assimp.assimp/code/AssetLib/Blender/BlenderLoader.cpp

/*
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*/

/** @file  BlenderLoader.cpp
 *  @brief Implementation of the Blender3D importer class.
 */

//#define ASSIMP_BUILD_NO_COMPRESSED_BLEND
// Uncomment this to disable support for (gzip)compressed .BLEND files

#ifndef ASSIMP_BUILD_NO_BLEND_IMPORTER

#include "BlenderBMesh.h"
#include "BlenderCustomData.h"
#include "BlenderIntermediate.h"
#include "BlenderModifier.h"
#include <assimp/StringUtils.h>
#include <assimp/importerdesc.h>
#include <assimp/scene.h>

#include <assimp/MemoryIOWrapper.h>
#include <assimp/StreamReader.h>
#include <assimp/StringComparison.h>

#include <cctype>

// zlib is needed for compressed blend files
#ifndef ASSIMP_BUILD_NO_COMPRESSED_BLEND
#  ifdef ASSIMP_BUILD_NO_OWN_ZLIB
#    include <zlib.h>
#  else
#    include "../contrib/zlib/zlib.h"
#  endif
#endif

namespace Assimp {

template <>
const char *LogFunctions<BlenderImporter>::Prefix() {
    static auto prefix = "BLEND: ";
    return prefix;
}

} // namespace Assimp

using namespace Assimp;
using namespace Assimp::Blender;
using namespace Assimp::Formatter;

static const aiImporterDesc blenderDesc = {
    "Blender 3D Importer (http://www.blender3d.org)",
    "",
    "",
    "No animation support yet",
    aiImporterFlags_SupportBinaryFlavour,
    0,
    0,
    2,
    50,
    "blend"
};

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
BlenderImporter::BlenderImporter() :
        modifier_cache(new BlenderModifierShowcase()) {
    // empty
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
BlenderImporter::~BlenderImporter() {
    delete modifier_cache;
}

static const char * const Tokens[] = { "BLENDER" };

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file.
bool BlenderImporter::CanRead(const std::string &pFile, IOSystem *pIOHandler, bool /*checkSig*/) const {
    // note: this won't catch compressed files
    static const char *tokens[] = { "<BLENDER", "blender" };

    return SearchFileHeaderForToken(pIOHandler, pFile, tokens, AI_COUNT_OF(tokens));
}

// ------------------------------------------------------------------------------------------------
// Loader registry entry
const aiImporterDesc *BlenderImporter::GetInfo() const {
    return &blenderDesc;
}

// ------------------------------------------------------------------------------------------------
// Setup configuration properties for the loader
void BlenderImporter::SetupProperties(const Importer * /*pImp*/) {
    // nothing to be done for the moment
}

// ------------------------------------------------------------------------------------------------
// Imports the given file into the given scene structure.
void BlenderImporter::InternReadFile(const std::string &pFile,
        aiScene *pScene, IOSystem *pIOHandler) {
#ifndef ASSIMP_BUILD_NO_COMPRESSED_BLEND
    std::vector<Bytef> uncompressed;
#endif

    FileDatabase file;
    std::shared_ptr<IOStream> stream(pIOHandler->Open(pFile, "rb"));
    if (!stream) {
        ThrowException("Could not open file for reading");
    }

    char magic[8] = { 0 };
    stream->Read(magic, 7, 1);
    if (strcmp(magic, Tokens[0])) {
        // Check for presence of the gzip header. If yes, assume it is a
        // compressed blend file and try uncompressing it, else fail. This is to
        // avoid uncompressing random files which our loader might end up with.
#ifdef ASSIMP_BUILD_NO_COMPRESSED_BLEND
        ThrowException("BLENDER magic bytes are missing, is this file compressed (Assimp was built without decompression support)?");
#else

        if (magic[0] != 0x1f || static_cast<uint8_t>(magic[1]) != 0x8b) {
            ThrowException("BLENDER magic bytes are missing, couldn't find GZIP header either");
        }

        LogDebug("Found no BLENDER magic word but a GZIP header, might be a compressed file");
        if (magic[2] != 8) {
            ThrowException("Unsupported GZIP compression method");
        }

        // http://www.gzip.org/zlib/rfc-gzip.html#header-trailer
        stream->Seek(0L, aiOrigin_SET);
        std::shared_ptr<StreamReaderLE> reader = std::shared_ptr<StreamReaderLE>(new StreamReaderLE(stream));

        // build a zlib stream
        z_stream zstream;
        zstream.opaque = Z_NULL;
        zstream.zalloc = Z_NULL;
        zstream.zfree = Z_NULL;
        zstream.data_type = Z_BINARY;

        // http://hewgill.com/journal/entries/349-how-to-decompress-gzip-stream-with-zlib
        inflateInit2(&zstream, 16 + MAX_WBITS);

        zstream.next_in = reinterpret_cast<Bytef *>(reader->GetPtr());
        zstream.avail_in = (uInt)reader->GetRemainingSize();

        size_t total = 0l;

        // TODO: be smarter about this, decompress directly into heap buffer
        // and decompress the data .... do 1k chunks in the hope that we won't kill the stack
#define MYBLOCK 1024
        Bytef block[MYBLOCK];
        int ret;
        do {
            zstream.avail_out = MYBLOCK;
            zstream.next_out = block;
            ret = inflate(&zstream, Z_NO_FLUSH);

            if (ret != Z_STREAM_END && ret != Z_OK) {
                ThrowException("Failure decompressing this file using gzip, seemingly it is NOT a compressed .BLEND file");
            }
            const size_t have = MYBLOCK - zstream.avail_out;
            total += have;
            uncompressed.resize(total);
            memcpy(uncompressed.data() + total - have, block, have);
        } while (ret != Z_STREAM_END);

        // terminate zlib
        inflateEnd(&zstream);

        // replace the input stream with a memory stream
        stream.reset(new MemoryIOStream(reinterpret_cast<uint8_t *>(uncompressed.data()), total));

        // .. and retry
        stream->Read(magic, 7, 1);
        if (strcmp(magic, "BLENDER")) {
            ThrowException("Found no BLENDER magic word in decompressed GZIP file");
        }
#endif
    }

    file.i64bit = (stream->Read(magic, 1, 1), magic[0] == '-');
    file.little = (stream->Read(magic, 1, 1), magic[0] == 'v');

    stream->Read(magic, 3, 1);
    magic[3] = '\0';

    LogInfo("Blender version is ", magic[0], ".", magic + 1,
            " (64bit: ", file.i64bit ? "true" : "false",
            ", little endian: ", file.little ? "true" : "false", ")");

    ParseBlendFile(file, stream);

    Scene scene;
    ExtractScene(scene, file);

    ConvertBlendFile(pScene, scene, file);
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::ParseBlendFile(FileDatabase &out, std::shared_ptr<IOStream> stream) {
    out.reader = std::make_shared<StreamReaderAny>(stream, out.little);

    DNAParser dna_reader(out);
    const DNA *dna = nullptr;

    out.entries.reserve(128);
    { // even small BLEND files tend to consist of many file blocks
        SectionParser parser(*out.reader.get(), out.i64bit);

        // first parse the file in search for the DNA and insert all other sections into the database
        while ((parser.Next(), 1)) {
            const FileBlockHead &head = parser.GetCurrent();

            if (head.id == "ENDB") {
                break; // only valid end of the file
            } else if (head.id == "DNA1") {
                dna_reader.Parse();
                dna = &dna_reader.GetDNA();
                continue;
            }

            out.entries.push_back(head);
        }
    }
    if (!dna) {
        ThrowException("SDNA not found");
    }

    std::sort(out.entries.begin(), out.entries.end());
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::ExtractScene(Scene &out, const FileDatabase &file) {
    const FileBlockHead *block = nullptr;
    std::map<std::string, size_t>::const_iterator it = file.dna.indices.find("Scene");
    if (it == file.dna.indices.end()) {
        ThrowException("There is no `Scene` structure record");
    }

    const Structure &ss = file.dna.structures[(*it).second];

    // we need a scene somewhere to start with.
    for (const FileBlockHead &bl : file.entries) {

        // Fix: using the DNA index is more reliable to locate scenes
        //if (bl.id == "SC") {

        if (bl.dna_index == (*it).second) {
            block = &bl;
            break;
        }
    }

    if (!block) {
        ThrowException("There is not a single `Scene` record to load");
    }

    file.reader->SetCurrentPos(block->start);
    ss.Convert(out, file);

#ifndef ASSIMP_BUILD_BLENDER_NO_STATS
    ASSIMP_LOG_INFO(
            "(Stats) Fields read: ", file.stats().fields_read,
            ", pointers resolved: ", file.stats().pointers_resolved,
            ", cache hits: ", file.stats().cache_hits,
            ", cached objects: ", file.stats().cached_objects);
#endif
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::ParseSubCollection(const Blender::Scene &in, aiNode *root, std::shared_ptr<Collection> collection, ConversionData &conv_data) {

    std::deque<Object *> root_objects;
    // Count number of objects
    for (std::shared_ptr<CollectionObject> cur = std::static_pointer_cast<CollectionObject>(collection->gobject.first); cur; cur = cur->next) {
        if (cur->ob) {
            root_objects.push_back(cur->ob);
        }
    }
    std::deque<Collection *> root_children;
    // Count number of child nodes
    for (std::shared_ptr<CollectionChild> cur = std::static_pointer_cast<CollectionChild>(collection->children.first); cur; cur = cur->next) {
        if (cur->collection) {
            root_children.push_back(cur->collection.get());
        }
    }
    root->mNumChildren = static_cast<unsigned int>(root_objects.size() + root_children.size());
    root->mChildren = new aiNode *[root->mNumChildren]();

    for (unsigned int i = 0; i < static_cast<unsigned int>(root_objects.size()); ++i) {
        root->mChildren[i] = ConvertNode(in, root_objects[i], conv_data, aiMatrix4x4());
        root->mChildren[i]->mParent = root;
    }

    // For each subcollection create a new node to represent it
    unsigned int iterator = static_cast<unsigned int>(root_objects.size());
    for (std::shared_ptr<CollectionChild> cur = std::static_pointer_cast<CollectionChild>(collection->children.first); cur; cur = cur->next) {
        if (cur->collection) {
            root->mChildren[iterator] = new aiNode(cur->collection->id.name + 2); // skip over the name prefix 'OB'
            root->mChildren[iterator]->mParent = root;
            ParseSubCollection(in, root->mChildren[iterator], cur->collection, conv_data);
        }
        iterator += 1;
    }
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::ConvertBlendFile(aiScene *out, const Scene &in, const FileDatabase &file) {
    ConversionData conv(file);

    aiNode *root = out->mRootNode = new aiNode("<BlenderRoot>");
    // Iterate over all objects directly under master_collection,
    // If in.master_collection == null, then we're parsing something older.
    if (in.master_collection) {
        ParseSubCollection(in, root, in.master_collection, conv);
    } else {
        std::deque<const Object *> no_parents;
        for (std::shared_ptr<Base> cur = std::static_pointer_cast<Base>(in.base.first); cur; cur = cur->next) {
            if (cur->object) {
                if (!cur->object->parent) {
                    no_parents.push_back(cur->object.get());
                } else {
                    conv.objects.insert(cur->object.get());
                }
            }
        }
        for (std::shared_ptr<Base> cur = in.basact; cur; cur = cur->next) {
            if (cur->object) {
                if (cur->object->parent) {
                    conv.objects.insert(cur->object.get());
                }
            }
        }

        if (no_parents.empty()) {
            ThrowException("Expected at least one object with no parent");
        }

        root->mNumChildren = static_cast<unsigned int>(no_parents.size());
        root->mChildren = new aiNode *[root->mNumChildren]();
        for (unsigned int i = 0; i < root->mNumChildren; ++i) {
            root->mChildren[i] = ConvertNode(in, no_parents[i], conv, aiMatrix4x4());
            root->mChildren[i]->mParent = root;
        }
    }

    BuildMaterials(conv);

    if (conv.meshes->size()) {
        out->mMeshes = new aiMesh *[out->mNumMeshes = static_cast<unsigned int>(conv.meshes->size())];
        std::copy(conv.meshes->begin(), conv.meshes->end(), out->mMeshes);
        conv.meshes.dismiss();
    }

    if (conv.lights->size()) {
        out->mLights = new aiLight *[out->mNumLights = static_cast<unsigned int>(conv.lights->size())];
        std::copy(conv.lights->begin(), conv.lights->end(), out->mLights);
        conv.lights.dismiss();
    }

    if (conv.cameras->size()) {
        out->mCameras = new aiCamera *[out->mNumCameras = static_cast<unsigned int>(conv.cameras->size())];
        std::copy(conv.cameras->begin(), conv.cameras->end(), out->mCameras);
        conv.cameras.dismiss();
    }

    if (conv.materials->size()) {
        out->mMaterials = new aiMaterial *[out->mNumMaterials = static_cast<unsigned int>(conv.materials->size())];
        std::copy(conv.materials->begin(), conv.materials->end(), out->mMaterials);
        conv.materials.dismiss();
    }

    if (conv.textures->size()) {
        out->mTextures = new aiTexture *[out->mNumTextures = static_cast<unsigned int>(conv.textures->size())];
        std::copy(conv.textures->begin(), conv.textures->end(), out->mTextures);
        conv.textures.dismiss();
    }

    // acknowledge that the scene might come out incomplete
    // by Assimp's definition of `complete`: blender scenes
    // can consist of thousands of cameras or lights with
    // not a single mesh between them.
    if (!out->mNumMeshes) {
        out->mFlags |= AI_SCENE_FLAGS_INCOMPLETE;
    }
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::ResolveImage(aiMaterial *out, const Material *mat, const MTex *tex, const Image *img, ConversionData &conv_data) {
    (void)mat;
    (void)tex;
    (void)conv_data;
    aiString name;

    // check if the file contents are bundled with the BLEND file
    if (img->packedfile) {
        name.data[0] = '*';
        name.length = 1 + ASSIMP_itoa10(name.data + 1, static_cast<unsigned int>(MAXLEN - 1), static_cast<int32_t>(conv_data.textures->size()));

        conv_data.textures->push_back(new aiTexture());
        aiTexture *curTex = conv_data.textures->back();

        // usually 'img->name' will be the original file name of the embedded textures,
        // so we can extract the file extension from it.
        const size_t nlen = strlen(img->name);
        const char *s = img->name + nlen, *e = s;
        while (s >= img->name && *s != '.') {
            --s;
        }

        curTex->achFormatHint[0] = s + 1 > e ? '\0' : (char)::tolower((unsigned char)s[1]);
        curTex->achFormatHint[1] = s + 2 > e ? '\0' : (char)::tolower((unsigned char)s[2]);
        curTex->achFormatHint[2] = s + 3 > e ? '\0' : (char)::tolower((unsigned char)s[3]);
        curTex->achFormatHint[3] = '\0';

        // tex->mHeight = 0;
        curTex->mWidth = img->packedfile->size;
        uint8_t *ch = new uint8_t[curTex->mWidth];

        conv_data.db.reader->SetCurrentPos(static_cast<size_t>(img->packedfile->data->val));
        conv_data.db.reader->CopyAndAdvance(ch, curTex->mWidth);

        curTex->pcData = reinterpret_cast<aiTexel *>(ch);

        LogInfo("Reading embedded texture, original file was ", img->name);
    } else {
        name = aiString(img->name);
    }

    aiTextureType texture_type = aiTextureType_UNKNOWN;
    MTex::MapType map_type = tex->mapto;

    if (map_type & MTex::MapType_COL)
        texture_type = aiTextureType_DIFFUSE;
    else if (map_type & MTex::MapType_NORM) {
        if (tex->tex->imaflag & Tex::ImageFlags_NORMALMAP) {
            texture_type = aiTextureType_NORMALS;
        } else {
            texture_type = aiTextureType_HEIGHT;
        }
        out->AddProperty(&tex->norfac, 1, AI_MATKEY_BUMPSCALING);
    } else if (map_type & MTex::MapType_COLSPEC)
        texture_type = aiTextureType_SPECULAR;
    else if (map_type & MTex::MapType_COLMIR)
        texture_type = aiTextureType_REFLECTION;
    //else if (map_type & MTex::MapType_REF)
    else if (map_type & MTex::MapType_SPEC)
        texture_type = aiTextureType_SHININESS;
    else if (map_type & MTex::MapType_EMIT)
        texture_type = aiTextureType_EMISSIVE;
    //else if (map_type & MTex::MapType_ALPHA)
    //else if (map_type & MTex::MapType_HAR)
    //else if (map_type & MTex::MapType_RAYMIRR)
    //else if (map_type & MTex::MapType_TRANSLU)
    else if (map_type & MTex::MapType_AMB)
        texture_type = aiTextureType_AMBIENT;
    else if (map_type & MTex::MapType_DISPLACE)
        texture_type = aiTextureType_DISPLACEMENT;
    //else if (map_type & MTex::MapType_WARP)

    out->AddProperty(&name, AI_MATKEY_TEXTURE(texture_type,
                                    conv_data.next_texture[texture_type]++));
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::AddSentinelTexture(aiMaterial *out, const Material *mat, const MTex *tex, ConversionData &conv_data) {
    (void)mat;
    (void)tex;
    (void)conv_data;

    aiString name;
    name.length = ai_snprintf(name.data, MAXLEN, "Procedural,num=%i,type=%s", conv_data.sentinel_cnt++,
            GetTextureTypeDisplayString(tex->tex->type));
    out->AddProperty(&name, AI_MATKEY_TEXTURE_DIFFUSE(
                                    conv_data.next_texture[aiTextureType_DIFFUSE]++));
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::ResolveTexture(aiMaterial *out, const Material *mat, const MTex *tex, ConversionData &conv_data) {
    const Tex *rtex = tex->tex.get();
    if (!rtex || !rtex->type) {
        return;
    }

    // We can't support most of the texture types because they're mostly procedural.
    // These are substituted by a dummy texture.
    const char *dispnam = "";
    switch (rtex->type) {
        // these are listed in blender's UI
    case Tex::Type_CLOUDS:
    case Tex::Type_WOOD:
    case Tex::Type_MARBLE:
    case Tex::Type_MAGIC:
    case Tex::Type_BLEND:
    case Tex::Type_STUCCI:
    case Tex::Type_NOISE:
    case Tex::Type_PLUGIN:
    case Tex::Type_MUSGRAVE:
    case Tex::Type_VORONOI:
    case Tex::Type_DISTNOISE:
    case Tex::Type_ENVMAP:

        // these do no appear in the UI, why?
    case Tex::Type_POINTDENSITY:
    case Tex::Type_VOXELDATA:

        LogWarn("Encountered a texture with an unsupported type: ", dispnam);
        AddSentinelTexture(out, mat, tex, conv_data);
        break;

    case Tex::Type_IMAGE:
        if (!rtex->ima) {
            LogError("A texture claims to be an Image, but no image reference is given");
            break;
        }
        ResolveImage(out, mat, tex, rtex->ima.get(), conv_data);
        break;

    default:
        ai_assert(false);
    };
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::BuildDefaultMaterial(Blender::ConversionData &conv_data) {
    // add a default material if necessary
    unsigned int index = static_cast<unsigned int>(-1);
    for (aiMesh *mesh : conv_data.meshes.get()) {
        if (mesh->mMaterialIndex == static_cast<unsigned int>(-1)) {

            if (index == static_cast<unsigned int>(-1)) {
                // Setup a default material.
                std::shared_ptr<Material> p(new Material());
                ai_assert(::strlen(AI_DEFAULT_MATERIAL_NAME) < sizeof(p->id.name) - 2);
                strcpy(p->id.name + 2, AI_DEFAULT_MATERIAL_NAME);

                // Note: MSVC11 does not zero-initialize Material here, although it should.
                // Thus all relevant fields should be explicitly initialized. We cannot add
                // a default constructor to Material since the DNA codegen does not support
                // parsing it.
                p->r = p->g = p->b = 0.6f;
                p->specr = p->specg = p->specb = 0.6f;
                p->ambr = p->ambg = p->ambb = 0.0f;
                p->mirr = p->mirg = p->mirb = 0.0f;
                p->emit = 0.f;
                p->alpha = 0.f;
                p->har = 0;

                index = static_cast<unsigned int>(conv_data.materials_raw.size());
                conv_data.materials_raw.push_back(p);
                LogInfo("Adding default material");
            }
            mesh->mMaterialIndex = index;
        }
    }
}

void BlenderImporter::AddBlendParams(aiMaterial *result, const Material *source) {
    aiColor3D diffuseColor(source->r, source->g, source->b);
    result->AddProperty(&diffuseColor, 1, "$mat.blend.diffuse.color", 0, 0);

    float diffuseIntensity = source->ref;
    result->AddProperty(&diffuseIntensity, 1, "$mat.blend.diffuse.intensity", 0, 0);

    int diffuseShader = source->diff_shader;
    result->AddProperty(&diffuseShader, 1, "$mat.blend.diffuse.shader", 0, 0);

    int diffuseRamp = 0;
    result->AddProperty(&diffuseRamp, 1, "$mat.blend.diffuse.ramp", 0, 0);

    aiColor3D specularColor(source->specr, source->specg, source->specb);
    result->AddProperty(&specularColor, 1, "$mat.blend.specular.color", 0, 0);

    float specularIntensity = source->spec;
    result->AddProperty(&specularIntensity, 1, "$mat.blend.specular.intensity", 0, 0);

    int specularShader = source->spec_shader;
    result->AddProperty(&specularShader, 1, "$mat.blend.specular.shader", 0, 0);

    int specularRamp = 0;
    result->AddProperty(&specularRamp, 1, "$mat.blend.specular.ramp", 0, 0);

    int specularHardness = source->har;
    result->AddProperty(&specularHardness, 1, "$mat.blend.specular.hardness", 0, 0);

    int transparencyUse = source->mode & MA_TRANSPARENCY ? 1 : 0;
    result->AddProperty(&transparencyUse, 1, "$mat.blend.transparency.use", 0, 0);

    int transparencyMethod = source->mode & MA_RAYTRANSP ? 2 : (source->mode & MA_ZTRANSP ? 1 : 0);
    result->AddProperty(&transparencyMethod, 1, "$mat.blend.transparency.method", 0, 0);

    float transparencyAlpha = source->alpha;
    result->AddProperty(&transparencyAlpha, 1, "$mat.blend.transparency.alpha", 0, 0);

    float transparencySpecular = source->spectra;
    result->AddProperty(&transparencySpecular, 1, "$mat.blend.transparency.specular", 0, 0);

    float transparencyFresnel = source->fresnel_tra;
    result->AddProperty(&transparencyFresnel, 1, "$mat.blend.transparency.fresnel", 0, 0);

    float transparencyBlend = source->fresnel_tra_i;
    result->AddProperty(&transparencyBlend, 1, "$mat.blend.transparency.blend", 0, 0);

    float transparencyIor = source->ang;
    result->AddProperty(&transparencyIor, 1, "$mat.blend.transparency.ior", 0, 0);

    float transparencyFilter = source->filter;
    result->AddProperty(&transparencyFilter, 1, "$mat.blend.transparency.filter", 0, 0);

    float transparencyFalloff = source->tx_falloff;
    result->AddProperty(&transparencyFalloff, 1, "$mat.blend.transparency.falloff", 0, 0);

    float transparencyLimit = source->tx_limit;
    result->AddProperty(&transparencyLimit, 1, "$mat.blend.transparency.limit", 0, 0);

    int transparencyDepth = source->ray_depth_tra;
    result->AddProperty(&transparencyDepth, 1, "$mat.blend.transparency.depth", 0, 0);

    float transparencyGlossAmount = source->gloss_tra;
    result->AddProperty(&transparencyGlossAmount, 1, "$mat.blend.transparency.glossAmount", 0, 0);

    float transparencyGlossThreshold = source->adapt_thresh_tra;
    result->AddProperty(&transparencyGlossThreshold, 1, "$mat.blend.transparency.glossThreshold", 0, 0);

    int transparencyGlossSamples = source->samp_gloss_tra;
    result->AddProperty(&transparencyGlossSamples, 1, "$mat.blend.transparency.glossSamples", 0, 0);

    int mirrorUse = source->mode & MA_RAYMIRROR ? 1 : 0;
    result->AddProperty(&mirrorUse, 1, "$mat.blend.mirror.use", 0, 0);

    float mirrorReflectivity = source->ray_mirror;
    result->AddProperty(&mirrorReflectivity, 1, "$mat.blend.mirror.reflectivity", 0, 0);

    aiColor3D mirrorColor(source->mirr, source->mirg, source->mirb);
    result->AddProperty(&mirrorColor, 1, "$mat.blend.mirror.color", 0, 0);

    float mirrorFresnel = source->fresnel_mir;
    result->AddProperty(&mirrorFresnel, 1, "$mat.blend.mirror.fresnel", 0, 0);

    float mirrorBlend = source->fresnel_mir_i;
    result->AddProperty(&mirrorBlend, 1, "$mat.blend.mirror.blend", 0, 0);

    int mirrorDepth = source->ray_depth;
    result->AddProperty(&mirrorDepth, 1, "$mat.blend.mirror.depth", 0, 0);

    float mirrorMaxDist = source->dist_mir;
    result->AddProperty(&mirrorMaxDist, 1, "$mat.blend.mirror.maxDist", 0, 0);

    int mirrorFadeTo = source->fadeto_mir;
    result->AddProperty(&mirrorFadeTo, 1, "$mat.blend.mirror.fadeTo", 0, 0);

    float mirrorGlossAmount = source->gloss_mir;
    result->AddProperty(&mirrorGlossAmount, 1, "$mat.blend.mirror.glossAmount", 0, 0);

    float mirrorGlossThreshold = source->adapt_thresh_mir;
    result->AddProperty(&mirrorGlossThreshold, 1, "$mat.blend.mirror.glossThreshold", 0, 0);

    int mirrorGlossSamples = source->samp_gloss_mir;
    result->AddProperty(&mirrorGlossSamples, 1, "$mat.blend.mirror.glossSamples", 0, 0);

    float mirrorGlossAnisotropic = source->aniso_gloss_mir;
    result->AddProperty(&mirrorGlossAnisotropic, 1, "$mat.blend.mirror.glossAnisotropic", 0, 0);
}

void BlenderImporter::BuildMaterials(ConversionData &conv_data) {
    conv_data.materials->reserve(conv_data.materials_raw.size());

    BuildDefaultMaterial(conv_data);

    for (const std::shared_ptr<Material> &mat : conv_data.materials_raw) {

        // reset per material global counters
        for (size_t i = 0; i < sizeof(conv_data.next_texture) / sizeof(conv_data.next_texture[0]); ++i) {
            conv_data.next_texture[i] = 0;
        }

        aiMaterial *mout = new aiMaterial();
        conv_data.materials->push_back(mout);
        // For any new material field handled here, the default material above must be updated with an appropriate default value.

        // set material name
        aiString name = aiString(mat->id.name + 2); // skip over the name prefix 'MA'
        mout->AddProperty(&name, AI_MATKEY_NAME);

        // basic material colors
        aiColor3D col(mat->r, mat->g, mat->b);
        if (mat->r || mat->g || mat->b) {

            // Usually, zero diffuse color means no diffuse color at all in the equation.
            // So we omit this member to express this intent.
            mout->AddProperty(&col, 1, AI_MATKEY_COLOR_DIFFUSE);

            if (mat->emit) {
                aiColor3D emit_col(mat->emit * mat->r, mat->emit * mat->g, mat->emit * mat->b);
                mout->AddProperty(&emit_col, 1, AI_MATKEY_COLOR_EMISSIVE);
            }
        }

        col = aiColor3D(mat->specr, mat->specg, mat->specb);
        mout->AddProperty(&col, 1, AI_MATKEY_COLOR_SPECULAR);

        // is hardness/shininess set?
        if (mat->har) {
            const float har = mat->har;
            mout->AddProperty(&har, 1, AI_MATKEY_SHININESS);
        }

        col = aiColor3D(mat->ambr, mat->ambg, mat->ambb);
        mout->AddProperty(&col, 1, AI_MATKEY_COLOR_AMBIENT);

        // is mirror enabled?
        if (mat->mode & MA_RAYMIRROR) {
            const float ray_mirror = mat->ray_mirror;
            mout->AddProperty(&ray_mirror, 1, AI_MATKEY_REFLECTIVITY);
        }

        col = aiColor3D(mat->mirr, mat->mirg, mat->mirb);
        mout->AddProperty(&col, 1, AI_MATKEY_COLOR_REFLECTIVE);

        for (size_t i = 0; i < sizeof(mat->mtex) / sizeof(mat->mtex[0]); ++i) {
            if (!mat->mtex[i]) {
                continue;
            }

            ResolveTexture(mout, mat.get(), mat->mtex[i].get(), conv_data);
        }

        AddBlendParams(mout, mat.get());
    }
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::CheckActualType(const ElemBase *dt, const char *check) {
    ai_assert(dt);
    if (strcmp(dt->dna_type, check)) {
        ThrowException("Expected object at ", std::hex, dt, " to be of type `", check,
                "`, but it claims to be a `", dt->dna_type, "`instead");
    }
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::NotSupportedObjectType(const Object *obj, const char *type) {
    LogWarn("Object `", obj->id.name, "` - type is unsupported: `", type, "`, skipping");
}

// ------------------------------------------------------------------------------------------------
void BlenderImporter::ConvertMesh(const Scene & /*in*/, const Object * /*obj*/, const Mesh *mesh,
        ConversionData &conv_data, TempArray<std::vector, aiMesh> &temp) {
    // TODO: Resolve various problems with BMesh triangulation before re-enabling.
    //       See issues #400, #373, #318  #315 and #132.
#if defined(TODO_FIX_BMESH_CONVERSION)
    BlenderBMeshConverter BMeshConverter(mesh);
    if (BMeshConverter.ContainsBMesh()) {
        mesh = BMeshConverter.TriangulateBMesh();
    }
#endif

    typedef std::pair<const int, size_t> MyPair;
    if ((!mesh->totface && !mesh->totloop) || !mesh->totvert) {
        return;
    }

    // some sanity checks
    if (static_cast<size_t>(mesh->totface) > mesh->mface.size()) {
        ThrowException("Number of faces is larger than the corresponding array");
    }

    if (static_cast<size_t>(mesh->totvert) > mesh->mvert.size()) {
        ThrowException("Number of vertices is larger than the corresponding array");
    }

    if (static_cast<size_t>(mesh->totloop) > mesh->mloop.size()) {
        ThrowException("Number of vertices is larger than the corresponding array");
    }

    // collect per-submesh numbers
    std::map<int, size_t> per_mat;
    std::map<int, size_t> per_mat_verts;
    for (int i = 0; i < mesh->totface; ++i) {

        const MFace &mf = mesh->mface[i];
        per_mat[mf.mat_nr]++;
        per_mat_verts[mf.mat_nr] += mf.v4 ? 4 : 3;
    }

    for (int i = 0; i < mesh->totpoly; ++i) {
        const MPoly &mp = mesh->mpoly[i];
        per_mat[mp.mat_nr]++;
        per_mat_verts[mp.mat_nr] += mp.totloop;
    }

    // ... and allocate the corresponding meshes
    const size_t old = temp->size();
    temp->reserve(temp->size() + per_mat.size());

    std::map<size_t, size_t> mat_num_to_mesh_idx;
    for (MyPair &it : per_mat) {

        mat_num_to_mesh_idx[it.first] = temp->size();
        temp->push_back(new aiMesh());

        aiMesh *out = temp->back();
        out->mVertices = new aiVector3D[per_mat_verts[it.first]];
        out->mNormals = new aiVector3D[per_mat_verts[it.first]];

        //out->mNumFaces = 0
        //out->mNumVertices = 0
        out->mFaces = new aiFace[it.second]();

        // all sub-meshes created from this mesh are named equally. this allows
        // curious users to recover the original adjacency.
        out->mName = aiString(mesh->id.name + 2);
        // skip over the name prefix 'ME'

        // resolve the material reference and add this material to the set of
        // output materials. The (temporary) material index is the index
        // of the material entry within the list of resolved materials.
        if (mesh->mat) {

            if (static_cast<size_t>(it.first) >= mesh->mat.size()) {
                ThrowException("Material index is out of range");
            }

            std::shared_ptr<Material> mat = mesh->mat[it.first];
            const std::deque<std::shared_ptr<Material>>::iterator has = std::find(
                    conv_data.materials_raw.begin(),
                    conv_data.materials_raw.end(), mat);

            if (has != conv_data.materials_raw.end()) {
                out->mMaterialIndex = static_cast<unsigned int>(std::distance(conv_data.materials_raw.begin(), has));
            } else {
                out->mMaterialIndex = static_cast<unsigned int>(conv_data.materials_raw.size());
                conv_data.materials_raw.push_back(mat);
            }
        } else
            out->mMaterialIndex = static_cast<unsigned int>(-1);
    }

    for (int i = 0; i < mesh->totface; ++i) {

        const MFace &mf = mesh->mface[i];

        aiMesh *const out = temp[mat_num_to_mesh_idx[mf.mat_nr]];
        aiFace &f = out->mFaces[out->mNumFaces++];

        f.mIndices = new unsigned int[f.mNumIndices = mf.v4 ? 4 : 3];
        aiVector3D *vo = out->mVertices + out->mNumVertices;
        aiVector3D *vn = out->mNormals + out->mNumVertices;

        // XXX we can't fold this easily, because we are restricted
        // to the member names from the BLEND file (v1,v2,v3,v4)
        // which are assigned by the genblenddna.py script and
        // cannot be changed without breaking the entire
        // import process.

        if (mf.v1 >= mesh->totvert) {
            ThrowException("Vertex index v1 out of range");
        }
        const MVert *v = &mesh->mvert[mf.v1];
        vo->x = v->co[0];
        vo->y = v->co[1];
        vo->z = v->co[2];
        vn->x = v->no[0];
        vn->y = v->no[1];
        vn->z = v->no[2];
        f.mIndices[0] = out->mNumVertices++;
        ++vo;
        ++vn;

        //  if (f.mNumIndices >= 2) {
        if (mf.v2 >= mesh->totvert) {
            ThrowException("Vertex index v2 out of range");
        }
        v = &mesh->mvert[mf.v2];
        vo->x = v->co[0];
        vo->y = v->co[1];
        vo->z = v->co[2];
        vn->x = v->no[0];
        vn->y = v->no[1];
        vn->z = v->no[2];
        f.mIndices[1] = out->mNumVertices++;
        ++vo;
        ++vn;

        if (mf.v3 >= mesh->totvert) {
            ThrowException("Vertex index v3 out of range");
        }
        //  if (f.mNumIndices >= 3) {
        v = &mesh->mvert[mf.v3];
        vo->x = v->co[0];
        vo->y = v->co[1];
        vo->z = v->co[2];
        vn->x = v->no[0];
        vn->y = v->no[1];
        vn->z = v->no[2];
        f.mIndices[2] = out->mNumVertices++;
        ++vo;
        ++vn;

        if (mf.v4 >= mesh->totvert) {
            ThrowException("Vertex index v4 out of range");
        }
        //  if (f.mNumIndices >= 4) {
        if (mf.v4) {
            v = &mesh->mvert[mf.v4];
            vo->x = v->co[0];
            vo->y = v->co[1];
            vo->z = v->co[2];
            vn->x = v->no[0];
            vn->y = v->no[1];
            vn->z = v->no[2];
            f.mIndices[3] = out->mNumVertices++;
            ++vo;
            ++vn;

            out->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
        } else
            out->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;

        //  }
        //  }
        //  }
    }

    for (int i = 0; i < mesh->totpoly; ++i) {

        const MPoly &mf = mesh->mpoly[i];

        aiMesh *const out = temp[mat_num_to_mesh_idx[mf.mat_nr]];
        aiFace &f = out->mFaces[out->mNumFaces++];

        f.mIndices = new unsigned int[f.mNumIndices = mf.totloop];
        aiVector3D *vo = out->mVertices + out->mNumVertices;
        aiVector3D *vn = out->mNormals + out->mNumVertices;

        // XXX we can't fold this easily, because we are restricted
        // to the member names from the BLEND file (v1,v2,v3,v4)
        // which are assigned by the genblenddna.py script and
        // cannot be changed without breaking the entire
        // import process.
        for (int j = 0; j < mf.totloop; ++j) {
            const MLoop &loop = mesh->mloop[mf.loopstart + j];

            if (loop.v >= mesh->totvert) {
                ThrowException("Vertex index out of range");
            }

            const MVert &v = mesh->mvert[loop.v];

            vo->x = v.co[0];
            vo->y = v.co[1];
            vo->z = v.co[2];
            vn->x = v.no[0];
            vn->y = v.no[1];
            vn->z = v.no[2];
            f.mIndices[j] = out->mNumVertices++;

            ++vo;
            ++vn;
        }
        if (mf.totloop == 3) {
            out->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
        } else {
            out->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
        }
    }

    // TODO should we create the TextureUVMapping map in Convert<Material> to prevent redundant processing?

    // create texture <-> uvname mapping for all materials
    // key is texture number, value is data *
    typedef std::map<uint32_t, const MLoopUV *> TextureUVMapping;
    // key is material number, value is the TextureUVMapping for the material
    typedef std::map<uint32_t, TextureUVMapping> MaterialTextureUVMappings;
    MaterialTextureUVMappings matTexUvMappings;
    const uint32_t maxMat = static_cast<const uint32_t>(mesh->mat.size());
    for (uint32_t m = 0; m < maxMat; ++m) {
        // get material by index
        const std::shared_ptr<Material> pMat = mesh->mat[m];
        TextureUVMapping texuv;
        const uint32_t maxTex = sizeof(pMat->mtex) / sizeof(pMat->mtex[0]);
        for (uint32_t t = 0; t < maxTex; ++t) {
            if (pMat->mtex[t] && pMat->mtex[t]->uvname[0]) {
                // get the CustomData layer for given uvname and correct type
                const ElemBase *pLoop = getCustomDataLayerData(mesh->ldata, CD_MLOOPUV, pMat->mtex[t]->uvname);
                if (pLoop) {
                    texuv.insert(std::make_pair(t, dynamic_cast<const MLoopUV *>(pLoop)));
                }
            }
        }
        if (texuv.size()) {
            matTexUvMappings.insert(std::make_pair(m, texuv));
        }
    }

    // collect texture coordinates, they're stored in a separate per-face buffer
    if (mesh->mtface || mesh->mloopuv) {
        if (mesh->totface > static_cast<int>(mesh->mtface.size())) {
            ThrowException("Number of UV faces is larger than the corresponding UV face array (#1)");
        }
        for (std::vector<aiMesh *>::iterator it = temp->begin() + old; it != temp->end(); ++it) {
            ai_assert(0 != (*it)->mNumVertices);
            ai_assert(0 != (*it)->mNumFaces);
            const auto itMatTexUvMapping = matTexUvMappings.find((*it)->mMaterialIndex);
            if (itMatTexUvMapping == matTexUvMappings.end()) {
                // default behaviour like before
                (*it)->mTextureCoords[0] = new aiVector3D[(*it)->mNumVertices];
            } else {
                // create texture coords for every mapped tex
                for (uint32_t i = 0; i < itMatTexUvMapping->second.size(); ++i) {
                    (*it)->mTextureCoords[i] = new aiVector3D[(*it)->mNumVertices];
                }
            }
            (*it)->mNumFaces = (*it)->mNumVertices = 0;
        }

        for (int i = 0; i < mesh->totface; ++i) {
            const MTFace *v = &mesh->mtface[i];

            aiMesh *const out = temp[mat_num_to_mesh_idx[mesh->mface[i].mat_nr]];
            const aiFace &f = out->mFaces[out->mNumFaces++];

            aiVector3D *vo = &out->mTextureCoords[0][out->mNumVertices];
            for (unsigned int j = 0; j < f.mNumIndices; ++j, ++vo, ++out->mNumVertices) {
                vo->x = v->uv[j][0];
                vo->y = v->uv[j][1];
            }
        }

        for (int i = 0; i < mesh->totpoly; ++i) {
            const MPoly &v = mesh->mpoly[i];
            aiMesh *const out = temp[mat_num_to_mesh_idx[v.mat_nr]];
            const aiFace &f = out->mFaces[out->mNumFaces++];

            const auto itMatTexUvMapping = matTexUvMappings.find(v.mat_nr);
            if (itMatTexUvMapping == matTexUvMappings.end()) {
                // old behavior
                aiVector3D *vo = &out->mTextureCoords[0][out->mNumVertices];
                for (unsigned int j = 0; j < f.mNumIndices; ++j, ++vo, ++out->mNumVertices) {
                    const MLoopUV &uv = mesh->mloopuv[v.loopstart + j];
                    vo->x = uv.uv[0];
                    vo->y = uv.uv[1];
                }
            } else {
                // create textureCoords for every mapped tex
                for (uint32_t m = 0; m < itMatTexUvMapping->second.size(); ++m) {
                    const MLoopUV *tm = itMatTexUvMapping->second[m];
                    aiVector3D *vo = &out->mTextureCoords[m][out->mNumVertices];
                    uint32_t j = 0;
                    for (; j < f.mNumIndices; ++j, ++vo) {
                        const MLoopUV &uv = tm[v.loopstart + j];
                        vo->x = uv.uv[0];
                        vo->y = uv.uv[1];
                    }
                    // only update written mNumVertices in last loop
                    // TODO why must the numVertices be incremented here?
                    if (m == itMatTexUvMapping->second.size() - 1) {
                        out->mNumVertices += j;
                    }
                }
            }
        }
    }

    // collect texture coordinates, old-style (marked as deprecated in current blender sources)
    if (mesh->tface) {
        if (mesh->totface > static_cast<int>(mesh->tface.size())) {
            ThrowException("Number of faces is larger than the corresponding UV face array (#2)");
        }
        for (std::vector<aiMesh *>::iterator it = temp->begin() + old; it != temp->end(); ++it) {
            ai_assert(0 != (*it)->mNumVertices);
            ai_assert(0 != (*it)->mNumFaces);

            (*it)->mTextureCoords[0] = new aiVector3D[(*it)->mNumVertices];
            (*it)->mNumFaces = (*it)->mNumVertices = 0;
        }

        for (int i = 0; i < mesh->totface; ++i) {
            const TFace *v = &mesh->tface[i];

            aiMesh *const out = temp[mat_num_to_mesh_idx[mesh->mface[i].mat_nr]];
            const aiFace &f = out->mFaces[out->mNumFaces++];

            aiVector3D *vo = &out->mTextureCoords[0][out->mNumVertices];
            for (unsigned int j = 0; j < f.mNumIndices; ++j, ++vo, ++out->mNumVertices) {
                vo->x = v->uv[j][0];
                vo->y = v->uv[j][1];
            }
        }
    }

    // collect vertex colors, stored separately as well
    if (mesh->mcol || mesh->mloopcol) {
        if (mesh->totface > static_cast<int>((mesh->mcol.size() / 4))) {
            ThrowException("Number of faces is larger than the corresponding color face array");
        }
        for (std::vector<aiMesh *>::iterator it = temp->begin() + old; it != temp->end(); ++it) {
            ai_assert(0 != (*it)->mNumVertices);
            ai_assert(0 != (*it)->mNumFaces);

            (*it)->mColors[0] = new aiColor4D[(*it)->mNumVertices];
            (*it)->mNumFaces = (*it)->mNumVertices = 0;
        }

        for (int i = 0; i < mesh->totface; ++i) {

            aiMesh *const out = temp[mat_num_to_mesh_idx[mesh->mface[i].mat_nr]];
            const aiFace &f = out->mFaces[out->mNumFaces++];

            aiColor4D *vo = &out->mColors[0][out->mNumVertices];
            for (unsigned int n = 0; n < f.mNumIndices; ++n, ++vo, ++out->mNumVertices) {
                const MCol *col = &mesh->mcol[(i << 2) + n];

                vo->r = col->r;
                vo->g = col->g;
                vo->b = col->b;
                vo->a = col->a;
            }
            for (unsigned int n = f.mNumIndices; n < 4; ++n)
                ;
        }

        for (int i = 0; i < mesh->totpoly; ++i) {
            const MPoly &v = mesh->mpoly[i];
            aiMesh *const out = temp[mat_num_to_mesh_idx[v.mat_nr]];
            const aiFace &f = out->mFaces[out->mNumFaces++];

            aiColor4D *vo = &out->mColors[0][out->mNumVertices];
            const ai_real scaleZeroToOne = 1.f / 255.f;
            for (unsigned int j = 0; j < f.mNumIndices; ++j, ++vo, ++out->mNumVertices) {
                const MLoopCol &col = mesh->mloopcol[v.loopstart + j];
                vo->r = ai_real(col.r) * scaleZeroToOne;
                vo->g = ai_real(col.g) * scaleZeroToOne;
                vo->b = ai_real(col.b) * scaleZeroToOne;
                vo->a = ai_real(col.a) * scaleZeroToOne;
            }
        }
    }

    return;
}

// ------------------------------------------------------------------------------------------------
aiCamera *BlenderImporter::ConvertCamera(const Scene & /*in*/, const Object *obj, const Camera *cam, ConversionData & /*conv_data*/) {
    std::unique_ptr<aiCamera> out(new aiCamera());
    out->mName = obj->id.name + 2;
    out->mPosition = aiVector3D(0.f, 0.f, 0.f);
    out->mUp = aiVector3D(0.f, 1.f, 0.f);
    out->mLookAt = aiVector3D(0.f, 0.f, -1.f);
    if (cam->sensor_x && cam->lens) {
        out->mHorizontalFOV = 2.f * std::atan2(cam->sensor_x, 2.f * cam->lens);
    }
    out->mClipPlaneNear = cam->clipsta;
    out->mClipPlaneFar = cam->clipend;

    return out.release();
}

// ------------------------------------------------------------------------------------------------
aiLight *BlenderImporter::ConvertLight(const Scene & /*in*/, const Object *obj, const Lamp *lamp, ConversionData & /*conv_data*/) {
    std::unique_ptr<aiLight> out(new aiLight());
    out->mName = obj->id.name + 2;

    switch (lamp->type) {
    case Lamp::Type_Local:
        out->mType = aiLightSource_POINT;
        break;
    case Lamp::Type_Spot:
        out->mType = aiLightSource_SPOT;

        // blender orients directional lights as facing toward -z
        out->mDirection = aiVector3D(0.f, 0.f, -1.f);
        out->mUp = aiVector3D(0.f, 1.f, 0.f);

        out->mAngleInnerCone = lamp->spotsize * (1.0f - lamp->spotblend);
        out->mAngleOuterCone = lamp->spotsize;
        break;
    case Lamp::Type_Sun:
        out->mType = aiLightSource_DIRECTIONAL;

        // blender orients directional lights as facing toward -z
        out->mDirection = aiVector3D(0.f, 0.f, -1.f);
        out->mUp = aiVector3D(0.f, 1.f, 0.f);
        break;

    case Lamp::Type_Area:
        out->mType = aiLightSource_AREA;

        if (lamp->area_shape == 0) {
            out->mSize = aiVector2D(lamp->area_size, lamp->area_size);
        } else {
            out->mSize = aiVector2D(lamp->area_size, lamp->area_sizey);
        }

        // blender orients directional lights as facing toward -z
        out->mDirection = aiVector3D(0.f, 0.f, -1.f);
        out->mUp = aiVector3D(0.f, 1.f, 0.f);
        break;

    default:
        break;
    }

    out->mColorAmbient = aiColor3D(lamp->r, lamp->g, lamp->b) * lamp->energy;
    out->mColorSpecular = aiColor3D(lamp->r, lamp->g, lamp->b) * lamp->energy;
    out->mColorDiffuse = aiColor3D(lamp->r, lamp->g, lamp->b) * lamp->energy;

    // If default values are supplied, compute the coefficients from light's max distance
    // Read this: https://imdoingitwrong.wordpress.com/2011/01/31/light-attenuation/
    //
    if (lamp->constant_coefficient == 1.0f && lamp->linear_coefficient == 0.0f && lamp->quadratic_coefficient == 0.0f && lamp->dist > 0.0f) {
        out->mAttenuationConstant = 1.0f;
        out->mAttenuationLinear = 2.0f / lamp->dist;
        out->mAttenuationQuadratic = 1.0f / (lamp->dist * lamp->dist);
    } else {
        out->mAttenuationConstant = lamp->constant_coefficient;
        out->mAttenuationLinear = lamp->linear_coefficient;
        out->mAttenuationQuadratic = lamp->quadratic_coefficient;
    }

    return out.release();
}

// ------------------------------------------------------------------------------------------------
aiNode *BlenderImporter::ConvertNode(const Scene &in, const Object *obj, ConversionData &conv_data, const aiMatrix4x4 &parentTransform) {
    std::deque<const Object *> children;
    for (ObjectSet::iterator it = conv_data.objects.begin(); it != conv_data.objects.end();) {
        const Object *object = *it;
        if (object->parent == obj) {
            children.push_back(object);

            conv_data.objects.erase(it++);
            continue;
        }
        ++it;
    }

    std::unique_ptr<aiNode> node(new aiNode(obj->id.name + 2)); // skip over the name prefix 'OB'
    if (obj->data) {
        switch (obj->type) {
        case Object ::Type_EMPTY:
            break; // do nothing

            // supported object types
        case Object ::Type_MESH: {
            const size_t old = conv_data.meshes->size();

            CheckActualType(obj->data.get(), "Mesh");
            ConvertMesh(in, obj, static_cast<const Mesh *>(obj->data.get()), conv_data, conv_data.meshes);

            if (conv_data.meshes->size() > old) {
                node->mMeshes = new unsigned int[node->mNumMeshes = static_cast<unsigned int>(conv_data.meshes->size() - old)];
                for (unsigned int i = 0; i < node->mNumMeshes; ++i) {
                    node->mMeshes[i] = static_cast<unsigned int>(i + old);
                }
            }
        } break;
        case Object ::Type_LAMP: {
            CheckActualType(obj->data.get(), "Lamp");
            aiLight *mesh = ConvertLight(in, obj, static_cast<const Lamp *>(obj->data.get()), conv_data);

            if (mesh) {
                conv_data.lights->push_back(mesh);
            }
        } break;
        case Object ::Type_CAMERA: {
            CheckActualType(obj->data.get(), "Camera");
            aiCamera *mesh = ConvertCamera(in, obj, static_cast<const Camera *>(obj->data.get()), conv_data);

            if (mesh) {
                conv_data.cameras->push_back(mesh);
            }
        } break;

            // unsupported object types / log, but do not break
        case Object ::Type_CURVE:
            NotSupportedObjectType(obj, "Curve");
            break;
        case Object ::Type_SURF:
            NotSupportedObjectType(obj, "Surface");
            break;
        case Object ::Type_FONT:
            NotSupportedObjectType(obj, "Font");
            break;
        case Object ::Type_MBALL:
            NotSupportedObjectType(obj, "MetaBall");
            break;
        case Object ::Type_WAVE:
            NotSupportedObjectType(obj, "Wave");
            break;
        case Object ::Type_LATTICE:
            NotSupportedObjectType(obj, "Lattice");
            break;

            // invalid or unknown type
        default:
            break;
        }
    }

    for (unsigned int x = 0; x < 4; ++x) {
        for (unsigned int y = 0; y < 4; ++y) {
            node->mTransformation[y][x] = obj->obmat[x][y];
        }
    }

    aiMatrix4x4 m = parentTransform;
    m = m.Inverse();

    node->mTransformation = m * node->mTransformation;

    if (children.size()) {
        node->mNumChildren = static_cast<unsigned int>(children.size());
        aiNode **nd = node->mChildren = new aiNode *[node->mNumChildren]();
        for (const Object *nobj : children) {
            *nd = ConvertNode(in, nobj, conv_data, node->mTransformation * parentTransform);
            (*nd++)->mParent = node.get();
        }
    }

    // apply modifiers
    modifier_cache->ApplyModifiers(*node, conv_data, in, *obj);

    return node.release();
}

#endif // ASSIMP_BUILD_NO_BLEND_IMPORTER