/*
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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 "FBXParser.h"
#include "FBXMeshGeometry.h"
#include "FBXDocument.h"
#include "FBXUtil.h"
#include "FBXProperties.h"
#include "FBXImporter.h"

#include <assimp/StringComparison.h>

#include <assimp/scene.h>

#include <assimp/CreateAnimMesh.h>

#include <tuple>
#include <memory>
#include <iterator>
#include <vector>
#include <sstream>
#include <iomanip>

namespace Assimp {
    namespace FBX {

        using namespace Util;

#define MAGIC_NODE_TAG "_$AssimpFbx$"

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

        FBXConverter::FBXConverter(aiScene* out, const Document& doc)
            : defaultMaterialIndex()
            , out(out)
            , doc(doc) {
            // 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();
            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, 0);
                        }
                    }
                }
            }

            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;
            }
        }


        FBXConverter::~FBXConverter() {
            std::for_each(meshes.begin(), meshes.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() {
            out->mRootNode = new aiNode();
            out->mRootNode->mName.Set("RootNode");

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

        void FBXConverter::ConvertNodes(uint64_t id, aiNode& parent, const aiMatrix4x4& parent_transform) {
            const std::vector<const Connection*>& conns = doc.GetConnectionsByDestinationSequenced(id, "Model");

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

            std::vector<aiNode*> nodes_chain;
            std::vector<aiNode*> post_nodes_chain;

            try {
                for (const Connection* con : conns) {

                    // ignore object-property links
                    if (con->PropertyName().length()) {
                        continue;
                    }

                    const Object* const object = con->SourceObject();
                    if (nullptr == object) {
                        FBXImporter::LogWarn("failed to convert source object for Model link");
                        continue;
                    }

                    const Model* const model = dynamic_cast<const Model*>(object);

                    if (nullptr != model) {
                        nodes_chain.clear();
                        post_nodes_chain.clear();

                        aiMatrix4x4 new_abs_transform = parent_transform;

                        // 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.
                        GenerateTransformationNodeChain(*model, nodes_chain, post_nodes_chain);

                        ai_assert(nodes_chain.size());

                        std::string original_name = FixNodeName(model->Name());

                        // check if any of the nodes in the chain has the name the fbx node
                        // is supposed to have. If there is none, add another node to
                        // preserve the name - people might have scripts etc. that rely
                        // on specific node names.
                        aiNode* name_carrier = NULL;
                        for (aiNode* prenode : nodes_chain) {
                            if (!strcmp(prenode->mName.C_Str(), original_name.c_str())) {
                                name_carrier = prenode;
                                break;
                            }
                        }

                        if (!name_carrier) {
                            std::string old_original_name = original_name;
                            GetUniqueName(old_original_name, original_name);
                            nodes_chain.push_back(new aiNode(original_name));
                        }
                        else {
                            original_name = nodes_chain.back()->mName.C_Str();
                        }

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

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

                            if (last_parent != &parent) {
                                last_parent->mNumChildren = 1;
                                last_parent->mChildren = new aiNode*[1];
                                last_parent->mChildren[0] = prenode;
                            }

                            prenode->mParent = last_parent;
                            last_parent = prenode;

                            new_abs_transform *= prenode->mTransformation;
                        }

                        // attach geometry
                        ConvertModel(*model, *nodes_chain.back(), 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 (aiNode* postnode : post_nodes_chain) {
                                ai_assert(postnode);

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

                                postnode->mParent = last_parent;
                                last_parent = postnode;

                                new_abs_transform *= postnode->mTransformation;
                            }
                        }
                        else {
                            // free the nodes we allocated as we don't need them
                            Util::delete_fun<aiNode> deleter;
                            std::for_each(
                                post_nodes_chain.begin(),
                                post_nodes_chain.end(),
                                deleter
                            );
                        }

                        // attach sub-nodes (if any)
                        ConvertNodes(model->ID(), *last_parent, new_abs_transform);

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

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

                        nodes.push_back(nodes_chain.front());
                        nodes_chain.clear();
                    }
                }

                if (nodes.size()) {
                    parent.mChildren = new aiNode*[nodes.size()]();
                    parent.mNumChildren = static_cast<unsigned int>(nodes.size());

                    std::swap_ranges(nodes.begin(), nodes.end(), parent.mChildren);
                }
            }
            catch (std::exception&) {
                Util::delete_fun<aiNode> deleter;
                std::for_each(nodes.begin(), nodes.end(), deleter);
                std::for_each(nodes_chain.begin(), nodes_chain.end(), deleter);
                std::for_each(post_nodes_chain.begin(), post_nodes_chain.end(), deleter);
            }
        }


        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);
            }
        }

        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();

            //cameras are defined along positive x direction
            out_camera->mPosition = cam.Position();
            out_camera->mLookAt = (cam.InterestPosition() - out_camera->mPosition).Normalize();
            out_camera->mUp = cam.UpVector();

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

        void FBXConverter::GetUniqueName(const std::string &name, std::string &uniqueName)
        {
            int i = 0;
            uniqueName = name;
            while (mNodeNames.find(uniqueName) != mNodeNames.end())
            {
                ++i;
                std::stringstream ext;
                ext << name << std::setfill('0') << std::setw(3) << i;
                uniqueName = ext.str();
            }
            mNodeNames.insert(uniqueName);
        }


        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 = 1e-6f;

            out = aiMatrix4x4();

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

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

            const float zero_epsilon = 1e-6f;
            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) {
                    continue;
                }

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

                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);
        }

        void FBXConverter::GenerateTransformationNodeChain(const Model& model, std::vector<aiNode*>& output_nodes,
            std::vector<aiNode*>& post_output_nodes) {
            const PropertyTable& props = model.Props();
            const Model::RotOrder rot = model.RotationOrder();

            bool ok;

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

            // generate transformation matrices for all the different transformation components
            const float zero_epsilon = 1e-6f;
            const aiVector3D all_ones(1.0f, 1.0f, 1.0f);
            bool is_complex = false;

            const aiVector3D& PreRotation = PropertyGet<aiVector3D>(props, "PreRotation", ok);
            if (ok && PreRotation.SquareLength() > zero_epsilon) {
                is_complex = true;

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

            const aiVector3D& PostRotation = PropertyGet<aiVector3D>(props, "PostRotation", ok);
            if (ok && PostRotation.SquareLength() > zero_epsilon) {
                is_complex = true;

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

            const aiVector3D& RotationPivot = PropertyGet<aiVector3D>(props, "RotationPivot", ok);
            if (ok && RotationPivot.SquareLength() > zero_epsilon) {
                is_complex = true;

                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) {
                is_complex = true;

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

            const aiVector3D& ScalingOffset = PropertyGet<aiVector3D>(props, "ScalingOffset", ok);
            if (ok && ScalingOffset.SquareLength() > zero_epsilon) {
                is_complex = true;

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

            const aiVector3D& ScalingPivot = PropertyGet<aiVector3D>(props, "ScalingPivot", ok);
            if (ok && ScalingPivot.SquareLength() > zero_epsilon) {
                is_complex = true;

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

            const aiVector3D& Scaling = PropertyGet<aiVector3D>(props, "Lcl Scaling", ok);
            if (ok && (Scaling - all_ones).SquareLength() > zero_epsilon) {
                aiMatrix4x4::Scaling(Scaling, chain[TransformationComp_Scaling]);
            }

            const aiVector3D& Rotation = PropertyGet<aiVector3D>(props, "Lcl Rotation", ok);
            if (ok && Rotation.SquareLength() > zero_epsilon) {
                GetRotationMatrix(rot, Rotation, chain[TransformationComp_Rotation]);
            }

            const aiVector3D& GeometricScaling = PropertyGet<aiVector3D>(props, "GeometricScaling", ok);
            if (ok && (GeometricScaling - all_ones).SquareLength() > zero_epsilon) {
                is_complex = true;
                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) {
                    aiMatrix4x4::Scaling(GeometricScalingInverse, chain[TransformationComp_GeometricScalingInverse]);
                }
            }

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

            // is_complex needs to be consistent with NeedsComplexTransformationChain()
            // or the interplay between this code and the animation converter would
            // not be guaranteed.
            ai_assert(NeedsComplexTransformationChain(model) == is_complex);

            std::string name = FixNodeName(model.Name());

            // 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 (is_complex && 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 (chain[i].IsIdentity() && (anim_chain_bitmask & bit) == 0) {
                        continue;
                    }

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

                    aiNode* nd = new aiNode();
                    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.push_back(nd);
                    }
                    else {
                        output_nodes.push_back(nd);
                    }
                }

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

            // else, we can just multiply the matrices together
            aiNode* nd = new aiNode();
            output_nodes.push_back(nd);
            std::string uniqueName;
            GetUniqueName(name, uniqueName);

            nd->mName.Set(uniqueName);

            for (const auto &transform : chain) {
                nd->mTransformation = nd->mTransformation * transform;
            }
        }

        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>* interpreted = prop.second->As<TypedProperty<bool> >()) {
                    data->Set(index++, prop.first, interpreted->Value());
                }
                else if (const TypedProperty<int>* interpreted = prop.second->As<TypedProperty<int> >()) {
                    data->Set(index++, prop.first, interpreted->Value());
                }
                else if (const TypedProperty<uint64_t>* interpreted = prop.second->As<TypedProperty<uint64_t> >()) {
                    data->Set(index++, prop.first, interpreted->Value());
                }
                else if (const TypedProperty<float>* interpreted = prop.second->As<TypedProperty<float> >()) {
                    data->Set(index++, prop.first, interpreted->Value());
                }
                else if (const TypedProperty<std::string>* interpreted = prop.second->As<TypedProperty<std::string> >()) {
                    data->Set(index++, prop.first, aiString(interpreted->Value()));
                }
                else if (const TypedProperty<aiVector3D>* interpreted = prop.second->As<TypedProperty<aiVector3D> >()) {
                    data->Set(index++, prop.first, interpreted->Value());
                }
                else {
                    ai_assert(false);
                }
            }
        }

        void FBXConverter::ConvertModel(const Model& model, aiNode& nd, const aiMatrix4x4& node_global_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, node_global_transform, nd);
                    std::copy(indices.begin(), indices.end(), std::back_inserter(meshes));
                }
                else if (line) {
                    const std::vector<unsigned int>& indices = ConvertLine(*line, model, node_global_transform, nd);
                    std::copy(indices.begin(), indices.end(), std::back_inserter(meshes));
                }
                else {
                    FBXImporter::LogWarn("ignoring unrecognized geometry: " + geo->Name());
                }
            }

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

                std::swap_ranges(meshes.begin(), meshes.end(), nd.mMeshes);
            }
        }

        std::vector<unsigned int> FBXConverter::ConvertMesh(const MeshGeometry& mesh, const Model& model,
            const aiMatrix4x4& node_global_transform, aiNode& nd)
        {
            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, node_global_transform, nd);
                    }
                }
            }

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

        std::vector<unsigned int> FBXConverter::ConvertLine(const LineGeometry& line, const Model& model,
            const aiMatrix4x4& node_global_transform, aiNode& nd)
        {
            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, nd);
            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 = 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>(meshes.size() - 1));
            return temp;
        }

        aiMesh* FBXConverter::SetupEmptyMesh(const Geometry& mesh, aiNode& nd)
        {
            aiMesh* const out_mesh = new aiMesh();
            meshes.push_back(out_mesh);
            meshes_converted[&mesh].push_back(static_cast<unsigned int>(meshes.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 = nd.mName;
            }

            return out_mesh;
        }

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

            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 = NULL;
                    }
                }

                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->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() != NULL) {
                ConvertWeights(out_mesh, model, mesh, node_global_transform, NO_MATERIAL_SEPARATION);
            }

            std::vector<aiAnimMesh*> animMeshes;
            for (const BlendShape* blendShape : mesh.GetBlendShapes()) {
                for (const BlendShapeChannel* blendShapeChannel : blendShape->BlendShapeChannels()) {
                    const std::vector<const ShapeGeometry*>& shapeGeometries = blendShapeChannel->GetShapeGeometries();
                    for (size_t i = 0; i < shapeGeometries.size(); i++) {
                        aiAnimMesh *animMesh = aiCreateAnimMesh(out_mesh);
                        const ShapeGeometry* shapeGeometry = shapeGeometries.at(i);
                        const std::vector<aiVector3D>& vertices = shapeGeometry->GetVertices();
                        const std::vector<aiVector3D>& normals = shapeGeometry->GetNormals();
                        const std::vector<unsigned int>& indices = shapeGeometry->GetIndices();
                        animMesh->mName.Set(FixAnimMeshName(shapeGeometry->Name()));
                        for (size_t j = 0; j < indices.size(); j++) {
                            unsigned int index = indices.at(j);
                            aiVector3D vertex = vertices.at(j);
                            aiVector3D normal = normals.at(j);
                            unsigned int count = 0;
                            const unsigned int* outIndices = mesh.ToOutputVertexIndex(index, 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);
                    }
                }
            }
            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>(meshes.size() - 1);
        }

        std::vector<unsigned int> FBXConverter::ConvertMeshMultiMaterial(const MeshGeometry& mesh, const Model& model,
            const aiMatrix4x4& node_global_transform, aiNode& nd)
        {
            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, index, node_global_transform, nd));
                    had.insert(index);
                }
            }

            return indices;
        }

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

            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() != NULL;

            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
            std::vector<unsigned int> reverseMapping;

            if (process_weights) {
                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[vertices.size()];
            }

            // 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 = NULL;
                    }
                }

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

                    out_mesh->mTangents = new aiVector3D[vertices.size()];
                    out_mesh->mBitangents = new aiVector3D[vertices.size()];
                }
            }

            // 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[vertices.size()];
                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[vertices.size()];
            }

            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;
                    }

                    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, model, mesh, node_global_transform, index, &reverseMapping);
            }

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

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

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

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

            std::vector<aiBone*> bones;
            bones.reserve(sk.Clusters().size());

            const bool no_mat_check = materialIndex == NO_MATERIAL_SEPARATION;
            ai_assert(no_mat_check || outputVertStartIndices);

            try {

                for (const Cluster* cluster : sk.Clusters()) {
                    ai_assert(cluster);

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

                    if (indices.empty()) {
                        continue;
                    }

                    const MatIndexArray& mats = geo.GetMaterialIndices();

                    bool ok = false;

                    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 NULL if index is out of bounds
                        // which should never happen
                        ai_assert(out_idx != NULL);

                        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();
                                ok = true;
                            }
                        }
                    }

                    // 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.
                    if (ok) {
                        ConvertCluster(bones, model, *cluster, out_indices, index_out_indices,
                            count_out_indices, node_global_transform);
                    }
                }
            }
            catch (std::exception&) {
                std::for_each(bones.begin(), bones.end(), Util::delete_fun<aiBone>());
                throw;
            }

            if (bones.empty()) {
                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*>& bones, const Model& /*model*/, const Cluster& cl,
            std::vector<size_t>& out_indices,
            std::vector<size_t>& index_out_indices,
            std::vector<size_t>& count_out_indices,
            const aiMatrix4x4& node_global_transform)
        {

            aiBone* const bone = new aiBone();
            bones.push_back(bone);

            bone->mName = FixNodeName(cl.TargetNode()->Name());

            bone->mOffsetMatrix = cl.TransformLink();
            bone->mOffsetMatrix.Inverse();

            bone->mOffsetMatrix = bone->mOffsetMatrix * node_global_transform;

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

            const size_t no_index_sentinel = std::numeric_limits<size_t>::max();
            const WeightArray& weights = cl.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) {
                    aiVertexWeight& out_weight = *cursor++;

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

        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);
            }

            // 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.FileName().empty() ? video.RelativeFilename() : video.FileName();
            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(video.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;

                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, 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 != 0)
            {
                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();
                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 mesh = dynamic_cast<const MeshGeometry*> (v.first);
                                if (!mesh) {
                                    continue;
                                }

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

                                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");
                                    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();
                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 mesh = dynamic_cast<const MeshGeometry*> (v.first);
                                if (!mesh) {
                                    continue;
                                }

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

                                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");
                                    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 );
            //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);
        }

        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 );
        }

        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);
            }

            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);
            }

            // 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);
            }

            // 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);
    }
}


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>* interpreted = prop.second->As<TypedProperty<aiVector3D> >())
        {
            out_mat->AddProperty(&interpreted->Value(), 1, name.c_str(), 0, 0);
        }
        else if (const TypedProperty<aiColor3D>* interpreted = prop.second->As<TypedProperty<aiColor3D> >())
        {
            out_mat->AddProperty(&interpreted->Value(), 1, name.c_str(), 0, 0);
        }
        else if (const TypedProperty<aiColor4D>* interpreted = prop.second->As<TypedProperty<aiColor4D> >())
        {
            out_mat->AddProperty(&interpreted->Value(), 1, name.c_str(), 0, 0);
        }
        else if (const TypedProperty<float>* interpreted = prop.second->As<TypedProperty<float> >())
        {
            out_mat->AddProperty(&interpreted->Value(), 1, name.c_str(), 0, 0);
        }
        else if (const TypedProperty<int>* interpreted = prop.second->As<TypedProperty<int> >())
        {
            out_mat->AddProperty(&interpreted->Value(), 1, name.c_str(), 0, 0);
        }
        else if (const TypedProperty<bool>* interpreted = prop.second->As<TypedProperty<bool> >())
        {
            int value = interpreted->Value() ? 1 : 0;
            out_mat->AddProperty(&value, 1, name.c_str(), 0, 0);
        }
        else if (const TypedProperty<std::string>* interpreted = prop.second->As<TypedProperty<std::string> >())
        {
            const aiString value = aiString(interpreted->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 it = textures_converted.find(media);
                if (it != textures_converted.end()) {
                    index = (*it).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, 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();
            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 mesh = dynamic_cast<const MeshGeometry*>(v.first);
                            if (!mesh) {
                                continue;
                            }

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

                            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");
                                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, (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*>& animations = doc.AnimationStacks();
            for (const AnimationStack* stack : animations) {
                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& name = FixNodeName(model->Name());
                        node_map[name].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 (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, 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(NULL);
            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 = NULL;
            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::LogDebug("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(),
                    layer_map,
                    start, stop,
                    max_time,
                    min_time,
                    true // input is TRS order, assimp is SRT
                );

                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 = 1e-6f;
            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 iter_end,
            const LayerMap& layer_map,
            int64_t start, int64_t stop,
            double& max_time,
            double& min_time,
            bool reverse_order)

        {
            std::unique_ptr<aiNodeAnim> na(new aiNodeAnim());
            na->mNodeName.Set(name);

            const PropertyTable& props = target.Props();

            // need to convert from TRS order to SRT?
            if (reverse_order) {

                aiVector3D def_scale = PropertyGet(props, "Lcl Scaling", aiVector3D(1.f, 1.f, 1.f));
                aiVector3D def_translate = PropertyGet(props, "Lcl Translation", aiVector3D(0.f, 0.f, 0.f));
                aiVector3D def_rot = PropertyGet(props, "Lcl Rotation", aiVector3D(0.f, 0.f, 0.f));

                KeyFrameListList scaling;
                KeyFrameListList translation;
                KeyFrameListList rotation;

                if (chain[TransformationComp_Scaling] != iter_end) {
                    scaling = GetKeyframeList((*chain[TransformationComp_Scaling]).second, start, stop);
                }

                if (chain[TransformationComp_Translation] != iter_end) {
                    translation = GetKeyframeList((*chain[TransformationComp_Translation]).second, start, stop);
                }

                if (chain[TransformationComp_Rotation] != iter_end) {
                    rotation = GetKeyframeList((*chain[TransformationComp_Rotation]).second, start, stop);
                }

                KeyFrameListList joined;
                joined.insert(joined.end(), scaling.begin(), scaling.end());
                joined.insert(joined.end(), translation.begin(), translation.end());
                joined.insert(joined.end(), rotation.begin(), rotation.end());

                const KeyTimeList& times = GetKeyTimeList(joined);

                aiQuatKey* out_quat = new aiQuatKey[times.size()];
                aiVectorKey* out_scale = new aiVectorKey[times.size()];
                aiVectorKey* out_translation = new aiVectorKey[times.size()];

                if (times.size())
                {
                    ConvertTransformOrder_TRStoSRT(out_quat, out_scale, out_translation,
                        scaling,
                        translation,
                        rotation,
                        times,
                        max_time,
                        min_time,
                        target.RotationOrder(),
                        def_scale,
                        def_translate,
                        def_rot);
                }

                // XXX remove duplicates / redundant keys which this operation did
                // likely produce if not all three channels were equally dense.

                na->mNumScalingKeys = static_cast<unsigned int>(times.size());
                na->mNumRotationKeys = na->mNumScalingKeys;
                na->mNumPositionKeys = na->mNumScalingKeys;

                na->mScalingKeys = out_scale;
                na->mRotationKeys = out_quat;
                na->mPositionKeys = out_translation;
            }
            else {

                // if a particular transformation is not given, grab it from
                // the corresponding node to meet the semantics of aiNodeAnim,
                // which requires all of rotation, scaling and translation
                // to be set.
                if (chain[TransformationComp_Scaling] != iter_end) {
                    ConvertScaleKeys(na.get(), (*chain[TransformationComp_Scaling]).second,
                        layer_map,
                        start, stop,
                        max_time,
                        min_time);
                }
                else {
                    na->mScalingKeys = new aiVectorKey[1];
                    na->mNumScalingKeys = 1;

                    na->mScalingKeys[0].mTime = 0.;
                    na->mScalingKeys[0].mValue = PropertyGet(props, "Lcl Scaling",
                        aiVector3D(1.f, 1.f, 1.f));
                }

                if (chain[TransformationComp_Rotation] != iter_end) {
                    ConvertRotationKeys(na.get(), (*chain[TransformationComp_Rotation]).second,
                        layer_map,
                        start, stop,
                        max_time,
                        min_time,
                        target.RotationOrder());
                }
                else {
                    na->mRotationKeys = new aiQuatKey[1];
                    na->mNumRotationKeys = 1;

                    na->mRotationKeys[0].mTime = 0.;
                    na->mRotationKeys[0].mValue = EulerToQuaternion(
                        PropertyGet(props, "Lcl Rotation", aiVector3D(0.f, 0.f, 0.f)),
                        target.RotationOrder());
                }

                if (chain[TransformationComp_Translation] != iter_end) {
                    ConvertTranslationKeys(na.get(), (*chain[TransformationComp_Translation]).second,
                        layer_map,
                        start, stop,
                        max_time,
                        min_time);
                }
                else {
                    na->mPositionKeys = new aiVectorKey[1];
                    na->mNumPositionKeys = 1;

                    na->mPositionKeys[0].mTime = 0.;
                    na->mPositionKeys[0].mValue = PropertyGet(props, "Lcl Translation",
                        aiVector3D(0.f, 0.f, 0.f));
                }

            }
            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() && 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.push_back(std::make_tuple(Keys, Values, mapto));
                }
            }
            return inputs; // pray for NRVO :-)
        }


        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.x = -quat.x;
                    quat.y = -quat.y;
                    quat.z = -quat.z;
                    quat.w = -quat.w;
                }
                lastq = quat;

                valOut[i].mValue = quat;
            }
        }

        void FBXConverter::ConvertTransformOrder_TRStoSRT(aiQuatKey* out_quat, aiVectorKey* out_scale,
            aiVectorKey* out_translation,
            const KeyFrameListList& scaling,
            const KeyFrameListList& translation,
            const KeyFrameListList& rotation,
            const KeyTimeList& times,
            double& maxTime,
            double& minTime,
            Model::RotOrder order,
            const aiVector3D& def_scale,
            const aiVector3D& def_translate,
            const aiVector3D& def_rotation)
        {
            if (rotation.size()) {
                InterpolateKeys(out_quat, times, rotation, def_rotation, maxTime, minTime, order);
            }
            else {
                for (size_t i = 0; i < times.size(); ++i) {
                    out_quat[i].mTime = CONVERT_FBX_TIME(times[i]) * anim_fps;
                    out_quat[i].mValue = EulerToQuaternion(def_rotation, order);
                }
            }

            if (scaling.size()) {
                InterpolateKeys(out_scale, times, scaling, def_scale, maxTime, minTime);
            }
            else {
                for (size_t i = 0; i < times.size(); ++i) {
                    out_scale[i].mTime = CONVERT_FBX_TIME(times[i]) * anim_fps;
                    out_scale[i].mValue = def_scale;
                }
            }

            if (translation.size()) {
                InterpolateKeys(out_translation, times, translation, def_translate, maxTime, minTime);
            }
            else {
                for (size_t i = 0; i < times.size(); ++i) {
                    out_translation[i].mTime = CONVERT_FBX_TIME(times[i]) * anim_fps;
                    out_translation[i].mValue = def_translate;
                }
            }

            const size_t count = times.size();
            for (size_t i = 0; i < count; ++i) {
                aiQuaternion& r = out_quat[i].mValue;
                aiVector3D& s = out_scale[i].mValue;
                aiVector3D& t = out_translation[i].mValue;

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

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

        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 = GetKeyframeList(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 == out) {
                return;
            }

            out->mMetaData = aiMetadata::Alloc(15);
            out->mMetaData->Set(0, "UpAxis", doc.GlobalSettings().UpAxis());
            out->mMetaData->Set(1, "UpAxisSign", doc.GlobalSettings().UpAxisSign());
            out->mMetaData->Set(2, "FrontAxis", doc.GlobalSettings().FrontAxis());
            out->mMetaData->Set(3, "FrontAxisSign", doc.GlobalSettings().FrontAxisSign());
            out->mMetaData->Set(4, "CoordAxis", doc.GlobalSettings().CoordAxis());
            out->mMetaData->Set(5, "CoordAxisSign", doc.GlobalSettings().CoordAxisSign());
            out->mMetaData->Set(6, "OriginalUpAxis", doc.GlobalSettings().OriginalUpAxis());
            out->mMetaData->Set(7, "OriginalUpAxisSign", doc.GlobalSettings().OriginalUpAxisSign());
            out->mMetaData->Set(8, "UnitScaleFactor", (double)doc.GlobalSettings().UnitScaleFactor());
            out->mMetaData->Set(9, "OriginalUnitScaleFactor", doc.GlobalSettings().OriginalUnitScaleFactor());
            out->mMetaData->Set(10, "AmbientColor", doc.GlobalSettings().AmbientColor());
            out->mMetaData->Set(11, "FrameRate", (int)doc.GlobalSettings().TimeMode());
            out->mMetaData->Set(12, "TimeSpanStart", doc.GlobalSettings().TimeSpanStart());
            out->mMetaData->Set(13, "TimeSpanStop", doc.GlobalSettings().TimeSpanStop());
            out->mMetaData->Set(14, "CustomFrameRate", doc.GlobalSettings().CustomFrameRate());
        }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    } // !FBX
} // !Assimp

#endif