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*/

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

#ifndef ASSIMP_BUILD_NO_3DS_IMPORTER

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

using namespace Assimp;

static const unsigned int NotSet = 0xcdcdcdcd;

// ------------------------------------------------------------------------------------------------
// 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(NotSet);
    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 (NotSet == 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;
                ASSIMP_LOG_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("%%%DEFAULT");
        sMat.mDiffuse = aiColor3D(0.3f, 0.3f, 0.3f);
        mScene->mMaterials.push_back(sMat);

        ASSIMP_LOG_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()) {
                ASSIMP_LOG_WARN("3DS: Vertex index overflow)");
                (*i).mIndices[a] = (uint32_t)sMesh.mPositions.size() - 1;
            }
            if (!sMesh.mTexCoords.empty() && (*i).mIndices[a] >= sMesh.mTexCoords.size()) {
                ASSIMP_LOG_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
    int mapMode = static_cast<int>(texture.mMapMode);
    mat.AddProperty<int>(&mapMode, 1, AI_MATKEY_MAPPINGMODE_U(type, 0));
    mat.AddProperty<int>(&mapMode, 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;
    }
    int eShading_ = static_cast<int>(eShading);
    mat.AddProperty<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(nullptr != 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] == nullptr) {
                // 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;
                    }
                    ASSIMP_LOG_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(nullptr != anim);

        if (pcIn->aCameraRollKeys.size() > 1) {
            ASSIMP_LOG_VERBOSE_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)
        {
            ASSIMP_LOG_VERBOSE_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 = static_cast<unsigned int>(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 ....
        //
        ASSIMP_LOG_WARN("No hierarchy information has been found in the file. ");

        pcOut->mRootNode->mNumChildren = pcOut->mNumMeshes +
                                         static_cast<unsigned int>(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] = nullptr;
        pcOut->mMeshes[a]->mColors[1] = nullptr;
    }

    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
