move 3rd-party librarys into libs/ and add built-in honeysuckle

1 files changed, 2799 insertions, 0 deletions

diff --git a/libs/assimp/code/AssetLib/FBX/FBXExporter.cpp b/libs/assimp/code/AssetLib/FBX/FBXExporter.cpp
new file mode 100644
index 0000000..6956728
--- /dev/null
+++ b/libs/assimp/code/AssetLib/FBX/FBXExporter.cpp
@@ -0,0 +1,2799 @@
+/*
+Open Asset Import Library (assimp)
+----------------------------------------------------------------------
+
+Copyright (c) 2006-2022, assimp team
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the
+following conditions are met:
+
+* Redistributions of source code must retain the above
+copyright notice, this list of conditions and the
+following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other
+materials provided with the distribution.
+
+* Neither the name of the assimp team, nor the names of its
+contributors may be used to endorse or promote products
+derived from this software without specific prior
+written permission of the assimp team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+----------------------------------------------------------------------
+*/
+#ifndef ASSIMP_BUILD_NO_EXPORT
+#ifndef ASSIMP_BUILD_NO_FBX_EXPORTER
+
+#include "FBXExporter.h"
+#include "FBXExportNode.h"
+#include "FBXExportProperty.h"
+#include "FBXCommon.h"
+#include "FBXUtil.h"
+
+#include <assimp/version.h> // aiGetVersion
+#include <assimp/IOSystem.hpp>
+#include <assimp/Exporter.hpp>
+#include <assimp/DefaultLogger.hpp>
+#include <assimp/StreamWriter.h> // StreamWriterLE
+#include <assimp/Exceptional.h> // DeadlyExportError
+#include <assimp/material.h> // aiTextureType
+#include <assimp/scene.h>
+#include <assimp/mesh.h>
+
+// Header files, standard library.
+#include <memory> // shared_ptr
+#include <string>
+#include <sstream> // stringstream
+#include <ctime> // localtime, tm_*
+#include <map>
+#include <set>
+#include <vector>
+#include <array>
+#include <unordered_set>
+#include <numeric>
+
+// RESOURCES:
+// https://code.blender.org/2013/08/fbx-binary-file-format-specification/
+// https://wiki.blender.org/index.php/User:Mont29/Foundation/FBX_File_Structure
+
+const ai_real DEG = ai_real( 57.29577951308232087679815481 ); // degrees per radian
+
+using namespace Assimp;
+using namespace Assimp::FBX;
+
+// some constants that we'll use for writing metadata
+namespace Assimp {
+namespace FBX {
+    const std::string EXPORT_VERSION_STR = "7.5.0";
+    const uint32_t EXPORT_VERSION_INT = 7500; // 7.5 == 2016+
+    // FBX files have some hashed values that depend on the creation time field,
+    // but for now we don't actually know how to generate these.
+    // what we can do is set them to a known-working version.
+    // this is the data that Blender uses in their FBX export process.
+    const std::string GENERIC_CTIME = "1970-01-01 10:00:00:000";
+    const std::string GENERIC_FILEID =
+        "\x28\xb3\x2a\xeb\xb6\x24\xcc\xc2\xbf\xc8\xb0\x2a\xa9\x2b\xfc\xf1";
+    const std::string GENERIC_FOOTID =
+        "\xfa\xbc\xab\x09\xd0\xc8\xd4\x66\xb1\x76\xfb\x83\x1c\xf7\x26\x7e";
+    const std::string FOOT_MAGIC =
+        "\xf8\x5a\x8c\x6a\xde\xf5\xd9\x7e\xec\xe9\x0c\xe3\x75\x8f\x29\x0b";
+    const std::string COMMENT_UNDERLINE =
+        ";------------------------------------------------------------------";
+}
+
+    // ---------------------------------------------------------------------
+    // Worker function for exporting a scene to binary FBX.
+    // Prototyped and registered in Exporter.cpp
+    void ExportSceneFBX (
+        const char* pFile,
+        IOSystem* pIOSystem,
+        const aiScene* pScene,
+        const ExportProperties* pProperties
+    ){
+        // initialize the exporter
+        FBXExporter exporter(pScene, pProperties);
+
+        // perform binary export
+        exporter.ExportBinary(pFile, pIOSystem);
+    }
+
+    // ---------------------------------------------------------------------
+    // Worker function for exporting a scene to ASCII FBX.
+    // Prototyped and registered in Exporter.cpp
+    void ExportSceneFBXA (
+        const char* pFile,
+        IOSystem* pIOSystem,
+        const aiScene* pScene,
+        const ExportProperties* pProperties
+
+    ){
+        // initialize the exporter
+        FBXExporter exporter(pScene, pProperties);
+
+        // perform ascii export
+        exporter.ExportAscii(pFile, pIOSystem);
+    }
+
+} // end of namespace Assimp
+
+FBXExporter::FBXExporter ( const aiScene* pScene, const ExportProperties* pProperties )
+: binary(false)
+, mScene(pScene)
+, mProperties(pProperties)
+, outfile()
+, connections()
+, mesh_uids()
+, material_uids()
+, node_uids() {
+    // will probably need to determine UIDs, connections, etc here.
+    // basically anything that needs to be known
+    // before we start writing sections to the stream.
+}
+
+void FBXExporter::ExportBinary (
+    const char* pFile,
+    IOSystem* pIOSystem
+){
+    // remember that we're exporting in binary mode
+    binary = true;
+
+    // we're not currently using these preferences,
+    // but clang will cry about it if we never touch it.
+    // TODO: some of these might be relevant to export
+    (void)mProperties;
+
+    // open the indicated file for writing (in binary mode)
+    outfile.reset(pIOSystem->Open(pFile,"wb"));
+    if (!outfile) {
+        throw DeadlyExportError(
+            "could not open output .fbx file: " + std::string(pFile)
+        );
+    }
+
+    // first a binary-specific file header
+    WriteBinaryHeader();
+
+    // the rest of the file is in node entries.
+    // we have to serialize each entry before we write to the output,
+    // as the first thing we write is the byte offset of the _next_ entry.
+    // Either that or we can skip back to write the offset when we finish.
+    WriteAllNodes();
+
+    // finally we have a binary footer to the file
+    WriteBinaryFooter();
+
+    // explicitly release file pointer,
+    // so we don't have to rely on class destruction.
+    outfile.reset();
+}
+
+void FBXExporter::ExportAscii (
+    const char* pFile,
+    IOSystem* pIOSystem
+){
+    // remember that we're exporting in ascii mode
+    binary = false;
+
+    // open the indicated file for writing in text mode
+    outfile.reset(pIOSystem->Open(pFile,"wt"));
+    if (!outfile) {
+        throw DeadlyExportError(
+            "could not open output .fbx file: " + std::string(pFile)
+        );
+    }
+
+    // write the ascii header
+    WriteAsciiHeader();
+
+    // write all the sections
+    WriteAllNodes();
+
+    // make sure the file ends with a newline.
+    // note: if the file is opened in text mode,
+    // this should do the right cross-platform thing.
+    outfile->Write("\n", 1, 1);
+
+    // explicitly release file pointer,
+    // so we don't have to rely on class destruction.
+    outfile.reset();
+}
+
+void FBXExporter::WriteAsciiHeader()
+{
+    // basically just a comment at the top of the file
+    std::stringstream head;
+    head << "; FBX " << EXPORT_VERSION_STR << " project file\n";
+    head << "; Created by the Open Asset Import Library (Assimp)\n";
+    head << "; http://assimp.org\n";
+    head << "; -------------------------------------------------\n";
+    const std::string ascii_header = head.str();
+    outfile->Write(ascii_header.c_str(), ascii_header.size(), 1);
+}
+
+void FBXExporter::WriteAsciiSectionHeader(const std::string& title)
+{
+    StreamWriterLE outstream(outfile);
+    std::stringstream s;
+    s << "\n\n; " << title << '\n';
+    s << FBX::COMMENT_UNDERLINE << "\n";
+    outstream.PutString(s.str());
+}
+
+void FBXExporter::WriteBinaryHeader()
+{
+    // first a specific sequence of 23 bytes, always the same
+    const char binary_header[24] = "Kaydara FBX Binary\x20\x20\x00\x1a\x00";
+    outfile->Write(binary_header, 1, 23);
+
+    // then FBX version number, "multiplied" by 1000, as little-endian uint32.
+    // so 7.3 becomes 7300 == 0x841C0000, 7.4 becomes 7400 == 0xE81C0000, etc
+    {
+        StreamWriterLE outstream(outfile);
+        outstream.PutU4(EXPORT_VERSION_INT);
+    } // StreamWriter destructor writes the data to the file
+
+    // after this the node data starts immediately
+    // (probably with the FBXHEaderExtension node)
+}
+
+void FBXExporter::WriteBinaryFooter()
+{
+    outfile->Write(NULL_RECORD.c_str(), NULL_RECORD.size(), 1);
+
+    outfile->Write(GENERIC_FOOTID.c_str(), GENERIC_FOOTID.size(), 1);
+
+    // here some padding is added for alignment to 16 bytes.
+    // if already aligned, the full 16 bytes is added.
+    size_t pos = outfile->Tell();
+    size_t pad = 16 - (pos % 16);
+    for (size_t i = 0; i < pad; ++i) {
+        outfile->Write("\x00", 1, 1);
+    }
+
+    // not sure what this is, but it seems to always be 0 in modern files
+    for (size_t i = 0; i < 4; ++i) {
+        outfile->Write("\x00", 1, 1);
+    }
+
+    // now the file version again
+    {
+        StreamWriterLE outstream(outfile);
+        outstream.PutU4(EXPORT_VERSION_INT);
+    } // StreamWriter destructor writes the data to the file
+
+    // and finally some binary footer added to all files
+    for (size_t i = 0; i < 120; ++i) {
+        outfile->Write("\x00", 1, 1);
+    }
+    outfile->Write(FOOT_MAGIC.c_str(), FOOT_MAGIC.size(), 1);
+}
+
+void FBXExporter::WriteAllNodes ()
+{
+    // header
+    // (and fileid, creation time, creator, if binary)
+    WriteHeaderExtension();
+
+    // global settings
+    WriteGlobalSettings();
+
+    // documents
+    WriteDocuments();
+
+    // references
+    WriteReferences();
+
+    // definitions
+    WriteDefinitions();
+
+    // objects
+    WriteObjects();
+
+    // connections
+    WriteConnections();
+
+    // WriteTakes? (deprecated since at least 2015 (fbx 7.4))
+}
+
+//FBXHeaderExtension top-level node
+void FBXExporter::WriteHeaderExtension ()
+{
+    if (!binary) {
+        // no title, follows directly from the top comment
+    }
+    FBX::Node n("FBXHeaderExtension");
+    StreamWriterLE outstream(outfile);
+    int indent = 0;
+
+    // begin node
+    n.Begin(outstream, binary, indent);
+
+    // write properties
+    // (none)
+
+    // finish properties
+    n.EndProperties(outstream, binary, indent, 0);
+
+    // begin children
+    n.BeginChildren(outstream, binary, indent);
+
+    indent = 1;
+
+    // write child nodes
+    FBX::Node::WritePropertyNode(
+        "FBXHeaderVersion", int32_t(1003), outstream, binary, indent
+    );
+    FBX::Node::WritePropertyNode(
+        "FBXVersion", int32_t(EXPORT_VERSION_INT), outstream, binary, indent
+    );
+    if (binary) {
+        FBX::Node::WritePropertyNode(
+            "EncryptionType", int32_t(0), outstream, binary, indent
+        );
+    }
+
+    FBX::Node CreationTimeStamp("CreationTimeStamp");
+    time_t rawtime;
+    time(&rawtime);
+    struct tm * now = localtime(&rawtime);
+    CreationTimeStamp.AddChild("Version", int32_t(1000));
+    CreationTimeStamp.AddChild("Year", int32_t(now->tm_year + 1900));
+    CreationTimeStamp.AddChild("Month", int32_t(now->tm_mon + 1));
+    CreationTimeStamp.AddChild("Day", int32_t(now->tm_mday));
+    CreationTimeStamp.AddChild("Hour", int32_t(now->tm_hour));
+    CreationTimeStamp.AddChild("Minute", int32_t(now->tm_min));
+    CreationTimeStamp.AddChild("Second", int32_t(now->tm_sec));
+    CreationTimeStamp.AddChild("Millisecond", int32_t(0));
+    CreationTimeStamp.Dump(outstream, binary, indent);
+
+    std::stringstream creator;
+    creator << "Open Asset Import Library (Assimp) " << aiGetVersionMajor()
+            << "." << aiGetVersionMinor() << "." << aiGetVersionRevision();
+    FBX::Node::WritePropertyNode(
+        "Creator", creator.str(), outstream, binary, indent
+    );
+
+    //FBX::Node sceneinfo("SceneInfo");
+    //sceneinfo.AddProperty("GlobalInfo" + FBX::SEPARATOR + "SceneInfo");
+    // not sure if any of this is actually needed,
+    // so just write an empty node for now.
+    //sceneinfo.Dump(outstream, binary, indent);
+
+    indent = 0;
+
+    // finish node
+    n.End(outstream, binary, indent, true);
+
+    // that's it for FBXHeaderExtension...
+    if (!binary) { return; }
+
+    // but binary files also need top-level FileID, CreationTime, Creator:
+    std::vector<uint8_t> raw(GENERIC_FILEID.size());
+    for (size_t i = 0; i < GENERIC_FILEID.size(); ++i) {
+        raw[i] = uint8_t(GENERIC_FILEID[i]);
+    }
+    FBX::Node::WritePropertyNode(
+        "FileId", raw, outstream, binary, indent
+    );
+    FBX::Node::WritePropertyNode(
+        "CreationTime", GENERIC_CTIME, outstream, binary, indent
+    );
+    FBX::Node::WritePropertyNode(
+        "Creator", creator.str(), outstream, binary, indent
+    );
+}
+
+// WriteGlobalSettings helpers
+
+void WritePropInt(const aiScene* scene, FBX::Node& p, const std::string& key, int defaultValue)
+{
+    int value;
+    if (scene->mMetaData != nullptr && scene->mMetaData->Get(key, value)) {
+        p.AddP70int(key, value);
+    } else {
+        p.AddP70int(key, defaultValue);
+    }
+}
+
+void WritePropDouble(const aiScene* scene, FBX::Node& p, const std::string& key, double defaultValue)
+{
+    double value;
+    if (scene->mMetaData != nullptr && scene->mMetaData->Get(key, value)) {
+        p.AddP70double(key, value);
+    } else {
+        // fallback lookup float instead
+        float floatValue;
+        if (scene->mMetaData != nullptr && scene->mMetaData->Get(key, floatValue)) {
+            p.AddP70double(key, (double)floatValue);
+        } else {
+            p.AddP70double(key, defaultValue);
+        }
+    }
+}
+
+void WritePropEnum(const aiScene* scene, FBX::Node& p, const std::string& key, int defaultValue)
+{
+    int value;
+    if (scene->mMetaData != nullptr && scene->mMetaData->Get(key, value)) {
+        p.AddP70enum(key, value);
+    } else {
+        p.AddP70enum(key, defaultValue);
+    }
+}
+
+void WritePropColor(const aiScene* scene, FBX::Node& p, const std::string& key, const aiVector3D& defaultValue)
+{
+    aiVector3D value;
+    if (scene->mMetaData != nullptr && scene->mMetaData->Get(key, value)) {
+        // ai_real can be float or double, cast to avoid warnings
+        p.AddP70color(key, (double)value.x, (double)value.y, (double)value.z);
+    } else {
+        p.AddP70color(key, (double)defaultValue.x, (double)defaultValue.y, (double)defaultValue.z);
+    }
+}
+
+void WritePropString(const aiScene* scene, FBX::Node& p, const std::string& key, const std::string& defaultValue)
+{
+    aiString value; // MetaData doesn't hold std::string
+    if (scene->mMetaData != nullptr && scene->mMetaData->Get(key, value)) {
+        p.AddP70string(key, value.C_Str());
+    } else {
+        p.AddP70string(key, defaultValue);
+    }
+}
+
+void FBXExporter::WriteGlobalSettings ()
+{
+    if (!binary) {
+        // no title, follows directly from the header extension
+    }
+    FBX::Node gs("GlobalSettings");
+    gs.AddChild("Version", int32_t(1000));
+
+    FBX::Node p("Properties70");
+    WritePropInt(mScene, p, "UpAxis", 1);
+    WritePropInt(mScene, p, "UpAxisSign", 1);
+    WritePropInt(mScene, p, "FrontAxis", 2);
+    WritePropInt(mScene, p, "FrontAxisSign", 1);
+    WritePropInt(mScene, p, "CoordAxis", 0);
+    WritePropInt(mScene, p, "CoordAxisSign", 1);
+    WritePropInt(mScene, p, "OriginalUpAxis", 1);
+    WritePropInt(mScene, p, "OriginalUpAxisSign", 1);
+    WritePropDouble(mScene, p, "UnitScaleFactor", 1.0);
+    WritePropDouble(mScene, p, "OriginalUnitScaleFactor", 1.0);
+    WritePropColor(mScene, p, "AmbientColor", aiVector3D((ai_real)0.0, (ai_real)0.0, (ai_real)0.0));
+    WritePropString(mScene, p,"DefaultCamera", "Producer Perspective");
+    WritePropEnum(mScene, p, "TimeMode", 11);
+    WritePropEnum(mScene, p, "TimeProtocol", 2);
+    WritePropEnum(mScene, p, "SnapOnFrameMode", 0);
+    p.AddP70time("TimeSpanStart", 0); // TODO: animation support
+    p.AddP70time("TimeSpanStop", FBX::SECOND); // TODO: animation support
+    WritePropDouble(mScene, p, "CustomFrameRate", -1.0);
+    p.AddP70("TimeMarker", "Compound", "", ""); // not sure what this is
+    WritePropInt(mScene, p, "CurrentTimeMarker", -1);
+    gs.AddChild(p);
+
+    gs.Dump(outfile, binary, 0);
+}
+
+void FBXExporter::WriteDocuments ()
+{
+    if (!binary) {
+        WriteAsciiSectionHeader("Documents Description");
+    }
+
+    // not sure what the use of multiple documents would be,
+    // or whether any end-application supports it
+    FBX::Node docs("Documents");
+    docs.AddChild("Count", int32_t(1));
+    FBX::Node doc("Document");
+
+    // generate uid
+    int64_t uid = generate_uid();
+    doc.AddProperties(uid, "", "Scene");
+    FBX::Node p("Properties70");
+    p.AddP70("SourceObject", "object", "", ""); // what is this even for?
+    p.AddP70string("ActiveAnimStackName", ""); // should do this properly?
+    doc.AddChild(p);
+
+    // UID for root node in scene hierarchy.
+    // always set to 0 in the case of a single document.
+    // not sure what happens if more than one document exists,
+    // but that won't matter to us as we're exporting a single scene.
+    doc.AddChild("RootNode", int64_t(0));
+
+    docs.AddChild(doc);
+    docs.Dump(outfile, binary, 0);
+}
+
+void FBXExporter::WriteReferences ()
+{
+    if (!binary) {
+        WriteAsciiSectionHeader("Document References");
+    }
+    // always empty for now.
+    // not really sure what this is for.
+    FBX::Node n("References");
+    n.force_has_children = true;
+    n.Dump(outfile, binary, 0);
+}
+
+
+// ---------------------------------------------------------------
+// some internal helper functions used for writing the definitions
+// (before any actual data is written)
+// ---------------------------------------------------------------
+
+size_t count_nodes(const aiNode* n, const aiNode* root) {
+    size_t count;
+    if (n == root) {
+        count = n->mNumMeshes; // (not counting root node)
+    } else if (n->mNumMeshes > 1) {
+        count = n->mNumMeshes + 1;
+    } else {
+        count = 1;
+    }
+    for (size_t i = 0; i < n->mNumChildren; ++i) {
+        count += count_nodes(n->mChildren[i], root);
+    }
+    return count;
+}
+
+bool has_phong_mat(const aiScene* scene)
+{
+    // just search for any material with a shininess exponent
+    for (size_t i = 0; i < scene->mNumMaterials; ++i) {
+        aiMaterial* mat = scene->mMaterials[i];
+        float shininess = 0;
+        mat->Get(AI_MATKEY_SHININESS, shininess);
+        if (shininess > 0) {
+            return true;
+        }
+    }
+    return false;
+}
+
+size_t count_images(const aiScene* scene) {
+    std::unordered_set<std::string> images;
+    aiString texpath;
+    for (size_t i = 0; i < scene->mNumMaterials; ++i) {
+        aiMaterial* mat = scene->mMaterials[i];
+        for (
+            size_t tt = aiTextureType_DIFFUSE;
+            tt < aiTextureType_UNKNOWN;
+            ++tt
+        ){
+            const aiTextureType textype = static_cast<aiTextureType>(tt);
+            const size_t texcount = mat->GetTextureCount(textype);
+            for (unsigned int j = 0; j < texcount; ++j) {
+                mat->GetTexture(textype, j, &texpath);
+                images.insert(std::string(texpath.C_Str()));
+            }
+        }
+    }
+    return images.size();
+}
+
+size_t count_textures(const aiScene* scene) {
+    size_t count = 0;
+    for (size_t i = 0; i < scene->mNumMaterials; ++i) {
+        aiMaterial* mat = scene->mMaterials[i];
+        for (
+            size_t tt = aiTextureType_DIFFUSE;
+            tt < aiTextureType_UNKNOWN;
+            ++tt
+        ){
+            // TODO: handle layered textures
+            if (mat->GetTextureCount(static_cast<aiTextureType>(tt)) > 0) {
+                count += 1;
+            }
+        }
+    }
+    return count;
+}
+
+size_t count_deformers(const aiScene* scene) {
+    size_t count = 0;
+    for (size_t i = 0; i < scene->mNumMeshes; ++i) {
+        const size_t n = scene->mMeshes[i]->mNumBones;
+        if (n) {
+            // 1 main deformer, 1 subdeformer per bone
+            count += n + 1;
+        }
+    }
+    return count;
+}
+
+void FBXExporter::WriteDefinitions ()
+{
+    // basically this is just bookkeeping:
+    // determining how many of each type of object there are
+    // and specifying the base properties to use when otherwise unspecified.
+
+    // ascii section header
+    if (!binary) {
+        WriteAsciiSectionHeader("Object definitions");
+    }
+
+    // we need to count the objects
+    int32_t count;
+    int32_t total_count = 0;
+
+    // and store them
+    std::vector<FBX::Node> object_nodes;
+    FBX::Node n, pt, p;
+
+    // GlobalSettings
+    // this seems to always be here in Maya exports
+    n = FBX::Node("ObjectType", "GlobalSettings");
+    count = 1;
+    n.AddChild("Count", count);
+    object_nodes.push_back(n);
+    total_count += count;
+
+    // AnimationStack / FbxAnimStack
+    // this seems to always be here in Maya exports,
+    // but no harm seems to come of leaving it out.
+    count = mScene->mNumAnimations;
+    if (count) {
+        n = FBX::Node("ObjectType", "AnimationStack");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate", "FbxAnimStack");
+        p = FBX::Node("Properties70");
+        p.AddP70string("Description", "");
+        p.AddP70time("LocalStart", 0);
+        p.AddP70time("LocalStop", 0);
+        p.AddP70time("ReferenceStart", 0);
+        p.AddP70time("ReferenceStop", 0);
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // AnimationLayer / FbxAnimLayer
+    // this seems to always be here in Maya exports,
+    // but no harm seems to come of leaving it out.
+    // Assimp doesn't support animation layers,
+    // so there will be one per aiAnimation
+    count = mScene->mNumAnimations;
+    if (count) {
+        n = FBX::Node("ObjectType", "AnimationLayer");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate", "FBXAnimLayer");
+        p = FBX::Node("Properties70");
+        p.AddP70("Weight", "Number", "", "A", double(100));
+        p.AddP70bool("Mute", 0);
+        p.AddP70bool("Solo", 0);
+        p.AddP70bool("Lock", 0);
+        p.AddP70color("Color", 0.8, 0.8, 0.8);
+        p.AddP70("BlendMode", "enum", "", "", int32_t(0));
+        p.AddP70("RotationAccumulationMode", "enum", "", "", int32_t(0));
+        p.AddP70("ScaleAccumulationMode", "enum", "", "", int32_t(0));
+        p.AddP70("BlendModeBypass", "ULongLong", "", "", int64_t(0));
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // NodeAttribute
+    // this is completely absurd.
+    // there can only be one "NodeAttribute" template,
+    // but FbxSkeleton, FbxCamera, FbxLight all are "NodeAttributes".
+    // so if only one exists we should set the template for that,
+    // otherwise... we just pick one :/.
+    // the others have to set all their properties every instance,
+    // because there's no template.
+    count = 1; // TODO: select properly
+    if (count) {
+        // FbxSkeleton
+        n = FBX::Node("ObjectType", "NodeAttribute");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate", "FbxSkeleton");
+        p = FBX::Node("Properties70");
+        p.AddP70color("Color", 0.8, 0.8, 0.8);
+        p.AddP70double("Size", 33.333333333333);
+        p.AddP70("LimbLength", "double", "Number", "H", double(1));
+        // note: not sure what the "H" flag is for - hidden?
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // Model / FbxNode
+    // <~~ node hierarchy
+    count = int32_t(count_nodes(mScene->mRootNode, mScene->mRootNode));
+    if (count) {
+        n = FBX::Node("ObjectType", "Model");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate", "FbxNode");
+        p = FBX::Node("Properties70");
+        p.AddP70enum("QuaternionInterpolate", 0);
+        p.AddP70vector("RotationOffset", 0.0, 0.0, 0.0);
+        p.AddP70vector("RotationPivot", 0.0, 0.0, 0.0);
+        p.AddP70vector("ScalingOffset", 0.0, 0.0, 0.0);
+        p.AddP70vector("ScalingPivot", 0.0, 0.0, 0.0);
+        p.AddP70bool("TranslationActive", 0);
+        p.AddP70vector("TranslationMin", 0.0, 0.0, 0.0);
+        p.AddP70vector("TranslationMax", 0.0, 0.0, 0.0);
+        p.AddP70bool("TranslationMinX", 0);
+        p.AddP70bool("TranslationMinY", 0);
+        p.AddP70bool("TranslationMinZ", 0);
+        p.AddP70bool("TranslationMaxX", 0);
+        p.AddP70bool("TranslationMaxY", 0);
+        p.AddP70bool("TranslationMaxZ", 0);
+        p.AddP70enum("RotationOrder", 0);
+        p.AddP70bool("RotationSpaceForLimitOnly", 0);
+        p.AddP70double("RotationStiffnessX", 0.0);
+        p.AddP70double("RotationStiffnessY", 0.0);
+        p.AddP70double("RotationStiffnessZ", 0.0);
+        p.AddP70double("AxisLen", 10.0);
+        p.AddP70vector("PreRotation", 0.0, 0.0, 0.0);
+        p.AddP70vector("PostRotation", 0.0, 0.0, 0.0);
+        p.AddP70bool("RotationActive", 0);
+        p.AddP70vector("RotationMin", 0.0, 0.0, 0.0);
+        p.AddP70vector("RotationMax", 0.0, 0.0, 0.0);
+        p.AddP70bool("RotationMinX", 0);
+        p.AddP70bool("RotationMinY", 0);
+        p.AddP70bool("RotationMinZ", 0);
+        p.AddP70bool("RotationMaxX", 0);
+        p.AddP70bool("RotationMaxY", 0);
+        p.AddP70bool("RotationMaxZ", 0);
+        p.AddP70enum("InheritType", 0);
+        p.AddP70bool("ScalingActive", 0);
+        p.AddP70vector("ScalingMin", 0.0, 0.0, 0.0);
+        p.AddP70vector("ScalingMax", 1.0, 1.0, 1.0);
+        p.AddP70bool("ScalingMinX", 0);
+        p.AddP70bool("ScalingMinY", 0);
+        p.AddP70bool("ScalingMinZ", 0);
+        p.AddP70bool("ScalingMaxX", 0);
+        p.AddP70bool("ScalingMaxY", 0);
+        p.AddP70bool("ScalingMaxZ", 0);
+        p.AddP70vector("GeometricTranslation", 0.0, 0.0, 0.0);
+        p.AddP70vector("GeometricRotation", 0.0, 0.0, 0.0);
+        p.AddP70vector("GeometricScaling", 1.0, 1.0, 1.0);
+        p.AddP70double("MinDampRangeX", 0.0);
+        p.AddP70double("MinDampRangeY", 0.0);
+        p.AddP70double("MinDampRangeZ", 0.0);
+        p.AddP70double("MaxDampRangeX", 0.0);
+        p.AddP70double("MaxDampRangeY", 0.0);
+        p.AddP70double("MaxDampRangeZ", 0.0);
+        p.AddP70double("MinDampStrengthX", 0.0);
+        p.AddP70double("MinDampStrengthY", 0.0);
+        p.AddP70double("MinDampStrengthZ", 0.0);
+        p.AddP70double("MaxDampStrengthX", 0.0);
+        p.AddP70double("MaxDampStrengthY", 0.0);
+        p.AddP70double("MaxDampStrengthZ", 0.0);
+        p.AddP70double("PreferedAngleX", 0.0);
+        p.AddP70double("PreferedAngleY", 0.0);
+        p.AddP70double("PreferedAngleZ", 0.0);
+        p.AddP70("LookAtProperty", "object", "", "");
+        p.AddP70("UpVectorProperty", "object", "", "");
+        p.AddP70bool("Show", 1);
+        p.AddP70bool("NegativePercentShapeSupport", 1);
+        p.AddP70int("DefaultAttributeIndex", -1);
+        p.AddP70bool("Freeze", 0);
+        p.AddP70bool("LODBox", 0);
+        p.AddP70(
+            "Lcl Translation", "Lcl Translation", "", "A",
+            double(0), double(0), double(0)
+        );
+        p.AddP70(
+            "Lcl Rotation", "Lcl Rotation", "", "A",
+            double(0), double(0), double(0)
+        );
+        p.AddP70(
+            "Lcl Scaling", "Lcl Scaling", "", "A",
+            double(1), double(1), double(1)
+        );
+        p.AddP70("Visibility", "Visibility", "", "A", double(1));
+        p.AddP70(
+            "Visibility Inheritance", "Visibility Inheritance", "", "",
+            int32_t(1)
+        );
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // Geometry / FbxMesh
+    // <~~ aiMesh
+    count = mScene->mNumMeshes;
+
+    // Blendshapes are considered Geometry
+    int32_t bsDeformerCount=0;
+    for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
+        aiMesh* m = mScene->mMeshes[mi];
+        if (m->mNumAnimMeshes > 0) {
+          count+=m->mNumAnimMeshes;
+          bsDeformerCount+=m->mNumAnimMeshes; // One deformer per blendshape
+          bsDeformerCount++;                  // Plus one master blendshape deformer
+        }
+    }
+
+    if (count) {
+        n = FBX::Node("ObjectType", "Geometry");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate", "FbxMesh");
+        p = FBX::Node("Properties70");
+        p.AddP70color("Color", 0, 0, 0);
+        p.AddP70vector("BBoxMin", 0, 0, 0);
+        p.AddP70vector("BBoxMax", 0, 0, 0);
+        p.AddP70bool("Primary Visibility", 1);
+        p.AddP70bool("Casts Shadows", 1);
+        p.AddP70bool("Receive Shadows", 1);
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // Material / FbxSurfacePhong, FbxSurfaceLambert, FbxSurfaceMaterial
+    // <~~ aiMaterial
+    // basically if there's any phong material this is defined as phong,
+    // and otherwise lambert.
+    // More complex materials cause a bare-bones FbxSurfaceMaterial definition
+    // and are treated specially, as they're not really supported by FBX.
+    // TODO: support Maya's Stingray PBS material
+    count = mScene->mNumMaterials;
+    if (count) {
+        bool has_phong = has_phong_mat(mScene);
+        n = FBX::Node("ObjectType", "Material");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate");
+        if (has_phong) {
+            pt.AddProperty("FbxSurfacePhong");
+        } else {
+            pt.AddProperty("FbxSurfaceLambert");
+        }
+        p = FBX::Node("Properties70");
+        if (has_phong) {
+            p.AddP70string("ShadingModel", "Phong");
+        } else {
+            p.AddP70string("ShadingModel", "Lambert");
+        }
+        p.AddP70bool("MultiLayer", 0);
+        p.AddP70colorA("EmissiveColor", 0.0, 0.0, 0.0);
+        p.AddP70numberA("EmissiveFactor", 1.0);
+        p.AddP70colorA("AmbientColor", 0.2, 0.2, 0.2);
+        p.AddP70numberA("AmbientFactor", 1.0);
+        p.AddP70colorA("DiffuseColor", 0.8, 0.8, 0.8);
+        p.AddP70numberA("DiffuseFactor", 1.0);
+        p.AddP70vector("Bump", 0.0, 0.0, 0.0);
+        p.AddP70vector("NormalMap", 0.0, 0.0, 0.0);
+        p.AddP70double("BumpFactor", 1.0);
+        p.AddP70colorA("TransparentColor", 0.0, 0.0, 0.0);
+        p.AddP70numberA("TransparencyFactor", 0.0);
+        p.AddP70color("DisplacementColor", 0.0, 0.0, 0.0);
+        p.AddP70double("DisplacementFactor", 1.0);
+        p.AddP70color("VectorDisplacementColor", 0.0, 0.0, 0.0);
+        p.AddP70double("VectorDisplacementFactor", 1.0);
+        if (has_phong) {
+            p.AddP70colorA("SpecularColor", 0.2, 0.2, 0.2);
+            p.AddP70numberA("SpecularFactor", 1.0);
+            p.AddP70numberA("ShininessExponent", 20.0);
+            p.AddP70colorA("ReflectionColor", 0.0, 0.0, 0.0);
+            p.AddP70numberA("ReflectionFactor", 1.0);
+        }
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // Video / FbxVideo
+    // one for each image file.
+    count = int32_t(count_images(mScene));
+    if (count) {
+        n = FBX::Node("ObjectType", "Video");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate", "FbxVideo");
+        p = FBX::Node("Properties70");
+        p.AddP70bool("ImageSequence", 0);
+        p.AddP70int("ImageSequenceOffset", 0);
+        p.AddP70double("FrameRate", 0.0);
+        p.AddP70int("LastFrame", 0);
+        p.AddP70int("Width", 0);
+        p.AddP70int("Height", 0);
+        p.AddP70("Path", "KString", "XRefUrl", "", "");
+        p.AddP70int("StartFrame", 0);
+        p.AddP70int("StopFrame", 0);
+        p.AddP70double("PlaySpeed", 0.0);
+        p.AddP70time("Offset", 0);
+        p.AddP70enum("InterlaceMode", 0);
+        p.AddP70bool("FreeRunning", 0);
+        p.AddP70bool("Loop", 0);
+        p.AddP70enum("AccessMode", 0);
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // Texture / FbxFileTexture
+    // <~~ aiTexture
+    count = int32_t(count_textures(mScene));
+    if (count) {
+        n = FBX::Node("ObjectType", "Texture");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate", "FbxFileTexture");
+        p = FBX::Node("Properties70");
+        p.AddP70enum("TextureTypeUse", 0);
+        p.AddP70numberA("Texture alpha", 1.0);
+        p.AddP70enum("CurrentMappingType", 0);
+        p.AddP70enum("WrapModeU", 0);
+        p.AddP70enum("WrapModeV", 0);
+        p.AddP70bool("UVSwap", 0);
+        p.AddP70bool("PremultiplyAlpha", 1);
+        p.AddP70vectorA("Translation", 0.0, 0.0, 0.0);
+        p.AddP70vectorA("Rotation", 0.0, 0.0, 0.0);
+        p.AddP70vectorA("Scaling", 1.0, 1.0, 1.0);
+        p.AddP70vector("TextureRotationPivot", 0.0, 0.0, 0.0);
+        p.AddP70vector("TextureScalingPivot", 0.0, 0.0, 0.0);
+        p.AddP70enum("CurrentTextureBlendMode", 1);
+        p.AddP70string("UVSet", "default");
+        p.AddP70bool("UseMaterial", 0);
+        p.AddP70bool("UseMipMap", 0);
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // AnimationCurveNode / FbxAnimCurveNode
+    count = mScene->mNumAnimations * 3;
+    if (count) {
+        n = FBX::Node("ObjectType", "AnimationCurveNode");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate", "FbxAnimCurveNode");
+        p = FBX::Node("Properties70");
+        p.AddP70("d", "Compound", "", "");
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // AnimationCurve / FbxAnimCurve
+    count = mScene->mNumAnimations * 9;
+    if (count) {
+        n = FBX::Node("ObjectType", "AnimationCurve");
+        n.AddChild("Count", count);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // Pose
+    count = 0;
+    for (size_t i = 0; i < mScene->mNumMeshes; ++i) {
+        aiMesh* mesh = mScene->mMeshes[i];
+        if (mesh->HasBones()) { ++count; }
+    }
+    if (count) {
+        n = FBX::Node("ObjectType", "Pose");
+        n.AddChild("Count", count);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // Deformer
+    count = int32_t(count_deformers(mScene))+bsDeformerCount;
+    if (count) {
+        n = FBX::Node("ObjectType", "Deformer");
+        n.AddChild("Count", count);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // (template)
+    count = 0;
+    if (count) {
+        n = FBX::Node("ObjectType", "");
+        n.AddChild("Count", count);
+        pt = FBX::Node("PropertyTemplate", "");
+        p = FBX::Node("Properties70");
+        pt.AddChild(p);
+        n.AddChild(pt);
+        object_nodes.push_back(n);
+        total_count += count;
+    }
+
+    // now write it all
+    FBX::Node defs("Definitions");
+    defs.AddChild("Version", int32_t(100));
+    defs.AddChild("Count", int32_t(total_count));
+    for (auto &on : object_nodes) {
+        defs.AddChild(on);
+    }
+    defs.Dump(outfile, binary, 0);
+}
+
+
+// -------------------------------------------------------------------
+// some internal helper functions used for writing the objects section
+// (which holds the actual data)
+// -------------------------------------------------------------------
+
+aiNode* get_node_for_mesh(unsigned int meshIndex, aiNode* node)
+{
+    for (size_t i = 0; i < node->mNumMeshes; ++i) {
+        if (node->mMeshes[i] == meshIndex) {
+            return node;
+        }
+    }
+    for (size_t i = 0; i < node->mNumChildren; ++i) {
+        aiNode* ret = get_node_for_mesh(meshIndex, node->mChildren[i]);
+        if (ret) { return ret; }
+    }
+    return nullptr;
+}
+
+aiMatrix4x4 get_world_transform(const aiNode* node, const aiScene* scene)
+{
+    std::vector<const aiNode*> node_chain;
+    while (node != scene->mRootNode) {
+        node_chain.push_back(node);
+        node = node->mParent;
+    }
+    aiMatrix4x4 transform;
+    for (auto n = node_chain.rbegin(); n != node_chain.rend(); ++n) {
+        transform *= (*n)->mTransformation;
+    }
+    return transform;
+}
+
+int64_t to_ktime(double ticks, const aiAnimation* anim) {
+    if (anim->mTicksPerSecond <= 0) {
+        return static_cast<int64_t>(ticks) * FBX::SECOND;
+    }
+    return (static_cast<int64_t>(ticks) / static_cast<int64_t>(anim->mTicksPerSecond)) * FBX::SECOND;
+}
+
+int64_t to_ktime(double time) {
+    return (static_cast<int64_t>(time * FBX::SECOND));
+}
+
+void FBXExporter::WriteObjects ()
+{
+    if (!binary) {
+        WriteAsciiSectionHeader("Object properties");
+    }
+    // numbers should match those given in definitions! make sure to check
+    StreamWriterLE outstream(outfile);
+    FBX::Node object_node("Objects");
+    int indent = 0;
+    object_node.Begin(outstream, binary, indent);
+    object_node.EndProperties(outstream, binary, indent);
+    object_node.BeginChildren(outstream, binary, indent);
+
+    bool bJoinIdenticalVertices = mProperties->GetPropertyBool("bJoinIdenticalVertices", true);
+    std::vector<std::vector<int32_t>> vVertexIndice;//save vertex_indices as it is needed later
+
+    // geometry (aiMesh)
+    mesh_uids.clear();
+    indent = 1;
+    for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
+        // it's all about this mesh
+        aiMesh* m = mScene->mMeshes[mi];
+
+        // start the node record
+        FBX::Node n("Geometry");
+        int64_t uid = generate_uid();
+        mesh_uids.push_back(uid);
+        n.AddProperty(uid);
+        n.AddProperty(FBX::SEPARATOR + "Geometry");
+        n.AddProperty("Mesh");
+        n.Begin(outstream, binary, indent);
+        n.DumpProperties(outstream, binary, indent);
+        n.EndProperties(outstream, binary, indent);
+        n.BeginChildren(outstream, binary, indent);
+        indent = 2;
+
+        // output vertex data - each vertex should be unique (probably)
+        std::vector<double> flattened_vertices;
+        // index of original vertex in vertex data vector
+        std::vector<int32_t> vertex_indices;
+        // map of vertex value to its index in the data vector
+        std::map<aiVector3D,size_t> index_by_vertex_value;
+        if(bJoinIdenticalVertices){
+            int32_t index = 0;
+            for (size_t vi = 0; vi < m->mNumVertices; ++vi) {
+                aiVector3D vtx = m->mVertices[vi];
+                auto elem = index_by_vertex_value.find(vtx);
+                if (elem == index_by_vertex_value.end()) {
+                    vertex_indices.push_back(index);
+                    index_by_vertex_value[vtx] = index;
+                    flattened_vertices.push_back(vtx[0]);
+                    flattened_vertices.push_back(vtx[1]);
+                    flattened_vertices.push_back(vtx[2]);
+                    ++index;
+                } else {
+                    vertex_indices.push_back(int32_t(elem->second));
+                }
+            }
+        }
+        else { // do not join vertex, respect the export flag
+            vertex_indices.resize(m->mNumVertices);
+            std::iota(vertex_indices.begin(), vertex_indices.end(), 0);
+            for(unsigned int v = 0; v < m->mNumVertices; ++ v) {
+                aiVector3D vtx = m->mVertices[v];
+                flattened_vertices.push_back(vtx.x);
+                flattened_vertices.push_back(vtx.y);
+                flattened_vertices.push_back(vtx.z);
+            }
+        }
+        vVertexIndice.push_back(vertex_indices);
+
+        FBX::Node::WritePropertyNode(
+            "Vertices", flattened_vertices, outstream, binary, indent
+        );
+
+        // output polygon data as a flattened array of vertex indices.
+        // the last vertex index of each polygon is negated and - 1
+        std::vector<int32_t> polygon_data;
+        for (size_t fi = 0; fi < m->mNumFaces; ++fi) {
+            const aiFace &f = m->mFaces[fi];
+            for (size_t pvi = 0; pvi < f.mNumIndices - 1; ++pvi) {
+                polygon_data.push_back(vertex_indices[f.mIndices[pvi]]);
+            }
+            polygon_data.push_back(
+                -1 - vertex_indices[f.mIndices[f.mNumIndices-1]]
+            );
+        }
+        FBX::Node::WritePropertyNode(
+            "PolygonVertexIndex", polygon_data, outstream, binary, indent
+        );
+
+        // here could be edges but they're insane.
+        // it's optional anyway, so let's ignore it.
+
+        FBX::Node::WritePropertyNode(
+            "GeometryVersion", int32_t(124), outstream, binary, indent
+        );
+
+        // normals, if any
+        if (m->HasNormals()) {
+            FBX::Node normals("LayerElementNormal", int32_t(0));
+            normals.Begin(outstream, binary, indent);
+            normals.DumpProperties(outstream, binary, indent);
+            normals.EndProperties(outstream, binary, indent);
+            normals.BeginChildren(outstream, binary, indent);
+            indent = 3;
+            FBX::Node::WritePropertyNode(
+                "Version", int32_t(101), outstream, binary, indent
+            );
+            FBX::Node::WritePropertyNode(
+                "Name", "", outstream, binary, indent
+            );
+            FBX::Node::WritePropertyNode(
+                "MappingInformationType", "ByPolygonVertex",
+                outstream, binary, indent
+            );
+            // TODO: vertex-normals or indexed normals when appropriate
+            FBX::Node::WritePropertyNode(
+                "ReferenceInformationType", "Direct",
+                outstream, binary, indent
+            );
+            std::vector<double> normal_data;
+            normal_data.reserve(3 * polygon_data.size());
+            for (size_t fi = 0; fi < m->mNumFaces; ++fi) {
+                const aiFace &f = m->mFaces[fi];
+                for (size_t pvi = 0; pvi < f.mNumIndices; ++pvi) {
+                    const aiVector3D &curN = m->mNormals[f.mIndices[pvi]];
+                    normal_data.push_back(curN.x);
+                    normal_data.push_back(curN.y);
+                    normal_data.push_back(curN.z);
+                }
+            }
+            FBX::Node::WritePropertyNode(
+                "Normals", normal_data, outstream, binary, indent
+            );
+            // note: version 102 has a NormalsW also... not sure what it is,
+            // so we can stick with version 101 for now.
+            indent = 2;
+            normals.End(outstream, binary, indent, true);
+        }
+
+        // colors, if any
+        // TODO only one color channel currently
+        const int32_t colorChannelIndex = 0;
+        if (m->HasVertexColors(colorChannelIndex)) {
+            FBX::Node vertexcolors("LayerElementColor", int32_t(colorChannelIndex));
+            vertexcolors.Begin(outstream, binary, indent);
+            vertexcolors.DumpProperties(outstream, binary, indent);
+            vertexcolors.EndProperties(outstream, binary, indent);
+            vertexcolors.BeginChildren(outstream, binary, indent);
+            indent = 3;
+            FBX::Node::WritePropertyNode(
+                "Version", int32_t(101), outstream, binary, indent
+            );
+            char layerName[8];
+            sprintf(layerName, "COLOR_%d", colorChannelIndex);
+            FBX::Node::WritePropertyNode(
+                "Name", (const char*)layerName, outstream, binary, indent
+            );
+            FBX::Node::WritePropertyNode(
+                "MappingInformationType", "ByPolygonVertex",
+                outstream, binary, indent
+            );
+            FBX::Node::WritePropertyNode(
+                "ReferenceInformationType", "Direct",
+                outstream, binary, indent
+            );
+            std::vector<double> color_data;
+            color_data.reserve(4 * polygon_data.size());
+            for (size_t fi = 0; fi < m->mNumFaces; ++fi) {
+                const aiFace &f = m->mFaces[fi];
+                for (size_t pvi = 0; pvi < f.mNumIndices; ++pvi) {
+                    const aiColor4D &c = m->mColors[colorChannelIndex][f.mIndices[pvi]];
+                    color_data.push_back(c.r);
+                    color_data.push_back(c.g);
+                    color_data.push_back(c.b);
+                    color_data.push_back(c.a);
+                }
+            }
+            FBX::Node::WritePropertyNode(
+                "Colors", color_data, outstream, binary, indent
+            );
+            indent = 2;
+            vertexcolors.End(outstream, binary, indent, true);
+        }
+
+        // uvs, if any
+        for (size_t uvi = 0; uvi < m->GetNumUVChannels(); ++uvi) {
+            if (m->mNumUVComponents[uvi] > 2) {
+                // FBX only supports 2-channel UV maps...
+                // or at least i'm not sure how to indicate a different number
+                std::stringstream err;
+                err << "Only 2-channel UV maps supported by FBX,";
+                err << " but mesh " << mi;
+                if (m->mName.length) {
+                    err << " (" << m->mName.C_Str() << ")";
+                }
+                err << " UV map " << uvi;
+                err << " has " << m->mNumUVComponents[uvi];
+                err << " components! Data will be preserved,";
+                err << " but may be incorrectly interpreted on load.";
+                ASSIMP_LOG_WARN(err.str());
+            }
+            FBX::Node uv("LayerElementUV", int32_t(uvi));
+            uv.Begin(outstream, binary, indent);
+            uv.DumpProperties(outstream, binary, indent);
+            uv.EndProperties(outstream, binary, indent);
+            uv.BeginChildren(outstream, binary, indent);
+            indent = 3;
+            FBX::Node::WritePropertyNode(
+                "Version", int32_t(101), outstream, binary, indent
+            );
+            // it doesn't seem like assimp keeps the uv map name,
+            // so just leave it blank.
+            FBX::Node::WritePropertyNode(
+                "Name", "", outstream, binary, indent
+            );
+            FBX::Node::WritePropertyNode(
+                "MappingInformationType", "ByPolygonVertex",
+                outstream, binary, indent
+            );
+            FBX::Node::WritePropertyNode(
+                "ReferenceInformationType", "IndexToDirect",
+                outstream, binary, indent
+            );
+
+            std::vector<double> uv_data;
+            std::vector<int32_t> uv_indices;
+            std::map<aiVector3D,int32_t> index_by_uv;
+            int32_t index = 0;
+            for (size_t fi = 0; fi < m->mNumFaces; ++fi) {
+                const aiFace &f = m->mFaces[fi];
+                for (size_t pvi = 0; pvi < f.mNumIndices; ++pvi) {
+                    const aiVector3D &curUv =
+                        m->mTextureCoords[uvi][f.mIndices[pvi]];
+                    auto elem = index_by_uv.find(curUv);
+                    if (elem == index_by_uv.end()) {
+                        index_by_uv[curUv] = index;
+                        uv_indices.push_back(index);
+                        for (unsigned int x = 0; x < m->mNumUVComponents[uvi]; ++x) {
+                            uv_data.push_back(curUv[x]);
+                        }
+                        ++index;
+                    } else {
+                        uv_indices.push_back(elem->second);
+                    }
+                }
+            }
+            FBX::Node::WritePropertyNode(
+                "UV", uv_data, outstream, binary, indent
+            );
+            FBX::Node::WritePropertyNode(
+                "UVIndex", uv_indices, outstream, binary, indent
+            );
+            indent = 2;
+            uv.End(outstream, binary, indent, true);
+        }
+
+        // i'm not really sure why this material section exists,
+        // as the material is linked via "Connections".
+        // it seems to always have the same "0" value.
+        FBX::Node mat("LayerElementMaterial", int32_t(0));
+        mat.AddChild("Version", int32_t(101));
+        mat.AddChild("Name", "");
+        mat.AddChild("MappingInformationType", "AllSame");
+        mat.AddChild("ReferenceInformationType", "IndexToDirect");
+        std::vector<int32_t> mat_indices = {0};
+        mat.AddChild("Materials", mat_indices);
+        mat.Dump(outstream, binary, indent);
+
+        // finally we have the layer specifications,
+        // which select the normals / UV set / etc to use.
+        // TODO: handle multiple uv sets correctly?
+        FBX::Node layer("Layer", int32_t(0));
+        layer.AddChild("Version", int32_t(100));
+        FBX::Node le("LayerElement");
+        le.AddChild("Type", "LayerElementNormal");
+        le.AddChild("TypedIndex", int32_t(0));
+        layer.AddChild(le);
+        // TODO only 1 color channel currently
+        le = FBX::Node("LayerElement");
+        le.AddChild("Type", "LayerElementColor");
+        le.AddChild("TypedIndex", int32_t(0));
+        layer.AddChild(le);
+        le = FBX::Node("LayerElement");
+        le.AddChild("Type", "LayerElementMaterial");
+        le.AddChild("TypedIndex", int32_t(0));
+        layer.AddChild(le);
+        le = FBX::Node("LayerElement");
+        le.AddChild("Type", "LayerElementUV");
+        le.AddChild("TypedIndex", int32_t(0));
+        layer.AddChild(le);
+        layer.Dump(outstream, binary, indent);
+
+        for(unsigned int lr = 1; lr < m->GetNumUVChannels(); ++ lr)
+        {
+            FBX::Node layerExtra("Layer", int32_t(lr));
+            layerExtra.AddChild("Version", int32_t(100));
+            FBX::Node leExtra("LayerElement");
+            leExtra.AddChild("Type", "LayerElementUV");
+            leExtra.AddChild("TypedIndex", int32_t(lr));
+            layerExtra.AddChild(leExtra);
+            layerExtra.Dump(outstream, binary, indent);
+        }
+        // finish the node record
+        indent = 1;
+        n.End(outstream, binary, indent, true);
+    }
+
+
+    // aiMaterial
+    material_uids.clear();
+    for (size_t i = 0; i < mScene->mNumMaterials; ++i) {
+        // it's all about this material
+        aiMaterial* m = mScene->mMaterials[i];
+
+        // these are used to receive material data
+        float f; aiColor3D c;
+
+        // start the node record
+        FBX::Node n("Material");
+
+        int64_t uid = generate_uid();
+        material_uids.push_back(uid);
+        n.AddProperty(uid);
+
+        aiString name;
+        m->Get(AI_MATKEY_NAME, name);
+        n.AddProperty(name.C_Str() + FBX::SEPARATOR + "Material");
+
+        n.AddProperty("");
+
+        n.AddChild("Version", int32_t(102));
+        f = 0;
+        m->Get(AI_MATKEY_SHININESS, f);
+        bool phong = (f > 0);
+        if (phong) {
+            n.AddChild("ShadingModel", "phong");
+        } else {
+            n.AddChild("ShadingModel", "lambert");
+        }
+        n.AddChild("MultiLayer", int32_t(0));
+
+        FBX::Node p("Properties70");
+
+        // materials exported using the FBX SDK have two sets of fields.
+        // there are the properties specified in the PropertyTemplate,
+        // which are those supported by the modernFBX SDK,
+        // and an extra set of properties with simpler names.
+        // The extra properties are a legacy material system from pre-2009.
+        //
+        // In the modern system, each property has "color" and "factor".
+        // Generally the interpretation of these seems to be
+        // that the colour is multiplied by the factor before use,
+        // but this is not always clear-cut.
+        //
+        // Usually assimp only stores the colour,
+        // so we can just leave the factors at the default "1.0".
+
+        // first we can export the "standard" properties
+        if (m->Get(AI_MATKEY_COLOR_AMBIENT, c) == aiReturn_SUCCESS) {
+            p.AddP70colorA("AmbientColor", c.r, c.g, c.b);
+            //p.AddP70numberA("AmbientFactor", 1.0);
+        }
+        if (m->Get(AI_MATKEY_COLOR_DIFFUSE, c) == aiReturn_SUCCESS) {
+            p.AddP70colorA("DiffuseColor", c.r, c.g, c.b);
+            //p.AddP70numberA("DiffuseFactor", 1.0);
+        }
+        if (m->Get(AI_MATKEY_COLOR_TRANSPARENT, c) == aiReturn_SUCCESS) {
+            // "TransparentColor" / "TransparencyFactor"...
+            // thanks FBX, for your insightful interpretation of consistency
+            p.AddP70colorA("TransparentColor", c.r, c.g, c.b);
+            // TransparencyFactor defaults to 0.0, so set it to 1.0.
+            // note: Maya always sets this to 1.0,
+            // so we can't use it sensibly as "Opacity".
+            // In stead we rely on the legacy "Opacity" value, below.
+            // Blender also relies on "Opacity" not "TransparencyFactor",
+            // probably for a similar reason.
+            p.AddP70numberA("TransparencyFactor", 1.0);
+        }
+        if (m->Get(AI_MATKEY_COLOR_REFLECTIVE, c) == aiReturn_SUCCESS) {
+            p.AddP70colorA("ReflectionColor", c.r, c.g, c.b);
+        }
+        if (m->Get(AI_MATKEY_REFLECTIVITY, f) == aiReturn_SUCCESS) {
+            p.AddP70numberA("ReflectionFactor", f);
+        }
+        if (phong) {
+            if (m->Get(AI_MATKEY_COLOR_SPECULAR, c) == aiReturn_SUCCESS) {
+                p.AddP70colorA("SpecularColor", c.r, c.g, c.b);
+            }
+            if (m->Get(AI_MATKEY_SHININESS_STRENGTH, f) == aiReturn_SUCCESS) {
+                p.AddP70numberA("ShininessFactor", f);
+            }
+            if (m->Get(AI_MATKEY_SHININESS, f) == aiReturn_SUCCESS) {
+                p.AddP70numberA("ShininessExponent", f);
+            }
+            if (m->Get(AI_MATKEY_REFLECTIVITY, f) == aiReturn_SUCCESS) {
+                p.AddP70numberA("ReflectionFactor", f);
+            }
+        }
+
+        // Now the legacy system.
+        // For safety let's include it.
+        // thrse values don't exist in the property template,
+        // and usually are completely ignored when loading.
+        // One notable exception is the "Opacity" property,
+        // which Blender uses as (1.0 - alpha).
+        c.r = 0.0f; c.g = 0.0f; c.b = 0.0f;
+        m->Get(AI_MATKEY_COLOR_EMISSIVE, c);
+        p.AddP70vector("Emissive", c.r, c.g, c.b);
+        c.r = 0.2f; c.g = 0.2f; c.b = 0.2f;
+        m->Get(AI_MATKEY_COLOR_AMBIENT, c);
+        p.AddP70vector("Ambient", c.r, c.g, c.b);
+        c.r = 0.8f; c.g = 0.8f; c.b = 0.8f;
+        m->Get(AI_MATKEY_COLOR_DIFFUSE, c);
+        p.AddP70vector("Diffuse", c.r, c.g, c.b);
+        // The FBX SDK determines "Opacity" from transparency colour (RGB)
+        // and factor (F) as: O = (1.0 - F * ((R + G + B) / 3)).
+        // However we actually have an opacity value,
+        // so we should take it from AI_MATKEY_OPACITY if possible.
+        // It might make more sense to use TransparencyFactor,
+        // but Blender actually loads "Opacity" correctly, so let's use it.
+        f = 1.0f;
+        if (m->Get(AI_MATKEY_COLOR_TRANSPARENT, c) == aiReturn_SUCCESS) {
+            f = 1.0f - ((c.r + c.g + c.b) / 3.0f);
+        }
+        m->Get(AI_MATKEY_OPACITY, f);
+        p.AddP70double("Opacity", f);
+        if (phong) {
+            // specular color is multiplied by shininess_strength
+            c.r = 0.2f; c.g = 0.2f; c.b = 0.2f;
+            m->Get(AI_MATKEY_COLOR_SPECULAR, c);
+            f = 1.0f;
+            m->Get(AI_MATKEY_SHININESS_STRENGTH, f);
+            p.AddP70vector("Specular", f*c.r, f*c.g, f*c.b);
+            f = 20.0f;
+            m->Get(AI_MATKEY_SHININESS, f);
+            p.AddP70double("Shininess", f);
+            // Legacy "Reflectivity" is F*F*((R+G+B)/3),
+            // where F is the proportion of light reflected (AKA reflectivity),
+            // and RGB is the reflective colour of the material.
+            // No idea why, but we might as well set it the same way.
+            f = 0.0f;
+            m->Get(AI_MATKEY_REFLECTIVITY, f);
+            c.r = 1.0f, c.g = 1.0f, c.b = 1.0f;
+            m->Get(AI_MATKEY_COLOR_REFLECTIVE, c);
+            p.AddP70double("Reflectivity", f*f*((c.r+c.g+c.b)/3.0));
+        }
+
+        n.AddChild(p);
+
+        n.Dump(outstream, binary, indent);
+    }
+
+    // we need to look up all the images we're using,
+    // so we can generate uids, and eliminate duplicates.
+    std::map<std::string, int64_t> uid_by_image;
+    for (size_t i = 0; i < mScene->mNumMaterials; ++i) {
+        aiString texpath;
+        aiMaterial* mat = mScene->mMaterials[i];
+        for (
+            size_t tt = aiTextureType_DIFFUSE;
+            tt < aiTextureType_UNKNOWN;
+            ++tt
+        ){
+            const aiTextureType textype = static_cast<aiTextureType>(tt);
+            const size_t texcount = mat->GetTextureCount(textype);
+            for (size_t j = 0; j < texcount; ++j) {
+                mat->GetTexture(textype, (unsigned int)j, &texpath);
+                const std::string texstring = texpath.C_Str();
+                auto elem = uid_by_image.find(texstring);
+                if (elem == uid_by_image.end()) {
+                    uid_by_image[texstring] = generate_uid();
+                }
+            }
+        }
+    }
+
+    // FbxVideo - stores images used by textures.
+    for (const auto &it : uid_by_image) {
+        FBX::Node n("Video");
+        const int64_t& uid = it.second;
+        const std::string name = ""; // TODO: ... name???
+        n.AddProperties(uid, name + FBX::SEPARATOR + "Video", "Clip");
+        n.AddChild("Type", "Clip");
+        FBX::Node p("Properties70");
+        // TODO: get full path... relative path... etc... ugh...
+        // for now just use the same path for everything,
+        // and hopefully one of them will work out.
+        std::string path = it.first;
+        // try get embedded texture
+        const aiTexture* embedded_texture = mScene->GetEmbeddedTexture(it.first.c_str());
+        if (embedded_texture != nullptr) {
+            // change the path (use original filename, if available. If name is empty, concatenate texture index with file extension)
+            std::stringstream newPath;
+            if (embedded_texture->mFilename.length > 0) {
+                newPath << embedded_texture->mFilename.C_Str();
+            } else if (embedded_texture->achFormatHint[0]) {
+                int texture_index = std::stoi(path.substr(1, path.size() - 1));
+                newPath << texture_index << "." << embedded_texture->achFormatHint;
+            }
+            path = newPath.str();
+            // embed the texture
+            size_t texture_size = static_cast<size_t>(embedded_texture->mWidth * std::max(embedded_texture->mHeight, 1u));
+            if (binary) {
+                // embed texture as binary data
+                std::vector<uint8_t> tex_data;
+                tex_data.resize(texture_size);
+                memcpy(&tex_data[0], (char*)embedded_texture->pcData, texture_size);
+                n.AddChild("Content", tex_data);
+            } else {
+                // embed texture in base64 encoding
+                std::string encoded_texture = FBX::Util::EncodeBase64((char*)embedded_texture->pcData, texture_size);
+                n.AddChild("Content", encoded_texture);
+            }
+        }
+        p.AddP70("Path", "KString", "XRefUrl", "", path);
+        n.AddChild(p);
+        n.AddChild("UseMipMap", int32_t(0));
+        n.AddChild("Filename", path);
+        n.AddChild("RelativeFilename", path);
+        n.Dump(outstream, binary, indent);
+    }
+
+    // Textures
+    // referenced by material_index/texture_type pairs.
+    std::map<std::pair<size_t,size_t>,int64_t> texture_uids;
+    const std::map<aiTextureType,std::string> prop_name_by_tt = {
+        {aiTextureType_DIFFUSE,      "DiffuseColor"},
+        {aiTextureType_SPECULAR,     "SpecularColor"},
+        {aiTextureType_AMBIENT,      "AmbientColor"},
+        {aiTextureType_EMISSIVE,     "EmissiveColor"},
+        {aiTextureType_HEIGHT,       "Bump"},
+        {aiTextureType_NORMALS,      "NormalMap"},
+        {aiTextureType_SHININESS,    "ShininessExponent"},
+        {aiTextureType_OPACITY,      "TransparentColor"},
+        {aiTextureType_DISPLACEMENT, "DisplacementColor"},
+        //{aiTextureType_LIGHTMAP, "???"},
+        {aiTextureType_REFLECTION,   "ReflectionColor"}
+        //{aiTextureType_UNKNOWN, ""}
+    };
+    for (size_t i = 0; i < mScene->mNumMaterials; ++i) {
+        // textures are attached to materials
+        aiMaterial* mat = mScene->mMaterials[i];
+        int64_t material_uid = material_uids[i];
+
+        for (
+            size_t j = aiTextureType_DIFFUSE;
+            j < aiTextureType_UNKNOWN;
+            ++j
+        ) {
+            const aiTextureType tt = static_cast<aiTextureType>(j);
+            size_t n = mat->GetTextureCount(tt);
+
+            if (n < 1) { // no texture of this type
+                continue;
+            }
+
+            if (n > 1) {
+                // TODO: multilayer textures
+                std::stringstream err;
+                err << "Multilayer textures not supported (for now),";
+                err << " skipping texture type " << j;
+                err << " of material " << i;
+                ASSIMP_LOG_WARN(err.str());
+            }
+
+            // get image path for this (single-image) texture
+            aiString tpath;
+            if (mat->GetTexture(tt, 0, &tpath) != aiReturn_SUCCESS) {
+                std::stringstream err;
+                err << "Failed to get texture 0 for texture of type " << tt;
+                err << " on material " << i;
+                err << ", however GetTextureCount returned 1.";
+                throw DeadlyExportError(err.str());
+            }
+            const std::string texture_path(tpath.C_Str());
+
+            // get connected image uid
+            auto elem = uid_by_image.find(texture_path);
+            if (elem == uid_by_image.end()) {
+                // this should never happen
+                std::stringstream err;
+                err << "Failed to find video element for texture with path";
+                err << " \"" << texture_path << "\"";
+                err << ", type " << j << ", material " << i;
+                throw DeadlyExportError(err.str());
+            }
+            const int64_t image_uid = elem->second;
+
+            // get the name of the material property to connect to
+            auto elem2 = prop_name_by_tt.find(tt);
+            if (elem2 == prop_name_by_tt.end()) {
+                // don't know how to handle this type of texture,
+                // so skip it.
+                std::stringstream err;
+                err << "Not sure how to handle texture of type " << j;
+                err << " on material " << i;
+                err << ", skipping...";
+                ASSIMP_LOG_WARN(err.str());
+                continue;
+            }
+            const std::string& prop_name = elem2->second;
+
+            // generate a uid for this texture
+            const int64_t texture_uid = generate_uid();
+
+            // link the texture to the material
+            connections.emplace_back(
+                "C", "OP", texture_uid, material_uid, prop_name
+            );
+
+            // link the image data to the texture
+            connections.emplace_back("C", "OO", image_uid, texture_uid);
+
+            aiUVTransform trafo;
+            unsigned int max = sizeof(aiUVTransform);
+            aiGetMaterialFloatArray(mat, AI_MATKEY_UVTRANSFORM(aiTextureType_DIFFUSE, 0), (ai_real *)&trafo, &max);
+
+            // now write the actual texture node
+            FBX::Node tnode("Texture");
+            // TODO: some way to determine texture name?
+            const std::string texture_name = "" + FBX::SEPARATOR + "Texture";
+            tnode.AddProperties(texture_uid, texture_name, "");
+            // there really doesn't seem to be a better type than this:
+            tnode.AddChild("Type", "TextureVideoClip");
+            tnode.AddChild("Version", int32_t(202));
+            tnode.AddChild("TextureName", texture_name);
+            FBX::Node p("Properties70");
+            p.AddP70vectorA("Translation", trafo.mTranslation[0], trafo.mTranslation[1], 0.0);
+            p.AddP70vectorA("Rotation", 0, 0, trafo.mRotation);
+            p.AddP70vectorA("Scaling", trafo.mScaling[0], trafo.mScaling[1], 0.0);
+            p.AddP70enum("CurrentTextureBlendMode", 0); // TODO: verify
+            //p.AddP70string("UVSet", ""); // TODO: how should this work?
+            p.AddP70bool("UseMaterial", 1);
+            tnode.AddChild(p);
+            // can't easily determine which texture path will be correct,
+            // so just store what we have in every field.
+            // these being incorrect is a common problem with FBX anyway.
+            tnode.AddChild("FileName", texture_path);
+            tnode.AddChild("RelativeFilename", texture_path);
+            tnode.AddChild("ModelUVTranslation", double(0.0), double(0.0));
+            tnode.AddChild("ModelUVScaling", double(1.0), double(1.0));
+            tnode.AddChild("Texture_Alpha_Source", "None");
+            tnode.AddChild(
+                "Cropping", int32_t(0), int32_t(0), int32_t(0), int32_t(0)
+            );
+            tnode.Dump(outstream, binary, indent);
+        }
+    }
+
+    // Blendshapes, if any
+    for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
+      const aiMesh* m = mScene->mMeshes[mi];
+      if (m->mNumAnimMeshes == 0) {
+        continue;
+      }
+      // make a deformer for this mesh
+      int64_t deformer_uid = generate_uid();
+      FBX::Node dnode("Deformer");
+      dnode.AddProperties(deformer_uid, m->mName.data + FBX::SEPARATOR + "Blendshapes", "BlendShape");
+      dnode.AddChild("Version", int32_t(101));
+      dnode.Dump(outstream, binary, indent);
+      // connect it
+      connections.emplace_back("C", "OO", deformer_uid, mesh_uids[mi]);
+      std::vector<int32_t> vertex_indices = vVertexIndice[mi];
+
+      for (unsigned int am = 0; am < m->mNumAnimMeshes; ++am) {
+        aiAnimMesh *pAnimMesh = m->mAnimMeshes[am];
+        std::string blendshape_name = pAnimMesh->mName.data;
+
+        // start the node record
+        FBX::Node bsnode("Geometry");
+        int64_t blendshape_uid = generate_uid();
+        mesh_uids.push_back(blendshape_uid);
+        bsnode.AddProperty(blendshape_uid);
+        bsnode.AddProperty(blendshape_name + FBX::SEPARATOR + "Blendshape");
+        bsnode.AddProperty("Shape");
+        bsnode.AddChild("Version", int32_t(100));
+        bsnode.Begin(outstream, binary, indent);
+        bsnode.DumpProperties(outstream, binary, indent);
+        bsnode.EndProperties(outstream, binary, indent);
+        bsnode.BeginChildren(outstream, binary, indent);
+        indent++;
+        if (pAnimMesh->HasPositions()) {
+          std::vector<int32_t>shape_indices;
+          std::vector<double>pPositionDiff;
+          std::vector<double>pNormalDiff;
+
+          for (unsigned int vt = 0; vt < vertex_indices.size(); ++vt) {
+              aiVector3D pDiff = (pAnimMesh->mVertices[vertex_indices[vt]] - m->mVertices[vertex_indices[vt]]);
+              if(pDiff.Length()>1e-8){
+                shape_indices.push_back(vertex_indices[vt]);
+                pPositionDiff.push_back(pDiff[0]);
+                pPositionDiff.push_back(pDiff[1]);
+                pPositionDiff.push_back(pDiff[2]);
+
+                if (pAnimMesh->HasNormals()) {
+                    aiVector3D nDiff = (pAnimMesh->mNormals[vertex_indices[vt]] - m->mNormals[vertex_indices[vt]]);
+                    pNormalDiff.push_back(nDiff[0]);
+                    pNormalDiff.push_back(nDiff[1]);
+                    pNormalDiff.push_back(nDiff[2]);
+                }
+              }
+          }
+
+          FBX::Node::WritePropertyNode(
+              "Indexes", shape_indices, outstream, binary, indent
+          );
+
+          FBX::Node::WritePropertyNode(
+              "Vertices", pPositionDiff, outstream, binary, indent
+          );
+
+          if (pNormalDiff.size()>0) {
+            FBX::Node::WritePropertyNode(
+                "Normals", pNormalDiff, outstream, binary, indent
+            );
+          }
+        }
+        indent--;
+        bsnode.End(outstream, binary, indent, true);
+
+        // Add blendshape Channel Deformer
+        FBX::Node sdnode("Deformer");
+        const int64_t blendchannel_uid = generate_uid();
+        sdnode.AddProperties(
+            blendchannel_uid, blendshape_name + FBX::SEPARATOR + "SubDeformer", "BlendShapeChannel"
+        );
+        sdnode.AddChild("Version", int32_t(100));
+        sdnode.AddChild("DeformPercent", float(0.0));
+        FBX::Node p("Properties70");
+        p.AddP70numberA("DeformPercent", 0.0);
+        sdnode.AddChild(p);
+        // TODO: Normally just one weight per channel, adding stub for later development
+        std::vector<float>fFullWeights;
+        fFullWeights.push_back(100.);
+        sdnode.AddChild("FullWeights", fFullWeights);
+        sdnode.Dump(outstream, binary, indent);
+
+        connections.emplace_back("C", "OO", blendchannel_uid, deformer_uid);
+        connections.emplace_back("C", "OO", blendshape_uid, blendchannel_uid);
+      }
+    }
+
+    // bones.
+    //
+    // output structure:
+    // subset of node hierarchy that are "skeleton",
+    // i.e. do not have meshes but only bones.
+    // but.. i'm not sure how anyone could guarantee that...
+    //
+    // input...
+    // well, for each mesh it has "bones",
+    // and the bone names correspond to nodes.
+    // of course we also need the parent nodes,
+    // as they give some of the transform........
+    //
+    // well. we can assume a sane input, i suppose.
+    //
+    // so input is the bone node hierarchy,
+    // with an extra thing for the transformation of the MESH in BONE space.
+    //
+    // output is a set of bone nodes,
+    // a "bindpose" which indicates the default local transform of all bones,
+    // and a set of "deformers".
+    // each deformer is parented to a mesh geometry,
+    // and has one or more "subdeformer"s as children.
+    // each subdeformer has one bone node as a child,
+    // and represents the influence of that bone on the grandparent mesh.
+    // the subdeformer has a list of indices, and weights,
+    // with indices specifying vertex indices,
+    // and weights specifying the corresponding influence of this bone.
+    // it also has Transform and TransformLink elements,
+    // specifying the transform of the MESH in BONE space,
+    // and the transformation of the BONE in WORLD space,
+    // likely in the bindpose.
+    //
+    // the input bone structure is different but similar,
+    // storing the number of weights for this bone,
+    // and an array of (vertex index, weight) pairs.
+    //
+    // one sticky point is that the number of vertices may not match,
+    // because assimp splits vertices by normal, uv, etc.
+
+    // functor for aiNode sorting
+    struct SortNodeByName
+    {
+        bool operator()(const aiNode *lhs, const aiNode *rhs) const
+        {
+            return strcmp(lhs->mName.C_Str(), rhs->mName.C_Str()) < 0;
+        }
+    };
+
+    // first we should mark the skeleton for each mesh.
+    // the skeleton must include not only the aiBones,
+    // but also all their parent nodes.
+    // anything that affects the position of any bone node must be included.
+    // Use SorNodeByName to make sure the exported result will be the same across all systems
+    // Otherwise the aiNodes of the skeleton would be sorted based on the pointer address, which isn't consistent
+    std::vector<std::set<const aiNode*, SortNodeByName>> skeleton_by_mesh(mScene->mNumMeshes);
+    // at the same time we can build a list of all the skeleton nodes,
+    // which will be used later to mark them as type "limbNode".
+    std::unordered_set<const aiNode*> limbnodes;
+
+    //actual bone nodes in fbx, without parenting-up
+    std::unordered_set<std::string> setAllBoneNamesInScene;
+    for(unsigned int m = 0; m < mScene->mNumMeshes; ++ m)
+    {
+        aiMesh* pMesh = mScene->mMeshes[m];
+        for(unsigned int b = 0; b < pMesh->mNumBones; ++ b)
+            setAllBoneNamesInScene.insert(pMesh->mBones[b]->mName.data);
+    }
+    aiMatrix4x4 mxTransIdentity;
+
+    // and a map of nodes by bone name, as finding them is annoying.
+    std::map<std::string,aiNode*> node_by_bone;
+    for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
+        const aiMesh* m = mScene->mMeshes[mi];
+        std::set<const aiNode*, SortNodeByName> skeleton;
+        for (size_t bi =0; bi < m->mNumBones; ++bi) {
+            const aiBone* b = m->mBones[bi];
+            const std::string name(b->mName.C_Str());
+            auto elem = node_by_bone.find(name);
+            aiNode* n;
+            if (elem != node_by_bone.end()) {
+                n = elem->second;
+            } else {
+                n = mScene->mRootNode->FindNode(b->mName);
+                if (!n) {
+                    // this should never happen
+                    std::stringstream err;
+                    err << "Failed to find node for bone: \"" << name << "\"";
+                    throw DeadlyExportError(err.str());
+                }
+                node_by_bone[name] = n;
+                limbnodes.insert(n);
+            }
+            skeleton.insert(n);
+            // mark all parent nodes as skeleton as well,
+            // up until we find the root node,
+            // or else the node containing the mesh,
+            // or else the parent of a node containing the mesh.
+            for (
+                const aiNode* parent = n->mParent;
+                parent && parent != mScene->mRootNode;
+                parent = parent->mParent
+            ) {
+                // if we've already done this node we can skip it all
+                if (skeleton.count(parent)) {
+                    break;
+                }
+                // ignore fbx transform nodes as these will be collapsed later
+                // TODO: cache this by aiNode*
+                const std::string node_name(parent->mName.C_Str());
+                if (node_name.find(MAGIC_NODE_TAG) != std::string::npos) {
+                    continue;
+                }
+                //not a bone in scene && no effect in transform
+                if(setAllBoneNamesInScene.find(node_name)==setAllBoneNamesInScene.end()
+                   && parent->mTransformation == mxTransIdentity) {
+                        continue;
+                }
+                // otherwise check if this is the root of the skeleton
+                bool end = false;
+                // is the mesh part of this node?
+                for (size_t i = 0; i < parent->mNumMeshes; ++i) {
+                    if (parent->mMeshes[i] == mi) {
+                        end = true;
+                        break;
+                    }
+                }
+                // is the mesh in one of the children of this node?
+                for (size_t j = 0; j < parent->mNumChildren; ++j) {
+                    aiNode* child = parent->mChildren[j];
+                    for (size_t i = 0; i < child->mNumMeshes; ++i) {
+                        if (child->mMeshes[i] == mi) {
+                            end = true;
+                            break;
+                        }
+                    }
+                    if (end) { break; }
+                }
+
+                // if it was the skeleton root we can finish here
+                if (end) { break; }
+            }
+        }
+        skeleton_by_mesh[mi] = skeleton;
+    }
+
+    // we'll need the uids for the bone nodes, so generate them now
+    for (size_t i = 0; i < mScene->mNumMeshes; ++i) {
+        auto &s = skeleton_by_mesh[i];
+        for (const aiNode* n : s) {
+            auto elem = node_uids.find(n);
+            if (elem == node_uids.end()) {
+                node_uids[n] = generate_uid();
+            }
+        }
+    }
+
+    // now, for each aiMesh, we need to export a deformer,
+    // and for each aiBone a subdeformer,
+    // which should have all the skinning info.
+    // these will need to be connected properly to the mesh,
+    // and we can do that all now.
+    for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
+        const aiMesh* m = mScene->mMeshes[mi];
+        if (!m->HasBones()) {
+            continue;
+        }
+        // make a deformer for this mesh
+        int64_t deformer_uid = generate_uid();
+        FBX::Node dnode("Deformer");
+        dnode.AddProperties(deformer_uid, FBX::SEPARATOR + "Deformer", "Skin");
+        dnode.AddChild("Version", int32_t(101));
+        // "acuracy"... this is not a typo....
+        dnode.AddChild("Link_DeformAcuracy", double(50));
+        dnode.AddChild("SkinningType", "Linear"); // TODO: other modes?
+        dnode.Dump(outstream, binary, indent);
+
+        // connect it
+        connections.emplace_back("C", "OO", deformer_uid, mesh_uids[mi]);
+
+        //computed before
+        std::vector<int32_t>& vertex_indices = vVertexIndice[mi];
+
+        // TODO, FIXME: this won't work if anything is not in the bind pose.
+        // for now if such a situation is detected, we throw an exception.
+        std::set<const aiBone*> not_in_bind_pose;
+        std::set<const aiNode*> no_offset_matrix;
+
+        // first get this mesh's position in world space,
+        // as we'll need it for each subdeformer.
+        //
+        // ...of course taking the position of the MESH doesn't make sense,
+        // as it can be instanced to many nodes.
+        // All we can do is assume no instancing,
+        // and take the first node we find that contains the mesh.
+        aiNode* mesh_node = get_node_for_mesh((unsigned int)mi, mScene->mRootNode);
+        aiMatrix4x4 mesh_xform = get_world_transform(mesh_node, mScene);
+
+        // now make a subdeformer for each bone in the skeleton
+        const std::set<const aiNode*, SortNodeByName> skeleton= skeleton_by_mesh[mi];
+        for (const aiNode* bone_node : skeleton) {
+            // if there's a bone for this node, find it
+            const aiBone* b = nullptr;
+            for (size_t bi = 0; bi < m->mNumBones; ++bi) {
+                // TODO: this probably should index by something else
+                const std::string name(m->mBones[bi]->mName.C_Str());
+                if (node_by_bone[name] == bone_node) {
+                    b = m->mBones[bi];
+                    break;
+                }
+            }
+            if (!b) {
+                no_offset_matrix.insert(bone_node);
+            }
+
+            // start the subdeformer node
+            const int64_t subdeformer_uid = generate_uid();
+            FBX::Node sdnode("Deformer");
+            sdnode.AddProperties(
+                subdeformer_uid, FBX::SEPARATOR + "SubDeformer", "Cluster"
+            );
+            sdnode.AddChild("Version", int32_t(100));
+            sdnode.AddChild("UserData", "", "");
+
+            std::set<int32_t> setWeightedVertex;
+            // add indices and weights, if any
+            if (b) {
+                std::vector<int32_t> subdef_indices;
+                std::vector<double> subdef_weights;
+                int32_t last_index = -1;
+                for (size_t wi = 0; wi < b->mNumWeights; ++wi) {
+                    int32_t vi = vertex_indices[b->mWeights[wi].mVertexId];
+                    bool bIsWeightedAlready = (setWeightedVertex.find(vi) != setWeightedVertex.end());
+                    if (vi == last_index || bIsWeightedAlready) {
+                        // only for vertices we exported to fbx
+                        // TODO, FIXME: this assumes identically-located vertices
+                        // will always deform in the same way.
+                        // as assimp doesn't store a separate list of "positions",
+                        // there's not much that can be done about this
+                        // other than assuming that identical position means
+                        // identical vertex.
+                        continue;
+                    }
+                    setWeightedVertex.insert(vi);
+                    subdef_indices.push_back(vi);
+                    subdef_weights.push_back(b->mWeights[wi].mWeight);
+                    last_index = vi;
+                }
+                // yes, "indexes"
+                sdnode.AddChild("Indexes", subdef_indices);
+                sdnode.AddChild("Weights", subdef_weights);
+            }
+
+            // transform is the transform of the mesh, but in bone space.
+            // if the skeleton is in the bind pose,
+            // we can take the inverse of the world-space bone transform
+            // and multiply by the world-space transform of the mesh.
+            aiMatrix4x4 bone_xform = get_world_transform(bone_node, mScene);
+            aiMatrix4x4 inverse_bone_xform = bone_xform;
+            inverse_bone_xform.Inverse();
+            aiMatrix4x4 tr = inverse_bone_xform * mesh_xform;
+
+            sdnode.AddChild("Transform", tr);
+
+
+            sdnode.AddChild("TransformLink", bone_xform);
+            // note: this means we ALWAYS rely on the mesh node transform
+            // being unchanged from the time the skeleton was bound.
+            // there's not really any way around this at the moment.
+
+            // done
+            sdnode.Dump(outstream, binary, indent);
+
+            // lastly, connect to the parent deformer
+            connections.emplace_back(
+                "C", "OO", subdeformer_uid, deformer_uid
+            );
+
+            // we also need to connect the limb node to the subdeformer.
+            connections.emplace_back(
+                "C", "OO", node_uids[bone_node], subdeformer_uid
+            );
+        }
+
+        // if we cannot create a valid FBX file, simply die.
+        // this will both prevent unnecessary bug reports,
+        // and tell the user what they can do to fix the situation
+        // (i.e. export their model in the bind pose).
+        if (no_offset_matrix.size() && not_in_bind_pose.size()) {
+            std::stringstream err;
+            err << "Not enough information to construct bind pose";
+            err << " for mesh " << mi << "!";
+            err << " Transform matrix for bone \"";
+            err << (*not_in_bind_pose.begin())->mName.C_Str() << "\"";
+            if (not_in_bind_pose.size() > 1) {
+                err << " (and " << not_in_bind_pose.size() - 1 << " more)";
+            }
+            err << " does not match mOffsetMatrix,";
+            err << " and node \"";
+            err << (*no_offset_matrix.begin())->mName.C_Str() << "\"";
+            if (no_offset_matrix.size() > 1) {
+                err << " (and " << no_offset_matrix.size() - 1 << " more)";
+            }
+            err << " has no offset matrix to rely on.";
+            err << " Please ensure bones are in the bind pose to export.";
+            throw DeadlyExportError(err.str());
+        }
+
+    }
+
+    // BindPose
+    //
+    // This is a legacy system, which should be unnecessary.
+    //
+    // Somehow including it slows file loading by the official FBX SDK,
+    // and as it can reconstruct it from the deformers anyway,
+    // this is not currently included.
+    //
+    // The code is kept here in case it's useful in the future,
+    // but it's pretty much a hack anyway,
+    // as assimp doesn't store bindpose information for full skeletons.
+    //
+    /*for (size_t mi = 0; mi < mScene->mNumMeshes; ++mi) {
+        aiMesh* mesh = mScene->mMeshes[mi];
+        if (! mesh->HasBones()) { continue; }
+        int64_t bindpose_uid = generate_uid();
+        FBX::Node bpnode("Pose");
+        bpnode.AddProperty(bindpose_uid);
+        // note: this uid is never linked or connected to anything.
+        bpnode.AddProperty(FBX::SEPARATOR + "Pose"); // blank name
+        bpnode.AddProperty("BindPose");
+
+        bpnode.AddChild("Type", "BindPose");
+        bpnode.AddChild("Version", int32_t(100));
+
+        aiNode* mesh_node = get_node_for_mesh(mi, mScene->mRootNode);
+
+        // next get the whole skeleton for this mesh.
+        // we need it all to define the bindpose section.
+        // the FBX SDK will complain if it's missing,
+        // and also if parents of used bones don't have a subdeformer.
+        // order shouldn't matter.
+        std::set<aiNode*> skeleton;
+        for (size_t bi = 0; bi < mesh->mNumBones; ++bi) {
+            // bone node should have already been indexed
+            const aiBone* b = mesh->mBones[bi];
+            const std::string bone_name(b->mName.C_Str());
+            aiNode* parent = node_by_bone[bone_name];
+            // insert all nodes down to the root or mesh node
+            while (
+                parent
+                && parent != mScene->mRootNode
+                && parent != mesh_node
+            ) {
+                skeleton.insert(parent);
+                parent = parent->mParent;
+            }
+        }
+
+        // number of pose nodes. includes one for the mesh itself.
+        bpnode.AddChild("NbPoseNodes", int32_t(1 + skeleton.size()));
+
+        // the first pose node is always the mesh itself
+        FBX::Node pose("PoseNode");
+        pose.AddChild("Node", mesh_uids[mi]);
+        aiMatrix4x4 mesh_node_xform = get_world_transform(mesh_node, mScene);
+        pose.AddChild("Matrix", mesh_node_xform);
+        bpnode.AddChild(pose);
+
+        for (aiNode* bonenode : skeleton) {
+            // does this node have a uid yet?
+            int64_t node_uid;
+            auto node_uid_iter = node_uids.find(bonenode);
+            if (node_uid_iter != node_uids.end()) {
+                node_uid = node_uid_iter->second;
+            } else {
+                node_uid = generate_uid();
+                node_uids[bonenode] = node_uid;
+            }
+
+            // make a pose thingy
+            pose = FBX::Node("PoseNode");
+            pose.AddChild("Node", node_uid);
+            aiMatrix4x4 node_xform = get_world_transform(bonenode, mScene);
+            pose.AddChild("Matrix", node_xform);
+            bpnode.AddChild(pose);
+        }
+
+        // now write it
+        bpnode.Dump(outstream, binary, indent);
+    }*/
+
+    // lights
+    indent = 1;
+    lights_uids.clear();
+    for (size_t li = 0; li < mScene->mNumLights; ++li) {
+        aiLight* l = mScene->mLights[li];
+
+        int64_t uid = generate_uid();
+        const std::string lightNodeAttributeName = l->mName.C_Str() + FBX::SEPARATOR + "NodeAttribute";
+
+        FBX::Node lna("NodeAttribute");
+        lna.AddProperties(uid, lightNodeAttributeName, "Light");
+        FBX::Node lnap("Properties70");
+
+        // Light color.
+        lnap.AddP70colorA("Color", l->mColorDiffuse.r, l->mColorDiffuse.g, l->mColorDiffuse.b);
+
+        // TODO Assimp light description is quite concise and do not handle light intensity.
+        // Default value to 1000W.
+        lnap.AddP70numberA("Intensity", 1000);
+
+        // FBXLight::EType conversion
+        switch (l->mType) {
+        case aiLightSource_POINT:
+            lnap.AddP70enum("LightType", 0);
+            break;
+        case aiLightSource_DIRECTIONAL:
+            lnap.AddP70enum("LightType", 1);
+            break;
+        case aiLightSource_SPOT:
+            lnap.AddP70enum("LightType", 2);
+            lnap.AddP70numberA("InnerAngle", AI_RAD_TO_DEG(l->mAngleInnerCone));
+            lnap.AddP70numberA("OuterAngle", AI_RAD_TO_DEG(l->mAngleOuterCone));
+            break;
+        // TODO Assimp do not handle 'area' nor 'volume' lights, but FBX does.
+        /*case aiLightSource_AREA:
+            lnap.AddP70enum("LightType", 3);
+            lnap.AddP70enum("AreaLightShape", 0); // 0=Rectangle, 1=Sphere
+            break;
+        case aiLightSource_VOLUME:
+            lnap.AddP70enum("LightType", 4);
+            break;*/
+        default:
+            break;
+        }
+
+        // Did not understood how to configure the decay so disabling attenuation.
+        lnap.AddP70enum("DecayType", 0);
+
+        // Dump to FBX stream
+        lna.AddChild(lnap);
+        lna.AddChild("TypeFlags", FBX::FBXExportProperty("Light"));
+        lna.AddChild("GeometryVersion", FBX::FBXExportProperty(int32_t(124)));
+        lna.Dump(outstream, binary, indent);
+
+        // Store name and uid (will be used later when parsing scene nodes)
+        lights_uids[l->mName.C_Str()] = uid;
+    }
+
+    // TODO: cameras
+
+    // write nodes (i.e. model hierarchy)
+    // start at root node
+    WriteModelNodes(
+        outstream, mScene->mRootNode, 0, limbnodes
+    );
+
+    // animations
+    //
+    // in FBX there are:
+    // * AnimationStack - corresponds to an aiAnimation
+    // * AnimationLayer - a combinable animation component
+    // * AnimationCurveNode - links the property to be animated
+    // * AnimationCurve - defines animation data for a single property value
+    //
+    // the CurveNode also provides the default value for a property,
+    // such as the X, Y, Z coordinates for animatable translation.
+    //
+    // the Curve only specifies values for one component of the property,
+    // so there will be a separate AnimationCurve for X, Y, and Z.
+    //
+    // Assimp has:
+    // * aiAnimation - basically corresponds to an AnimationStack
+    // * aiNodeAnim - defines all animation for one aiNode
+    // * aiVectorKey/aiQuatKey - define the keyframe data for T/R/S
+    //
+    // assimp has no equivalent for AnimationLayer,
+    // and these are flattened on FBX import.
+    // we can assume there will be one per AnimationStack.
+    //
+    // the aiNodeAnim contains all animation data for a single aiNode,
+    // which will correspond to three AnimationCurveNode's:
+    // one each for translation, rotation and scale.
+    // The data for each of these will be put in 9 AnimationCurve's,
+    // T.X, T.Y, T.Z, R.X, R.Y, R.Z, etc.
+
+    // AnimationStack / aiAnimation
+    std::vector<int64_t> animation_stack_uids(mScene->mNumAnimations);
+    for (size_t ai = 0; ai < mScene->mNumAnimations; ++ai) {
+        int64_t animstack_uid = generate_uid();
+        animation_stack_uids[ai] = animstack_uid;
+        const aiAnimation* anim = mScene->mAnimations[ai];
+
+        FBX::Node asnode("AnimationStack");
+        std::string name = anim->mName.C_Str() + FBX::SEPARATOR + "AnimStack";
+        asnode.AddProperties(animstack_uid, name, "");
+        FBX::Node p("Properties70");
+        p.AddP70time("LocalStart", 0); // assimp doesn't store this
+        p.AddP70time("LocalStop", to_ktime(anim->mDuration, anim));
+        p.AddP70time("ReferenceStart", 0);
+        p.AddP70time("ReferenceStop", to_ktime(anim->mDuration, anim));
+        asnode.AddChild(p);
+
+        // this node absurdly always pretends it has children
+        // (in this case it does, but just in case...)
+        asnode.force_has_children = true;
+        asnode.Dump(outstream, binary, indent);
+
+        // note: animation stacks are not connected to anything
+    }
+
+    // AnimationLayer - one per aiAnimation
+    std::vector<int64_t> animation_layer_uids(mScene->mNumAnimations);
+    for (size_t ai = 0; ai < mScene->mNumAnimations; ++ai) {
+        int64_t animlayer_uid = generate_uid();
+        animation_layer_uids[ai] = animlayer_uid;
+        FBX::Node alnode("AnimationLayer");
+        alnode.AddProperties(animlayer_uid, FBX::SEPARATOR + "AnimLayer", "");
+
+        // this node absurdly always pretends it has children
+        alnode.force_has_children = true;
+        alnode.Dump(outstream, binary, indent);
+
+        // connect to the relevant animstack
+        connections.emplace_back(
+            "C", "OO", animlayer_uid, animation_stack_uids[ai]
+        );
+    }
+
+    // AnimCurveNode - three per aiNodeAnim
+    std::vector<std::vector<std::array<int64_t,3>>> curve_node_uids;
+    for (size_t ai = 0; ai < mScene->mNumAnimations; ++ai) {
+        const aiAnimation* anim = mScene->mAnimations[ai];
+        const int64_t layer_uid = animation_layer_uids[ai];
+        std::vector<std::array<int64_t,3>> nodeanim_uids;
+        for (size_t nai = 0; nai < anim->mNumChannels; ++nai) {
+            const aiNodeAnim* na = anim->mChannels[nai];
+            // get the corresponding aiNode
+            const aiNode* node = mScene->mRootNode->FindNode(na->mNodeName);
+            // and its transform
+            const aiMatrix4x4 node_xfm = get_world_transform(node, mScene);
+            aiVector3D T, R, S;
+            node_xfm.Decompose(S, R, T);
+
+            // AnimationCurveNode uids
+            std::array<int64_t,3> ids;
+            ids[0] = generate_uid(); // T
+            ids[1] = generate_uid(); // R
+            ids[2] = generate_uid(); // S
+
+            // translation
+            WriteAnimationCurveNode(outstream,
+                ids[0], "T", T, "Lcl Translation",
+                layer_uid, node_uids[node]
+            );
+
+            // rotation
+            WriteAnimationCurveNode(outstream,
+                ids[1], "R", R, "Lcl Rotation",
+                layer_uid, node_uids[node]
+            );
+
+            // scale
+            WriteAnimationCurveNode(outstream,
+                ids[2], "S", S, "Lcl Scale",
+                layer_uid, node_uids[node]
+            );
+
+            // store the uids for later use
+            nodeanim_uids.push_back(ids);
+        }
+        curve_node_uids.push_back(nodeanim_uids);
+    }
+
+    // AnimCurve - defines actual keyframe data.
+    // there's a separate curve for every component of every vector,
+    // for example a transform curvenode will have separate X/Y/Z AnimCurve's
+    for (size_t ai = 0; ai < mScene->mNumAnimations; ++ai) {
+        const aiAnimation* anim = mScene->mAnimations[ai];
+        for (size_t nai = 0; nai < anim->mNumChannels; ++nai) {
+            const aiNodeAnim* na = anim->mChannels[nai];
+            // get the corresponding aiNode
+            const aiNode* node = mScene->mRootNode->FindNode(na->mNodeName);
+            // and its transform
+            const aiMatrix4x4 node_xfm = get_world_transform(node, mScene);
+            aiVector3D T, R, S;
+            node_xfm.Decompose(S, R, T);
+            const std::array<int64_t,3>& ids = curve_node_uids[ai][nai];
+
+            std::vector<int64_t> times;
+            std::vector<float> xval, yval, zval;
+
+            // position/translation
+            for (size_t ki = 0; ki < na->mNumPositionKeys; ++ki) {
+                const aiVectorKey& k = na->mPositionKeys[ki];
+                times.push_back(to_ktime(k.mTime));
+                xval.push_back(k.mValue.x);
+                yval.push_back(k.mValue.y);
+                zval.push_back(k.mValue.z);
+            }
+            // one curve each for X, Y, Z
+            WriteAnimationCurve(outstream, T.x, times, xval, ids[0], "d|X");
+            WriteAnimationCurve(outstream, T.y, times, yval, ids[0], "d|Y");
+            WriteAnimationCurve(outstream, T.z, times, zval, ids[0], "d|Z");
+
+            // rotation
+            times.clear(); xval.clear(); yval.clear(); zval.clear();
+            for (size_t ki = 0; ki < na->mNumRotationKeys; ++ki) {
+                const aiQuatKey& k = na->mRotationKeys[ki];
+                times.push_back(to_ktime(k.mTime));
+                // TODO: aiQuaternion method to convert to Euler...
+                aiMatrix4x4 m(k.mValue.GetMatrix());
+                aiVector3D qs, qr, qt;
+                m.Decompose(qs, qr, qt);
+                qr *= DEG;
+                xval.push_back(qr.x);
+                yval.push_back(qr.y);
+                zval.push_back(qr.z);
+            }
+            WriteAnimationCurve(outstream, R.x, times, xval, ids[1], "d|X");
+            WriteAnimationCurve(outstream, R.y, times, yval, ids[1], "d|Y");
+            WriteAnimationCurve(outstream, R.z, times, zval, ids[1], "d|Z");
+
+            // scaling/scale
+            times.clear(); xval.clear(); yval.clear(); zval.clear();
+            for (size_t ki = 0; ki < na->mNumScalingKeys; ++ki) {
+                const aiVectorKey& k = na->mScalingKeys[ki];
+                times.push_back(to_ktime(k.mTime));
+                xval.push_back(k.mValue.x);
+                yval.push_back(k.mValue.y);
+                zval.push_back(k.mValue.z);
+            }
+            WriteAnimationCurve(outstream, S.x, times, xval, ids[2], "d|X");
+            WriteAnimationCurve(outstream, S.y, times, yval, ids[2], "d|Y");
+            WriteAnimationCurve(outstream, S.z, times, zval, ids[2], "d|Z");
+        }
+    }
+
+    indent = 0;
+    object_node.End(outstream, binary, indent, true);
+}
+
+// convenience map of magic node name strings to FBX properties,
+// including the expected type of transform.
+const std::map<std::string,std::pair<std::string,char>> transform_types = {
+    {"Translation", {"Lcl Translation", 't'}},
+    {"RotationOffset", {"RotationOffset", 't'}},
+    {"RotationPivot", {"RotationPivot", 't'}},
+    {"PreRotation", {"PreRotation", 'r'}},
+    {"Rotation", {"Lcl Rotation", 'r'}},
+    {"PostRotation", {"PostRotation", 'r'}},
+    {"RotationPivotInverse", {"RotationPivotInverse", 'i'}},
+    {"ScalingOffset", {"ScalingOffset", 't'}},
+    {"ScalingPivot", {"ScalingPivot", 't'}},
+    {"Scaling", {"Lcl Scaling", 's'}},
+    {"ScalingPivotInverse", {"ScalingPivotInverse", 'i'}},
+    {"GeometricScaling", {"GeometricScaling", 's'}},
+    {"GeometricRotation", {"GeometricRotation", 'r'}},
+    {"GeometricTranslation", {"GeometricTranslation", 't'}},
+    {"GeometricTranslationInverse", {"GeometricTranslationInverse", 'i'}},
+    {"GeometricRotationInverse", {"GeometricRotationInverse", 'i'}},
+    {"GeometricScalingInverse", {"GeometricScalingInverse", 'i'}}
+};
+
+// write a single model node to the stream
+void FBXExporter::WriteModelNode(
+    StreamWriterLE& outstream,
+    bool,
+    const aiNode* node,
+    int64_t node_uid,
+    const std::string& type,
+    const std::vector<std::pair<std::string,aiVector3D>>& transform_chain,
+    TransformInheritance inherit_type
+){
+    const aiVector3D zero = {0, 0, 0};
+    const aiVector3D one = {1, 1, 1};
+    FBX::Node m("Model");
+    std::string name = node->mName.C_Str() + FBX::SEPARATOR + "Model";
+    m.AddProperties(node_uid, name, type);
+    m.AddChild("Version", int32_t(232));
+    FBX::Node p("Properties70");
+    p.AddP70bool("RotationActive", 1);
+    p.AddP70int("DefaultAttributeIndex", 0);
+    p.AddP70enum("InheritType", inherit_type);
+    if (transform_chain.empty()) {
+        // decompose 4x4 transform matrix into TRS
+        aiVector3D t, r, s;
+        node->mTransformation.Decompose(s, r, t);
+        if (t != zero) {
+            p.AddP70(
+                "Lcl Translation", "Lcl Translation", "", "A",
+                double(t.x), double(t.y), double(t.z)
+            );
+        }
+        if (r != zero) {
+            p.AddP70(
+                "Lcl Rotation", "Lcl Rotation", "", "A",
+                double(DEG*r.x), double(DEG*r.y), double(DEG*r.z)
+            );
+        }
+        if (s != one) {
+            p.AddP70(
+                "Lcl Scaling", "Lcl Scaling", "", "A",
+                double(s.x), double(s.y), double(s.z)
+            );
+        }
+    } else {
+        // apply the transformation chain.
+        // these transformation elements are created when importing FBX,
+        // which has a complex transformation hierarchy for each node.
+        // as such we can bake the hierarchy back into the node on export.
+        for (auto &item : transform_chain) {
+            auto elem = transform_types.find(item.first);
+            if (elem == transform_types.end()) {
+                // then this is a bug
+                std::stringstream err;
+                err << "unrecognized FBX transformation type: ";
+                err << item.first;
+                throw DeadlyExportError(err.str());
+            }
+            const std::string &cur_name = elem->second.first;
+            const aiVector3D &v = item.second;
+            if (cur_name.compare(0, 4, "Lcl ") == 0) {
+                // special handling for animatable properties
+                p.AddP70( cur_name, cur_name, "", "A", double(v.x), double(v.y), double(v.z) );
+            } else {
+                p.AddP70vector(cur_name, v.x, v.y, v.z);
+            }
+        }
+    }
+    m.AddChild(p);
+
+    // not sure what these are for,
+    // but they seem to be omnipresent
+    m.AddChild("Shading", FBXExportProperty(true));
+    m.AddChild("Culling", FBXExportProperty("CullingOff"));
+
+    m.Dump(outstream, binary, 1);
+}
+
+// wrapper for WriteModelNodes to create and pass a blank transform chain
+void FBXExporter::WriteModelNodes(
+    StreamWriterLE& s,
+    const aiNode* node,
+    int64_t parent_uid,
+    const std::unordered_set<const aiNode*>& limbnodes
+) {
+    std::vector<std::pair<std::string,aiVector3D>> chain;
+    WriteModelNodes(s, node, parent_uid, limbnodes, chain);
+}
+
+void FBXExporter::WriteModelNodes(
+    StreamWriterLE& outstream,
+    const aiNode* node,
+    int64_t parent_uid,
+    const std::unordered_set<const aiNode*>& limbnodes,
+    std::vector<std::pair<std::string,aiVector3D>>& transform_chain
+) {
+    // first collapse any expanded transformation chains created by FBX import.
+    std::string node_name(node->mName.C_Str());
+    if (node_name.find(MAGIC_NODE_TAG) != std::string::npos) {
+        auto pos = node_name.find(MAGIC_NODE_TAG) + MAGIC_NODE_TAG.size() + 1;
+        std::string type_name = node_name.substr(pos);
+        auto elem = transform_types.find(type_name);
+        if (elem == transform_types.end()) {
+            // then this is a bug and should be fixed
+            std::stringstream err;
+            err << "unrecognized FBX transformation node";
+            err << " of type " << type_name << " in node " << node_name;
+            throw DeadlyExportError(err.str());
+        }
+        aiVector3D t, r, s;
+        node->mTransformation.Decompose(s, r, t);
+        switch (elem->second.second) {
+        case 'i': // inverse
+            // we don't need to worry about the inverse matrices
+            break;
+        case 't': // translation
+            transform_chain.emplace_back(elem->first, t);
+            break;
+        case 'r': // rotation
+            r *= float(DEG);
+            transform_chain.emplace_back(elem->first, r);
+            break;
+        case 's': // scale
+            transform_chain.emplace_back(elem->first, s);
+            break;
+        default:
+            // this should never happen
+            std::stringstream err;
+            err << "unrecognized FBX transformation type code: ";
+            err << elem->second.second;
+            throw DeadlyExportError(err.str());
+        }
+        // now continue on to any child nodes
+        for (unsigned i = 0; i < node->mNumChildren; ++i) {
+            WriteModelNodes(
+                outstream,
+                node->mChildren[i],
+                parent_uid,
+                limbnodes,
+                transform_chain
+            );
+        }
+        return;
+    }
+
+    int64_t node_uid = 0;
+    // generate uid and connect to parent, if not the root node,
+    if (node != mScene->mRootNode) {
+        auto elem = node_uids.find(node);
+        if (elem != node_uids.end()) {
+            node_uid = elem->second;
+        } else {
+            node_uid = generate_uid();
+            node_uids[node] = node_uid;
+        }
+        connections.emplace_back("C", "OO", node_uid, parent_uid);
+    }
+
+    // what type of node is this?
+    if (node == mScene->mRootNode) {
+        // handled later
+    } else if (node->mNumMeshes == 1) {
+        // connect to child mesh, which should have been written previously
+        connections.emplace_back(
+            "C", "OO", mesh_uids[node->mMeshes[0]], node_uid
+        );
+        // also connect to the material for the child mesh
+        connections.emplace_back(
+            "C", "OO",
+            material_uids[mScene->mMeshes[node->mMeshes[0]]->mMaterialIndex],
+            node_uid
+        );
+        // write model node
+        WriteModelNode(
+            outstream, binary, node, node_uid, "Mesh", transform_chain
+        );
+    } else if (limbnodes.count(node)) {
+        WriteModelNode(
+            outstream, binary, node, node_uid, "LimbNode", transform_chain
+        );
+        // we also need to write a nodeattribute to mark it as a skeleton
+        int64_t node_attribute_uid = generate_uid();
+        FBX::Node na("NodeAttribute");
+        na.AddProperties(
+            node_attribute_uid, FBX::SEPARATOR + "NodeAttribute", "LimbNode"
+        );
+        na.AddChild("TypeFlags", FBXExportProperty("Skeleton"));
+        na.Dump(outstream, binary, 1);
+        // and connect them
+        connections.emplace_back("C", "OO", node_attribute_uid, node_uid);
+    } else {
+        const auto& lightIt = lights_uids.find(node->mName.C_Str());
+        if(lightIt != lights_uids.end()) {
+            // Node has a light connected to it.
+            WriteModelNode(
+                outstream, binary, node, node_uid, "Light", transform_chain
+            );
+            connections.emplace_back("C", "OO", lightIt->second, node_uid);
+        } else {
+            // generate a null node so we can add children to it
+            WriteModelNode(
+                outstream, binary, node, node_uid, "Null", transform_chain
+            );
+        }
+    }
+
+    // if more than one child mesh, make nodes for each mesh
+    if (node->mNumMeshes > 1 || node == mScene->mRootNode) {
+        for (size_t i = 0; i < node->mNumMeshes; ++i) {
+            // make a new model node
+            int64_t new_node_uid = generate_uid();
+            // connect to parent node
+            connections.emplace_back("C", "OO", new_node_uid, node_uid);
+            // connect to child mesh, which should have been written previously
+            connections.emplace_back(
+                "C", "OO", mesh_uids[node->mMeshes[i]], new_node_uid
+            );
+            // also connect to the material for the child mesh
+            connections.emplace_back(
+                "C", "OO",
+                material_uids[
+                    mScene->mMeshes[node->mMeshes[i]]->mMaterialIndex
+                ],
+                new_node_uid
+            );
+
+            aiNode new_node;
+            // take name from mesh name, if it exists
+            new_node.mName = mScene->mMeshes[node->mMeshes[i]]->mName;
+            // write model node
+            WriteModelNode(
+                outstream, binary, &new_node, new_node_uid, "Mesh", std::vector<std::pair<std::string,aiVector3D>>()
+            );
+        }
+    }
+
+    // now recurse into children
+    for (size_t i = 0; i < node->mNumChildren; ++i) {
+        WriteModelNodes(
+            outstream, node->mChildren[i], node_uid, limbnodes
+        );
+    }
+}
+
+void FBXExporter::WriteAnimationCurveNode(
+        StreamWriterLE &outstream,
+        int64_t uid,
+        const std::string &name, // "T", "R", or "S"
+        aiVector3D default_value,
+        const std::string &property_name, // "Lcl Translation" etc
+        int64_t layer_uid,
+        int64_t node_uid) {
+    FBX::Node n("AnimationCurveNode");
+    n.AddProperties(uid, name + FBX::SEPARATOR + "AnimCurveNode", "");
+    FBX::Node p("Properties70");
+    p.AddP70numberA("d|X", default_value.x);
+    p.AddP70numberA("d|Y", default_value.y);
+    p.AddP70numberA("d|Z", default_value.z);
+    n.AddChild(p);
+    n.Dump(outstream, binary, 1);
+    // connect to layer
+    this->connections.emplace_back("C", "OO", uid, layer_uid);
+    // connect to bone
+    this->connections.emplace_back("C", "OP", uid, node_uid, property_name);
+}
+
+void FBXExporter::WriteAnimationCurve(
+    StreamWriterLE& outstream,
+    double default_value,
+    const std::vector<int64_t>& times,
+    const std::vector<float>& values,
+    int64_t curvenode_uid,
+    const std::string& property_link // "d|X", "d|Y", etc
+) {
+    FBX::Node n("AnimationCurve");
+    int64_t curve_uid = generate_uid();
+    n.AddProperties(curve_uid, FBX::SEPARATOR + "AnimCurve", "");
+    n.AddChild("Default", default_value);
+    n.AddChild("KeyVer", int32_t(4009));
+    n.AddChild("KeyTime", times);
+    n.AddChild("KeyValueFloat", values);
+    // TODO: keyattr flags and data (STUB for now)
+    n.AddChild("KeyAttrFlags", std::vector<int32_t>{0});
+    n.AddChild("KeyAttrDataFloat", std::vector<float>{0,0,0,0});
+    n.AddChild(
+        "KeyAttrRefCount",
+        std::vector<int32_t>{static_cast<int32_t>(times.size())}
+    );
+    n.Dump(outstream, binary, 1);
+    this->connections.emplace_back(
+        "C", "OP", curve_uid, curvenode_uid, property_link
+    );
+}
+
+
+void FBXExporter::WriteConnections ()
+{
+    // we should have completed the connection graph already,
+    // so basically just dump it here
+    if (!binary) {
+        WriteAsciiSectionHeader("Object connections");
+    }
+    // TODO: comments with names in the ascii version
+    FBX::Node conn("Connections");
+    StreamWriterLE outstream(outfile);
+    conn.Begin(outstream, binary, 0);
+    conn.BeginChildren(outstream, binary, 0);
+    for (auto &n : connections) {
+        n.Dump(outstream, binary, 1);
+    }
+    conn.End(outstream, binary, 0, !connections.empty());
+    connections.clear();
+}
+
+#endif // ASSIMP_BUILD_NO_FBX_EXPORTER
+#endif // ASSIMP_BUILD_NO_EXPORT