add assimp submodule

1 files changed, 1748 insertions, 0 deletions

diff --git a/src/mesh/assimp-master/code/AssetLib/Collada/ColladaExporter.cpp b/src/mesh/assimp-master/code/AssetLib/Collada/ColladaExporter.cpp
new file mode 100644
index 0000000..5c91daa
--- /dev/null
+++ b/src/mesh/assimp-master/code/AssetLib/Collada/ColladaExporter.cpp
@@ -0,0 +1,1748 @@
+/*
+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_COLLADA_EXPORTER
+
+#include "ColladaExporter.h"
+
+#include <assimp/Bitmap.h>
+#include <assimp/ColladaMetaData.h>
+#include <assimp/DefaultIOSystem.h>
+#include <assimp/Exceptional.h>
+#include <assimp/MathFunctions.h>
+#include <assimp/SceneCombiner.h>
+#include <assimp/StringUtils.h>
+#include <assimp/XMLTools.h>
+#include <assimp/commonMetaData.h>
+#include <assimp/fast_atof.h>
+#include <assimp/scene.h>
+#include <assimp/Exporter.hpp>
+#include <assimp/IOSystem.hpp>
+
+#include <ctime>
+#include <memory>
+
+namespace Assimp {
+
+// ------------------------------------------------------------------------------------------------
+// Worker function for exporting a scene to Collada. Prototyped and registered in Exporter.cpp
+void ExportSceneCollada(const char *pFile, IOSystem *pIOSystem, const aiScene *pScene, const ExportProperties * /*pProperties*/) {
+    std::string path = DefaultIOSystem::absolutePath(std::string(pFile));
+    std::string file = DefaultIOSystem::completeBaseName(std::string(pFile));
+
+    // invoke the exporter
+    ColladaExporter iDoTheExportThing(pScene, pIOSystem, path, file);
+
+    if (iDoTheExportThing.mOutput.fail()) {
+        throw DeadlyExportError("output data creation failed. Most likely the file became too large: " + std::string(pFile));
+    }
+
+    // we're still here - export successfully completed. Write result to the given IOSYstem
+    std::unique_ptr<IOStream> outfile(pIOSystem->Open(pFile, "wt"));
+    if (outfile == nullptr) {
+        throw DeadlyExportError("could not open output .dae file: " + std::string(pFile));
+    }
+
+    // XXX maybe use a small wrapper around IOStream that behaves like std::stringstream in order to avoid the extra copy.
+    outfile->Write(iDoTheExportThing.mOutput.str().c_str(), static_cast<size_t>(iDoTheExportThing.mOutput.tellp()), 1);
+}
+
+// ------------------------------------------------------------------------------------------------
+// Encodes a string into a valid XML ID using the xsd:ID schema qualifications.
+static const std::string XMLIDEncode(const std::string &name) {
+    const char XML_ID_CHARS[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_-.";
+    const unsigned int XML_ID_CHARS_COUNT = sizeof(XML_ID_CHARS) / sizeof(char);
+
+    if (name.length() == 0) {
+        return name;
+    }
+
+    std::stringstream idEncoded;
+
+    // xsd:ID must start with letter or underscore
+    if (!((name[0] >= 'A' && name[0] <= 'z') || name[0] == '_')) {
+        idEncoded << '_';
+    }
+
+    for (std::string::const_iterator it = name.begin(); it != name.end(); ++it) {
+        // xsd:ID can only contain letters, digits, underscores, hyphens and periods
+        if (strchr(XML_ID_CHARS, *it) != nullptr) {
+            idEncoded << *it;
+        } else {
+            // Select placeholder character based on invalid character to reduce ID collisions
+            idEncoded << XML_ID_CHARS[(*it) % XML_ID_CHARS_COUNT];
+        }
+    }
+
+    return idEncoded.str();
+}
+
+// ------------------------------------------------------------------------------------------------
+// Helper functions to create unique ids
+inline bool IsUniqueId(const std::unordered_set<std::string> &idSet, const std::string &idStr) {
+    return (idSet.find(idStr) == idSet.end());
+}
+
+inline std::string MakeUniqueId(const std::unordered_set<std::string> &idSet, const std::string &idPrefix, const std::string &postfix) {
+    std::string result(idPrefix + postfix);
+    if (!IsUniqueId(idSet, result)) {
+        // Select a number to append
+        size_t idnum = 1;
+        do {
+            result = idPrefix + '_' + ai_to_string(idnum) + postfix;
+            ++idnum;
+        } while (!IsUniqueId(idSet, result));
+    }
+    return result;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Constructor for a specific scene to export
+ColladaExporter::ColladaExporter(const aiScene *pScene, IOSystem *pIOSystem, const std::string &path, const std::string &file) :
+        mIOSystem(pIOSystem),
+        mPath(path),
+        mFile(file),
+        mScene(pScene),
+        endstr("\n") {
+    // make sure that all formatting happens using the standard, C locale and not the user's current locale
+    mOutput.imbue(std::locale("C"));
+    mOutput.precision(ASSIMP_AI_REAL_TEXT_PRECISION);
+
+    // start writing the file
+    WriteFile();
+}
+
+// ------------------------------------------------------------------------------------------------
+// Destructor
+ColladaExporter::~ColladaExporter() {
+}
+
+// ------------------------------------------------------------------------------------------------
+// Starts writing the contents
+void ColladaExporter::WriteFile() {
+    // write the DTD
+    mOutput << "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?>" << endstr;
+    // COLLADA element start
+    mOutput << "<COLLADA xmlns=\"http://www.collada.org/2005/11/COLLADASchema\" version=\"1.4.1\">" << endstr;
+    PushTag();
+
+    WriteTextures();
+    WriteHeader();
+
+    // Add node names to the unique id database first so they are most likely to use their names as unique ids
+    CreateNodeIds(mScene->mRootNode);
+
+    WriteCamerasLibrary();
+    WriteLightsLibrary();
+    WriteMaterials();
+    WriteGeometryLibrary();
+    WriteControllerLibrary();
+
+    WriteSceneLibrary();
+
+    // customized, Writes the animation library
+    WriteAnimationsLibrary();
+
+    // instantiate the scene(s)
+    // For Assimp there will only ever be one
+    mOutput << startstr << "<scene>" << endstr;
+    PushTag();
+    mOutput << startstr << "<instance_visual_scene url=\"#" + mSceneId + "\" />" << endstr;
+    PopTag();
+    mOutput << startstr << "</scene>" << endstr;
+    PopTag();
+    mOutput << "</COLLADA>" << endstr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes the asset header
+void ColladaExporter::WriteHeader() {
+    static const ai_real epsilon = Math::getEpsilon<ai_real>();
+    static const aiQuaternion x_rot(aiMatrix3x3(
+            0, -1, 0,
+            1, 0, 0,
+            0, 0, 1));
+    static const aiQuaternion y_rot(aiMatrix3x3(
+            1, 0, 0,
+            0, 1, 0,
+            0, 0, 1));
+    static const aiQuaternion z_rot(aiMatrix3x3(
+            1, 0, 0,
+            0, 0, 1,
+            0, -1, 0));
+
+    static const unsigned int date_nb_chars = 20;
+    char date_str[date_nb_chars];
+    std::time_t date = std::time(nullptr);
+    std::strftime(date_str, date_nb_chars, "%Y-%m-%dT%H:%M:%S", std::localtime(&date));
+
+    aiVector3D scaling;
+    aiQuaternion rotation;
+    aiVector3D position;
+    mScene->mRootNode->mTransformation.Decompose(scaling, rotation, position);
+    rotation.Normalize();
+
+    mAdd_root_node = false;
+
+    ai_real scale = 1.0;
+    if (std::abs(scaling.x - scaling.y) <= epsilon && std::abs(scaling.x - scaling.z) <= epsilon && std::abs(scaling.y - scaling.z) <= epsilon) {
+        scale = (ai_real)((((double)scaling.x) + ((double)scaling.y) + ((double)scaling.z)) / 3.0);
+    } else {
+        mAdd_root_node = true;
+    }
+
+    std::string up_axis = "Y_UP";
+    if (rotation.Equal(x_rot, epsilon)) {
+        up_axis = "X_UP";
+    } else if (rotation.Equal(y_rot, epsilon)) {
+        up_axis = "Y_UP";
+    } else if (rotation.Equal(z_rot, epsilon)) {
+        up_axis = "Z_UP";
+    } else {
+        mAdd_root_node = true;
+    }
+
+    if (!position.Equal(aiVector3D(0, 0, 0))) {
+        mAdd_root_node = true;
+    }
+
+    // Assimp root nodes can have meshes, Collada Scenes cannot
+    if (mScene->mRootNode->mNumChildren == 0 || mScene->mRootNode->mMeshes != 0) {
+        mAdd_root_node = true;
+    }
+
+    if (mAdd_root_node) {
+        up_axis = "Y_UP";
+        scale = 1.0;
+    }
+
+    mOutput << startstr << "<asset>" << endstr;
+    PushTag();
+    mOutput << startstr << "<contributor>" << endstr;
+    PushTag();
+
+    // If no Scene metadata, use root node metadata
+    aiMetadata *meta = mScene->mMetaData;
+    if (nullptr == meta) {
+        meta = mScene->mRootNode->mMetaData;
+    }
+
+    aiString value;
+    if (!meta || !meta->Get("Author", value)) {
+        mOutput << startstr << "<author>"
+                << "Assimp"
+                << "</author>" << endstr;
+    } else {
+        mOutput << startstr << "<author>" << XMLEscape(value.C_Str()) << "</author>" << endstr;
+    }
+
+    if (nullptr == meta || !meta->Get(AI_METADATA_SOURCE_GENERATOR, value)) {
+        mOutput << startstr << "<authoring_tool>"
+                << "Assimp Exporter"
+                << "</authoring_tool>" << endstr;
+    } else {
+        mOutput << startstr << "<authoring_tool>" << XMLEscape(value.C_Str()) << "</authoring_tool>" << endstr;
+    }
+
+    if (meta) {
+        if (meta->Get("Comments", value)) {
+            mOutput << startstr << "<comments>" << XMLEscape(value.C_Str()) << "</comments>" << endstr;
+        }
+        if (meta->Get(AI_METADATA_SOURCE_COPYRIGHT, value)) {
+            mOutput << startstr << "<copyright>" << XMLEscape(value.C_Str()) << "</copyright>" << endstr;
+        }
+        if (meta->Get("SourceData", value)) {
+            mOutput << startstr << "<source_data>" << XMLEscape(value.C_Str()) << "</source_data>" << endstr;
+        }
+    }
+
+    PopTag();
+    mOutput << startstr << "</contributor>" << endstr;
+
+    if (nullptr == meta || !meta->Get("Created", value)) {
+        mOutput << startstr << "<created>" << date_str << "</created>" << endstr;
+    } else {
+        mOutput << startstr << "<created>" << XMLEscape(value.C_Str()) << "</created>" << endstr;
+    }
+
+    // Modified date is always the date saved
+    mOutput << startstr << "<modified>" << date_str << "</modified>" << endstr;
+
+    if (meta) {
+        if (meta->Get("Keywords", value)) {
+            mOutput << startstr << "<keywords>" << XMLEscape(value.C_Str()) << "</keywords>" << endstr;
+        }
+        if (meta->Get("Revision", value)) {
+            mOutput << startstr << "<revision>" << XMLEscape(value.C_Str()) << "</revision>" << endstr;
+        }
+        if (meta->Get("Subject", value)) {
+            mOutput << startstr << "<subject>" << XMLEscape(value.C_Str()) << "</subject>" << endstr;
+        }
+        if (meta->Get("Title", value)) {
+            mOutput << startstr << "<title>" << XMLEscape(value.C_Str()) << "</title>" << endstr;
+        }
+    }
+
+    mOutput << startstr << "<unit name=\"meter\" meter=\"" << scale << "\" />" << endstr;
+    mOutput << startstr << "<up_axis>" << up_axis << "</up_axis>" << endstr;
+    PopTag();
+    mOutput << startstr << "</asset>" << endstr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Write the embedded textures
+void ColladaExporter::WriteTextures() {
+    static const unsigned int buffer_size = 1024;
+    char str[buffer_size];
+
+    if (mScene->HasTextures()) {
+        for (unsigned int i = 0; i < mScene->mNumTextures; i++) {
+            // It would be great to be able to create a directory in portable standard C++, but it's not the case,
+            // so we just write the textures in the current directory.
+
+            aiTexture *texture = mScene->mTextures[i];
+            if (nullptr == texture) {
+                continue;
+            }
+
+            ASSIMP_itoa10(str, buffer_size, i + 1);
+
+            std::string name = mFile + "_texture_" + (i < 1000 ? "0" : "") + (i < 100 ? "0" : "") + (i < 10 ? "0" : "") + str + "." + ((const char *)texture->achFormatHint);
+
+            std::unique_ptr<IOStream> outfile(mIOSystem->Open(mPath + mIOSystem->getOsSeparator() + name, "wb"));
+            if (outfile == nullptr) {
+                throw DeadlyExportError("could not open output texture file: " + mPath + name);
+            }
+
+            if (texture->mHeight == 0) {
+                outfile->Write((void *)texture->pcData, texture->mWidth, 1);
+            } else {
+                Bitmap::Save(texture, outfile.get());
+            }
+
+            outfile->Flush();
+
+            textures.insert(std::make_pair(i, name));
+        }
+    }
+}
+
+// ------------------------------------------------------------------------------------------------
+// Write the embedded textures
+void ColladaExporter::WriteCamerasLibrary() {
+    if (mScene->HasCameras()) {
+
+        mOutput << startstr << "<library_cameras>" << endstr;
+        PushTag();
+
+        for (size_t a = 0; a < mScene->mNumCameras; ++a)
+            WriteCamera(a);
+
+        PopTag();
+        mOutput << startstr << "</library_cameras>" << endstr;
+    }
+}
+
+void ColladaExporter::WriteCamera(size_t pIndex) {
+
+    const aiCamera *cam = mScene->mCameras[pIndex];
+    const std::string cameraId = GetObjectUniqueId(AiObjectType::Camera, pIndex);
+    const std::string cameraName = GetObjectName(AiObjectType::Camera, pIndex);
+
+    mOutput << startstr << "<camera id=\"" << cameraId << "\" name=\"" << cameraName << "\" >" << endstr;
+    PushTag();
+    mOutput << startstr << "<optics>" << endstr;
+    PushTag();
+    mOutput << startstr << "<technique_common>" << endstr;
+    PushTag();
+    //assimp doesn't support the import of orthographic cameras! se we write
+    //always perspective
+    mOutput << startstr << "<perspective>" << endstr;
+    PushTag();
+    mOutput << startstr << "<xfov sid=\"xfov\">" << AI_RAD_TO_DEG(cam->mHorizontalFOV)
+            << "</xfov>" << endstr;
+    mOutput << startstr << "<aspect_ratio>"
+            << cam->mAspect
+            << "</aspect_ratio>" << endstr;
+    mOutput << startstr << "<znear sid=\"znear\">"
+            << cam->mClipPlaneNear
+            << "</znear>" << endstr;
+    mOutput << startstr << "<zfar sid=\"zfar\">"
+            << cam->mClipPlaneFar
+            << "</zfar>" << endstr;
+    PopTag();
+    mOutput << startstr << "</perspective>" << endstr;
+    PopTag();
+    mOutput << startstr << "</technique_common>" << endstr;
+    PopTag();
+    mOutput << startstr << "</optics>" << endstr;
+    PopTag();
+    mOutput << startstr << "</camera>" << endstr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Write the embedded textures
+void ColladaExporter::WriteLightsLibrary() {
+    if (mScene->HasLights()) {
+
+        mOutput << startstr << "<library_lights>" << endstr;
+        PushTag();
+
+        for (size_t a = 0; a < mScene->mNumLights; ++a)
+            WriteLight(a);
+
+        PopTag();
+        mOutput << startstr << "</library_lights>" << endstr;
+    }
+}
+
+void ColladaExporter::WriteLight(size_t pIndex) {
+
+    const aiLight *light = mScene->mLights[pIndex];
+    const std::string lightId = GetObjectUniqueId(AiObjectType::Light, pIndex);
+    const std::string lightName = GetObjectName(AiObjectType::Light, pIndex);
+
+    mOutput << startstr << "<light id=\"" << lightId << "\" name=\""
+            << lightName << "\" >" << endstr;
+    PushTag();
+    mOutput << startstr << "<technique_common>" << endstr;
+    PushTag();
+    switch (light->mType) {
+    case aiLightSource_AMBIENT:
+        WriteAmbienttLight(light);
+        break;
+    case aiLightSource_DIRECTIONAL:
+        WriteDirectionalLight(light);
+        break;
+    case aiLightSource_POINT:
+        WritePointLight(light);
+        break;
+    case aiLightSource_SPOT:
+        WriteSpotLight(light);
+        break;
+    case aiLightSource_AREA:
+    case aiLightSource_UNDEFINED:
+    case _aiLightSource_Force32Bit:
+        break;
+    }
+    PopTag();
+    mOutput << startstr << "</technique_common>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</light>" << endstr;
+}
+
+void ColladaExporter::WritePointLight(const aiLight *const light) {
+    const aiColor3D &color = light->mColorDiffuse;
+    mOutput << startstr << "<point>" << endstr;
+    PushTag();
+    mOutput << startstr << "<color sid=\"color\">"
+            << color.r << " " << color.g << " " << color.b
+            << "</color>" << endstr;
+    mOutput << startstr << "<constant_attenuation>"
+            << light->mAttenuationConstant
+            << "</constant_attenuation>" << endstr;
+    mOutput << startstr << "<linear_attenuation>"
+            << light->mAttenuationLinear
+            << "</linear_attenuation>" << endstr;
+    mOutput << startstr << "<quadratic_attenuation>"
+            << light->mAttenuationQuadratic
+            << "</quadratic_attenuation>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</point>" << endstr;
+}
+
+void ColladaExporter::WriteDirectionalLight(const aiLight *const light) {
+    const aiColor3D &color = light->mColorDiffuse;
+    mOutput << startstr << "<directional>" << endstr;
+    PushTag();
+    mOutput << startstr << "<color sid=\"color\">"
+            << color.r << " " << color.g << " " << color.b
+            << "</color>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</directional>" << endstr;
+}
+
+void ColladaExporter::WriteSpotLight(const aiLight *const light) {
+
+    const aiColor3D &color = light->mColorDiffuse;
+    mOutput << startstr << "<spot>" << endstr;
+    PushTag();
+    mOutput << startstr << "<color sid=\"color\">"
+            << color.r << " " << color.g << " " << color.b
+            << "</color>" << endstr;
+    mOutput << startstr << "<constant_attenuation>"
+            << light->mAttenuationConstant
+            << "</constant_attenuation>" << endstr;
+    mOutput << startstr << "<linear_attenuation>"
+            << light->mAttenuationLinear
+            << "</linear_attenuation>" << endstr;
+    mOutput << startstr << "<quadratic_attenuation>"
+            << light->mAttenuationQuadratic
+            << "</quadratic_attenuation>" << endstr;
+    /*
+    out->mAngleOuterCone = AI_DEG_TO_RAD (std::acos(std::pow(0.1f,1.f/srcLight->mFalloffExponent))+
+                            srcLight->mFalloffAngle);
+    */
+
+    const ai_real fallOffAngle = AI_RAD_TO_DEG(light->mAngleInnerCone);
+    mOutput << startstr << "<falloff_angle sid=\"fall_off_angle\">"
+            << fallOffAngle
+            << "</falloff_angle>" << endstr;
+    double temp = light->mAngleOuterCone - light->mAngleInnerCone;
+
+    temp = std::cos(temp);
+    temp = std::log(temp) / std::log(0.1);
+    temp = 1 / temp;
+    mOutput << startstr << "<falloff_exponent sid=\"fall_off_exponent\">"
+            << temp
+            << "</falloff_exponent>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</spot>" << endstr;
+}
+
+void ColladaExporter::WriteAmbienttLight(const aiLight *const light) {
+
+    const aiColor3D &color = light->mColorAmbient;
+    mOutput << startstr << "<ambient>" << endstr;
+    PushTag();
+    mOutput << startstr << "<color sid=\"color\">"
+            << color.r << " " << color.g << " " << color.b
+            << "</color>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</ambient>" << endstr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Reads a single surface entry from the given material keys
+bool ColladaExporter::ReadMaterialSurface(Surface &poSurface, const aiMaterial &pSrcMat, aiTextureType pTexture, const char *pKey, size_t pType, size_t pIndex) {
+    if (pSrcMat.GetTextureCount(pTexture) > 0) {
+        aiString texfile;
+        unsigned int uvChannel = 0;
+        pSrcMat.GetTexture(pTexture, 0, &texfile, nullptr, &uvChannel);
+
+        std::string index_str(texfile.C_Str());
+
+        if (index_str.size() != 0 && index_str[0] == '*') {
+            unsigned int index;
+
+            index_str = index_str.substr(1, std::string::npos);
+
+            try {
+                index = (unsigned int)strtoul10_64<DeadlyExportError>(index_str.c_str());
+            } catch (std::exception &error) {
+                throw DeadlyExportError(error.what());
+            }
+
+            std::map<unsigned int, std::string>::const_iterator name = textures.find(index);
+
+            if (name != textures.end()) {
+                poSurface.texture = name->second;
+            } else {
+                throw DeadlyExportError("could not find embedded texture at index " + index_str);
+            }
+        } else {
+            poSurface.texture = texfile.C_Str();
+        }
+
+        poSurface.channel = uvChannel;
+        poSurface.exist = true;
+    } else {
+        if (pKey)
+            poSurface.exist = pSrcMat.Get(pKey, static_cast<unsigned int>(pType), static_cast<unsigned int>(pIndex), poSurface.color) == aiReturn_SUCCESS;
+    }
+    return poSurface.exist;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Reimplementation of isalnum(,C locale), because AppVeyor does not see standard version.
+static bool isalnum_C(char c) {
+    return (nullptr != strchr("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz", c));
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes an image entry for the given surface
+void ColladaExporter::WriteImageEntry(const Surface &pSurface, const std::string &imageId) {
+    if (!pSurface.texture.empty()) {
+        mOutput << startstr << "<image id=\"" << imageId << "\">" << endstr;
+        PushTag();
+        mOutput << startstr << "<init_from>";
+
+        // URL encode image file name first, then XML encode on top
+        std::stringstream imageUrlEncoded;
+        for (std::string::const_iterator it = pSurface.texture.begin(); it != pSurface.texture.end(); ++it) {
+            if (isalnum_C((unsigned char)*it) || *it == ':' || *it == '_' || *it == '-' || *it == '.' || *it == '/' || *it == '\\')
+                imageUrlEncoded << *it;
+            else
+                imageUrlEncoded << '%' << std::hex << size_t((unsigned char)*it) << std::dec;
+        }
+        mOutput << XMLEscape(imageUrlEncoded.str());
+        mOutput << "</init_from>" << endstr;
+        PopTag();
+        mOutput << startstr << "</image>" << endstr;
+    }
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes a color-or-texture entry into an effect definition
+void ColladaExporter::WriteTextureColorEntry(const Surface &pSurface, const std::string &pTypeName, const std::string &imageId) {
+    if (pSurface.exist) {
+        mOutput << startstr << "<" << pTypeName << ">" << endstr;
+        PushTag();
+        if (pSurface.texture.empty()) {
+            mOutput << startstr << "<color sid=\"" << pTypeName << "\">" << pSurface.color.r << "   " << pSurface.color.g << "   " << pSurface.color.b << "   " << pSurface.color.a << "</color>" << endstr;
+        } else {
+            mOutput << startstr << "<texture texture=\"" << imageId << "\" texcoord=\"CHANNEL" << pSurface.channel << "\" />" << endstr;
+        }
+        PopTag();
+        mOutput << startstr << "</" << pTypeName << ">" << endstr;
+    }
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes the two parameters necessary for referencing a texture in an effect entry
+void ColladaExporter::WriteTextureParamEntry(const Surface &pSurface, const std::string &pTypeName, const std::string &materialId) {
+    // if surface is a texture, write out the sampler and the surface parameters necessary to reference the texture
+    if (!pSurface.texture.empty()) {
+        mOutput << startstr << "<newparam sid=\"" << materialId << "-" << pTypeName << "-surface\">" << endstr;
+        PushTag();
+        mOutput << startstr << "<surface type=\"2D\">" << endstr;
+        PushTag();
+        mOutput << startstr << "<init_from>" << materialId << "-" << pTypeName << "-image</init_from>" << endstr;
+        PopTag();
+        mOutput << startstr << "</surface>" << endstr;
+        PopTag();
+        mOutput << startstr << "</newparam>" << endstr;
+
+        mOutput << startstr << "<newparam sid=\"" << materialId << "-" << pTypeName << "-sampler\">" << endstr;
+        PushTag();
+        mOutput << startstr << "<sampler2D>" << endstr;
+        PushTag();
+        mOutput << startstr << "<source>" << materialId << "-" << pTypeName << "-surface</source>" << endstr;
+        PopTag();
+        mOutput << startstr << "</sampler2D>" << endstr;
+        PopTag();
+        mOutput << startstr << "</newparam>" << endstr;
+    }
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes a scalar property
+void ColladaExporter::WriteFloatEntry(const Property &pProperty, const std::string &pTypeName) {
+    if (pProperty.exist) {
+        mOutput << startstr << "<" << pTypeName << ">" << endstr;
+        PushTag();
+        mOutput << startstr << "<float sid=\"" << pTypeName << "\">" << pProperty.value << "</float>" << endstr;
+        PopTag();
+        mOutput << startstr << "</" << pTypeName << ">" << endstr;
+    }
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes the material setup
+void ColladaExporter::WriteMaterials() {
+    std::vector<Material> materials;
+    materials.resize(mScene->mNumMaterials);
+
+    /// collect all materials from the scene
+    size_t numTextures = 0;
+    for (size_t a = 0; a < mScene->mNumMaterials; ++a) {
+        Material &material = materials[a];
+        material.id = GetObjectUniqueId(AiObjectType::Material, a);
+        material.name = GetObjectName(AiObjectType::Material, a);
+
+        const aiMaterial &mat = *(mScene->mMaterials[a]);
+        aiShadingMode shading = aiShadingMode_Flat;
+        material.shading_model = "phong";
+        if (mat.Get(AI_MATKEY_SHADING_MODEL, shading) == aiReturn_SUCCESS) {
+            if (shading == aiShadingMode_Phong) {
+                material.shading_model = "phong";
+            } else if (shading == aiShadingMode_Blinn) {
+                material.shading_model = "blinn";
+            } else if (shading == aiShadingMode_NoShading) {
+                material.shading_model = "constant";
+            } else if (shading == aiShadingMode_Gouraud) {
+                material.shading_model = "lambert";
+            }
+        }
+
+        if (ReadMaterialSurface(material.ambient, mat, aiTextureType_AMBIENT, AI_MATKEY_COLOR_AMBIENT))
+            ++numTextures;
+        if (ReadMaterialSurface(material.diffuse, mat, aiTextureType_DIFFUSE, AI_MATKEY_COLOR_DIFFUSE))
+            ++numTextures;
+        if (ReadMaterialSurface(material.specular, mat, aiTextureType_SPECULAR, AI_MATKEY_COLOR_SPECULAR))
+            ++numTextures;
+        if (ReadMaterialSurface(material.emissive, mat, aiTextureType_EMISSIVE, AI_MATKEY_COLOR_EMISSIVE))
+            ++numTextures;
+        if (ReadMaterialSurface(material.reflective, mat, aiTextureType_REFLECTION, AI_MATKEY_COLOR_REFLECTIVE))
+            ++numTextures;
+        if (ReadMaterialSurface(material.transparent, mat, aiTextureType_OPACITY, AI_MATKEY_COLOR_TRANSPARENT))
+            ++numTextures;
+        if (ReadMaterialSurface(material.normal, mat, aiTextureType_NORMALS, nullptr, 0, 0))
+            ++numTextures;
+
+        material.shininess.exist = mat.Get(AI_MATKEY_SHININESS, material.shininess.value) == aiReturn_SUCCESS;
+        material.transparency.exist = mat.Get(AI_MATKEY_OPACITY, material.transparency.value) == aiReturn_SUCCESS;
+        material.index_refraction.exist = mat.Get(AI_MATKEY_REFRACTI, material.index_refraction.value) == aiReturn_SUCCESS;
+    }
+
+    // output textures if present
+    if (numTextures > 0) {
+        mOutput << startstr << "<library_images>" << endstr;
+        PushTag();
+        for (const Material &mat : materials) {
+            WriteImageEntry(mat.ambient, mat.id + "-ambient-image");
+            WriteImageEntry(mat.diffuse, mat.id + "-diffuse-image");
+            WriteImageEntry(mat.specular, mat.id + "-specular-image");
+            WriteImageEntry(mat.emissive, mat.id + "-emission-image");
+            WriteImageEntry(mat.reflective, mat.id + "-reflective-image");
+            WriteImageEntry(mat.transparent, mat.id + "-transparent-image");
+            WriteImageEntry(mat.normal, mat.id + "-normal-image");
+        }
+        PopTag();
+        mOutput << startstr << "</library_images>" << endstr;
+    }
+
+    // output effects - those are the actual carriers of information
+    if (!materials.empty()) {
+        mOutput << startstr << "<library_effects>" << endstr;
+        PushTag();
+        for (const Material &mat : materials) {
+            // this is so ridiculous it must be right
+            mOutput << startstr << "<effect id=\"" << mat.id << "-fx\" name=\"" << mat.name << "\">" << endstr;
+            PushTag();
+            mOutput << startstr << "<profile_COMMON>" << endstr;
+            PushTag();
+
+            // write sampler- and surface params for the texture entries
+            WriteTextureParamEntry(mat.emissive, "emission", mat.id);
+            WriteTextureParamEntry(mat.ambient, "ambient", mat.id);
+            WriteTextureParamEntry(mat.diffuse, "diffuse", mat.id);
+            WriteTextureParamEntry(mat.specular, "specular", mat.id);
+            WriteTextureParamEntry(mat.reflective, "reflective", mat.id);
+            WriteTextureParamEntry(mat.transparent, "transparent", mat.id);
+            WriteTextureParamEntry(mat.normal, "normal", mat.id);
+
+            mOutput << startstr << "<technique sid=\"standard\">" << endstr;
+            PushTag();
+            mOutput << startstr << "<" << mat.shading_model << ">" << endstr;
+            PushTag();
+
+            WriteTextureColorEntry(mat.emissive, "emission", mat.id + "-emission-sampler");
+            WriteTextureColorEntry(mat.ambient, "ambient", mat.id + "-ambient-sampler");
+            WriteTextureColorEntry(mat.diffuse, "diffuse", mat.id + "-diffuse-sampler");
+            WriteTextureColorEntry(mat.specular, "specular", mat.id + "-specular-sampler");
+            WriteFloatEntry(mat.shininess, "shininess");
+            WriteTextureColorEntry(mat.reflective, "reflective", mat.id + "-reflective-sampler");
+            WriteTextureColorEntry(mat.transparent, "transparent", mat.id + "-transparent-sampler");
+            WriteFloatEntry(mat.transparency, "transparency");
+            WriteFloatEntry(mat.index_refraction, "index_of_refraction");
+
+            if (!mat.normal.texture.empty()) {
+                WriteTextureColorEntry(mat.normal, "bump", mat.id + "-normal-sampler");
+            }
+
+            PopTag();
+            mOutput << startstr << "</" << mat.shading_model << ">" << endstr;
+            PopTag();
+            mOutput << startstr << "</technique>" << endstr;
+            PopTag();
+            mOutput << startstr << "</profile_COMMON>" << endstr;
+            PopTag();
+            mOutput << startstr << "</effect>" << endstr;
+        }
+        PopTag();
+        mOutput << startstr << "</library_effects>" << endstr;
+
+        // write materials - they're just effect references
+        mOutput << startstr << "<library_materials>" << endstr;
+        PushTag();
+        for (std::vector<Material>::const_iterator it = materials.begin(); it != materials.end(); ++it) {
+            const Material &mat = *it;
+            mOutput << startstr << "<material id=\"" << mat.id << "\" name=\"" << mat.name << "\">" << endstr;
+            PushTag();
+            mOutput << startstr << "<instance_effect url=\"#" << mat.id << "-fx\"/>" << endstr;
+            PopTag();
+            mOutput << startstr << "</material>" << endstr;
+        }
+        PopTag();
+        mOutput << startstr << "</library_materials>" << endstr;
+    }
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes the controller library
+void ColladaExporter::WriteControllerLibrary() {
+    mOutput << startstr << "<library_controllers>" << endstr;
+    PushTag();
+
+    for (size_t a = 0; a < mScene->mNumMeshes; ++a) {
+        WriteController(a);
+    }
+
+    PopTag();
+    mOutput << startstr << "</library_controllers>" << endstr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes a skin controller of the given mesh
+void ColladaExporter::WriteController(size_t pIndex) {
+    const aiMesh *mesh = mScene->mMeshes[pIndex];
+    // Is there a skin controller?
+    if (mesh->mNumBones == 0 || mesh->mNumFaces == 0 || mesh->mNumVertices == 0)
+        return;
+
+    const std::string idstr = GetObjectUniqueId(AiObjectType::Mesh, pIndex);
+    const std::string namestr = GetObjectName(AiObjectType::Mesh, pIndex);
+
+    mOutput << startstr << "<controller id=\"" << idstr << "-skin\" ";
+    mOutput << "name=\"skinCluster" << pIndex << "\">" << endstr;
+    PushTag();
+
+    mOutput << startstr << "<skin source=\"#" << idstr << "\">" << endstr;
+    PushTag();
+
+    // bind pose matrix
+    mOutput << startstr << "<bind_shape_matrix>" << endstr;
+    PushTag();
+
+    // I think it is identity in general cases.
+    aiMatrix4x4 mat;
+    mOutput << startstr << mat.a1 << " " << mat.a2 << " " << mat.a3 << " " << mat.a4 << endstr;
+    mOutput << startstr << mat.b1 << " " << mat.b2 << " " << mat.b3 << " " << mat.b4 << endstr;
+    mOutput << startstr << mat.c1 << " " << mat.c2 << " " << mat.c3 << " " << mat.c4 << endstr;
+    mOutput << startstr << mat.d1 << " " << mat.d2 << " " << mat.d3 << " " << mat.d4 << endstr;
+
+    PopTag();
+    mOutput << startstr << "</bind_shape_matrix>" << endstr;
+
+    mOutput << startstr << "<source id=\"" << idstr << "-skin-joints\" name=\"" << namestr << "-skin-joints\">" << endstr;
+    PushTag();
+
+    mOutput << startstr << "<Name_array id=\"" << idstr << "-skin-joints-array\" count=\"" << mesh->mNumBones << "\">";
+
+    for (size_t i = 0; i < mesh->mNumBones; ++i)
+        mOutput << GetBoneUniqueId(mesh->mBones[i]) << ' ';
+
+    mOutput << "</Name_array>" << endstr;
+
+    mOutput << startstr << "<technique_common>" << endstr;
+    PushTag();
+
+    mOutput << startstr << "<accessor source=\"#" << idstr << "-skin-joints-array\" count=\"" << mesh->mNumBones << "\" stride=\"" << 1 << "\">" << endstr;
+    PushTag();
+
+    mOutput << startstr << "<param name=\"JOINT\" type=\"Name\"></param>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</accessor>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</technique_common>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</source>" << endstr;
+
+    std::vector<ai_real> bind_poses;
+    bind_poses.reserve(mesh->mNumBones * 16);
+    for (unsigned int i = 0; i < mesh->mNumBones; ++i)
+        for (unsigned int j = 0; j < 4; ++j)
+            bind_poses.insert(bind_poses.end(), mesh->mBones[i]->mOffsetMatrix[j], mesh->mBones[i]->mOffsetMatrix[j] + 4);
+
+    WriteFloatArray(idstr + "-skin-bind_poses", FloatType_Mat4x4, (const ai_real *)bind_poses.data(), bind_poses.size() / 16);
+
+    bind_poses.clear();
+
+    std::vector<ai_real> skin_weights;
+    skin_weights.reserve(mesh->mNumVertices * mesh->mNumBones);
+    for (size_t i = 0; i < mesh->mNumBones; ++i)
+        for (size_t j = 0; j < mesh->mBones[i]->mNumWeights; ++j)
+            skin_weights.push_back(mesh->mBones[i]->mWeights[j].mWeight);
+
+    WriteFloatArray(idstr + "-skin-weights", FloatType_Weight, (const ai_real *)skin_weights.data(), skin_weights.size());
+
+    skin_weights.clear();
+
+    mOutput << startstr << "<joints>" << endstr;
+    PushTag();
+
+    mOutput << startstr << "<input semantic=\"JOINT\" source=\"#" << idstr << "-skin-joints\"></input>" << endstr;
+    mOutput << startstr << "<input semantic=\"INV_BIND_MATRIX\" source=\"#" << idstr << "-skin-bind_poses\"></input>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</joints>" << endstr;
+
+    mOutput << startstr << "<vertex_weights count=\"" << mesh->mNumVertices << "\">" << endstr;
+    PushTag();
+
+    mOutput << startstr << "<input semantic=\"JOINT\" source=\"#" << idstr << "-skin-joints\" offset=\"0\"></input>" << endstr;
+    mOutput << startstr << "<input semantic=\"WEIGHT\" source=\"#" << idstr << "-skin-weights\" offset=\"1\"></input>" << endstr;
+
+    mOutput << startstr << "<vcount>";
+
+    std::vector<ai_uint> num_influences(mesh->mNumVertices, (ai_uint)0);
+    for (size_t i = 0; i < mesh->mNumBones; ++i)
+        for (size_t j = 0; j < mesh->mBones[i]->mNumWeights; ++j)
+            ++num_influences[mesh->mBones[i]->mWeights[j].mVertexId];
+
+    for (size_t i = 0; i < mesh->mNumVertices; ++i)
+        mOutput << num_influences[i] << " ";
+
+    mOutput << "</vcount>" << endstr;
+
+    mOutput << startstr << "<v>";
+
+    ai_uint joint_weight_indices_length = 0;
+    std::vector<ai_uint> accum_influences;
+    accum_influences.reserve(num_influences.size());
+    for (size_t i = 0; i < num_influences.size(); ++i) {
+        accum_influences.push_back(joint_weight_indices_length);
+        joint_weight_indices_length += num_influences[i];
+    }
+
+    ai_uint weight_index = 0;
+    std::vector<ai_int> joint_weight_indices(2 * joint_weight_indices_length, (ai_int)-1);
+    for (unsigned int i = 0; i < mesh->mNumBones; ++i)
+        for (unsigned j = 0; j < mesh->mBones[i]->mNumWeights; ++j) {
+            unsigned int vId = mesh->mBones[i]->mWeights[j].mVertexId;
+            for (ai_uint k = 0; k < num_influences[vId]; ++k) {
+                if (joint_weight_indices[2 * (accum_influences[vId] + k)] == -1) {
+                    joint_weight_indices[2 * (accum_influences[vId] + k)] = i;
+                    joint_weight_indices[2 * (accum_influences[vId] + k) + 1] = weight_index;
+                    break;
+                }
+            }
+            ++weight_index;
+        }
+
+    for (size_t i = 0; i < joint_weight_indices.size(); ++i)
+        mOutput << joint_weight_indices[i] << " ";
+
+    num_influences.clear();
+    accum_influences.clear();
+    joint_weight_indices.clear();
+
+    mOutput << "</v>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</vertex_weights>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</skin>" << endstr;
+
+    PopTag();
+    mOutput << startstr << "</controller>" << endstr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes the geometry library
+void ColladaExporter::WriteGeometryLibrary() {
+    mOutput << startstr << "<library_geometries>" << endstr;
+    PushTag();
+
+    for (size_t a = 0; a < mScene->mNumMeshes; ++a)
+        WriteGeometry(a);
+
+    PopTag();
+    mOutput << startstr << "</library_geometries>" << endstr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes the given mesh
+void ColladaExporter::WriteGeometry(size_t pIndex) {
+    const aiMesh *mesh = mScene->mMeshes[pIndex];
+    const std::string geometryId = GetObjectUniqueId(AiObjectType::Mesh, pIndex);
+    const std::string geometryName = GetObjectName(AiObjectType::Mesh, pIndex);
+
+    if (mesh->mNumFaces == 0 || mesh->mNumVertices == 0)
+        return;
+
+    // opening tag
+    mOutput << startstr << "<geometry id=\"" << geometryId << "\" name=\"" << geometryName << "\" >" << endstr;
+    PushTag();
+
+    mOutput << startstr << "<mesh>" << endstr;
+    PushTag();
+
+    // Positions
+    WriteFloatArray(geometryId + "-positions", FloatType_Vector, (ai_real *)mesh->mVertices, mesh->mNumVertices);
+    // Normals, if any
+    if (mesh->HasNormals())
+        WriteFloatArray(geometryId + "-normals", FloatType_Vector, (ai_real *)mesh->mNormals, mesh->mNumVertices);
+
+    // texture coords
+    for (size_t a = 0; a < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++a) {
+        if (mesh->HasTextureCoords(static_cast<unsigned int>(a))) {
+            WriteFloatArray(geometryId + "-tex" + ai_to_string(a), mesh->mNumUVComponents[a] == 3 ? FloatType_TexCoord3 : FloatType_TexCoord2,
+                    (ai_real *)mesh->mTextureCoords[a], mesh->mNumVertices);
+        }
+    }
+
+    // vertex colors
+    for (size_t a = 0; a < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++a) {
+        if (mesh->HasVertexColors(static_cast<unsigned int>(a)))
+            WriteFloatArray(geometryId + "-color" + ai_to_string(a), FloatType_Color, (ai_real *)mesh->mColors[a], mesh->mNumVertices);
+    }
+
+    // assemble vertex structure
+    // Only write input for POSITION since we will write other as shared inputs in polygon definition
+    mOutput << startstr << "<vertices id=\"" << geometryId << "-vertices"
+            << "\">" << endstr;
+    PushTag();
+    mOutput << startstr << "<input semantic=\"POSITION\" source=\"#" << geometryId << "-positions\" />" << endstr;
+    PopTag();
+    mOutput << startstr << "</vertices>" << endstr;
+
+    // count the number of lines, triangles and polygon meshes
+    int countLines = 0;
+    int countPoly = 0;
+    for (size_t a = 0; a < mesh->mNumFaces; ++a) {
+        if (mesh->mFaces[a].mNumIndices == 2)
+            countLines++;
+        else if (mesh->mFaces[a].mNumIndices >= 3)
+            countPoly++;
+    }
+
+    // lines
+    if (countLines) {
+        mOutput << startstr << "<lines count=\"" << countLines << "\" material=\"defaultMaterial\">" << endstr;
+        PushTag();
+        mOutput << startstr << "<input offset=\"0\" semantic=\"VERTEX\" source=\"#" << geometryId << "-vertices\" />" << endstr;
+        if (mesh->HasNormals())
+            mOutput << startstr << "<input semantic=\"NORMAL\" source=\"#" << geometryId << "-normals\" />" << endstr;
+        for (size_t a = 0; a < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++a) {
+            if (mesh->HasTextureCoords(static_cast<unsigned int>(a)))
+                mOutput << startstr << "<input semantic=\"TEXCOORD\" source=\"#" << geometryId << "-tex" << a << "\" "
+                        << "set=\"" << a << "\""
+                        << " />" << endstr;
+        }
+        for (size_t a = 0; a < AI_MAX_NUMBER_OF_COLOR_SETS; ++a) {
+            if (mesh->HasVertexColors(static_cast<unsigned int>(a)))
+                mOutput << startstr << "<input semantic=\"COLOR\" source=\"#" << geometryId << "-color" << a << "\" "
+                        << "set=\"" << a << "\""
+                        << " />" << endstr;
+        }
+
+        mOutput << startstr << "<p>";
+        for (size_t a = 0; a < mesh->mNumFaces; ++a) {
+            const aiFace &face = mesh->mFaces[a];
+            if (face.mNumIndices != 2) continue;
+            for (size_t b = 0; b < face.mNumIndices; ++b)
+                mOutput << face.mIndices[b] << " ";
+        }
+        mOutput << "</p>" << endstr;
+        PopTag();
+        mOutput << startstr << "</lines>" << endstr;
+    }
+
+    // triangle - don't use it, because compatibility problems
+
+    // polygons
+    if (countPoly) {
+        mOutput << startstr << "<polylist count=\"" << countPoly << "\" material=\"defaultMaterial\">" << endstr;
+        PushTag();
+        mOutput << startstr << "<input offset=\"0\" semantic=\"VERTEX\" source=\"#" << geometryId << "-vertices\" />" << endstr;
+        if (mesh->HasNormals())
+            mOutput << startstr << "<input offset=\"0\" semantic=\"NORMAL\" source=\"#" << geometryId << "-normals\" />" << endstr;
+        for (size_t a = 0; a < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++a) {
+            if (mesh->HasTextureCoords(static_cast<unsigned int>(a)))
+                mOutput << startstr << "<input offset=\"0\" semantic=\"TEXCOORD\" source=\"#" << geometryId << "-tex" << a << "\" "
+                        << "set=\"" << a << "\""
+                        << " />" << endstr;
+        }
+        for (size_t a = 0; a < AI_MAX_NUMBER_OF_COLOR_SETS; ++a) {
+            if (mesh->HasVertexColors(static_cast<unsigned int>(a)))
+                mOutput << startstr << "<input offset=\"0\" semantic=\"COLOR\" source=\"#" << geometryId << "-color" << a << "\" "
+                        << "set=\"" << a << "\""
+                        << " />" << endstr;
+        }
+
+        mOutput << startstr << "<vcount>";
+        for (size_t a = 0; a < mesh->mNumFaces; ++a) {
+            if (mesh->mFaces[a].mNumIndices < 3) continue;
+            mOutput << mesh->mFaces[a].mNumIndices << " ";
+        }
+        mOutput << "</vcount>" << endstr;
+
+        mOutput << startstr << "<p>";
+        for (size_t a = 0; a < mesh->mNumFaces; ++a) {
+            const aiFace &face = mesh->mFaces[a];
+            if (face.mNumIndices < 3) continue;
+            for (size_t b = 0; b < face.mNumIndices; ++b)
+                mOutput << face.mIndices[b] << " ";
+        }
+        mOutput << "</p>" << endstr;
+        PopTag();
+        mOutput << startstr << "</polylist>" << endstr;
+    }
+
+    // closing tags
+    PopTag();
+    mOutput << startstr << "</mesh>" << endstr;
+    PopTag();
+    mOutput << startstr << "</geometry>" << endstr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes a float array of the given type
+void ColladaExporter::WriteFloatArray(const std::string &pIdString, FloatDataType pType, const ai_real *pData, size_t pElementCount) {
+    size_t floatsPerElement = 0;
+    switch (pType) {
+    case FloatType_Vector: floatsPerElement = 3; break;
+    case FloatType_TexCoord2: floatsPerElement = 2; break;
+    case FloatType_TexCoord3: floatsPerElement = 3; break;
+    case FloatType_Color: floatsPerElement = 3; break;
+    case FloatType_Mat4x4: floatsPerElement = 16; break;
+    case FloatType_Weight: floatsPerElement = 1; break;
+    case FloatType_Time: floatsPerElement = 1; break;
+    default:
+        return;
+    }
+
+    std::string arrayId = XMLIDEncode(pIdString) + "-array";
+
+    mOutput << startstr << "<source id=\"" << XMLIDEncode(pIdString) << "\" name=\"" << XMLEscape(pIdString) << "\">" << endstr;
+    PushTag();
+
+    // source array
+    mOutput << startstr << "<float_array id=\"" << arrayId << "\" count=\"" << pElementCount * floatsPerElement << "\"> ";
+    PushTag();
+
+    if (pType == FloatType_TexCoord2) {
+        for (size_t a = 0; a < pElementCount; ++a) {
+            mOutput << pData[a * 3 + 0] << " ";
+            mOutput << pData[a * 3 + 1] << " ";
+        }
+    } else if (pType == FloatType_Color) {
+        for (size_t a = 0; a < pElementCount; ++a) {
+            mOutput << pData[a * 4 + 0] << " ";
+            mOutput << pData[a * 4 + 1] << " ";
+            mOutput << pData[a * 4 + 2] << " ";
+        }
+    } else {
+        for (size_t a = 0; a < pElementCount * floatsPerElement; ++a)
+            mOutput << pData[a] << " ";
+    }
+    mOutput << "</float_array>" << endstr;
+    PopTag();
+
+    // the usual Collada fun. Let's bloat it even more!
+    mOutput << startstr << "<technique_common>" << endstr;
+    PushTag();
+    mOutput << startstr << "<accessor count=\"" << pElementCount << "\" offset=\"0\" source=\"#" << arrayId << "\" stride=\"" << floatsPerElement << "\">" << endstr;
+    PushTag();
+
+    switch (pType) {
+    case FloatType_Vector:
+        mOutput << startstr << "<param name=\"X\" type=\"float\" />" << endstr;
+        mOutput << startstr << "<param name=\"Y\" type=\"float\" />" << endstr;
+        mOutput << startstr << "<param name=\"Z\" type=\"float\" />" << endstr;
+        break;
+
+    case FloatType_TexCoord2:
+        mOutput << startstr << "<param name=\"S\" type=\"float\" />" << endstr;
+        mOutput << startstr << "<param name=\"T\" type=\"float\" />" << endstr;
+        break;
+
+    case FloatType_TexCoord3:
+        mOutput << startstr << "<param name=\"S\" type=\"float\" />" << endstr;
+        mOutput << startstr << "<param name=\"T\" type=\"float\" />" << endstr;
+        mOutput << startstr << "<param name=\"P\" type=\"float\" />" << endstr;
+        break;
+
+    case FloatType_Color:
+        mOutput << startstr << "<param name=\"R\" type=\"float\" />" << endstr;
+        mOutput << startstr << "<param name=\"G\" type=\"float\" />" << endstr;
+        mOutput << startstr << "<param name=\"B\" type=\"float\" />" << endstr;
+        break;
+
+    case FloatType_Mat4x4:
+        mOutput << startstr << "<param name=\"TRANSFORM\" type=\"float4x4\" />" << endstr;
+        break;
+
+    case FloatType_Weight:
+        mOutput << startstr << "<param name=\"WEIGHT\" type=\"float\" />" << endstr;
+        break;
+
+    // customized, add animation related
+    case FloatType_Time:
+        mOutput << startstr << "<param name=\"TIME\" type=\"float\" />" << endstr;
+        break;
+    }
+
+    PopTag();
+    mOutput << startstr << "</accessor>" << endstr;
+    PopTag();
+    mOutput << startstr << "</technique_common>" << endstr;
+    PopTag();
+    mOutput << startstr << "</source>" << endstr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Writes the scene library
+void ColladaExporter::WriteSceneLibrary() {
+    // Determine if we are using the aiScene root or our own
+    std::string sceneName("Scene");
+    if (mAdd_root_node) {
+        mSceneId = MakeUniqueId(mUniqueIds, sceneName, std::string());
+        mUniqueIds.insert(mSceneId);
+    } else {
+        mSceneId = GetNodeUniqueId(mScene->mRootNode);
+        sceneName = GetNodeName(mScene->mRootNode);
+    }
+
+    mOutput << startstr << "<library_visual_scenes>" << endstr;
+    PushTag();
+    mOutput << startstr << "<visual_scene id=\"" + mSceneId + "\" name=\"" + sceneName + "\">" << endstr;
+    PushTag();
+
+    if (mAdd_root_node) {
+        // Export the root node
+        WriteNode(mScene->mRootNode);
+    } else {
+        // Have already exported the root node
+        for (size_t a = 0; a < mScene->mRootNode->mNumChildren; ++a)
+            WriteNode(mScene->mRootNode->mChildren[a]);
+    }
+
+    PopTag();
+    mOutput << startstr << "</visual_scene>" << endstr;
+    PopTag();
+    mOutput << startstr << "</library_visual_scenes>" << endstr;
+}
+// ------------------------------------------------------------------------------------------------
+void ColladaExporter::WriteAnimationLibrary(size_t pIndex) {
+    const aiAnimation *anim = mScene->mAnimations[pIndex];
+
+    if (anim->mNumChannels == 0 && anim->mNumMeshChannels == 0 && anim->mNumMorphMeshChannels == 0)
+        return;
+
+    const std::string animationNameEscaped = GetObjectName(AiObjectType::Animation, pIndex);
+    const std::string idstrEscaped = GetObjectUniqueId(AiObjectType::Animation, pIndex);
+
+    mOutput << startstr << "<animation id=\"" + idstrEscaped + "\" name=\"" + animationNameEscaped + "\">" << endstr;
+    PushTag();
+
+    std::string cur_node_idstr;
+    for (size_t a = 0; a < anim->mNumChannels; ++a) {
+        const aiNodeAnim *nodeAnim = anim->mChannels[a];
+
+        // sanity check
+        if (nodeAnim->mNumPositionKeys != nodeAnim->mNumScalingKeys || nodeAnim->mNumPositionKeys != nodeAnim->mNumRotationKeys) {
+            continue;
+        }
+
+        {
+            cur_node_idstr.clear();
+            cur_node_idstr += nodeAnim->mNodeName.data;
+            cur_node_idstr += std::string("_matrix-input");
+
+            std::vector<ai_real> frames;
+            for (size_t i = 0; i < nodeAnim->mNumPositionKeys; ++i) {
+                frames.push_back(static_cast<ai_real>(nodeAnim->mPositionKeys[i].mTime));
+            }
+
+            WriteFloatArray(cur_node_idstr, FloatType_Time, (const ai_real *)frames.data(), frames.size());
+            frames.clear();
+        }
+
+        {
+            cur_node_idstr.clear();
+
+            cur_node_idstr += nodeAnim->mNodeName.data;
+            cur_node_idstr += std::string("_matrix-output");
+
+            std::vector<ai_real> keyframes;
+            keyframes.reserve(nodeAnim->mNumPositionKeys * 16);
+            for (size_t i = 0; i < nodeAnim->mNumPositionKeys; ++i) {
+                aiVector3D Scaling = nodeAnim->mScalingKeys[i].mValue;
+                aiMatrix4x4 ScalingM; // identity
+                ScalingM[0][0] = Scaling.x;
+                ScalingM[1][1] = Scaling.y;
+                ScalingM[2][2] = Scaling.z;
+
+                aiQuaternion RotationQ = nodeAnim->mRotationKeys[i].mValue;
+                aiMatrix4x4 s = aiMatrix4x4(RotationQ.GetMatrix());
+                aiMatrix4x4 RotationM(s.a1, s.a2, s.a3, 0, s.b1, s.b2, s.b3, 0, s.c1, s.c2, s.c3, 0, 0, 0, 0, 1);
+
+                aiVector3D Translation = nodeAnim->mPositionKeys[i].mValue;
+                aiMatrix4x4 TranslationM; // identity
+                TranslationM[0][3] = Translation.x;
+                TranslationM[1][3] = Translation.y;
+                TranslationM[2][3] = Translation.z;
+
+                // Combine the above transformations
+                aiMatrix4x4 mat = TranslationM * RotationM * ScalingM;
+
+                for (unsigned int j = 0; j < 4; ++j) {
+                    keyframes.insert(keyframes.end(), mat[j], mat[j] + 4);
+                }
+            }
+
+            WriteFloatArray(cur_node_idstr, FloatType_Mat4x4, (const ai_real *)keyframes.data(), keyframes.size() / 16);
+        }
+
+        {
+            std::vector<std::string> names;
+            for (size_t i = 0; i < nodeAnim->mNumPositionKeys; ++i) {
+                if (nodeAnim->mPreState == aiAnimBehaviour_DEFAULT || nodeAnim->mPreState == aiAnimBehaviour_LINEAR || nodeAnim->mPreState == aiAnimBehaviour_REPEAT) {
+                    names.push_back("LINEAR");
+                } else if (nodeAnim->mPostState == aiAnimBehaviour_CONSTANT) {
+                    names.push_back("STEP");
+                }
+            }
+
+            const std::string cur_node_idstr2 = nodeAnim->mNodeName.data + std::string("_matrix-interpolation");
+            std::string arrayId = XMLIDEncode(cur_node_idstr2) + "-array";
+
+            mOutput << startstr << "<source id=\"" << XMLIDEncode(cur_node_idstr2) << "\">" << endstr;
+            PushTag();
+
+            // source array
+            mOutput << startstr << "<Name_array id=\"" << arrayId << "\" count=\"" << names.size() << "\"> ";
+            for (size_t aa = 0; aa < names.size(); ++aa) {
+                mOutput << names[aa] << " ";
+            }
+            mOutput << "</Name_array>" << endstr;
+
+            mOutput << startstr << "<technique_common>" << endstr;
+            PushTag();
+
+            mOutput << startstr << "<accessor source=\"#" << arrayId << "\" count=\"" << names.size() << "\" stride=\"" << 1 << "\">" << endstr;
+            PushTag();
+
+            mOutput << startstr << "<param name=\"INTERPOLATION\" type=\"name\"></param>" << endstr;
+
+            PopTag();
+            mOutput << startstr << "</accessor>" << endstr;
+
+            PopTag();
+            mOutput << startstr << "</technique_common>" << endstr;
+
+            PopTag();
+            mOutput << startstr << "</source>" << endstr;
+        }
+    }
+
+    for (size_t a = 0; a < anim->mNumChannels; ++a) {
+        const aiNodeAnim *nodeAnim = anim->mChannels[a];
+
+        {
+            // samplers
+            const std::string node_idstr = nodeAnim->mNodeName.data + std::string("_matrix-sampler");
+            mOutput << startstr << "<sampler id=\"" << XMLIDEncode(node_idstr) << "\">" << endstr;
+            PushTag();
+
+            mOutput << startstr << "<input semantic=\"INPUT\" source=\"#" << XMLIDEncode(nodeAnim->mNodeName.data + std::string("_matrix-input")) << "\"/>" << endstr;
+            mOutput << startstr << "<input semantic=\"OUTPUT\" source=\"#" << XMLIDEncode(nodeAnim->mNodeName.data + std::string("_matrix-output")) << "\"/>" << endstr;
+            mOutput << startstr << "<input semantic=\"INTERPOLATION\" source=\"#" << XMLIDEncode(nodeAnim->mNodeName.data + std::string("_matrix-interpolation")) << "\"/>" << endstr;
+
+            PopTag();
+            mOutput << startstr << "</sampler>" << endstr;
+        }
+    }
+
+    for (size_t a = 0; a < anim->mNumChannels; ++a) {
+        const aiNodeAnim *nodeAnim = anim->mChannels[a];
+
+        {
+            // channels
+            mOutput << startstr << "<channel source=\"#" << XMLIDEncode(nodeAnim->mNodeName.data + std::string("_matrix-sampler")) << "\" target=\"" << XMLIDEncode(nodeAnim->mNodeName.data) << "/matrix\"/>" << endstr;
+        }
+    }
+
+    PopTag();
+    mOutput << startstr << "</animation>" << endstr;
+}
+// ------------------------------------------------------------------------------------------------
+void ColladaExporter::WriteAnimationsLibrary() {
+    if (mScene->mNumAnimations > 0) {
+        mOutput << startstr << "<library_animations>" << endstr;
+        PushTag();
+
+        // start recursive write at the root node
+        for (size_t a = 0; a < mScene->mNumAnimations; ++a)
+            WriteAnimationLibrary(a);
+
+        PopTag();
+        mOutput << startstr << "</library_animations>" << endstr;
+    }
+}
+// ------------------------------------------------------------------------------------------------
+// Helper to find a bone by name in the scene
+aiBone *findBone(const aiScene *scene, const aiString &name) {
+    for (size_t m = 0; m < scene->mNumMeshes; m++) {
+        aiMesh *mesh = scene->mMeshes[m];
+        for (size_t b = 0; b < mesh->mNumBones; b++) {
+            aiBone *bone = mesh->mBones[b];
+            if (name == bone->mName) {
+                return bone;
+            }
+        }
+    }
+    return nullptr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Helper to find the node associated with a bone in the scene
+const aiNode *findBoneNode(const aiNode *aNode, const aiBone *bone) {
+    if (aNode && bone && aNode->mName == bone->mName) {
+        return aNode;
+    }
+
+    if (aNode && bone) {
+        for (unsigned int i = 0; i < aNode->mNumChildren; ++i) {
+            aiNode *aChild = aNode->mChildren[i];
+            const aiNode *foundFromChild = nullptr;
+            if (aChild) {
+                foundFromChild = findBoneNode(aChild, bone);
+                if (foundFromChild) {
+                    return foundFromChild;
+                }
+            }
+        }
+    }
+
+    return nullptr;
+}
+
+const aiNode *findSkeletonRootNode(const aiScene *scene, const aiMesh *mesh) {
+    std::set<const aiNode *> topParentBoneNodes;
+    if (mesh && mesh->mNumBones > 0) {
+        for (unsigned int i = 0; i < mesh->mNumBones; ++i) {
+            aiBone *bone = mesh->mBones[i];
+
+            const aiNode *node = findBoneNode(scene->mRootNode, bone);
+            if (node) {
+                while (node->mParent && findBone(scene, node->mParent->mName) != nullptr) {
+                    node = node->mParent;
+                }
+                topParentBoneNodes.insert(node);
+            }
+        }
+    }
+
+    if (!topParentBoneNodes.empty()) {
+        const aiNode *parentBoneNode = *topParentBoneNodes.begin();
+        if (topParentBoneNodes.size() == 1) {
+            return parentBoneNode;
+        } else {
+            for (auto it : topParentBoneNodes) {
+                if (it->mParent) return it->mParent;
+            }
+            return parentBoneNode;
+        }
+    }
+
+    return nullptr;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Recursively writes the given node
+void ColladaExporter::WriteNode(const aiNode *pNode) {
+    // If the node is associated with a bone, it is a joint node (JOINT)
+    // otherwise it is a normal node (NODE)
+    // Assimp-specific: nodes with no name cannot be associated with bones
+    const char *node_type;
+    bool is_joint, is_skeleton_root = false;
+    if (pNode->mName.length == 0 || nullptr == findBone(mScene, pNode->mName)) {
+        node_type = "NODE";
+        is_joint = false;
+    } else {
+        node_type = "JOINT";
+        is_joint = true;
+        if (!pNode->mParent || nullptr == findBone(mScene, pNode->mParent->mName)) {
+            is_skeleton_root = true;
+        }
+    }
+
+    const std::string node_id = GetNodeUniqueId(pNode);
+    const std::string node_name = GetNodeName(pNode);
+    mOutput << startstr << "<node ";
+    if (is_skeleton_root) {
+        mFoundSkeletonRootNodeID = node_id; // For now, only support one skeleton in a scene.
+    }
+    mOutput << "id=\"" << node_id << "\" " << (is_joint ? "sid=\"" + node_id + "\" " : "");
+    mOutput << "name=\"" << node_name
+            << "\" type=\"" << node_type
+            << "\">" << endstr;
+    PushTag();
+
+    // write transformation - we can directly put the matrix there
+    // TODO: (thom) decompose into scale - rot - quad to allow addressing it by animations afterwards
+    aiMatrix4x4 mat = pNode->mTransformation;
+
+    // If this node is a Camera node, the camera coordinate system needs to be multiplied in.
+    // When importing from Collada, the mLookAt is set to 0, 0, -1, and the node transform is unchanged.
+    // When importing from a different format, mLookAt is set to 0, 0, 1. Therefore, the local camera
+    // coordinate system must be changed to matche the Collada specification.
+    for (size_t i = 0; i < mScene->mNumCameras; i++) {
+        if (mScene->mCameras[i]->mName == pNode->mName) {
+            aiMatrix4x4 sourceView;
+            mScene->mCameras[i]->GetCameraMatrix(sourceView);
+
+            aiMatrix4x4 colladaView;
+            colladaView.a1 = colladaView.c3 = -1; // move into -z space.
+            mat *= (sourceView * colladaView);
+            break;
+        }
+    }
+
+    // customized, sid should be 'matrix' to match with loader code.
+    //mOutput << startstr << "<matrix sid=\"transform\">";
+    mOutput << startstr << "<matrix sid=\"matrix\">";
+
+    mOutput << mat.a1 << " " << mat.a2 << " " << mat.a3 << " " << mat.a4 << " ";
+    mOutput << mat.b1 << " " << mat.b2 << " " << mat.b3 << " " << mat.b4 << " ";
+    mOutput << mat.c1 << " " << mat.c2 << " " << mat.c3 << " " << mat.c4 << " ";
+    mOutput << mat.d1 << " " << mat.d2 << " " << mat.d3 << " " << mat.d4;
+    mOutput << "</matrix>" << endstr;
+
+    if (pNode->mNumMeshes == 0) {
+        //check if it is a camera node
+        for (size_t i = 0; i < mScene->mNumCameras; i++) {
+            if (mScene->mCameras[i]->mName == pNode->mName) {
+                mOutput << startstr << "<instance_camera url=\"#" << GetObjectUniqueId(AiObjectType::Camera, i) << "\"/>" << endstr;
+                break;
+            }
+        }
+        //check if it is a light node
+        for (size_t i = 0; i < mScene->mNumLights; i++) {
+            if (mScene->mLights[i]->mName == pNode->mName) {
+                mOutput << startstr << "<instance_light url=\"#" << GetObjectUniqueId(AiObjectType::Light, i) << "\"/>" << endstr;
+                break;
+            }
+        }
+
+    } else
+        // instance every geometry
+        for (size_t a = 0; a < pNode->mNumMeshes; ++a) {
+            const aiMesh *mesh = mScene->mMeshes[pNode->mMeshes[a]];
+            // do not instantiate mesh if empty. I wonder how this could happen
+            if (mesh->mNumFaces == 0 || mesh->mNumVertices == 0)
+                continue;
+
+            const std::string meshId = GetObjectUniqueId(AiObjectType::Mesh, pNode->mMeshes[a]);
+
+            if (mesh->mNumBones == 0) {
+                mOutput << startstr << "<instance_geometry url=\"#" << meshId << "\">" << endstr;
+                PushTag();
+            } else {
+                mOutput << startstr
+                        << "<instance_controller url=\"#" << meshId << "-skin\">"
+                        << endstr;
+                PushTag();
+
+                // note! this mFoundSkeletonRootNodeID some how affects animation, it makes the mesh attaches to armature skeleton root node.
+                // use the first bone to find skeleton root
+                const aiNode *skeletonRootBoneNode = findSkeletonRootNode(mScene, mesh);
+                if (skeletonRootBoneNode) {
+                    mFoundSkeletonRootNodeID = GetNodeUniqueId(skeletonRootBoneNode);
+                }
+                mOutput << startstr << "<skeleton>#" << mFoundSkeletonRootNodeID << "</skeleton>" << endstr;
+            }
+            mOutput << startstr << "<bind_material>" << endstr;
+            PushTag();
+            mOutput << startstr << "<technique_common>" << endstr;
+            PushTag();
+            mOutput << startstr << "<instance_material symbol=\"defaultMaterial\" target=\"#" << GetObjectUniqueId(AiObjectType::Material, mesh->mMaterialIndex) << "\">" << endstr;
+            PushTag();
+            for (size_t aa = 0; aa < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++aa) {
+                if (mesh->HasTextureCoords(static_cast<unsigned int>(aa)))
+                    // semantic       as in <texture texcoord=...>
+                    // input_semantic as in <input semantic=...>
+                    // input_set      as in <input set=...>
+                    mOutput << startstr << "<bind_vertex_input semantic=\"CHANNEL" << aa << "\" input_semantic=\"TEXCOORD\" input_set=\"" << aa << "\"/>" << endstr;
+            }
+            PopTag();
+            mOutput << startstr << "</instance_material>" << endstr;
+            PopTag();
+            mOutput << startstr << "</technique_common>" << endstr;
+            PopTag();
+            mOutput << startstr << "</bind_material>" << endstr;
+
+            PopTag();
+            if (mesh->mNumBones == 0)
+                mOutput << startstr << "</instance_geometry>" << endstr;
+            else
+                mOutput << startstr << "</instance_controller>" << endstr;
+        }
+
+    // recurse into subnodes
+    for (size_t a = 0; a < pNode->mNumChildren; ++a)
+        WriteNode(pNode->mChildren[a]);
+
+    PopTag();
+    mOutput << startstr << "</node>" << endstr;
+}
+
+void ColladaExporter::CreateNodeIds(const aiNode *node) {
+    GetNodeUniqueId(node);
+    for (size_t a = 0; a < node->mNumChildren; ++a)
+        CreateNodeIds(node->mChildren[a]);
+}
+
+std::string ColladaExporter::GetNodeUniqueId(const aiNode *node) {
+    // Use the pointer as the key. This is safe because the scene is immutable.
+    auto idIt = mNodeIdMap.find(node);
+    if (idIt != mNodeIdMap.cend())
+        return idIt->second;
+
+    // Prefer the requested Collada Id if extant
+    std::string idStr;
+    aiString origId;
+    if (node->mMetaData && node->mMetaData->Get(AI_METADATA_COLLADA_ID, origId)) {
+        idStr = origId.C_Str();
+    } else {
+        idStr = node->mName.C_Str();
+    }
+    // Make sure the requested id is valid
+    if (idStr.empty())
+        idStr = "node";
+    else
+        idStr = XMLIDEncode(idStr);
+
+    // Ensure it's unique
+    idStr = MakeUniqueId(mUniqueIds, idStr, std::string());
+    mUniqueIds.insert(idStr);
+    mNodeIdMap.insert(std::make_pair(node, idStr));
+    return idStr;
+}
+
+std::string ColladaExporter::GetNodeName(const aiNode *node) {
+
+    return XMLEscape(node->mName.C_Str());
+}
+
+std::string ColladaExporter::GetBoneUniqueId(const aiBone *bone) {
+    // Find the Node that is this Bone
+    const aiNode *boneNode = findBoneNode(mScene->mRootNode, bone);
+    if (boneNode == nullptr)
+        return std::string();
+
+    return GetNodeUniqueId(boneNode);
+}
+
+std::string ColladaExporter::GetObjectUniqueId(AiObjectType type, size_t pIndex) {
+    auto idIt = GetObjectIdMap(type).find(pIndex);
+    if (idIt != GetObjectIdMap(type).cend())
+        return idIt->second;
+
+    // Not seen this object before, create and add
+    NameIdPair result = AddObjectIndexToMaps(type, pIndex);
+    return result.second;
+}
+
+std::string ColladaExporter::GetObjectName(AiObjectType type, size_t pIndex) {
+    auto objectName = GetObjectNameMap(type).find(pIndex);
+    if (objectName != GetObjectNameMap(type).cend())
+        return objectName->second;
+
+    // Not seen this object before, create and add
+    NameIdPair result = AddObjectIndexToMaps(type, pIndex);
+    return result.first;
+}
+
+// Determine unique id and add the name and id to the maps
+// @param type object type
+// @param index object index
+// @param name in/out. Caller to set the original name if known.
+// @param idStr in/out. Caller to set the preferred id if known.
+ColladaExporter::NameIdPair ColladaExporter::AddObjectIndexToMaps(AiObjectType type, size_t index) {
+
+    std::string name;
+    std::string idStr;
+    std::string idPostfix;
+
+    // Get the name and id postfix
+    switch (type) {
+    case AiObjectType::Mesh: name = mScene->mMeshes[index]->mName.C_Str(); break;
+    case AiObjectType::Material: name = mScene->mMaterials[index]->GetName().C_Str(); break;
+    case AiObjectType::Animation: name = mScene->mAnimations[index]->mName.C_Str(); break;
+    case AiObjectType::Light:
+        name = mScene->mLights[index]->mName.C_Str();
+        idPostfix = "-light";
+        break;
+    case AiObjectType::Camera:
+        name = mScene->mCameras[index]->mName.C_Str();
+        idPostfix = "-camera";
+        break;
+    case AiObjectType::Count: throw std::logic_error("ColladaExporter::AiObjectType::Count is not an object type");
+    }
+
+    if (name.empty()) {
+        // Default ids if empty name
+        switch (type) {
+        case AiObjectType::Mesh: idStr = std::string("mesh_"); break;
+        case AiObjectType::Material: idStr = std::string("material_"); break; // This one should never happen
+        case AiObjectType::Animation: idStr = std::string("animation_"); break;
+        case AiObjectType::Light: idStr = std::string("light_"); break;
+        case AiObjectType::Camera: idStr = std::string("camera_"); break;
+        case AiObjectType::Count: throw std::logic_error("ColladaExporter::AiObjectType::Count is not an object type");
+        }
+        idStr.append(ai_to_string(index));
+    } else {
+        idStr = XMLIDEncode(name);
+    }
+
+    if (!name.empty())
+        name = XMLEscape(name);
+
+    idStr = MakeUniqueId(mUniqueIds, idStr, idPostfix);
+
+    // Add to maps
+    mUniqueIds.insert(idStr);
+    GetObjectIdMap(type).insert(std::make_pair(index, idStr));
+    GetObjectNameMap(type).insert(std::make_pair(index, name));
+
+    return std::make_pair(name, idStr);
+}
+
+} // end of namespace Assimp
+
+#endif
+#endif