int64_t tc = curve->GetKeys().at(1);
                float vc = curve->GetValues().at(1);
                for (size_t n = 1; n < count; n++) {
                    while (std::abs(vc - vp) >= 180.0f) {
                        double step = std::floor(double(tc - tp) / std::abs(vc - vp) * 179.0f);
                        int64_t tnew = tp + int64_t(step);
                        float vnew = vp + (vc - vp) * float(step / (tc - tp));
                        if (tnew >= adj_start && tnew <= adj_stop) {
                            Keys->push_back(tnew);
                            Values->push_back(vnew);
                        }
                        else {
                            // Something broke
                            break;
                        }
                        tp = tnew;
                        vp = vnew;
                    }
                    if (tc >= adj_start && tc <= adj_stop) {
                        Keys->push_back(tc);
                        Values->push_back(vc);
                    }
                    if (n + 1 < count) {
                        tp = tc;
                        vp = vc;
                        tc = curve->GetKeys().at(n + 1);
                        vc = curve->GetValues().at(n + 1);
                    }
                }
            }
            inputs.emplace_back(Keys, Values, mapto);
        }
    }
    return inputs;
}

KeyTimeList FBXConverter::GetKeyTimeList(const KeyFrameListList &inputs) {
    ai_assert(!inputs.empty());

    // reserve some space upfront - it is likely that the key-frame lists
    // have matching time values, so max(of all key-frame lists) should
    // be a good estimate.
    KeyTimeList keys;

    size_t estimate = 0;
    for (const KeyFrameList &kfl : inputs) {
        estimate = std::max(estimate, std::get<0>(kfl)->size());
    }

    keys.reserve(estimate);

    std::vector<unsigned int> next_pos;
    next_pos.resize(inputs.size(), 0);

    const size_t count = inputs.size();
    while (true) {

        int64_t min_tick = std::numeric_limits<int64_t>::max();
        for (size_t i = 0; i < count; ++i) {
            const KeyFrameList &kfl = inputs[i];

            if (std::get<0>(kfl)->size() > next_pos[i] && std::get<0>(kfl)->at(next_pos[i]) < min_tick) {
                min_tick = std::get<0>(kfl)->at(next_pos[i]);
            }
        }

        if (min_tick == std::numeric_limits<int64_t>::max()) {
            break;
        }
        keys.push_back(min_tick);

        for (size_t i = 0; i < count; ++i) {
            const KeyFrameList &kfl = inputs[i];

            while (std::get<0>(kfl)->size() > next_pos[i] && std::get<0>(kfl)->at(next_pos[i]) == min_tick) {
                ++next_pos[i];
            }
        }
    }

    return keys;
}

void FBXConverter::InterpolateKeys(aiVectorKey *valOut, const KeyTimeList &keys, const KeyFrameListList &inputs,
        const aiVector3D &def_value,
        double &max_time,
        double &min_time) {
    ai_assert(!keys.empty());
    ai_assert(nullptr != valOut);

    std::vector<unsigned int> next_pos;
    const size_t count(inputs.size());

    next_pos.resize(inputs.size(), 0);

    for (KeyTimeList::value_type time : keys) {
        ai_real result[3] = { def_value.x, def_value.y, def_value.z };

        for (size_t i = 0; i < count; ++i) {
            const KeyFrameList &kfl = inputs[i];

            const size_t ksize = std::get<0>(kfl)->size();
            if (ksize == 0) {
                continue;
            }
            if (ksize > next_pos[i] && std::get<0>(kfl)->at(next_pos[i]) == time) {
                ++next_pos[i];
            }

            const size_t id0 = next_pos[i] > 0 ? next_pos[i] - 1 : 0;
            const size_t id1 = next_pos[i] == ksize ? ksize - 1 : next_pos[i];

            // use lerp for interpolation
            const KeyValueList::value_type valueA = std::get<1>(kfl)->at(id0);
            const KeyValueList::value_type valueB = std::get<1>(kfl)->at(id1);

            const KeyTimeList::value_type timeA = std::get<0>(kfl)->at(id0);
            const KeyTimeList::value_type timeB = std::get<0>(kfl)->at(id1);

            const ai_real factor = timeB == timeA ? ai_real(0.) : static_cast<ai_real>((time - timeA)) / (timeB - timeA);
            const ai_real interpValue = static_cast<ai_real>(valueA + (valueB - valueA) * factor);

            result[std::get<2>(kfl)] = interpValue;
        }

        // magic value to convert fbx times to seconds
        valOut->mTime = CONVERT_FBX_TIME(time) * anim_fps;

        min_time = std::min(min_time, valOut->mTime);
        max_time = std::max(max_time, valOut->mTime);

        valOut->mValue.x = result[0];
        valOut->mValue.y = result[1];
        valOut->mValue.z = result[2];

        ++valOut;
    }
}

void FBXConverter::InterpolateKeys(aiQuatKey *valOut, const KeyTimeList &keys, const KeyFrameListList &inputs,
        const aiVector3D &def_value,
        double &maxTime,
        double &minTime,
        Model::RotOrder order) {
    ai_assert(!keys.empty());
    ai_assert(nullptr != valOut);

    std::unique_ptr<aiVectorKey[]> temp(new aiVectorKey[keys.size()]);
    InterpolateKeys(temp.get(), keys, inputs, def_value, maxTime, minTime);

    aiMatrix4x4 m;

    aiQuaternion lastq;

    for (size_t i = 0, c = keys.size(); i < c; ++i) {

        valOut[i].mTime = temp[i].mTime;

        GetRotationMatrix(order, temp[i].mValue, m);
        aiQuaternion quat = aiQuaternion(aiMatrix3x3(m));

        // take shortest path by checking the inner product
        // http://www.3dkingdoms.com/weekly/weekly.php?a=36
        if (quat.x * lastq.x + quat.y * lastq.y + quat.z * lastq.z + quat.w * lastq.w < 0) {
            quat.Conjugate();
            quat.w = -quat.w;
        }
        lastq = quat;

        valOut[i].mValue = quat;
    }
}

aiQuaternion FBXConverter::EulerToQuaternion(const aiVector3D &rot, Model::RotOrder order) {
    aiMatrix4x4 m;
    GetRotationMatrix(order, rot, m);

    return aiQuaternion(aiMatrix3x3(m));
}

void FBXConverter::ConvertScaleKeys(aiNodeAnim *na, const std::vector<const AnimationCurveNode *> &nodes, const LayerMap & /*layers*/,
        int64_t start, int64_t stop,
        double &maxTime,
        double &minTime) {
    ai_assert(nodes.size());

    // XXX for now, assume scale should be blended geometrically (i.e. two
    // layers should be multiplied with each other). There is a FBX
    // property in the layer to specify the behaviour, though.

    const KeyFrameListList &inputs = GetKeyframeList(nodes, start, stop);
    const KeyTimeList &keys = GetKeyTimeList(inputs);

    na->mNumScalingKeys = static_cast<unsigned int>(keys.size());
    na->mScalingKeys = new aiVectorKey[keys.size()];
    if (keys.size() > 0) {
        InterpolateKeys(na->mScalingKeys, keys, inputs, aiVector3D(1.0f, 1.0f, 1.0f), maxTime, minTime);
    }
}

void FBXConverter::ConvertTranslationKeys(aiNodeAnim *na, const std::vector<const AnimationCurveNode *> &nodes,
        const LayerMap & /*layers*/,
        int64_t start, int64_t stop,
        double &maxTime,
        double &minTime) {
    ai_assert(nodes.size());

    // XXX see notes in ConvertScaleKeys()
    const KeyFrameListList &inputs = GetKeyframeList(nodes, start, stop);
    const KeyTimeList &keys = GetKeyTimeList(inputs);

    na->mNumPositionKeys = static_cast<unsigned int>(keys.size());
    na->mPositionKeys = new aiVectorKey[keys.size()];
    if (keys.size() > 0)
        InterpolateKeys(na->mPositionKeys, keys, inputs, aiVector3D(0.0f, 0.0f, 0.0f), maxTime, minTime);
}

void FBXConverter::ConvertRotationKeys(aiNodeAnim *na, const std::vector<const AnimationCurveNode *> &nodes,
        const LayerMap & /*layers*/,
        int64_t start, int64_t stop,
        double &maxTime,
        double &minTime,
        Model::RotOrder order) {
    ai_assert(nodes.size());

    // XXX see notes in ConvertScaleKeys()
    const std::vector<KeyFrameList> &inputs = GetRotationKeyframeList(nodes, start, stop);
    const KeyTimeList &keys = GetKeyTimeList(inputs);

    na->mNumRotationKeys = static_cast<unsigned int>(keys.size());
    na->mRotationKeys = new aiQuatKey[keys.size()];
    if (!keys.empty()) {
        InterpolateKeys(na->mRotationKeys, keys, inputs, aiVector3D(0.0f, 0.0f, 0.0f), maxTime, minTime, order);
    }
}

void FBXConverter::ConvertGlobalSettings() {
    if (nullptr == mSceneOut) {
        return;
    }

    const bool hasGenerator = !doc.Creator().empty();

    mSceneOut->mMetaData = aiMetadata::Alloc(16 + (hasGenerator ? 1 : 0));
    mSceneOut->mMetaData->Set(0, "UpAxis", doc.GlobalSettings().UpAxis());
    mSceneOut->mMetaData->Set(1, "UpAxisSign", doc.GlobalSettings().UpAxisSign());
    mSceneOut->mMetaData->Set(2, "FrontAxis", doc.GlobalSettings().FrontAxis());
    mSceneOut->mMetaData->Set(3, "FrontAxisSign", doc.GlobalSettings().FrontAxisSign());
    mSceneOut->mMetaData->Set(4, "CoordAxis", doc.GlobalSettings().CoordAxis());
    mSceneOut->mMetaData->Set(5, "CoordAxisSign", doc.GlobalSettings().CoordAxisSign());
    mSceneOut->mMetaData->Set(6, "OriginalUpAxis", doc.GlobalSettings().OriginalUpAxis());
    mSceneOut->mMetaData->Set(7, "OriginalUpAxisSign", doc.GlobalSettings().OriginalUpAxisSign());
    //const double unitScaleFactor = (double)doc.GlobalSettings().UnitScaleFactor();
    mSceneOut->mMetaData->Set(8, "UnitScaleFactor", doc.GlobalSettings().UnitScaleFactor());
    mSceneOut->mMetaData->Set(9, "OriginalUnitScaleFactor", doc.GlobalSettings().OriginalUnitScaleFactor());
    mSceneOut->mMetaData->Set(10, "AmbientColor", doc.GlobalSettings().AmbientColor());
    mSceneOut->mMetaData->Set(11, "FrameRate", (int)doc.GlobalSettings().TimeMode());
    mSceneOut->mMetaData->Set(12, "TimeSpanStart", doc.GlobalSettings().TimeSpanStart());
    mSceneOut->mMetaData->Set(13, "TimeSpanStop", doc.GlobalSettings().TimeSpanStop());
    mSceneOut->mMetaData->Set(14, "CustomFrameRate", doc.GlobalSettings().CustomFrameRate());
    mSceneOut->mMetaData->Set(15, AI_METADATA_SOURCE_FORMAT_VERSION, aiString(ai_to_string(doc.FBXVersion())));
    if (hasGenerator) {
        mSceneOut->mMetaData->Set(16, AI_METADATA_SOURCE_GENERATOR, aiString(doc.Creator()));
    }
}

void FBXConverter::TransferDataToScene() {
    ai_assert(!mSceneOut->mMeshes);
    ai_assert(!mSceneOut->mNumMeshes);

    // note: the trailing () ensures initialization with nullptr - not
    // many C++ users seem to know this, so pointing it out to avoid
    // confusion why this code works.

    if (!mMeshes.empty()) {
        mSceneOut->mMeshes = new aiMesh *[mMeshes.size()]();
        mSceneOut->mNumMeshes = static_cast<unsigned int>(mMeshes.size());

        std::swap_ranges(mMeshes.begin(), mMeshes.end(), mSceneOut->mMeshes);
    }

    if (!materials.empty()) {
        mSceneOut->mMaterials = new aiMaterial *[materials.size()]();
        mSceneOut->mNumMaterials = static_cast<unsigned int>(materials.size());

        std::swap_ranges(materials.begin(), materials.end(), mSceneOut->mMaterials);
    }

    if (!animations.empty()) {
        mSceneOut->mAnimations = new aiAnimation *[animations.size()]();
        mSceneOut->mNumAnimations = static_cast<unsigned int>(animations.size());

        std::swap_ranges(animations.begin(), animations.end(), mSceneOut->mAnimations);
    }

    if (!lights.empty()) {
        mSceneOut->mLights = new aiLight *[lights.size()]();
        mSceneOut->mNumLights = static_cast<unsigned int>(lights.size());

        std::swap_ranges(lights.begin(), lights.end(), mSceneOut->mLights);
    }

    if (!cameras.empty()) {
        mSceneOut->mCameras = new aiCamera *[cameras.size()]();
        mSceneOut->mNumCameras = static_cast<unsigned int>(cameras.size());

        std::swap_ranges(cameras.begin(), cameras.end(), mSceneOut->mCameras);
    }

    if (!textures.empty()) {
        mSceneOut->mTextures = new aiTexture *[textures.size()]();
        mSceneOut->mNumTextures = static_cast<unsigned int>(textures.size());

        std::swap_ranges(textures.begin(), textures.end(), mSceneOut->mTextures);
    }

    if (!mSkeletons.empty()) {
        mSceneOut->mSkeletons = new aiSkeleton *[mSkeletons.size()];
        mSceneOut->mNumSkeletons = static_cast<unsigned int>(mSkeletons.size());
        std::swap_ranges(mSkeletons.begin(), mSkeletons.end(), mSceneOut->mSkeletons);
    }
}

void FBXConverter::ConvertOrphanedEmbeddedTextures() {
    // in C++14 it could be:
    // for (auto&& [id, object] : objects)
    for (auto &&id_and_object : doc.Objects()) {
        auto &&id = std::get<0>(id_and_object);
        auto &&object = std::get<1>(id_and_object);
        // If an object doesn't have parent
        if (doc.ConnectionsBySource().count(id) == 0) {
            const Texture *realTexture = nullptr;
            try {
                const auto &element = object->GetElement();
                const Token &key = element.KeyToken();
                const char *obtype = key.begin();
                const size_t length = static_cast<size_t>(key.end() - key.begin());
                if (strncmp(obtype, "Texture", length) == 0) {
                    if (const Texture *texture = static_cast<const Texture *>(object->Get())) {
                        if (texture->Media() && texture->Media()->ContentLength() > 0) {
                            realTexture = texture;
                        }
                    }
                }
            } catch (...) {
                // do nothing
            }
            if (realTexture) {
                const Video *media = realTexture->Media();
                unsigned int index = ConvertVideo(*media);
                textures_converted[media] = index;
            }
        }
    }
}

// ------------------------------------------------------------------------------------------------
void ConvertToAssimpScene(aiScene *out, const Document &doc, bool removeEmptyBones) {
    FBXConverter converter(out, doc, removeEmptyBones);
}

} // namespace FBX
} // namespace Assimp

#endif
