assimp.assimp/code/AssetLib/X/XFileImporter.cpp

/*
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/** @file  XFileImporter.cpp
 *  @brief Implementation of the XFile importer class
 */

#ifndef ASSIMP_BUILD_NO_X_IMPORTER

#include "AssetLib/X/XFileImporter.h"
#include "AssetLib/X/XFileParser.h"
#include "PostProcessing/ConvertToLHProcess.h"

#include <assimp/TinyFormatter.h>
#include <assimp/Defines.h>
#include <assimp/IOSystem.hpp>
#include <assimp/scene.h>
#include <assimp/DefaultLogger.hpp>
#include <assimp/importerdesc.h>

#include <cctype>
#include <memory>

using namespace Assimp;
using namespace Assimp::Formatter;

static const aiImporterDesc desc = {
    "Direct3D XFile Importer",
    "",
    "",
    "",
    aiImporterFlags_SupportTextFlavour | aiImporterFlags_SupportBinaryFlavour | aiImporterFlags_SupportCompressedFlavour,
    1,
    3,
    1,
    5,
    "x"
};

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
XFileImporter::XFileImporter()
: mBuffer() {
    // empty
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
XFileImporter::~XFileImporter() {
    // empty
}

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file.
bool XFileImporter::CanRead( const std::string& pFile, IOSystem* pIOHandler, bool checkSig) const {
    std::string extension = GetExtension(pFile);
    if(extension == "x") {
        return true;
    }
    if (!extension.length() || checkSig) {
        uint32_t token[1];
        token[0] = AI_MAKE_MAGIC("xof ");
        return CheckMagicToken(pIOHandler,pFile,token,1,0);
    }
    return false;
}

// ------------------------------------------------------------------------------------------------
// Get file extension list
const aiImporterDesc* XFileImporter::GetInfo () const {
    return &desc;
}

// ------------------------------------------------------------------------------------------------
// Imports the given file into the given scene structure.
void XFileImporter::InternReadFile( const std::string& pFile, aiScene* pScene, IOSystem* pIOHandler) {
    // read file into memory
    std::unique_ptr<IOStream> file( pIOHandler->Open( pFile));
    if ( file.get() == nullptr ) {
        throw DeadlyImportError( "Failed to open file " + pFile + "." );
    }

    static const size_t MinSize = 16;
    size_t fileSize = file->FileSize();
    if ( fileSize < MinSize ) {
        throw DeadlyImportError( "XFile is too small." );
    }

    // in the hope that binary files will never start with a BOM ...
    mBuffer.resize( fileSize + 1);
    file->Read( &mBuffer.front(), 1, fileSize);
    ConvertToUTF8(mBuffer);

    // parse the file into a temporary representation
    XFileParser parser( mBuffer);

    // and create the proper return structures out of it
    CreateDataRepresentationFromImport( pScene, parser.GetImportedData());

    // if nothing came from it, report it as error
    if ( !pScene->mRootNode ) {
        throw DeadlyImportError( "XFile is ill-formatted - no content imported." );
    }
}

// ------------------------------------------------------------------------------------------------
// Constructs the return data structure out of the imported data.
void XFileImporter::CreateDataRepresentationFromImport( aiScene* pScene, XFile::Scene* pData)
{
    // Read the global materials first so that meshes referring to them can find them later
    ConvertMaterials( pScene, pData->mGlobalMaterials);

    // copy nodes, extracting meshes and materials on the way
    pScene->mRootNode = CreateNodes( pScene, nullptr, pData->mRootNode);

    // extract animations
    CreateAnimations( pScene, pData);

    // read the global meshes that were stored outside of any node
    if( !pData->mGlobalMeshes.empty() )  {
        // create a root node to hold them if there isn't any, yet
        if( pScene->mRootNode == nullptr ) {
            pScene->mRootNode = new aiNode;
            pScene->mRootNode->mName.Set( "$dummy_node");
        }

        // convert all global meshes and store them in the root node.
        // If there was one before, the global meshes now suddenly have its transformation matrix...
        // Don't know what to do there, I don't want to insert another node under the present root node
        // just to avoid this.
        CreateMeshes( pScene, pScene->mRootNode, pData->mGlobalMeshes);
    }

    if (!pScene->mRootNode) {
        throw DeadlyImportError( "No root node" );
    }

    // Convert everything to OpenGL space... it's the same operation as the conversion back, so we can reuse the step directly
    MakeLeftHandedProcess convertProcess;
    convertProcess.Execute( pScene);

    FlipWindingOrderProcess flipper;
    flipper.Execute(pScene);

    // finally: create a dummy material if not material was imported
    if( pScene->mNumMaterials == 0) {
        pScene->mNumMaterials = 1;
        // create the Material
        aiMaterial* mat = new aiMaterial;
        int shadeMode = (int) aiShadingMode_Gouraud;
        mat->AddProperty<int>( &shadeMode, 1, AI_MATKEY_SHADING_MODEL);
        // material colours
        int specExp = 1;

        aiColor3D clr = aiColor3D( 0, 0, 0);
        mat->AddProperty( &clr, 1, AI_MATKEY_COLOR_EMISSIVE);
        mat->AddProperty( &clr, 1, AI_MATKEY_COLOR_SPECULAR);

        clr = aiColor3D( 0.5f, 0.5f, 0.5f);
        mat->AddProperty( &clr, 1, AI_MATKEY_COLOR_DIFFUSE);
        mat->AddProperty( &specExp, 1, AI_MATKEY_SHININESS);

        pScene->mMaterials = new aiMaterial*[1];
        pScene->mMaterials[0] = mat;
    }
}

// ------------------------------------------------------------------------------------------------
// Recursively creates scene nodes from the imported hierarchy.
aiNode* XFileImporter::CreateNodes( aiScene* pScene, aiNode* pParent, const XFile::Node* pNode) {
    if ( !pNode ) {
        return nullptr;
    }

    // create node
    aiNode* node = new aiNode;
    node->mName.length = (ai_uint32)pNode->mName.length();
    node->mParent = pParent;
    memcpy( node->mName.data, pNode->mName.c_str(), pNode->mName.length());
    node->mName.data[node->mName.length] = 0;
    node->mTransformation = pNode->mTrafoMatrix;

    // convert meshes from the source node
    CreateMeshes( pScene, node, pNode->mMeshes);

    // handle childs
    if( !pNode->mChildren.empty() ) {
        node->mNumChildren = (unsigned int)pNode->mChildren.size();
        node->mChildren = new aiNode* [node->mNumChildren];

        for ( unsigned int a = 0; a < pNode->mChildren.size(); ++a ) {
            node->mChildren[ a ] = CreateNodes( pScene, node, pNode->mChildren[ a ] );
        }
    }

    return node;
}

// ------------------------------------------------------------------------------------------------
// Creates the meshes for the given node.
void XFileImporter::CreateMeshes( aiScene* pScene, aiNode* pNode, const std::vector<XFile::Mesh*>& pMeshes) {
    if (pMeshes.empty()) {
        return;
    }

    // create a mesh for each mesh-material combination in the source node
    std::vector<aiMesh*> meshes;
    for( unsigned int a = 0; a < pMeshes.size(); ++a ) {
        XFile::Mesh* sourceMesh = pMeshes[a];
        if ( nullptr == sourceMesh ) {
            continue;
        }

        // first convert its materials so that we can find them with their index afterwards
        ConvertMaterials( pScene, sourceMesh->mMaterials);

        unsigned int numMaterials = std::max( (unsigned int)sourceMesh->mMaterials.size(), 1u);
        for( unsigned int b = 0; b < numMaterials; ++b ) {
            // collect the faces belonging to this material
            std::vector<unsigned int> faces;
            unsigned int numVertices = 0;
            if( !sourceMesh->mFaceMaterials.empty() ) {
                // if there is a per-face material defined, select the faces with the corresponding material
                for( unsigned int c = 0; c < sourceMesh->mFaceMaterials.size(); ++c ) {
                    if( sourceMesh->mFaceMaterials[c] == b) {
                        faces.push_back( c);
                        numVertices += (unsigned int)sourceMesh->mPosFaces[c].mIndices.size();
                    }
                }
            } else {
                // if there is no per-face material, place everything into one mesh
                for( unsigned int c = 0; c < sourceMesh->mPosFaces.size(); ++c ) {
                    faces.push_back( c);
                    numVertices += (unsigned int)sourceMesh->mPosFaces[c].mIndices.size();
                }
            }

            // no faces/vertices using this material? strange...
            if ( numVertices == 0 ) {
                continue;
            }

            // create a submesh using this material
            aiMesh* mesh = new aiMesh;
            meshes.push_back( mesh);

            // find the material in the scene's material list. Either own material
            // or referenced material, it should already have a valid index
            if( !sourceMesh->mFaceMaterials.empty() ) {
                mesh->mMaterialIndex = static_cast<unsigned int>(sourceMesh->mMaterials[b].sceneIndex);
            } else {
                mesh->mMaterialIndex = 0;
            }

            // Create properly sized data arrays in the mesh. We store unique vertices per face,
            // as specified
            mesh->mNumVertices = numVertices;
            mesh->mVertices = new aiVector3D[numVertices];
            mesh->mNumFaces = (unsigned int)faces.size();
            mesh->mFaces = new aiFace[mesh->mNumFaces];

            // name
            mesh->mName.Set(sourceMesh->mName);

            // normals?
            if ( sourceMesh->mNormals.size() > 0 ) {
                mesh->mNormals = new aiVector3D[ numVertices ];
            }
            // texture coords
            for( unsigned int c = 0; c < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++c ) {
                if ( !sourceMesh->mTexCoords[ c ].empty() ) {
                    mesh->mTextureCoords[ c ] = new aiVector3D[ numVertices ];
                }
            }
            // vertex colors
            for( unsigned int c = 0; c < AI_MAX_NUMBER_OF_COLOR_SETS; ++c ) {
                if ( !sourceMesh->mColors[ c ].empty() ) {
                    mesh->mColors[ c ] = new aiColor4D[ numVertices ];
                }
            }

            // now collect the vertex data of all data streams present in the imported mesh
            unsigned int newIndex( 0 );
            std::vector<unsigned int> orgPoints; // from which original point each new vertex stems
            orgPoints.resize( numVertices, 0);

            for( unsigned int c = 0; c < faces.size(); ++c ) {
                unsigned int f = faces[c]; // index of the source face
                const XFile::Face& pf = sourceMesh->mPosFaces[f]; // position source face

                // create face. either triangle or triangle fan depending on the index count
                aiFace& df = mesh->mFaces[c]; // destination face
                df.mNumIndices = (unsigned int)pf.mIndices.size();
                df.mIndices = new unsigned int[ df.mNumIndices];

                // collect vertex data for indices of this face
                for( unsigned int d = 0; d < df.mNumIndices; ++d ) {
                    df.mIndices[ d ] = newIndex;
                    const unsigned int newIdx( pf.mIndices[ d ] );
                    if ( newIdx > sourceMesh->mPositions.size() ) {
                        continue;
                    }

                    orgPoints[newIndex] = pf.mIndices[d];

                    // Position
                    mesh->mVertices[newIndex] = sourceMesh->mPositions[pf.mIndices[d]];
                    // Normal, if present
                    if ( mesh->HasNormals() ) {
                        if ( sourceMesh->mNormFaces[ f ].mIndices.size() > d ) {
                            const size_t idx( sourceMesh->mNormFaces[ f ].mIndices[ d ] );
                            mesh->mNormals[ newIndex ] = sourceMesh->mNormals[ idx ];
                        }
                    }

                    // texture coord sets
                    for( unsigned int e = 0; e < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++e ) {
                        if( mesh->HasTextureCoords( e)) {
                            aiVector2D tex = sourceMesh->mTexCoords[e][pf.mIndices[d]];
                            mesh->mTextureCoords[e][newIndex] = aiVector3D( tex.x, 1.0f - tex.y, 0.0f);
                        }
                    }
                    // vertex color sets
                    for ( unsigned int e = 0; e < AI_MAX_NUMBER_OF_COLOR_SETS; ++e ) {
                        if ( mesh->HasVertexColors( e ) ) {
                            mesh->mColors[ e ][ newIndex ] = sourceMesh->mColors[ e ][ pf.mIndices[ d ] ];
                        }
                    }

                    newIndex++;
                }
            }

            // there should be as much new vertices as we calculated before
            ai_assert( newIndex == numVertices);

            // convert all bones of the source mesh which influence vertices in this newly created mesh
            const std::vector<XFile::Bone>& bones = sourceMesh->mBones;
            std::vector<aiBone*> newBones;
            for( unsigned int c = 0; c < bones.size(); ++c ) {
                const XFile::Bone& obone = bones[c];
                // set up a vertex-linear array of the weights for quick searching if a bone influences a vertex
                std::vector<ai_real> oldWeights( sourceMesh->mPositions.size(), 0.0);
                for ( unsigned int d = 0; d < obone.mWeights.size(); ++d ) {
                    oldWeights[ obone.mWeights[ d ].mVertex ] = obone.mWeights[ d ].mWeight;
                }

                // collect all vertex weights that influence a vertex in the new mesh
                std::vector<aiVertexWeight> newWeights;
                newWeights.reserve( numVertices);
                for( unsigned int d = 0; d < orgPoints.size(); ++d ) {
                    // does the new vertex stem from an old vertex which was influenced by this bone?
                    ai_real w = oldWeights[orgPoints[d]];
                    if ( w > 0.0 ) {
                        newWeights.push_back( aiVertexWeight( d, w ) );
                    }
                }

                // if the bone has no weights in the newly created mesh, ignore it
                if ( newWeights.empty() ) {
                    continue;
                }

                // create
                aiBone* nbone = new aiBone;
                newBones.push_back( nbone);
                // copy name and matrix
                nbone->mName.Set( obone.mName);
                nbone->mOffsetMatrix = obone.mOffsetMatrix;
                nbone->mNumWeights = (unsigned int)newWeights.size();
                nbone->mWeights = new aiVertexWeight[nbone->mNumWeights];
                for ( unsigned int d = 0; d < newWeights.size(); ++d ) {
                    nbone->mWeights[ d ] = newWeights[ d ];
                }
            }

            // store the bones in the mesh
            mesh->mNumBones = (unsigned int)newBones.size();
            if( !newBones.empty()) {
                mesh->mBones = new aiBone*[mesh->mNumBones];
                std::copy( newBones.begin(), newBones.end(), mesh->mBones);
            }
        }
    }

    // reallocate scene mesh array to be large enough
    aiMesh** prevArray = pScene->mMeshes;
    pScene->mMeshes = new aiMesh*[pScene->mNumMeshes + meshes.size()];
    if( prevArray) {
        memcpy( pScene->mMeshes, prevArray, pScene->mNumMeshes * sizeof( aiMesh*));
        delete [] prevArray;
    }

    // allocate mesh index array in the node
    pNode->mNumMeshes = (unsigned int)meshes.size();
    pNode->mMeshes = new unsigned int[pNode->mNumMeshes];

    // store all meshes in the mesh library of the scene and store their indices in the node
    for( unsigned int a = 0; a < meshes.size(); a++) {
        pScene->mMeshes[pScene->mNumMeshes] = meshes[a];
        pNode->mMeshes[a] = pScene->mNumMeshes;
        pScene->mNumMeshes++;
    }
}

// ------------------------------------------------------------------------------------------------
// Converts the animations from the given imported data and creates them in the scene.
void XFileImporter::CreateAnimations( aiScene* pScene, const XFile::Scene* pData) {
    std::vector<aiAnimation*> newAnims;

    for( unsigned int a = 0; a < pData->mAnims.size(); ++a ) {
        const XFile::Animation* anim = pData->mAnims[a];
        // some exporters mock me with empty animation tags.
        if ( anim->mAnims.empty() ) {
            continue;
        }

        // create a new animation to hold the data
        aiAnimation* nanim = new aiAnimation;
        newAnims.push_back( nanim);
        nanim->mName.Set( anim->mName);
        // duration will be determined by the maximum length
        nanim->mDuration = 0;
        nanim->mTicksPerSecond = pData->mAnimTicksPerSecond;
        nanim->mNumChannels = (unsigned int)anim->mAnims.size();
        nanim->mChannels = new aiNodeAnim*[nanim->mNumChannels];

        for( unsigned int b = 0; b < anim->mAnims.size(); ++b ) {
            const XFile::AnimBone* bone = anim->mAnims[b];
            aiNodeAnim* nbone = new aiNodeAnim;
            nbone->mNodeName.Set( bone->mBoneName);
            nanim->mChannels[b] = nbone;

            // key-frames are given as combined transformation matrix keys
            if( !bone->mTrafoKeys.empty() )
            {
                nbone->mNumPositionKeys = (unsigned int)bone->mTrafoKeys.size();
                nbone->mPositionKeys = new aiVectorKey[nbone->mNumPositionKeys];
                nbone->mNumRotationKeys = (unsigned int)bone->mTrafoKeys.size();
                nbone->mRotationKeys = new aiQuatKey[nbone->mNumRotationKeys];
                nbone->mNumScalingKeys = (unsigned int)bone->mTrafoKeys.size();
                nbone->mScalingKeys = new aiVectorKey[nbone->mNumScalingKeys];

                for( unsigned int c = 0; c < bone->mTrafoKeys.size(); ++c)  {
                    // deconstruct each matrix into separate position, rotation and scaling
                    double time = bone->mTrafoKeys[c].mTime;
                    aiMatrix4x4 trafo = bone->mTrafoKeys[c].mMatrix;

                    // extract position
                    aiVector3D pos( trafo.a4, trafo.b4, trafo.c4);

                    nbone->mPositionKeys[c].mTime = time;
                    nbone->mPositionKeys[c].mValue = pos;

                    // extract scaling
                    aiVector3D scale;
                    scale.x = aiVector3D( trafo.a1, trafo.b1, trafo.c1).Length();
                    scale.y = aiVector3D( trafo.a2, trafo.b2, trafo.c2).Length();
                    scale.z = aiVector3D( trafo.a3, trafo.b3, trafo.c3).Length();
                    nbone->mScalingKeys[c].mTime = time;
                    nbone->mScalingKeys[c].mValue = scale;

                    // reconstruct rotation matrix without scaling
                    aiMatrix3x3 rotmat(
                        trafo.a1 / scale.x, trafo.a2 / scale.y, trafo.a3 / scale.z,
                        trafo.b1 / scale.x, trafo.b2 / scale.y, trafo.b3 / scale.z,
                        trafo.c1 / scale.x, trafo.c2 / scale.y, trafo.c3 / scale.z);

                    // and convert it into a quaternion
                    nbone->mRotationKeys[c].mTime = time;
                    nbone->mRotationKeys[c].mValue = aiQuaternion( rotmat);
                }

                // longest lasting key sequence determines duration
                nanim->mDuration = std::max( nanim->mDuration, bone->mTrafoKeys.back().mTime);
            } else {
                // separate key sequences for position, rotation, scaling
                nbone->mNumPositionKeys = (unsigned int)bone->mPosKeys.size();
                if (nbone->mNumPositionKeys != 0) {
                    nbone->mPositionKeys = new aiVectorKey[nbone->mNumPositionKeys];
                    for( unsigned int c = 0; c < nbone->mNumPositionKeys; ++c ) {
                        aiVector3D pos = bone->mPosKeys[c].mValue;

                        nbone->mPositionKeys[c].mTime = bone->mPosKeys[c].mTime;
                        nbone->mPositionKeys[c].mValue = pos;
                    }
                }

                // rotation
                nbone->mNumRotationKeys = (unsigned int)bone->mRotKeys.size();
                if (nbone->mNumRotationKeys != 0) {
                    nbone->mRotationKeys = new aiQuatKey[nbone->mNumRotationKeys];
                    for( unsigned int c = 0; c < nbone->mNumRotationKeys; ++c ) {
                        aiMatrix3x3 rotmat = bone->mRotKeys[c].mValue.GetMatrix();

                        nbone->mRotationKeys[c].mTime = bone->mRotKeys[c].mTime;
                        nbone->mRotationKeys[c].mValue = aiQuaternion( rotmat);
                        nbone->mRotationKeys[c].mValue.w *= -1.0f; // needs quat inversion
                    }
                }

                // scaling
                nbone->mNumScalingKeys = (unsigned int)bone->mScaleKeys.size();
                if (nbone->mNumScalingKeys != 0) {
                    nbone->mScalingKeys = new aiVectorKey[nbone->mNumScalingKeys];
                    for( unsigned int c = 0; c < nbone->mNumScalingKeys; c++)
                        nbone->mScalingKeys[c] = bone->mScaleKeys[c];
                }

                // longest lasting key sequence determines duration
                if( bone->mPosKeys.size() > 0)
                    nanim->mDuration = std::max( nanim->mDuration, bone->mPosKeys.back().mTime);
                if( bone->mRotKeys.size() > 0)
                    nanim->mDuration = std::max( nanim->mDuration, bone->mRotKeys.back().mTime);
                if( bone->mScaleKeys.size() > 0)
                    nanim->mDuration = std::max( nanim->mDuration, bone->mScaleKeys.back().mTime);
            }
        }
    }

    // store all converted animations in the scene
    if( newAnims.size() > 0)
    {
        pScene->mNumAnimations = (unsigned int)newAnims.size();
        pScene->mAnimations = new aiAnimation* [pScene->mNumAnimations];
        for( unsigned int a = 0; a < newAnims.size(); a++)
            pScene->mAnimations[a] = newAnims[a];
    }
}

// ------------------------------------------------------------------------------------------------
// Converts all materials in the given array and stores them in the scene's material list.
void XFileImporter::ConvertMaterials( aiScene* pScene, std::vector<XFile::Material>& pMaterials)
{
    // count the non-referrer materials in the array
    unsigned int numNewMaterials( 0 );
    for ( unsigned int a = 0; a < pMaterials.size(); ++a ) {
        if ( !pMaterials[ a ].mIsReference ) {
            ++numNewMaterials;
        }
    }

    // resize the scene's material list to offer enough space for the new materials
    if( numNewMaterials > 0 ) {
        aiMaterial** prevMats = pScene->mMaterials;
        pScene->mMaterials = new aiMaterial*[pScene->mNumMaterials + numNewMaterials];
        if( nullptr != prevMats)  {
            ::memcpy( pScene->mMaterials, prevMats, pScene->mNumMaterials * sizeof( aiMaterial*));
            delete [] prevMats;
        }
    }

    // convert all the materials given in the array
    for( unsigned int a = 0; a < pMaterials.size(); ++a ) {
        XFile::Material& oldMat = pMaterials[a];
        if( oldMat.mIsReference) {
            // find the material it refers to by name, and store its index
            for( size_t b = 0; b < pScene->mNumMaterials; ++b ) {
                aiString name;
                pScene->mMaterials[b]->Get( AI_MATKEY_NAME, name);
                if( strcmp( name.C_Str(), oldMat.mName.data()) == 0 ) {
                    oldMat.sceneIndex = a;
                    break;
                }
            }

            if( oldMat.sceneIndex == SIZE_MAX ) {
                ASSIMP_LOG_WARN_F( "Could not resolve global material reference \"", oldMat.mName, "\"" );
                oldMat.sceneIndex = 0;
            }

            continue;
        }

        aiMaterial* mat = new aiMaterial;
        aiString name;
        name.Set( oldMat.mName);
        mat->AddProperty( &name, AI_MATKEY_NAME);

        // Shading model: hard-coded to PHONG, there is no such information in an XFile
        // FIX (aramis): If the specular exponent is 0, use gouraud shading. This is a bugfix
        // for some models in the SDK (e.g. good old tiny.x)
        int shadeMode = (int)oldMat.mSpecularExponent == 0.0f
            ? aiShadingMode_Gouraud : aiShadingMode_Phong;

        mat->AddProperty<int>( &shadeMode, 1, AI_MATKEY_SHADING_MODEL);
        // material colours
        // Unclear: there's no ambient colour, but emissive. What to put for ambient?
        // Probably nothing at all, let the user select a suitable default.
        mat->AddProperty( &oldMat.mEmissive, 1, AI_MATKEY_COLOR_EMISSIVE);
        mat->AddProperty( &oldMat.mDiffuse, 1, AI_MATKEY_COLOR_DIFFUSE);
        mat->AddProperty( &oldMat.mSpecular, 1, AI_MATKEY_COLOR_SPECULAR);
        mat->AddProperty( &oldMat.mSpecularExponent, 1, AI_MATKEY_SHININESS);


        // texture, if there is one
        if (1 == oldMat.mTextures.size() ) {
            const XFile::TexEntry& otex = oldMat.mTextures.back();
            if (otex.mName.length()) {
                // if there is only one texture assume it contains the diffuse color
                aiString tex( otex.mName);
                if ( otex.mIsNormalMap ) {
                    mat->AddProperty( &tex, AI_MATKEY_TEXTURE_NORMALS( 0 ) );
                } else {
                    mat->AddProperty( &tex, AI_MATKEY_TEXTURE_DIFFUSE( 0 ) );
                }
            }
        } else {
            // Otherwise ... try to search for typical strings in the
            // texture's file name like 'bump' or 'diffuse'
            unsigned int iHM = 0,iNM = 0,iDM = 0,iSM = 0,iAM = 0,iEM = 0;
            for( unsigned int b = 0; b < oldMat.mTextures.size(); ++b ) {
                const XFile::TexEntry& otex = oldMat.mTextures[b];
                std::string sz = otex.mName;
                if ( !sz.length() ) {
                    continue;
                }

                // find the file name
                std::string::size_type s = sz.find_last_of("\\/");
                if ( std::string::npos == s ) {
                    s = 0;
                }

                // cut off the file extension
                std::string::size_type sExt = sz.find_last_of('.');
                if (std::string::npos != sExt){
                    sz[sExt] = '\0';
                }

                // convert to lower case for easier comparison
                for ( unsigned int c = 0; c < sz.length(); ++c ) {
                    if ( isalpha( sz[ c ] ) ) {
                        sz[ c ] = (char) tolower( sz[ c ] );
                    }
                }

                // Place texture filename property under the corresponding name
                aiString tex( oldMat.mTextures[b].mName);

                // bump map
                if (std::string::npos != sz.find("bump", s) || std::string::npos != sz.find("height", s)) {
                    mat->AddProperty( &tex, AI_MATKEY_TEXTURE_HEIGHT(iHM++));
                } else if (otex.mIsNormalMap || std::string::npos != sz.find( "normal", s) || std::string::npos != sz.find("nm", s)) {
                    mat->AddProperty( &tex, AI_MATKEY_TEXTURE_NORMALS(iNM++));
                } else if (std::string::npos != sz.find( "spec", s) || std::string::npos != sz.find( "glanz", s)) {
                    mat->AddProperty( &tex, AI_MATKEY_TEXTURE_SPECULAR(iSM++));
                } else if (std::string::npos != sz.find( "ambi", s) || std::string::npos != sz.find( "env", s)) {
                    mat->AddProperty( &tex, AI_MATKEY_TEXTURE_AMBIENT(iAM++));
                } else if (std::string::npos != sz.find( "emissive", s) || std::string::npos != sz.find( "self", s)) {
                    mat->AddProperty( &tex, AI_MATKEY_TEXTURE_EMISSIVE(iEM++));
                } else {
                    // Assume it is a diffuse texture
                    mat->AddProperty( &tex, AI_MATKEY_TEXTURE_DIFFUSE(iDM++));
                }
            }
        }

        pScene->mMaterials[pScene->mNumMaterials] = mat;
        oldMat.sceneIndex = pScene->mNumMaterials;
        pScene->mNumMaterials++;
    }
}

#endif // !! ASSIMP_BUILD_NO_X_IMPORTER