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/** @file Implementation of the material oart of the LWO importer class */


#ifndef ASSIMP_BUILD_NO_LWO_IMPORTER

// internal headers
#include "LWOLoader.h"
#include "ByteSwapper.h"


using namespace Assimp;

// ------------------------------------------------------------------------------------------------
template <class T>
T lerp(const T& one, const T& two, float val)
{
    return one + (two-one)*val;
}

// ------------------------------------------------------------------------------------------------
// Convert a lightwave mapping mode to our's
inline aiTextureMapMode GetMapMode(LWO::Texture::Wrap in)
{
    switch (in)
    {
        case LWO::Texture::REPEAT:
            return aiTextureMapMode_Wrap;

        case LWO::Texture::MIRROR:
            return aiTextureMapMode_Mirror;

        case LWO::Texture::RESET:
            DefaultLogger::get()->warn("LWO2: Unsupported texture map mode: RESET");

            // fall though here
        case LWO::Texture::EDGE:
            return aiTextureMapMode_Clamp;
    }
    return (aiTextureMapMode)0;
}

// ------------------------------------------------------------------------------------------------
bool LWOImporter::HandleTextures(aiMaterial* pcMat, const TextureList& in, aiTextureType type)
{
    ai_assert(NULL != pcMat);

    unsigned int cur = 0, temp = 0;
    aiString s;
    bool ret = false;

    for (const auto &texture : in)    {
        if (!texture.enabled || !texture.bCanUse)
            continue;
        ret = true;

        // Convert lightwave's mapping modes to ours. We let them
        // as they are, the GenUVcoords step will compute UV
        // channels if they're not there.

        aiTextureMapping mapping;
        switch (texture.mapMode)
        {
            case LWO::Texture::Planar:
                mapping = aiTextureMapping_PLANE;
                break;
            case LWO::Texture::Cylindrical:
                mapping = aiTextureMapping_CYLINDER;
                break;
            case LWO::Texture::Spherical:
                mapping = aiTextureMapping_SPHERE;
                break;
            case LWO::Texture::Cubic:
                mapping = aiTextureMapping_BOX;
                break;
            case LWO::Texture::FrontProjection:
                DefaultLogger::get()->error("LWO2: Unsupported texture mapping: FrontProjection");
                mapping = aiTextureMapping_OTHER;
                break;
            case LWO::Texture::UV:
                {
                    if( UINT_MAX == texture.mRealUVIndex ) {
                        // We have no UV index for this texture, so we can't display it
                        continue;
                    }

                    // add the UV source index
                    temp = texture.mRealUVIndex;
                    pcMat->AddProperty<int>((int*)&temp,1,AI_MATKEY_UVWSRC(type,cur));

                    mapping = aiTextureMapping_UV;
                }
                break;
            default:
                ai_assert(false);
        };

        if (mapping != aiTextureMapping_UV) {
            // Setup the main axis
            aiVector3D v;
            switch (texture.majorAxis) {
                case Texture::AXIS_X:
                    v = aiVector3D(1.0,0.0,0.0);
                    break;
                case Texture::AXIS_Y:
                    v = aiVector3D(0.0,1.0,0.0);
                    break;
                default: // case Texture::AXIS_Z:
                    v = aiVector3D(0.0,0.0,1.0);
                    break;
            }

            pcMat->AddProperty(&v,1,AI_MATKEY_TEXMAP_AXIS(type,cur));

            // Setup UV scalings for cylindric and spherical projections
            if (mapping == aiTextureMapping_CYLINDER || mapping == aiTextureMapping_SPHERE) {
                aiUVTransform trafo;
                trafo.mScaling.x = texture.wrapAmountW;
                trafo.mScaling.y = texture.wrapAmountH;

                static_assert(sizeof(aiUVTransform)/sizeof(ai_real) == 5, "sizeof(aiUVTransform)/sizeof(ai_real) == 5");
                pcMat->AddProperty(&trafo,1,AI_MATKEY_UVTRANSFORM(type,cur));
            }
            DefaultLogger::get()->debug("LWO2: Setting up non-UV mapping");
        }

        // The older LWOB format does not use indirect references to clips.
        // The file name of a texture is directly specified in the tex chunk.
        if (mIsLWO2)    {
            // find the corresponding clip (take the last one if multiple
            // share the same index)
            ClipList::iterator end = mClips.end(), candidate = end;
            temp = texture.mClipIdx;
            for (ClipList::iterator clip = mClips.begin(); clip != end; ++clip) {
                if ((*clip).idx == temp) {
                    candidate = clip;
                }

            }
            if (candidate == end)   {
                DefaultLogger::get()->error("LWO2: Clip index is out of bounds");
                temp = 0;

                // fixme: apparently some LWO files shipping with Doom3 don't
                // have clips at all ... check whether that's true or whether
                // it's a bug in the loader.

                s.Set("$texture.png");

                //continue;
            }
            else {
                if (Clip::UNSUPPORTED == (*candidate).type) {
                    DefaultLogger::get()->error("LWO2: Clip type is not supported");
                    continue;
                }
                AdjustTexturePath((*candidate).path);
                s.Set((*candidate).path);

                // Additional image settings
                int flags = 0;
                if ((*candidate).negate) {
                    flags |= aiTextureFlags_Invert;
                }
                pcMat->AddProperty(&flags,1,AI_MATKEY_TEXFLAGS(type,cur));
            }
        }
        else
        {
            std::string ss = texture.mFileName;
            if (!ss.length()) {
                DefaultLogger::get()->error("LWOB: Empty file name");
                continue;
            }
            AdjustTexturePath(ss);
            s.Set(ss);
        }
        pcMat->AddProperty(&s,AI_MATKEY_TEXTURE(type,cur));

        // add the blend factor
        pcMat->AddProperty<float>(&texture.mStrength,1,AI_MATKEY_TEXBLEND(type,cur));

        // add the blend operation
        switch (texture.blendType)
        {
            case LWO::Texture::Normal:
            case LWO::Texture::Multiply:
                temp = (unsigned int)aiTextureOp_Multiply;
                break;

            case LWO::Texture::Subtractive:
            case LWO::Texture::Difference:
                temp = (unsigned int)aiTextureOp_Subtract;
                break;

            case LWO::Texture::Divide:
                temp = (unsigned int)aiTextureOp_Divide;
                break;

            case LWO::Texture::Additive:
                temp = (unsigned int)aiTextureOp_Add;
                break;

            default:
                temp = (unsigned int)aiTextureOp_Multiply;
                DefaultLogger::get()->warn("LWO2: Unsupported texture blend mode: alpha or displacement");

        }
        // Setup texture operation
        pcMat->AddProperty<int>((int*)&temp,1,AI_MATKEY_TEXOP(type,cur));

        // setup the mapping mode
        pcMat->AddProperty<int>((int*)&mapping,1,AI_MATKEY_MAPPING(type,cur));

        // add the u-wrapping
        temp = (unsigned int)GetMapMode(texture.wrapModeWidth);
        pcMat->AddProperty<int>((int*)&temp,1,AI_MATKEY_MAPPINGMODE_U(type,cur));

        // add the v-wrapping
        temp = (unsigned int)GetMapMode(texture.wrapModeHeight);
        pcMat->AddProperty<int>((int*)&temp,1,AI_MATKEY_MAPPINGMODE_V(type,cur));

        ++cur;
    }
    return ret;
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::ConvertMaterial(const LWO::Surface& surf,aiMaterial* pcMat)
{
    // copy the name of the surface
    aiString st;
    st.Set(surf.mName);
    pcMat->AddProperty(&st,AI_MATKEY_NAME);

    const int i = surf.bDoubleSided ? 1 : 0;
    pcMat->AddProperty(&i,1,AI_MATKEY_TWOSIDED);

    // add the refraction index and the bump intensity
    pcMat->AddProperty(&surf.mIOR,1,AI_MATKEY_REFRACTI);
    pcMat->AddProperty(&surf.mBumpIntensity,1,AI_MATKEY_BUMPSCALING);

    aiShadingMode m;
    if (surf.mSpecularValue && surf.mGlossiness)
    {
        float fGloss;
        if (mIsLWO2)    {
            fGloss = std::pow( surf.mGlossiness*ai_real( 10.0 )+ ai_real( 2.0 ), ai_real( 2.0 ) );
        }
        else
        {
            if (16.0 >= surf.mGlossiness)
                fGloss = 6.0;
            else if (64.0 >= surf.mGlossiness)
                fGloss = 20.0;
            else if (256.0 >= surf.mGlossiness)
                fGloss = 50.0;
            else fGloss = 80.0;
        }

        pcMat->AddProperty(&surf.mSpecularValue,1,AI_MATKEY_SHININESS_STRENGTH);
        pcMat->AddProperty(&fGloss,1,AI_MATKEY_SHININESS);
        m = aiShadingMode_Phong;
    }
    else m = aiShadingMode_Gouraud;

    // specular color
    aiColor3D clr = lerp( aiColor3D(1.0,1.0,1.0), surf.mColor, surf.mColorHighlights );
    pcMat->AddProperty(&clr,1,AI_MATKEY_COLOR_SPECULAR);
    pcMat->AddProperty(&surf.mSpecularValue,1,AI_MATKEY_SHININESS_STRENGTH);

    // emissive color
    // luminosity is not really the same but it affects the surface in a similar way. Some scaling looks good.
    clr.g = clr.b = clr.r = surf.mLuminosity*ai_real( 0.8 );
    pcMat->AddProperty<aiColor3D>(&clr,1,AI_MATKEY_COLOR_EMISSIVE);

    // opacity ... either additive or default-blended, please
    if (0.0 != surf.mAdditiveTransparency)  {

        const int add = aiBlendMode_Additive;
        pcMat->AddProperty(&surf.mAdditiveTransparency,1,AI_MATKEY_OPACITY);
        pcMat->AddProperty(&add,1,AI_MATKEY_BLEND_FUNC);
    }

    else if (10e10f != surf.mTransparency)  {
        const int def = aiBlendMode_Default;
        const float f = 1.0f-surf.mTransparency;
        pcMat->AddProperty(&f,1,AI_MATKEY_OPACITY);
        pcMat->AddProperty(&def,1,AI_MATKEY_BLEND_FUNC);
    }


    // ADD TEXTURES to the material
    // TODO: find out how we can handle COLOR textures correctly...
    bool b = HandleTextures(pcMat,surf.mColorTextures,aiTextureType_DIFFUSE);
    b = (b || HandleTextures(pcMat,surf.mDiffuseTextures,aiTextureType_DIFFUSE));
    HandleTextures(pcMat,surf.mSpecularTextures,aiTextureType_SPECULAR);
    HandleTextures(pcMat,surf.mGlossinessTextures,aiTextureType_SHININESS);
    HandleTextures(pcMat,surf.mBumpTextures,aiTextureType_HEIGHT);
    HandleTextures(pcMat,surf.mOpacityTextures,aiTextureType_OPACITY);
    HandleTextures(pcMat,surf.mReflectionTextures,aiTextureType_REFLECTION);

    // Now we need to know which shader to use .. iterate through the shader list of
    // the surface and  search for a name which we know ...
    for (const auto &shader : surf.mShaders)   {
        if (shader.functionName == "LW_SuperCelShader" || shader.functionName == "AH_CelShader")  {
            DefaultLogger::get()->info("LWO2: Mapping LW_SuperCelShader/AH_CelShader to aiShadingMode_Toon");

            m = aiShadingMode_Toon;
            break;
        }
        else if (shader.functionName == "LW_RealFresnel" || shader.functionName == "LW_FastFresnel")  {
            DefaultLogger::get()->info("LWO2: Mapping LW_RealFresnel/LW_FastFresnel to aiShadingMode_Fresnel");

            m = aiShadingMode_Fresnel;
            break;
        }
        else
        {
            DefaultLogger::get()->warn("LWO2: Unknown surface shader: " + shader.functionName);
        }
    }
    if (surf.mMaximumSmoothAngle <= 0.0)
        m = aiShadingMode_Flat;
    pcMat->AddProperty((int*)&m,1,AI_MATKEY_SHADING_MODEL);

    // (the diffuse value is just a scaling factor)
    // If a diffuse texture is set, we set this value to 1.0
    clr = (b && false ? aiColor3D(1.0,1.0,1.0) : surf.mColor);
    clr.r *= surf.mDiffuseValue;
    clr.g *= surf.mDiffuseValue;
    clr.b *= surf.mDiffuseValue;
    pcMat->AddProperty<aiColor3D>(&clr,1,AI_MATKEY_COLOR_DIFFUSE);
}

// ------------------------------------------------------------------------------------------------
char LWOImporter::FindUVChannels(LWO::TextureList& list,
    LWO::Layer& /*layer*/,LWO::UVChannel& uv, unsigned int next)
{
    char ret = 0;
    for (auto &texture : list)  {

        // Ignore textures with non-UV mappings for the moment.
        if (!texture.enabled || !texture.bCanUse || texture.mapMode != LWO::Texture::UV)  {
            continue;
        }

        if (texture.mUVChannelIndex == uv.name) {
            ret = 1;

            // got it.
            if (texture.mRealUVIndex == UINT_MAX || texture.mRealUVIndex == next)
            {
                texture.mRealUVIndex = next;
            }
            else {
                // channel mismatch. need to duplicate the material.
                DefaultLogger::get()->warn("LWO: Channel mismatch, would need to duplicate surface [design bug]");

                // TODO
            }
        }
    }
    return ret;
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::FindUVChannels(LWO::Surface& surf,
    LWO::SortedRep& sorted,LWO::Layer& layer,
    unsigned int out[AI_MAX_NUMBER_OF_TEXTURECOORDS])
{
    unsigned int next = 0, extra = 0, num_extra = 0;

    // Check whether we have an UV entry != 0 for one of the faces in 'sorted'
    for (unsigned int i = 0; i < layer.mUVChannels.size();++i)  {
        LWO::UVChannel& uv = layer.mUVChannels[i];

        for (LWO::SortedRep::const_iterator it = sorted.begin(); it != sorted.end(); ++it)  {

            LWO::Face& face = layer.mFaces[*it];

            for (unsigned int n = 0; n < face.mNumIndices; ++n) {
                unsigned int idx = face.mIndices[n];

                if (uv.abAssigned[idx] && ((aiVector2D*)&uv.rawData[0])[idx] != aiVector2D()) {

                    if (extra >= AI_MAX_NUMBER_OF_TEXTURECOORDS) {

                        DefaultLogger::get()->error("LWO: Maximum number of UV channels for "
                            "this mesh reached. Skipping channel \'" + uv.name + "\'");

                    }
                    else {
                        // Search through all textures assigned to 'surf' and look for this UV channel
                        char had = 0;
                        had |= FindUVChannels(surf.mColorTextures,layer,uv,next);
                        had |= FindUVChannels(surf.mDiffuseTextures,layer,uv,next);
                        had |= FindUVChannels(surf.mSpecularTextures,layer,uv,next);
                        had |= FindUVChannels(surf.mGlossinessTextures,layer,uv,next);
                        had |= FindUVChannels(surf.mOpacityTextures,layer,uv,next);
                        had |= FindUVChannels(surf.mBumpTextures,layer,uv,next);
                        had |= FindUVChannels(surf.mReflectionTextures,layer,uv,next);

                        // We have a texture referencing this UV channel so we have to take special care
                        // and are willing to drop unreferenced channels in favour of it.
                        if (had != 0) {
                            if (num_extra) {

                                for (unsigned int a = next; a < std::min( extra, AI_MAX_NUMBER_OF_TEXTURECOORDS-1u ); ++a) {
                                    out[a+1] = out[a];
                                }
                            }
                            ++extra;
                            out[next++] = i;
                        }
                        // Bah ... seems not to be used at all. Push to end if enough space is available.
                        else {
                            out[extra++] = i;
                            ++num_extra;
                        }
                    }
                    it = sorted.end()-1;
                    break;
                }
            }
        }
    }
    if (extra < AI_MAX_NUMBER_OF_TEXTURECOORDS) {
        out[extra] = UINT_MAX;
    }
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::FindVCChannels(const LWO::Surface& surf, LWO::SortedRep& sorted, const LWO::Layer& layer,
    unsigned int out[AI_MAX_NUMBER_OF_COLOR_SETS])
{
    unsigned int next = 0;

    // Check whether we have an vc entry != 0 for one of the faces in 'sorted'
    for (unsigned int i = 0; i < layer.mVColorChannels.size();++i)  {
        const LWO::VColorChannel& vc = layer.mVColorChannels[i];

        if (surf.mVCMap == vc.name) {
            // The vertex color map is explicitly requested by the surface so we need to take special care of it
            for (unsigned int a = 0; a < std::min(next,AI_MAX_NUMBER_OF_COLOR_SETS-1u); ++a) {
                out[a+1] = out[a];
            }
            out[0] = i;
            ++next;
        }
        else {

            for (LWO::SortedRep::iterator it = sorted.begin(); it != sorted.end(); ++it)    {
                const LWO::Face& face = layer.mFaces[*it];

                for (unsigned int n = 0; n < face.mNumIndices; ++n) {
                    unsigned int idx = face.mIndices[n];

                    if (vc.abAssigned[idx] && ((aiColor4D*)&vc.rawData[0])[idx] != aiColor4D(0.0,0.0,0.0,1.0)) {
                        if (next >= AI_MAX_NUMBER_OF_COLOR_SETS) {

                            DefaultLogger::get()->error("LWO: Maximum number of vertex color channels for "
                                "this mesh reached. Skipping channel \'" + vc.name + "\'");

                        }
                        else {
                            out[next++] = i;
                        }
                        it = sorted.end()-1;
                        break;
                    }
                }
            }
        }
    }
    if (next != AI_MAX_NUMBER_OF_COLOR_SETS) {
        out[next] = UINT_MAX;
    }
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2ImageMap(unsigned int size, LWO::Texture& tex )
{
    LE_NCONST uint8_t* const end = mFileBuffer + size;
    while (true)
    {
        if (mFileBuffer + 6 >= end)break;
        LE_NCONST IFF::SubChunkHeader head = IFF::LoadSubChunk(mFileBuffer);

        if (mFileBuffer + head.length > end)
            throw DeadlyImportError("LWO2: Invalid SURF.BLOCK chunk length");

        uint8_t* const next = mFileBuffer+head.length;
        switch (head.type)
        {
        case AI_LWO_PROJ:
            tex.mapMode = (Texture::MappingMode)GetU2();
            break;
        case AI_LWO_WRAP:
            tex.wrapModeWidth  = (Texture::Wrap)GetU2();
            tex.wrapModeHeight = (Texture::Wrap)GetU2();
            break;
        case AI_LWO_AXIS:
            tex.majorAxis = (Texture::Axes)GetU2();
            break;
        case AI_LWO_IMAG:
            tex.mClipIdx = GetU2();
            break;
        case AI_LWO_VMAP:
            GetS0(tex.mUVChannelIndex,head.length);
            break;
        case AI_LWO_WRPH:
            tex.wrapAmountH = GetF4();
            break;
        case AI_LWO_WRPW:
            tex.wrapAmountW = GetF4();
            break;
        }
        mFileBuffer = next;
    }
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2Procedural(unsigned int /*size*/, LWO::Texture& tex )
{
    // --- not supported at the moment
    DefaultLogger::get()->error("LWO2: Found procedural texture, this is not supported");
    tex.bCanUse = false;
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2Gradient(unsigned int /*size*/, LWO::Texture& tex  )
{
    // --- not supported at the moment
    DefaultLogger::get()->error("LWO2: Found gradient texture, this is not supported");
    tex.bCanUse = false;
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2TextureHeader(unsigned int size, LWO::Texture& tex )
{
    LE_NCONST uint8_t* const end = mFileBuffer + size;

    // get the ordinal string
    GetS0( tex.ordinal, size);

    // we could crash later if this is an empty string ...
    if (!tex.ordinal.length())
    {
        DefaultLogger::get()->error("LWO2: Ill-formed SURF.BLOK ordinal string");
        tex.ordinal = "\x00";
    }
    while (true)
    {
        if (mFileBuffer + 6 >= end)break;
        const IFF::SubChunkHeader head = IFF::LoadSubChunk(mFileBuffer);

        if (mFileBuffer + head.length > end)
            throw DeadlyImportError("LWO2: Invalid texture header chunk length");

        uint8_t* const next = mFileBuffer+head.length;
        switch (head.type)
        {
        case AI_LWO_CHAN:
            tex.type = GetU4();
            break;
        case AI_LWO_ENAB:
            tex.enabled = GetU2() ? true : false;
            break;
        case AI_LWO_OPAC:
            tex.blendType = (Texture::BlendType)GetU2();
            tex.mStrength = GetF4();
            break;
        }
        mFileBuffer = next;
    }
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2TextureBlock(LE_NCONST IFF::SubChunkHeader* head, unsigned int size )
{
    ai_assert(!mSurfaces->empty());
    LWO::Surface& surf = mSurfaces->back();
    LWO::Texture tex;

    // load the texture header
    LoadLWO2TextureHeader(head->length,tex);
    size -= head->length + 6;

    // now get the exact type of the texture
    switch (head->type)
    {
    case AI_LWO_PROC:
        LoadLWO2Procedural(size,tex);
        break;
    case AI_LWO_GRAD:
        LoadLWO2Gradient(size,tex);
        break;
    case AI_LWO_IMAP:
        LoadLWO2ImageMap(size,tex);
    }

    // get the destination channel
    TextureList* listRef = NULL;
    switch (tex.type)
    {
    case AI_LWO_COLR:
        listRef = &surf.mColorTextures;break;
    case AI_LWO_DIFF:
        listRef = &surf.mDiffuseTextures;break;
    case AI_LWO_SPEC:
        listRef = &surf.mSpecularTextures;break;
    case AI_LWO_GLOS:
        listRef = &surf.mGlossinessTextures;break;
    case AI_LWO_BUMP:
        listRef = &surf.mBumpTextures;break;
    case AI_LWO_TRAN:
        listRef = &surf.mOpacityTextures;break;
    case AI_LWO_REFL:
        listRef = &surf.mReflectionTextures;break;
    default:
        DefaultLogger::get()->warn("LWO2: Encountered unknown texture type");
        return;
    }

    // now attach the texture to the parent surface - sort by ordinal string
    for (TextureList::iterator it = listRef->begin();it != listRef->end(); ++it)    {
        if (::strcmp(tex.ordinal.c_str(),(*it).ordinal.c_str()) < 0)    {
            listRef->insert(it,tex);
            return;
        }
    }
    listRef->push_back(tex);
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2ShaderBlock(LE_NCONST IFF::SubChunkHeader* /*head*/, unsigned int size )
{
    LE_NCONST uint8_t* const end = mFileBuffer + size;

    ai_assert(!mSurfaces->empty());
    LWO::Surface& surf = mSurfaces->back();
    LWO::Shader shader;

    // get the ordinal string
    GetS0( shader.ordinal, size);

    // we could crash later if this is an empty string ...
    if (!shader.ordinal.length())
    {
        DefaultLogger::get()->error("LWO2: Ill-formed SURF.BLOK ordinal string");
        shader.ordinal = "\x00";
    }

    // read the header
    while (true)
    {
        if (mFileBuffer + 6 >= end)break;
        const IFF::SubChunkHeader head = IFF::LoadSubChunk(mFileBuffer);

        if (mFileBuffer + head.length > end)
            throw DeadlyImportError("LWO2: Invalid shader header chunk length");

        uint8_t* const next = mFileBuffer+head.length;
        switch (head.type)
        {
        case AI_LWO_ENAB:
            shader.enabled = GetU2() ? true : false;
            break;

        case AI_LWO_FUNC:
            GetS0( shader.functionName, head.length );
        }
        mFileBuffer = next;
    }

    // now attach the shader to the parent surface - sort by ordinal string
    for (ShaderList::iterator it = surf.mShaders.begin();it != surf.mShaders.end(); ++it)   {
        if (::strcmp(shader.ordinal.c_str(),(*it).ordinal.c_str()) < 0) {
            surf.mShaders.insert(it,shader);
            return;
        }
    }
    surf.mShaders.push_back(shader);
}

// ------------------------------------------------------------------------------------------------
void LWOImporter::LoadLWO2Surface(unsigned int size)
{
    LE_NCONST uint8_t* const end = mFileBuffer + size;

    mSurfaces->push_back( LWO::Surface () );
    LWO::Surface& surf = mSurfaces->back();

    GetS0(surf.mName,size);

    // check whether this surface was derived from any other surface
    std::string derived;
    GetS0(derived,(unsigned int)(end - mFileBuffer));
    if (derived.length())   {
        // yes, find this surface
        for (SurfaceList::iterator it = mSurfaces->begin(), end = mSurfaces->end()-1; it != end; ++it)  {
            if ((*it).mName == derived) {
                // we have it ...
                surf = *it;
                derived.clear();break;
            }
        }
        if (derived.size())
            DefaultLogger::get()->warn("LWO2: Unable to find source surface: " + derived);
    }

    while (true)
    {
        if (mFileBuffer + 6 >= end)
            break;
        const IFF::SubChunkHeader head = IFF::LoadSubChunk(mFileBuffer);

        if (mFileBuffer + head.length > end)
            throw DeadlyImportError("LWO2: Invalid surface chunk length");

        uint8_t* const next = mFileBuffer+head.length;
        switch (head.type)
        {
            // diffuse color
        case AI_LWO_COLR:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,COLR,12);
                surf.mColor.r = GetF4();
                surf.mColor.g = GetF4();
                surf.mColor.b = GetF4();
                break;
            }
            // diffuse strength ... hopefully
        case AI_LWO_DIFF:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,DIFF,4);
                surf.mDiffuseValue = GetF4();
                break;
            }
            // specular strength ... hopefully
        case AI_LWO_SPEC:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,SPEC,4);
                surf.mSpecularValue = GetF4();
                break;
            }
            // transparency
        case AI_LWO_TRAN:
            {
                // transparency explicitly disabled?
                if (surf.mTransparency == 10e10f)
                    break;

                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,TRAN,4);
                surf.mTransparency = GetF4();
                break;
            }
            // additive transparency
        case AI_LWO_ADTR:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,ADTR,4);
                surf.mAdditiveTransparency = GetF4();
                break;
            }
            // wireframe mode
        case AI_LWO_LINE:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,LINE,2);
                if (GetU2() & 0x1)
                    surf.mWireframe = true;
                break;
            }
            // glossiness
        case AI_LWO_GLOS:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,GLOS,4);
                surf.mGlossiness = GetF4();
                break;
            }
            // bump intensity
        case AI_LWO_BUMP:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,BUMP,4);
                surf.mBumpIntensity = GetF4();
                break;
            }
            // color highlights
        case AI_LWO_CLRH:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,CLRH,4);
                surf.mColorHighlights = GetF4();
                break;
            }
            // index of refraction
        case AI_LWO_RIND:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,RIND,4);
                surf.mIOR = GetF4();
                break;
            }
            // polygon sidedness
        case AI_LWO_SIDE:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,SIDE,2);
                surf.bDoubleSided = (3 == GetU2());
                break;
            }
            // maximum smoothing angle
        case AI_LWO_SMAN:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,SMAN,4);
                surf.mMaximumSmoothAngle = std::fabs( GetF4() );
                break;
            }
            // vertex color channel to be applied to the surface
        case AI_LWO_VCOL:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,VCOL,12);
                surf.mDiffuseValue *= GetF4();              // strength
                ReadVSizedIntLWO2(mFileBuffer);             // skip envelope
                surf.mVCMapType = GetU4();                  // type of the channel

                // name of the channel
                GetS0(surf.mVCMap, (unsigned int) (next - mFileBuffer ));
                break;
            }
            // surface bock entry
        case AI_LWO_BLOK:
            {
                AI_LWO_VALIDATE_CHUNK_LENGTH(head.length,BLOK,4);
                IFF::SubChunkHeader head2 = IFF::LoadSubChunk(mFileBuffer);

                switch (head2.type)
                {
                case AI_LWO_PROC:
                case AI_LWO_GRAD:
                case AI_LWO_IMAP:
                    LoadLWO2TextureBlock(&head2, head.length);
                    break;
                case AI_LWO_SHDR:
                    LoadLWO2ShaderBlock(&head2, head.length);
                    break;

                default:
                    DefaultLogger::get()->warn("LWO2: Found an unsupported surface BLOK");
                };

                break;
            }
        }
        mFileBuffer = next;
    }
}

#endif // !! ASSIMP_BUILD_NO_X_IMPORTER