/*
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*/

/** @file Implementation of the 3ds importer class */


#ifndef ASSIMP_BUILD_NO_3DS_IMPORTER

// internal headers
#include "3DSLoader.h"
#include "TargetAnimation.h"
#include <assimp/scene.h>
#include <assimp/DefaultLogger.hpp>
#include "StringComparison.h"
#include <memory>
#include <cctype>

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Setup final material indices, generae a default material if necessary
void Discreet3DSImporter::ReplaceDefaultMaterial()
{

    // Try to find an existing material that matches the
    // typical default material setting:
    // - no textures
    // - diffuse color (in grey!)
    // NOTE: This is here to workaround the fact that some
    // exporters are writing a default material, too.
    unsigned int idx = 0xcdcdcdcd;
    for (unsigned int i = 0; i < mScene->mMaterials.size();++i)
    {
        std::string s = mScene->mMaterials[i].mName;
        for ( std::string::iterator it = s.begin(); it != s.end(); ++it ) {
            *it = static_cast< char >( ::tolower( *it ) );
        }

        if (std::string::npos == s.find("default"))continue;

        if (mScene->mMaterials[i].mDiffuse.r !=
            mScene->mMaterials[i].mDiffuse.g ||
            mScene->mMaterials[i].mDiffuse.r !=
            mScene->mMaterials[i].mDiffuse.b)continue;

        if (mScene->mMaterials[i].sTexDiffuse.mMapName.length()   != 0  ||
            mScene->mMaterials[i].sTexBump.mMapName.length()      != 0  ||
            mScene->mMaterials[i].sTexOpacity.mMapName.length()   != 0  ||
            mScene->mMaterials[i].sTexEmissive.mMapName.length()  != 0  ||
            mScene->mMaterials[i].sTexSpecular.mMapName.length()  != 0  ||
            mScene->mMaterials[i].sTexShininess.mMapName.length() != 0 )
        {
            continue;
        }
        idx = i;
    }
    if (0xcdcdcdcd == idx)idx = (unsigned int)mScene->mMaterials.size();

    // now iterate through all meshes and through all faces and
    // find all faces that are using the default material
    unsigned int cnt = 0;
    for (std::vector<D3DS::Mesh>::iterator
        i =  mScene->mMeshes.begin();
        i != mScene->mMeshes.end();++i)
    {
        for (std::vector<unsigned int>::iterator
            a =  (*i).mFaceMaterials.begin();
            a != (*i).mFaceMaterials.end();++a)
        {
            // NOTE: The additional check seems to be necessary,
            // some exporters seem to generate invalid data here
            if (0xcdcdcdcd == (*a))
            {
                (*a) = idx;
                ++cnt;
            }
            else if ( (*a) >= mScene->mMaterials.size())
            {
                (*a) = idx;
                DefaultLogger::get()->warn("Material index overflow in 3DS file. Using default material");
                ++cnt;
            }
        }
    }
    if (cnt && idx == mScene->mMaterials.size())
    {
        // We need to create our own default material
        D3DS::Material sMat;
        sMat.mDiffuse = aiColor3D(0.3f,0.3f,0.3f);
        sMat.mName = "%%%DEFAULT";
        mScene->mMaterials.push_back(sMat);

        DefaultLogger::get()->info("3DS: Generating default material");
    }
}

// ------------------------------------------------------------------------------------------------
// Check whether all indices are valid. Otherwise we'd crash before the validation step is reached
void Discreet3DSImporter::CheckIndices(D3DS::Mesh& sMesh)
{
    for (std::vector< D3DS::Face >::iterator i =  sMesh.mFaces.begin(); i != sMesh.mFaces.end();++i)
    {
        // check whether all indices are in range
        for (unsigned int a = 0; a < 3;++a)
        {
            if ((*i).mIndices[a] >= sMesh.mPositions.size())
            {
                DefaultLogger::get()->warn("3DS: Vertex index overflow)");
                (*i).mIndices[a] = (uint32_t)sMesh.mPositions.size()-1;
            }
            if ( !sMesh.mTexCoords.empty() && (*i).mIndices[a] >= sMesh.mTexCoords.size())
            {
                DefaultLogger::get()->warn("3DS: Texture coordinate index overflow)");
                (*i).mIndices[a] = (uint32_t)sMesh.mTexCoords.size()-1;
            }
        }
    }
}

// ------------------------------------------------------------------------------------------------
// Generate out unique verbose format representation
void Discreet3DSImporter::MakeUnique(D3DS::Mesh& sMesh)
{
    // TODO: really necessary? I don't think. Just a waste of memory and time
    // to do it now in a separate buffer.

    // Allocate output storage
    std::vector<aiVector3D> vNew  (sMesh.mFaces.size() * 3);
    std::vector<aiVector3D> vNew2;
    if (sMesh.mTexCoords.size())
        vNew2.resize(sMesh.mFaces.size() * 3);

    for (unsigned int i = 0, base = 0; i < sMesh.mFaces.size();++i)
    {
        D3DS::Face& face = sMesh.mFaces[i];

        // Positions
        for (unsigned int a = 0; a < 3;++a,++base)
        {
            vNew[base] = sMesh.mPositions[face.mIndices[a]];
            if (sMesh.mTexCoords.size())
                vNew2[base] = sMesh.mTexCoords[face.mIndices[a]];

            face.mIndices[a] = base;
        }
    }
    sMesh.mPositions = vNew;
    sMesh.mTexCoords = vNew2;
}

// ------------------------------------------------------------------------------------------------
// Convert a 3DS texture to texture keys in an aiMaterial
void CopyTexture(aiMaterial& mat, D3DS::Texture& texture, aiTextureType type)
{
    // Setup the texture name
    aiString tex;
    tex.Set( texture.mMapName);
    mat.AddProperty( &tex, AI_MATKEY_TEXTURE(type,0));

    // Setup the texture blend factor
    if (is_not_qnan(texture.mTextureBlend))
        mat.AddProperty<ai_real>( &texture.mTextureBlend, 1, AI_MATKEY_TEXBLEND(type,0));

    // Setup the texture mapping mode
    mat.AddProperty<int>((int*)&texture.mMapMode,1,AI_MATKEY_MAPPINGMODE_U(type,0));
    mat.AddProperty<int>((int*)&texture.mMapMode,1,AI_MATKEY_MAPPINGMODE_V(type,0));

    // Mirroring - double the scaling values
    // FIXME: this is not really correct ...
    if (texture.mMapMode == aiTextureMapMode_Mirror)
    {
        texture.mScaleU *= 2.0;
        texture.mScaleV *= 2.0;
        texture.mOffsetU /= 2.0;
        texture.mOffsetV /= 2.0;
    }

    // Setup texture UV transformations
    mat.AddProperty<ai_real>(&texture.mOffsetU,5,AI_MATKEY_UVTRANSFORM(type,0));
}

// ------------------------------------------------------------------------------------------------
// Convert a 3DS material to an aiMaterial
void Discreet3DSImporter::ConvertMaterial(D3DS::Material& oldMat,
    aiMaterial& mat)
{
    // NOTE: Pass the background image to the viewer by bypassing the
    // material system. This is an evil hack, never do it again!
    if (0 != mBackgroundImage.length() && bHasBG)
    {
        aiString tex;
        tex.Set( mBackgroundImage);
        mat.AddProperty( &tex, AI_MATKEY_GLOBAL_BACKGROUND_IMAGE);

        // Be sure this is only done for the first material
        mBackgroundImage = std::string("");
    }

    // At first add the base ambient color of the scene to the material
    oldMat.mAmbient.r += mClrAmbient.r;
    oldMat.mAmbient.g += mClrAmbient.g;
    oldMat.mAmbient.b += mClrAmbient.b;

    aiString name;
    name.Set( oldMat.mName);
    mat.AddProperty( &name, AI_MATKEY_NAME);

    // Material colors
    mat.AddProperty( &oldMat.mAmbient, 1, AI_MATKEY_COLOR_AMBIENT);
    mat.AddProperty( &oldMat.mDiffuse, 1, AI_MATKEY_COLOR_DIFFUSE);
    mat.AddProperty( &oldMat.mSpecular, 1, AI_MATKEY_COLOR_SPECULAR);
    mat.AddProperty( &oldMat.mEmissive, 1, AI_MATKEY_COLOR_EMISSIVE);

    // Phong shininess and shininess strength
    if (D3DS::Discreet3DS::Phong == oldMat.mShading ||
        D3DS::Discreet3DS::Metal == oldMat.mShading)
    {
        if (!oldMat.mSpecularExponent || !oldMat.mShininessStrength)
        {
            oldMat.mShading = D3DS::Discreet3DS::Gouraud;
        }
        else
        {
            mat.AddProperty( &oldMat.mSpecularExponent, 1, AI_MATKEY_SHININESS);
            mat.AddProperty( &oldMat.mShininessStrength, 1, AI_MATKEY_SHININESS_STRENGTH);
        }
    }

    // Opacity
    mat.AddProperty<ai_real>( &oldMat.mTransparency,1,AI_MATKEY_OPACITY);

    // Bump height scaling
    mat.AddProperty<ai_real>( &oldMat.mBumpHeight,1,AI_MATKEY_BUMPSCALING);

    // Two sided rendering?
    if (oldMat.mTwoSided)
    {
        int i = 1;
        mat.AddProperty<int>(&i,1,AI_MATKEY_TWOSIDED);
    }

    // Shading mode
    aiShadingMode eShading = aiShadingMode_NoShading;
    switch (oldMat.mShading)
    {
        case D3DS::Discreet3DS::Flat:
            eShading = aiShadingMode_Flat; break;

        // I don't know what "Wire" shading should be,
        // assume it is simple lambertian diffuse shading
        case D3DS::Discreet3DS::Wire:
            {
                // Set the wireframe flag
                unsigned int iWire = 1;
                mat.AddProperty<int>( (int*)&iWire,1,AI_MATKEY_ENABLE_WIREFRAME);
            }

        case D3DS::Discreet3DS::Gouraud:
            eShading = aiShadingMode_Gouraud; break;

        // assume cook-torrance shading for metals.
        case D3DS::Discreet3DS::Phong :
            eShading = aiShadingMode_Phong; break;

        case D3DS::Discreet3DS::Metal :
            eShading = aiShadingMode_CookTorrance; break;

            // FIX to workaround a warning with GCC 4 who complained
            // about a missing case Blinn: here - Blinn isn't a valid
            // value in the 3DS Loader, it is just needed for ASE
        case D3DS::Discreet3DS::Blinn :
            eShading = aiShadingMode_Blinn; break;
    }
    mat.AddProperty<int>( (int*)&eShading,1,AI_MATKEY_SHADING_MODEL);

    // DIFFUSE texture
    if( oldMat.sTexDiffuse.mMapName.length() > 0)
        CopyTexture(mat,oldMat.sTexDiffuse, aiTextureType_DIFFUSE);

    // SPECULAR texture
    if( oldMat.sTexSpecular.mMapName.length() > 0)
        CopyTexture(mat,oldMat.sTexSpecular, aiTextureType_SPECULAR);

    // OPACITY texture
    if( oldMat.sTexOpacity.mMapName.length() > 0)
        CopyTexture(mat,oldMat.sTexOpacity, aiTextureType_OPACITY);

    // EMISSIVE texture
    if( oldMat.sTexEmissive.mMapName.length() > 0)
        CopyTexture(mat,oldMat.sTexEmissive, aiTextureType_EMISSIVE);

    // BUMP texture
    if( oldMat.sTexBump.mMapName.length() > 0)
        CopyTexture(mat,oldMat.sTexBump, aiTextureType_HEIGHT);

    // SHININESS texture
    if( oldMat.sTexShininess.mMapName.length() > 0)
        CopyTexture(mat,oldMat.sTexShininess, aiTextureType_SHININESS);

    // REFLECTION texture
    if( oldMat.sTexReflective.mMapName.length() > 0)
        CopyTexture(mat,oldMat.sTexReflective, aiTextureType_REFLECTION);

    // Store the name of the material itself, too
    if( oldMat.mName.length())  {
        aiString tex;
        tex.Set( oldMat.mName);
        mat.AddProperty( &tex, AI_MATKEY_NAME);
    }
}

// ------------------------------------------------------------------------------------------------
// Split meshes by their materials and generate output aiMesh'es
void Discreet3DSImporter::ConvertMeshes(aiScene* pcOut)
{
    std::vector<aiMesh*> avOutMeshes;
    avOutMeshes.reserve(mScene->mMeshes.size() * 2);

    unsigned int iFaceCnt = 0,num = 0;
    aiString name;

    // we need to split all meshes by their materials
    for (std::vector<D3DS::Mesh>::iterator i =  mScene->mMeshes.begin(); i != mScene->mMeshes.end();++i)    {
        std::unique_ptr< std::vector<unsigned int>[] > aiSplit(new std::vector<unsigned int>[mScene->mMaterials.size()]);

        name.length = ASSIMP_itoa10(name.data,num++);

        unsigned int iNum = 0;
        for (std::vector<unsigned int>::const_iterator a =  (*i).mFaceMaterials.begin();
            a != (*i).mFaceMaterials.end();++a,++iNum)
        {
            aiSplit[*a].push_back(iNum);
        }
        // now generate submeshes
        for (unsigned int p = 0; p < mScene->mMaterials.size();++p)
        {
            if (aiSplit[p].empty()) {
                continue;
            }
            aiMesh* meshOut = new aiMesh();
            meshOut->mName = name;
            meshOut->mPrimitiveTypes = aiPrimitiveType_TRIANGLE;

            // be sure to setup the correct material index
            meshOut->mMaterialIndex = p;

            // use the color data as temporary storage
            meshOut->mColors[0] = (aiColor4D*)(&*i);
            avOutMeshes.push_back(meshOut);

            // convert vertices
            meshOut->mNumFaces = (unsigned int)aiSplit[p].size();
            meshOut->mNumVertices = meshOut->mNumFaces*3;

            // allocate enough storage for faces
            meshOut->mFaces = new aiFace[meshOut->mNumFaces];
            iFaceCnt += meshOut->mNumFaces;

            meshOut->mVertices = new aiVector3D[meshOut->mNumVertices];
            meshOut->mNormals  = new aiVector3D[meshOut->mNumVertices];
            if ((*i).mTexCoords.size())
            {
                meshOut->mTextureCoords[0] = new aiVector3D[meshOut->mNumVertices];
            }
            for (unsigned int q = 0, base = 0; q < aiSplit[p].size();++q)
            {
                unsigned int index = aiSplit[p][q];
                aiFace& face = meshOut->mFaces[q];

                face.mIndices = new unsigned int[3];
                face.mNumIndices = 3;

                for (unsigned int a = 0; a < 3;++a,++base)
                {
                    unsigned int idx = (*i).mFaces[index].mIndices[a];
                    meshOut->mVertices[base]  = (*i).mPositions[idx];
                    meshOut->mNormals [base]  = (*i).mNormals[idx];

                    if ((*i).mTexCoords.size())
                        meshOut->mTextureCoords[0][base] = (*i).mTexCoords[idx];

                    face.mIndices[a] = base;
                }
            }
        }
    }

    // Copy them to the output array
    pcOut->mNumMeshes = (unsigned int)avOutMeshes.size();
    pcOut->mMeshes = new aiMesh*[pcOut->mNumMeshes]();
    for (unsigned int a = 0; a < pcOut->mNumMeshes;++a) {
        pcOut->mMeshes[a] = avOutMeshes[a];
    }

    // We should have at least one face here
    if (!iFaceCnt) {
        throw DeadlyImportError("No faces loaded. The mesh is empty");
    }
}

// ------------------------------------------------------------------------------------------------
// Add a node to the scenegraph and setup its final transformation
void Discreet3DSImporter::AddNodeToGraph(aiScene* pcSOut,aiNode* pcOut,
    D3DS::Node* pcIn, aiMatrix4x4& /*absTrafo*/)
{
    std::vector<unsigned int> iArray;
    iArray.reserve(3);

    aiMatrix4x4 abs;

    // Find all meshes with the same name as the node
    for (unsigned int a = 0; a < pcSOut->mNumMeshes;++a)
    {
        const D3DS::Mesh* pcMesh = (const D3DS::Mesh*)pcSOut->mMeshes[a]->mColors[0];
        ai_assert(NULL != pcMesh);

        if (pcIn->mName == pcMesh->mName)
            iArray.push_back(a);
    }
    if (!iArray.empty())
    {
        // The matrix should be identical for all meshes with the
        // same name. It HAS to be identical for all meshes .....
        D3DS::Mesh* imesh = ((D3DS::Mesh*)pcSOut->mMeshes[iArray[0]]->mColors[0]);

        // Compute the inverse of the transformation matrix to move the
        // vertices back to their relative and local space
        aiMatrix4x4 mInv = imesh->mMat, mInvTransposed = imesh->mMat;
        mInv.Inverse();mInvTransposed.Transpose();
        aiVector3D pivot = pcIn->vPivot;

        pcOut->mNumMeshes = (unsigned int)iArray.size();
        pcOut->mMeshes = new unsigned int[iArray.size()];
        for (unsigned int i = 0;i < iArray.size();++i)  {
            const unsigned int iIndex = iArray[i];
            aiMesh* const mesh = pcSOut->mMeshes[iIndex];

            if (mesh->mColors[1] == NULL)
            {
                // Transform the vertices back into their local space
                // fixme: consider computing normals after this, so we don't need to transform them
                const aiVector3D* const pvEnd = mesh->mVertices + mesh->mNumVertices;
                aiVector3D* pvCurrent = mesh->mVertices, *t2 = mesh->mNormals;

                for (; pvCurrent != pvEnd; ++pvCurrent, ++t2) {
                    *pvCurrent = mInv * (*pvCurrent);
                    *t2 = mInvTransposed * (*t2);
                }

                // Handle negative transformation matrix determinant -> invert vertex x
                if (imesh->mMat.Determinant() < 0.0f)
                {
                    /* we *must* have normals */
                    for (pvCurrent = mesh->mVertices, t2 = mesh->mNormals; pvCurrent != pvEnd; ++pvCurrent, ++t2) {
                        pvCurrent->x *= -1.f;
                        t2->x *= -1.f;
                    }
                    DefaultLogger::get()->info("3DS: Flipping mesh X-Axis");
                }

                // Handle pivot point
                if (pivot.x || pivot.y || pivot.z)
                {
                    for (pvCurrent = mesh->mVertices; pvCurrent != pvEnd; ++pvCurrent)  {
                        *pvCurrent -= pivot;
                    }
                }

                mesh->mColors[1] = (aiColor4D*)1;
            }
            else
                mesh->mColors[1] = (aiColor4D*)1;

            // Setup the mesh index
            pcOut->mMeshes[i] = iIndex;
        }
    }

    // Setup the name of the node
    // First instance keeps its name otherwise something might break, all others will be postfixed with their instance number
    if (pcIn->mInstanceNumber > 1)
    {
        char tmp[12];
        ASSIMP_itoa10(tmp, pcIn->mInstanceNumber);
        std::string tempStr = pcIn->mName + "_inst_";
        tempStr += tmp;
        pcOut->mName.Set(tempStr);
    }
    else
        pcOut->mName.Set(pcIn->mName);

    // Now build the transformation matrix of the node
    // ROTATION
    if (pcIn->aRotationKeys.size()){

        // FIX to get to Assimp's quaternion conventions
        for (std::vector<aiQuatKey>::iterator it = pcIn->aRotationKeys.begin(); it != pcIn->aRotationKeys.end(); ++it) {
            (*it).mValue.w *= -1.f;
        }

        pcOut->mTransformation = aiMatrix4x4( pcIn->aRotationKeys[0].mValue.GetMatrix() );
    }
    else if (pcIn->aCameraRollKeys.size())
    {
        aiMatrix4x4::RotationZ(AI_DEG_TO_RAD(- pcIn->aCameraRollKeys[0].mValue),
            pcOut->mTransformation);
    }

    // SCALING
    aiMatrix4x4& m = pcOut->mTransformation;
    if (pcIn->aScalingKeys.size())
    {
        const aiVector3D& v = pcIn->aScalingKeys[0].mValue;
        m.a1 *= v.x; m.b1 *= v.x; m.c1 *= v.x;
        m.a2 *= v.y; m.b2 *= v.y; m.c2 *= v.y;
        m.a3 *= v.z; m.b3 *= v.z; m.c3 *= v.z;
    }

    // TRANSLATION
    if (pcIn->aPositionKeys.size())
    {
        const aiVector3D& v = pcIn->aPositionKeys[0].mValue;
        m.a4 += v.x;
        m.b4 += v.y;
        m.c4 += v.z;
    }

    // Generate animation channels for the node
    if (pcIn->aPositionKeys.size()  > 1  || pcIn->aRotationKeys.size()   > 1 ||
        pcIn->aScalingKeys.size()   > 1  || pcIn->aCameraRollKeys.size() > 1 ||
        pcIn->aTargetPositionKeys.size() > 1)
    {
        aiAnimation* anim = pcSOut->mAnimations[0];
        ai_assert(NULL != anim);

        if (pcIn->aCameraRollKeys.size() > 1)
        {
            DefaultLogger::get()->debug("3DS: Converting camera roll track ...");

            // Camera roll keys - in fact they're just rotations
            // around the camera's z axis. The angles are given
            // in degrees (and they're clockwise).
            pcIn->aRotationKeys.resize(pcIn->aCameraRollKeys.size());
            for (unsigned int i = 0; i < pcIn->aCameraRollKeys.size();++i)
            {
                aiQuatKey&  q = pcIn->aRotationKeys[i];
                aiFloatKey& f = pcIn->aCameraRollKeys[i];

                q.mTime  = f.mTime;

                // FIX to get to Assimp quaternion conventions
                q.mValue = aiQuaternion(0.f,0.f,AI_DEG_TO_RAD( /*-*/ f.mValue));
            }
        }
#if 0
        if (pcIn->aTargetPositionKeys.size() > 1)
        {
            DefaultLogger::get()->debug("3DS: Converting target track ...");

            // Camera or spot light - need to convert the separate
            // target position channel to our representation
            TargetAnimationHelper helper;

            if (pcIn->aPositionKeys.empty())
            {
                // We can just pass zero here ...
                helper.SetFixedMainAnimationChannel(aiVector3D());
            }
            else  helper.SetMainAnimationChannel(&pcIn->aPositionKeys);
            helper.SetTargetAnimationChannel(&pcIn->aTargetPositionKeys);

            // Do the conversion
            std::vector<aiVectorKey> distanceTrack;
            helper.Process(&distanceTrack);

            // Now add a new node as child, name it <ourName>.Target
            // and assign the distance track to it. This is that the
            // information where the target is and how it moves is
            // not lost
            D3DS::Node* nd = new D3DS::Node();
            pcIn->push_back(nd);

            nd->mName = pcIn->mName + ".Target";

            aiNodeAnim* nda = anim->mChannels[anim->mNumChannels++] = new aiNodeAnim();
            nda->mNodeName.Set(nd->mName);

            nda->mNumPositionKeys = (unsigned int)distanceTrack.size();
            nda->mPositionKeys = new aiVectorKey[nda->mNumPositionKeys];
            ::memcpy(nda->mPositionKeys,&distanceTrack[0],
                sizeof(aiVectorKey)*nda->mNumPositionKeys);
        }
#endif

        // Cameras or lights define their transformation in their parent node and in the
        // corresponding light or camera chunks. However, we read and process the latter
        // to to be able to return valid cameras/lights even if no scenegraph is given.
        for (unsigned int n = 0; n < pcSOut->mNumCameras;++n)   {
            if (pcSOut->mCameras[n]->mName == pcOut->mName) {
                pcSOut->mCameras[n]->mLookAt = aiVector3D(0.f,0.f,1.f);
            }
        }
        for (unsigned int n = 0; n < pcSOut->mNumLights;++n)    {
            if (pcSOut->mLights[n]->mName == pcOut->mName) {
                pcSOut->mLights[n]->mDirection = aiVector3D(0.f,0.f,1.f);
            }
        }

        // Allocate a new node anim and setup its name
        aiNodeAnim* nda = anim->mChannels[anim->mNumChannels++] = new aiNodeAnim();
        nda->mNodeName.Set(pcIn->mName);

        // POSITION keys
        if (pcIn->aPositionKeys.size()  > 0)
        {
            nda->mNumPositionKeys = (unsigned int)pcIn->aPositionKeys.size();
            nda->mPositionKeys = new aiVectorKey[nda->mNumPositionKeys];
            ::memcpy(nda->mPositionKeys,&pcIn->aPositionKeys[0],
                sizeof(aiVectorKey)*nda->mNumPositionKeys);
        }

        // ROTATION keys
        if (pcIn->aRotationKeys.size()  > 0)
        {
            nda->mNumRotationKeys = (unsigned int)pcIn->aRotationKeys.size();
            nda->mRotationKeys = new aiQuatKey[nda->mNumRotationKeys];

            // Rotations are quaternion offsets
            aiQuaternion abs1;
            for (unsigned int n = 0; n < nda->mNumRotationKeys;++n)
            {
                const aiQuatKey& q = pcIn->aRotationKeys[n];

                abs1 = (n ? abs1 * q.mValue : q.mValue);
                nda->mRotationKeys[n].mTime  = q.mTime;
                nda->mRotationKeys[n].mValue = abs1.Normalize();
            }
        }

        // SCALING keys
        if (pcIn->aScalingKeys.size()  > 0)
        {
            nda->mNumScalingKeys = (unsigned int)pcIn->aScalingKeys.size();
            nda->mScalingKeys = new aiVectorKey[nda->mNumScalingKeys];
            ::memcpy(nda->mScalingKeys,&pcIn->aScalingKeys[0],
                sizeof(aiVectorKey)*nda->mNumScalingKeys);
        }
    }

    // Allocate storage for children
    pcOut->mNumChildren = (unsigned int)pcIn->mChildren.size();
    pcOut->mChildren = new aiNode*[pcIn->mChildren.size()];

    // Recursively process all children
    const unsigned int size = pcIn->mChildren.size();
    for (unsigned int i = 0; i < size;++i)
    {
        pcOut->mChildren[i] = new aiNode();
        pcOut->mChildren[i]->mParent = pcOut;
        AddNodeToGraph(pcSOut,pcOut->mChildren[i],pcIn->mChildren[i],abs);
    }
}

// ------------------------------------------------------------------------------------------------
// Find out how many node animation channels we'll have finally
void CountTracks(D3DS::Node* node, unsigned int& cnt)
{
    //////////////////////////////////////////////////////////////////////////////
    // We will never generate more than one channel for a node, so
    // this is rather easy here.

    if (node->aPositionKeys.size()  > 1  || node->aRotationKeys.size()   > 1   ||
        node->aScalingKeys.size()   > 1  || node->aCameraRollKeys.size() > 1 ||
        node->aTargetPositionKeys.size()  > 1)
    {
        ++cnt;

        // account for the additional channel for the camera/spotlight target position
        if (node->aTargetPositionKeys.size()  > 1)++cnt;
    }

    // Recursively process all children
    for (unsigned int i = 0; i < node->mChildren.size();++i)
        CountTracks(node->mChildren[i],cnt);
}

// ------------------------------------------------------------------------------------------------
// Generate the output node graph
void Discreet3DSImporter::GenerateNodeGraph(aiScene* pcOut)
{
    pcOut->mRootNode = new aiNode();
    if (0 == mRootNode->mChildren.size())
    {
        //////////////////////////////////////////////////////////////////////////////
        // It seems the file is so messed up that it has not even a hierarchy.
        // generate a flat hiearachy which looks like this:
        //
        //                ROOT_NODE
        //                   |
        //   ----------------------------------------
        //   |       |       |            |         |
        // MESH_0  MESH_1  MESH_2  ...  MESH_N    CAMERA_0 ....
        //
        DefaultLogger::get()->warn("No hierarchy information has been found in the file. ");

        pcOut->mRootNode->mNumChildren = pcOut->mNumMeshes +
            mScene->mCameras.size() + mScene->mLights.size();

        pcOut->mRootNode->mChildren = new aiNode* [ pcOut->mRootNode->mNumChildren ];
        pcOut->mRootNode->mName.Set("<3DSDummyRoot>");

        // Build dummy nodes for all meshes
        unsigned int a = 0;
        for (unsigned int i = 0; i < pcOut->mNumMeshes;++i,++a)
        {
            aiNode* pcNode = pcOut->mRootNode->mChildren[a] = new aiNode();
            pcNode->mParent = pcOut->mRootNode;
            pcNode->mMeshes = new unsigned int[1];
            pcNode->mMeshes[0] = i;
            pcNode->mNumMeshes = 1;

            // Build a name for the node
            pcNode->mName.length = ai_snprintf(pcNode->mName.data, MAXLEN, "3DSMesh_%u",i);
        }

        // Build dummy nodes for all cameras
        for (unsigned int i = 0; i < (unsigned int )mScene->mCameras.size();++i,++a)
        {
            aiNode* pcNode = pcOut->mRootNode->mChildren[a] = new aiNode();
            pcNode->mParent = pcOut->mRootNode;

            // Build a name for the node
            pcNode->mName = mScene->mCameras[i]->mName;
        }

        // Build dummy nodes for all lights
        for (unsigned int i = 0; i < (unsigned int )mScene->mLights.size();++i,++a)
        {
            aiNode* pcNode = pcOut->mRootNode->mChildren[a] = new aiNode();
            pcNode->mParent = pcOut->mRootNode;

            // Build a name for the node
            pcNode->mName = mScene->mLights[i]->mName;
        }
    }
    else
    {
        // First of all: find out how many scaling, rotation and translation
        // animation tracks we'll have afterwards
        unsigned int numChannel = 0;
        CountTracks(mRootNode,numChannel);

        if (numChannel)
        {
            // Allocate a primary animation channel
            pcOut->mNumAnimations = 1;
            pcOut->mAnimations    = new aiAnimation*[1];
            aiAnimation* anim     = pcOut->mAnimations[0] = new aiAnimation();

            anim->mName.Set("3DSMasterAnim");

            // Allocate enough storage for all node animation channels,
            // but don't set the mNumChannels member - we'll use it to
            // index into the array
            anim->mChannels = new aiNodeAnim*[numChannel];
        }

        aiMatrix4x4 m;
        AddNodeToGraph(pcOut,  pcOut->mRootNode, mRootNode,m);
    }

    // We used the first and second vertex color set to store some temporary values so we need to cleanup here
    for (unsigned int a = 0; a < pcOut->mNumMeshes; ++a)
    {
        pcOut->mMeshes[a]->mColors[0] = NULL;
        pcOut->mMeshes[a]->mColors[1] = NULL;
    }

    pcOut->mRootNode->mTransformation = aiMatrix4x4(
        1.f,0.f,0.f,0.f,
        0.f,0.f,1.f,0.f,
        0.f,-1.f,0.f,0.f,
        0.f,0.f,0.f,1.f) * pcOut->mRootNode->mTransformation;

    // If the root node is unnamed name it "<3DSRoot>"
    if (::strstr( pcOut->mRootNode->mName.data, "UNNAMED" ) ||
        (pcOut->mRootNode->mName.data[0] == '$' && pcOut->mRootNode->mName.data[1] == '$') )
    {
        pcOut->mRootNode->mName.Set("<3DSRoot>");
    }
}

// ------------------------------------------------------------------------------------------------
// Convert all meshes in the scene and generate the final output scene.
void Discreet3DSImporter::ConvertScene(aiScene* pcOut)
{
    // Allocate enough storage for all output materials
    pcOut->mNumMaterials = (unsigned int)mScene->mMaterials.size();
    pcOut->mMaterials    = new aiMaterial*[pcOut->mNumMaterials];

    //  ... and convert the 3DS materials to aiMaterial's
    for (unsigned int i = 0; i < pcOut->mNumMaterials;++i)
    {
        aiMaterial* pcNew = new aiMaterial();
        ConvertMaterial(mScene->mMaterials[i],*pcNew);
        pcOut->mMaterials[i] = pcNew;
    }

    // Generate the output mesh list
    ConvertMeshes(pcOut);

    // Now copy all light sources to the output scene
    pcOut->mNumLights = (unsigned int)mScene->mLights.size();
    if (pcOut->mNumLights)
    {
        pcOut->mLights = new aiLight*[pcOut->mNumLights];
        ::memcpy(pcOut->mLights,&mScene->mLights[0],sizeof(void*)*pcOut->mNumLights);
    }

    // Now copy all cameras to the output scene
    pcOut->mNumCameras = (unsigned int)mScene->mCameras.size();
    if (pcOut->mNumCameras)
    {
        pcOut->mCameras = new aiCamera*[pcOut->mNumCameras];
        ::memcpy(pcOut->mCameras,&mScene->mCameras[0],sizeof(void*)*pcOut->mNumCameras);
    }
}

#endif // !! ASSIMP_BUILD_NO_3DS_IMPORTER
