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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>

namespace Assimp {

static constexpr unsigned int NotSet = 0xcdcdcdcd;

using namespace D3DS;

// ------------------------------------------------------------------------------------------------

// Setup final material indices, generate 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 work-around 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) {

        auto s = mScene->mMaterials[i].mName;

        for (char &it : s) {

            it = static_cast<char>(::tolower(static_cast<unsigned char>(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 (ContainsTextures(i)) {

            continue;

        }

        idx = i;

    }

    if (NotSet == idx) {

        idx = static_cast<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 (auto i = mScene->mMeshes.begin(); i != mScene->mMeshes.end(); ++i) {

        for (auto 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 (NotSet == *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

        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(Mesh &sMesh) {

    for (auto 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] = static_cast<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] = static_cast<uint32_t>(sMesh.mTexCoords.size() - 1);

            }

        }

    }

}

// ------------------------------------------------------------------------------------------------

// Generate out unique verbose format representation

void Discreet3DSImporter::MakeUnique(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) {

        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, Texture &texture, aiTextureType type) {

    // Setup the texture name

    aiString tex(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

    auto 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(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 (mBackgroundImage.empty() && bHasBG) {

        aiString tex(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(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 (Discreet3DS::Phong == oldMat.mShading || Discreet3DS::Metal == oldMat.mShading) {

        if (!oldMat.mSpecularExponent || !oldMat.mShininessStrength) {

            oldMat.mShading = 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 Discreet3DS::Flat:

        eShading = aiShadingMode_Flat;

        break;

    // I don't know what "Wire" shading should be,

    // assume it is simple lambertian diffuse shading

    case Discreet3DS::Wire: {

        // Set the wireframe flag

        unsigned int iWire = 1;

        mat.AddProperty<int>((int *)&iWire, 1, AI_MATKEY_ENABLE_WIREFRAME);

    }

        [[fallthrough]];

    case Discreet3DS::Gouraud:

        eShading = aiShadingMode_Gouraud;

        break;

    // assume cook-torrance shading for metals.

    case Discreet3DS::Phong:

        eShading = aiShadingMode_Phong;

        break;

    case 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 Discreet3DS::Blinn:

        eShading = aiShadingMode_Blinn;

        break;

    }

    const int eShading_ = 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 (auto 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);

        ++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;

            }

            auto *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 = static_cast<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 auto *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 .....

        auto *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 = static_cast<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] = {'\0'};

        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 (auto 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 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

        auto *nda = anim->mChannels[anim->mNumChannels++] = new aiNodeAnim();

        nda->mNodeName.Set(pcIn->mName);

        // POSITION keys

        if (!pcIn->aPositionKeys.empty()) {

            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.empty()) {

            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.empty()) {

            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

    const auto size = static_cast<unsigned int>(pcIn->mChildren.size());

    pcOut->mNumChildren = size;

    if (size == 0) {

        return;

    }

    pcOut->mChildren = new aiNode *[pcIn->mChildren.size()];

    // Recursively process all children

    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 (mRootNode->mChildren.empty()) {

        //////////////////////////////////////////////////////////////////////////////

        // 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) {

            pcOut->mRootNode->mChildren[a] = new aiNode();  

            auto *pcNode = pcOut->mRootNode->mChildren[a];

            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, AI_MAXLEN, "3DSMesh_%u", i);

        }

        // Build dummy nodes for all cameras

        for (unsigned int i = 0; i < (unsigned int)mScene->mCameras.size(); ++i, ++a) {

            auto *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) {

            auto *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];

            auto *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 = static_cast<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) {

        auto *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 = static_cast<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 = static_cast<unsigned int>(mScene->mCameras.size());

    if (pcOut->mNumCameras) {

        pcOut->mCameras = new aiCamera *[pcOut->mNumCameras];

        memcpy(pcOut->mCameras, &mScene->mCameras[0], sizeof(void *) * pcOut->mNumCameras);

    }

}

} // namespace Assimp

#endif // !! ASSIMP_BUILD_NO_3DS_IMPORTER