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/// \file AMFImporter_Postprocess.cpp
/// \brief Convert built scenegraph and objects to Assimp scenegraph.
/// \date 2016
/// \author smal.root@gmail.com

#ifndef ASSIMP_BUILD_NO_AMF_IMPORTER

#include "AMFImporter.hpp"

#include <assimp/SceneCombiner.h>
#include <assimp/StandardShapes.h>
#include <assimp/StringUtils.h>

#include <iterator>

namespace Assimp {

aiColor4D AMFImporter::SPP_Material::GetColor(const float /*pX*/, const float /*pY*/, const float /*pZ*/) const {
    aiColor4D tcol;

    // Check if stored data are supported.
    if (!Composition.empty()) {
        throw DeadlyImportError("IME. GetColor for composition");
    }

    if (Color->Composed) {
        throw DeadlyImportError("IME. GetColor, composed color");
    }

    tcol = Color->Color;
    
    // Check if default color must be used
    if ((tcol.r == 0) && (tcol.g == 0) && (tcol.b == 0) && (tcol.a == 0)) {
        tcol.r = 0.5f;
        tcol.g = 0.5f;
        tcol.b = 0.5f;
        tcol.a = 1;
    }

    return tcol;
}

void AMFImporter::PostprocessHelper_CreateMeshDataArray(const AMFMesh &nodeElement, std::vector<aiVector3D> &vertexCoordinateArray,
        std::vector<AMFColor *> &pVertexColorArray) const {
    AMFVertices  *vn = nullptr;
    size_t col_idx;

    // All data stored in "vertices", search for it.
    for (AMFNodeElementBase *ne_child : nodeElement.Child) {
        if (ne_child->Type == AMFNodeElementBase::ENET_Vertices) {
            vn = (AMFVertices*)ne_child;
        }
    }

    // If "vertices" not found then no work for us.
    if (vn == nullptr) {
        return;
    }

    // all coordinates stored as child and we need to reserve space for future push_back's.
    vertexCoordinateArray.reserve(vn->Child.size()); 

    // colors count equal vertices count.
    pVertexColorArray.resize(vn->Child.size()); 
    col_idx = 0;

    // Inside vertices collect all data and place to arrays
    for (AMFNodeElementBase *vn_child : vn->Child) {
        // vertices, colors
        if (vn_child->Type == AMFNodeElementBase::ENET_Vertex) {
            // by default clear color for current vertex
            pVertexColorArray[col_idx] = nullptr;

            for (AMFNodeElementBase *vtx : vn_child->Child) {
                if (vtx->Type == AMFNodeElementBase::ENET_Coordinates) {
                    vertexCoordinateArray.push_back(((AMFCoordinates *)vtx)->Coordinate);
                    continue;
                }

                if (vtx->Type == AMFNodeElementBase::ENET_Color) {
                    pVertexColorArray[col_idx] = (AMFColor *)vtx;
                    continue;
                }
            }

            ++col_idx;
        }
    }
}

size_t AMFImporter::PostprocessHelper_GetTextureID_Or_Create(const std::string &r, const std::string &g, const std::string &b, const std::string &a) {
    if (r.empty() && g.empty() && b.empty() && a.empty()) {
        throw DeadlyImportError("PostprocessHelper_GetTextureID_Or_Create. At least one texture ID must be defined.");
    }

    std::string TextureConverted_ID = r + "_" + g + "_" + b + "_" + a;
    size_t TextureConverted_Index = 0;
    for (const SPP_Texture &tex_convd : mTexture_Converted) {
        if (tex_convd.ID == TextureConverted_ID) {
            return TextureConverted_Index;
        } else {
            ++TextureConverted_Index;
        }
    }

    // Converted texture not found, create it.
    AMFTexture *src_texture[4] {
        nullptr
    };
    std::vector<AMFTexture *> src_texture_4check;
    SPP_Texture converted_texture;

    { // find all specified source textures
        AMFNodeElementBase *t_tex = nullptr;

        // R
        if (!r.empty()) {
            if (!Find_NodeElement(r, AMFNodeElementBase::EType::ENET_Texture, &t_tex)) {
                Throw_ID_NotFound(r);
            }

            src_texture[0] = (AMFTexture *)t_tex;
            src_texture_4check.push_back((AMFTexture *)t_tex);
        } else {
            src_texture[0] = nullptr;
        }

        // G
        if (!g.empty()) {
            if (!Find_NodeElement(g, AMFNodeElementBase::ENET_Texture, &t_tex)) {
                Throw_ID_NotFound(g);
            }

            src_texture[1] = (AMFTexture *)t_tex;
            src_texture_4check.push_back((AMFTexture *)t_tex);
        } else {
            src_texture[1] = nullptr;
        }

        // B
        if (!b.empty()) {
            if (!Find_NodeElement(b, AMFNodeElementBase::ENET_Texture, &t_tex)) {
                Throw_ID_NotFound(b);
            }

            src_texture[2] = (AMFTexture *)t_tex;
            src_texture_4check.push_back((AMFTexture *)t_tex);
        } else {
            src_texture[2] = nullptr;
        }

        // A
        if (!a.empty()) {
            if (!Find_NodeElement(a, AMFNodeElementBase::ENET_Texture, &t_tex)) {
                Throw_ID_NotFound(a);
            }

            src_texture[3] = (AMFTexture *)t_tex;
            src_texture_4check.push_back((AMFTexture *)t_tex);
        } else {
            src_texture[3] = nullptr;
        }
    } // END: find all specified source textures

    // check that all textures has same size
    if (src_texture_4check.size() > 1) {
        for (size_t i = 0, i_e = (src_texture_4check.size() - 1); i < i_e; i++) {
            if ((src_texture_4check[i]->Width != src_texture_4check[i + 1]->Width) || (src_texture_4check[i]->Height != src_texture_4check[i + 1]->Height) ||
                    (src_texture_4check[i]->Depth != src_texture_4check[i + 1]->Depth)) {
                throw DeadlyImportError("PostprocessHelper_GetTextureID_Or_Create. Source texture must has the same size.");
            }
        }
    } // if(src_texture_4check.size() > 1)

    // set texture attributes
    converted_texture.Width = src_texture_4check[0]->Width;
    converted_texture.Height = src_texture_4check[0]->Height;
    converted_texture.Depth = src_texture_4check[0]->Depth;
    // if one of source texture is tiled then converted texture is tiled too.
    converted_texture.Tiled = false;
    for (uint8_t i = 0; i < src_texture_4check.size(); ++i) {
        converted_texture.Tiled |= src_texture_4check[i]->Tiled;
    }

    // Create format hint.
    strcpy(converted_texture.FormatHint, "rgba0000"); // copy initial string.
    if (!r.empty()) converted_texture.FormatHint[4] = '8';
    if (!g.empty()) converted_texture.FormatHint[5] = '8';
    if (!b.empty()) converted_texture.FormatHint[6] = '8';
    if (!a.empty()) converted_texture.FormatHint[7] = '8';

    // Сopy data of textures.
    size_t tex_size = 0;
    size_t step = 0;
    size_t off_g = 0;
    size_t off_b = 0;

    // Calculate size of the target array and rule how data will be copied.
    if (!r.empty() && nullptr != src_texture[0]) {
        tex_size += src_texture[0]->Data.size();
        step++, off_g++, off_b++;
    }
    if (!g.empty() && nullptr != src_texture[1]) {
        tex_size += src_texture[1]->Data.size();
        step++, off_b++;
    }
    if (!b.empty() && nullptr != src_texture[2]) {
        tex_size += src_texture[2]->Data.size();
        step++;
    }
    if (!a.empty() && nullptr != src_texture[3]) {
        tex_size += src_texture[3]->Data.size();
        step++;
    }

    // Create target array.
    converted_texture.Data = new uint8_t[tex_size];
    // And copy data
    auto CopyTextureData = [&](const std::string &pID, const size_t pOffset, const size_t pStep, const uint8_t pSrcTexNum) -> void {
        if (!pID.empty()) {
            for (size_t idx_target = pOffset, idx_src = 0; idx_target < tex_size; idx_target += pStep, idx_src++) {
                AMFTexture *tex = src_texture[pSrcTexNum];
                ai_assert(tex);
                converted_texture.Data[idx_target] = tex->Data.at(idx_src);
            }
        }
    }; // auto CopyTextureData = [&](const size_t pOffset, const size_t pStep, const uint8_t pSrcTexNum) -> void

    CopyTextureData(r, 0, step, 0);
    CopyTextureData(g, off_g, step, 1);
    CopyTextureData(b, off_b, step, 2);
    CopyTextureData(a, step - 1, step, 3);

    // Store new converted texture ID
    converted_texture.ID = TextureConverted_ID;
    // Store new converted texture
    mTexture_Converted.push_back(converted_texture);

    return TextureConverted_Index;
}

void AMFImporter::PostprocessHelper_SplitFacesByTextureID(std::list<SComplexFace> &pInputList, std::list<std::list<SComplexFace>> &pOutputList_Separated) {
    auto texmap_is_equal = [](const AMFTexMap *pTexMap1, const AMFTexMap *pTexMap2) -> bool {
        if ((pTexMap1 == nullptr) && (pTexMap2 == nullptr)) return true;
        if (pTexMap1 == nullptr) return false;
        if (pTexMap2 == nullptr) return false;

        if (pTexMap1->TextureID_R != pTexMap2->TextureID_R) return false;
        if (pTexMap1->TextureID_G != pTexMap2->TextureID_G) return false;
        if (pTexMap1->TextureID_B != pTexMap2->TextureID_B) return false;
        if (pTexMap1->TextureID_A != pTexMap2->TextureID_A) return false;

        return true;
    };

    pOutputList_Separated.clear();
    if (pInputList.empty()) return;

    do {
        SComplexFace face_start = pInputList.front();
        std::list<SComplexFace> face_list_cur;

        for (std::list<SComplexFace>::iterator it = pInputList.begin(), it_end = pInputList.end(); it != it_end;) {
            if (texmap_is_equal(face_start.TexMap, it->TexMap)) {
                auto it_old = it;

                ++it;
                face_list_cur.push_back(*it_old);
                pInputList.erase(it_old);
            } else {
                ++it;
            }
        }

        if (!face_list_cur.empty()) pOutputList_Separated.push_back(face_list_cur);

    } while (!pInputList.empty());
}

void AMFImporter::Postprocess_AddMetadata(const AMFMetaDataArray &metadataList, aiNode &sceneNode) const {
    if (metadataList.empty()) {
        return;
    }

    if (sceneNode.mMetaData != nullptr) {
        throw DeadlyImportError("Postprocess. MetaData member in node are not nullptr. Something went wrong.");
    }

    // copy collected metadata to output node.
    sceneNode.mMetaData = aiMetadata::Alloc(static_cast<unsigned int>(metadataList.size()));
    size_t meta_idx(0);

    for (const AMFMetadata *metadata : metadataList) {
        sceneNode.mMetaData->Set(static_cast<unsigned int>(meta_idx++), metadata->Type, aiString(metadata->Value));
    }
}

void AMFImporter::Postprocess_BuildNodeAndObject(const AMFObject &pNodeElement, MeshArray &meshList, aiNode **pSceneNode) {
    AMFColor *object_color = nullptr;

    // create new aiNode and set name as <object> has.
    *pSceneNode = new aiNode;
    (*pSceneNode)->mName = pNodeElement.ID;
    // read mesh and color
    for (const AMFNodeElementBase *ne_child : pNodeElement.Child) {
        std::vector<aiVector3D> vertex_arr;
        std::vector<AMFColor *> color_arr;

        // color for object
        if (ne_child->Type == AMFNodeElementBase::ENET_Color) {
            object_color = (AMFColor *) ne_child;
        }

        if (ne_child->Type == AMFNodeElementBase::ENET_Mesh) {
            // Create arrays from children of mesh: vertices.
            PostprocessHelper_CreateMeshDataArray(*((AMFMesh *)ne_child), vertex_arr, color_arr);
            // Use this arrays as a source when creating every aiMesh
            Postprocess_BuildMeshSet(*((AMFMesh *)ne_child), vertex_arr, color_arr, object_color, meshList, **pSceneNode);
        }
    } // for(const CAMFImporter_NodeElement* ne_child: pNodeElement)
}

void AMFImporter::Postprocess_BuildMeshSet(const AMFMesh &pNodeElement, const std::vector<aiVector3D> &pVertexCoordinateArray,
        const std::vector<AMFColor *> &pVertexColorArray, const AMFColor *pObjectColor, MeshArray &pMeshList, aiNode &pSceneNode) {
    std::list<unsigned int> mesh_idx;

    // all data stored in "volume", search for it.
    for (const AMFNodeElementBase *ne_child : pNodeElement.Child) {
        const AMFColor *ne_volume_color = nullptr;
        const SPP_Material *cur_mat = nullptr;

        if (ne_child->Type == AMFNodeElementBase::ENET_Volume) {
            /******************* Get faces *******************/
            const AMFVolume *ne_volume = reinterpret_cast<const AMFVolume *>(ne_child);

            std::list<SComplexFace> complex_faces_list; // List of the faces of the volume.
            std::list<std::list<SComplexFace>> complex_faces_toplist; // List of the face list for every mesh.

            // check if volume use material
            if (!ne_volume->MaterialID.empty()) {
                if (!Find_ConvertedMaterial(ne_volume->MaterialID, &cur_mat)) {
                    Throw_ID_NotFound(ne_volume->MaterialID);
                }
            }

            // inside "volume" collect all data and place to arrays or create new objects
            for (const AMFNodeElementBase *ne_volume_child : ne_volume->Child) {
                // color for volume
                if (ne_volume_child->Type == AMFNodeElementBase::ENET_Color) {
                    ne_volume_color = reinterpret_cast<const AMFColor *>(ne_volume_child);
                } else if (ne_volume_child->Type == AMFNodeElementBase::ENET_Triangle) // triangles, triangles colors
                {
                    const AMFTriangle &tri_al = *reinterpret_cast<const AMFTriangle *>(ne_volume_child);

                    SComplexFace complex_face;

                    // initialize pointers
                    complex_face.Color = nullptr;
                    complex_face.TexMap = nullptr;
                    // get data from triangle children: color, texture coordinates.
                    if (tri_al.Child.size()) {
                        for (const AMFNodeElementBase *ne_triangle_child : tri_al.Child) {
                            if (ne_triangle_child->Type == AMFNodeElementBase::ENET_Color)
                                complex_face.Color = reinterpret_cast<const AMFColor *>(ne_triangle_child);
                            else if (ne_triangle_child->Type == AMFNodeElementBase::ENET_TexMap)
                                complex_face.TexMap = reinterpret_cast<const AMFTexMap *>(ne_triangle_child);
                        }
                    } // if(tri_al.Child.size())

                    // create new face and store it.
                    complex_face.Face.mNumIndices = 3;
                    complex_face.Face.mIndices = new unsigned int[3];
                    complex_face.Face.mIndices[0] = static_cast<unsigned int>(tri_al.V[0]);
                    complex_face.Face.mIndices[1] = static_cast<unsigned int>(tri_al.V[1]);
                    complex_face.Face.mIndices[2] = static_cast<unsigned int>(tri_al.V[2]);
                    complex_faces_list.push_back(complex_face);
                }
            } // for(const CAMFImporter_NodeElement* ne_volume_child: ne_volume->Child)

            /**** Split faces list: one list per mesh ****/
            PostprocessHelper_SplitFacesByTextureID(complex_faces_list, complex_faces_toplist);

            /***** Create mesh for every faces list ******/
            for (std::list<SComplexFace> &face_list_cur : complex_faces_toplist) {
                auto VertexIndex_GetMinimal = [](const std::list<SComplexFace> &pFaceList, const size_t *pBiggerThan) -> size_t {
                    size_t rv = 0;

                    if (pBiggerThan != nullptr) {
                        bool found = false;
                        const size_t biggerThan = *pBiggerThan;
                        for (const SComplexFace &face : pFaceList) {
                            for (size_t idx_vert = 0; idx_vert < face.Face.mNumIndices; idx_vert++) {
                                if (face.Face.mIndices[idx_vert] > biggerThan) {
                                    rv = face.Face.mIndices[idx_vert];
                                    found = true;
                                    break;
                                }
                            }

                            if (found) {
                                break;
                            }
                        }

                        if (!found) {
                            return *pBiggerThan;
                        }
                    } else {
                        rv = pFaceList.front().Face.mIndices[0];
                    } // if(pBiggerThan != nullptr) else

                    for (const SComplexFace &face : pFaceList) {
                        for (size_t vi = 0; vi < face.Face.mNumIndices; vi++) {
                            if (face.Face.mIndices[vi] < rv) {
                                if (pBiggerThan != nullptr) {
                                    if (face.Face.mIndices[vi] > *pBiggerThan) rv = face.Face.mIndices[vi];
                                } else {
                                    rv = face.Face.mIndices[vi];
                                }
                            }
                        }
                    } // for(const SComplexFace& face: pFaceList)

                    return rv;
                }; // auto VertexIndex_GetMinimal = [](const std::list<SComplexFace>& pFaceList, const size_t* pBiggerThan) -> size_t

                auto VertexIndex_Replace = [](std::list<SComplexFace> &pFaceList, const size_t pIdx_From, const size_t pIdx_To) -> void {
                    for (const SComplexFace &face : pFaceList) {
                        for (size_t vi = 0; vi < face.Face.mNumIndices; vi++) {
                            if (face.Face.mIndices[vi] == pIdx_From) face.Face.mIndices[vi] = static_cast<unsigned int>(pIdx_To);
                        }
                    }
                }; // auto VertexIndex_Replace = [](std::list<SComplexFace>& pFaceList, const size_t pIdx_From, const size_t pIdx_To) -> void

                auto Vertex_CalculateColor = [&](const size_t pIdx) -> aiColor4D {
                    // Color priorities(In descending order):
                    // 1. triangle color;
                    // 2. vertex color;
                    // 3. volume color;
                    // 4. object color;
                    // 5. material;
                    // 6. default - invisible coat.
                    //
                    // Fill vertices colors in color priority list above that's points from 1 to 6.
                    if ((pIdx < pVertexColorArray.size()) && (pVertexColorArray[pIdx] != nullptr)) // check for vertex color
                    {
                        if (pVertexColorArray[pIdx]->Composed)
                            throw DeadlyImportError("IME: vertex color composed");
                        else
                            return pVertexColorArray[pIdx]->Color;
                    } else if (ne_volume_color != nullptr) // check for volume color
                    {
                        if (ne_volume_color->Composed)
                            throw DeadlyImportError("IME: volume color composed");
                        else
                            return ne_volume_color->Color;
                    } else if (pObjectColor != nullptr) // check for object color
                    {
                        if (pObjectColor->Composed)
                            throw DeadlyImportError("IME: object color composed");
                        else
                            return pObjectColor->Color;
                    } else if (cur_mat != nullptr) // check for material
                    {
                        return cur_mat->GetColor(pVertexCoordinateArray.at(pIdx).x, pVertexCoordinateArray.at(pIdx).y, pVertexCoordinateArray.at(pIdx).z);
                    } else // set default color.
                    {
                        return { 0, 0, 0, 0 };
                    } // if((vi < pVertexColorArray.size()) && (pVertexColorArray[vi] != nullptr)) else
                }; // auto Vertex_CalculateColor = [&](const size_t pIdx) -> aiColor4D

                aiMesh *tmesh = new aiMesh;

                tmesh->mPrimitiveTypes = aiPrimitiveType_TRIANGLE; // Only triangles is supported by AMF.
                //
                // set geometry and colors (vertices)
                //
                // copy faces/triangles
                tmesh->mNumFaces = static_cast<unsigned int>(face_list_cur.size());
                tmesh->mFaces = new aiFace[tmesh->mNumFaces];

                // Create vertices list and optimize indices. Optimization mean following.In AMF all volumes use one big list of vertices. And one volume
                // can use only part of vertices list, for example: vertices list contain few thousands of vertices and volume use vertices 1, 3, 10.
                // Do you need all this thousands of garbage? Of course no. So, optimization step transform sparse indices set to continuous.
                size_t VertexCount_Max = tmesh->mNumFaces * 3; // 3 - triangles.
                std::vector<aiVector3D> vert_arr, texcoord_arr;
                std::vector<aiColor4D> col_arr;

                vert_arr.reserve(VertexCount_Max * 2); // "* 2" - see below TODO.
                col_arr.reserve(VertexCount_Max * 2);

                { // fill arrays
                    size_t vert_idx_from, vert_idx_to;

                    // first iteration.
                    vert_idx_to = 0;
                    vert_idx_from = VertexIndex_GetMinimal(face_list_cur, nullptr);
                    vert_arr.push_back(pVertexCoordinateArray.at(vert_idx_from));
                    col_arr.push_back(Vertex_CalculateColor(vert_idx_from));
                    if (vert_idx_from != vert_idx_to) VertexIndex_Replace(face_list_cur, vert_idx_from, vert_idx_to);

                    // rest iterations
                    do {
                        vert_idx_from = VertexIndex_GetMinimal(face_list_cur, &vert_idx_to);
                        if (vert_idx_from == vert_idx_to) break; // all indices are transferred,

                        vert_arr.push_back(pVertexCoordinateArray.at(vert_idx_from));
                        col_arr.push_back(Vertex_CalculateColor(vert_idx_from));
                        vert_idx_to++;
                        if (vert_idx_from != vert_idx_to) VertexIndex_Replace(face_list_cur, vert_idx_from, vert_idx_to);

                    } while (true);
                } // fill arrays. END.

                //
                // check if triangle colors are used and create additional faces if needed.
                //
                for (const SComplexFace &face_cur : face_list_cur) {
                    if (face_cur.Color != nullptr) {
                        aiColor4D face_color;
                        size_t vert_idx_new = vert_arr.size();

                        if (face_cur.Color->Composed)
                            throw DeadlyImportError("IME: face color composed");
                        else
                            face_color = face_cur.Color->Color;

                        for (size_t idx_ind = 0; idx_ind < face_cur.Face.mNumIndices; idx_ind++) {
                            vert_arr.push_back(vert_arr.at(face_cur.Face.mIndices[idx_ind]));
                            col_arr.push_back(face_color);
                            face_cur.Face.mIndices[idx_ind] = static_cast<unsigned int>(vert_idx_new++);
                        }
                    } // if(face_cur.Color != nullptr)
                } // for(const SComplexFace& face_cur: face_list_cur)

                //
                // if texture is used then copy texture coordinates too.
                //
                if (face_list_cur.front().TexMap != nullptr) {
                    size_t idx_vert_new = vert_arr.size();
                    ///TODO: clean unused vertices. "* 2": in certain cases - mesh full of triangle colors - vert_arr will contain duplicated vertices for
                    /// colored triangles and initial vertices (for colored vertices) which in real became unused. This part need more thinking about
                    /// optimization.
                    bool *idx_vert_used;

                    idx_vert_used = new bool[VertexCount_Max * 2];
                    for (size_t i = 0, i_e = VertexCount_Max * 2; i < i_e; i++)
                        idx_vert_used[i] = false;

                    // This ID's will be used when set materials ID in scene.
                    tmesh->mMaterialIndex = static_cast<unsigned int>(PostprocessHelper_GetTextureID_Or_Create(face_list_cur.front().TexMap->TextureID_R,
                            face_list_cur.front().TexMap->TextureID_G,
                            face_list_cur.front().TexMap->TextureID_B,
                            face_list_cur.front().TexMap->TextureID_A));
                    texcoord_arr.resize(VertexCount_Max * 2);
                    for (const SComplexFace &face_cur : face_list_cur) {
                        for (size_t idx_ind = 0; idx_ind < face_cur.Face.mNumIndices; idx_ind++) {
                            const size_t idx_vert = face_cur.Face.mIndices[idx_ind];

                            if (!idx_vert_used[idx_vert]) {
                                texcoord_arr.at(idx_vert) = face_cur.TexMap->TextureCoordinate[idx_ind];
                                idx_vert_used[idx_vert] = true;
                            } else if (texcoord_arr.at(idx_vert) != face_cur.TexMap->TextureCoordinate[idx_ind]) {
                                // in that case one vertex is shared with many texture coordinates. We need to duplicate vertex with another texture
                                // coordinates.
                                vert_arr.push_back(vert_arr.at(idx_vert));
                                col_arr.push_back(col_arr.at(idx_vert));
                                texcoord_arr.at(idx_vert_new) = face_cur.TexMap->TextureCoordinate[idx_ind];
                                face_cur.Face.mIndices[idx_ind] = static_cast<unsigned int>(idx_vert_new++);
                            }
                        } // for(size_t idx_ind = 0; idx_ind < face_cur.Face.mNumIndices; idx_ind++)
                    } // for(const SComplexFace& face_cur: face_list_cur)

                    delete[] idx_vert_used;
                    // shrink array
                    texcoord_arr.resize(idx_vert_new);
                } // if(face_list_cur.front().TexMap != nullptr)

                //
                // copy collected data to mesh
                //
                tmesh->mNumVertices = static_cast<unsigned int>(vert_arr.size());
                tmesh->mVertices = new aiVector3D[tmesh->mNumVertices];
                tmesh->mColors[0] = new aiColor4D[tmesh->mNumVertices];

                memcpy(tmesh->mVertices, vert_arr.data(), tmesh->mNumVertices * sizeof(aiVector3D));
                memcpy(tmesh->mColors[0], col_arr.data(), tmesh->mNumVertices * sizeof(aiColor4D));
                if (texcoord_arr.size() > 0) {
                    tmesh->mTextureCoords[0] = new aiVector3D[tmesh->mNumVertices];
                    memcpy(tmesh->mTextureCoords[0], texcoord_arr.data(), tmesh->mNumVertices * sizeof(aiVector3D));
                    tmesh->mNumUVComponents[0] = 2; // U and V stored in "x", "y" of aiVector3D.
                }

                size_t idx_face = 0;
                for (const SComplexFace &face_cur : face_list_cur)
                    tmesh->mFaces[idx_face++] = face_cur.Face;

                // store new aiMesh
                mesh_idx.push_back(static_cast<unsigned int>(pMeshList.size()));
                pMeshList.push_back(tmesh);
            } // for(const std::list<SComplexFace>& face_list_cur: complex_faces_toplist)
        } // if(ne_child->Type == CAMFImporter_NodeElement::ENET_Volume)
    } // for(const CAMFImporter_NodeElement* ne_child: pNodeElement.Child)

    // if meshes was created then assign new indices with current aiNode
    if (!mesh_idx.empty()) {
        std::list<unsigned int>::const_iterator mit = mesh_idx.begin();

        pSceneNode.mNumMeshes = static_cast<unsigned int>(mesh_idx.size());
        pSceneNode.mMeshes = new unsigned int[pSceneNode.mNumMeshes];
        for (size_t i = 0; i < pSceneNode.mNumMeshes; i++)
            pSceneNode.mMeshes[i] = *mit++;
    } // if(mesh_idx.size() > 0)
}

void AMFImporter::Postprocess_BuildMaterial(const AMFMaterial &pMaterial) {
    SPP_Material new_mat;

    new_mat.ID = pMaterial.ID;
    for (const AMFNodeElementBase *mat_child : pMaterial.Child) {
        if (mat_child->Type == AMFNodeElementBase::ENET_Color) {
            new_mat.Color = (AMFColor*)mat_child;
        } else if (mat_child->Type == AMFNodeElementBase::ENET_Metadata) {
            new_mat.Metadata.push_back((AMFMetadata *)mat_child);
        }
    } // for(const CAMFImporter_NodeElement* mat_child; pMaterial.Child)

    // place converted material to special list
    mMaterial_Converted.push_back(new_mat);
}

void AMFImporter::Postprocess_BuildConstellation(AMFConstellation &pConstellation, NodeArray &nodeArray) const {
    aiNode *con_node;
    std::list<aiNode *> ch_node;

    // We will build next hierarchy:
    // aiNode as parent (<constellation>) for set of nodes as a children
    //  |- aiNode for transformation (<instance> -> <delta...>, <r...>) - aiNode for pointing to object ("objectid")
    //  ...
    //  \_ aiNode for transformation (<instance> -> <delta...>, <r...>) - aiNode for pointing to object ("objectid")
    con_node = new aiNode;
    con_node->mName = pConstellation.ID;
    // Walk through children and search for instances of another objects, constellations.
    for (const AMFNodeElementBase *ne : pConstellation.Child) {
        aiMatrix4x4 tmat;
        aiNode *t_node;
        aiNode *found_node;

        if (ne->Type == AMFNodeElementBase::ENET_Metadata) continue;
        if (ne->Type != AMFNodeElementBase::ENET_Instance) throw DeadlyImportError("Only <instance> nodes can be in <constellation>.");

        // create alias for conveniance
        AMFInstance &als = *((AMFInstance *)ne);
        // find referenced object
        if (!Find_ConvertedNode(als.ObjectID, nodeArray, &found_node)) Throw_ID_NotFound(als.ObjectID);

        // create node for applying transformation
        t_node = new aiNode;
        t_node->mParent = con_node;
        // apply transformation
        aiMatrix4x4::Translation(als.Delta, tmat), t_node->mTransformation *= tmat;
        aiMatrix4x4::RotationX(als.Rotation.x, tmat), t_node->mTransformation *= tmat;
        aiMatrix4x4::RotationY(als.Rotation.y, tmat), t_node->mTransformation *= tmat;
        aiMatrix4x4::RotationZ(als.Rotation.z, tmat), t_node->mTransformation *= tmat;
        // create array for one child node
        t_node->mNumChildren = 1;
        t_node->mChildren = new aiNode *[t_node->mNumChildren];
        SceneCombiner::Copy(&t_node->mChildren[0], found_node);
        t_node->mChildren[0]->mParent = t_node;
        ch_node.push_back(t_node);
    } // for(const CAMFImporter_NodeElement* ne: pConstellation.Child)

    // copy found aiNode's as children
    if (ch_node.empty()) throw DeadlyImportError("<constellation> must have at least one <instance>.");

    size_t ch_idx = 0;

    con_node->mNumChildren = static_cast<unsigned int>(ch_node.size());
    con_node->mChildren = new aiNode *[con_node->mNumChildren];
    for (aiNode *node : ch_node)
        con_node->mChildren[ch_idx++] = node;

    // and place "root" of <constellation> node to node list
    nodeArray.push_back(con_node);
}

void AMFImporter::Postprocess_BuildScene(aiScene *pScene) {
    NodeArray nodeArray;
    MeshArray mesh_list;
    AMFMetaDataArray meta_list;

    //
    // Because for AMF "material" is just complex colors mixing so aiMaterial will not be used.
    // For building aiScene we are must to do few steps:
    // at first creating root node for aiScene.
    pScene->mRootNode = new aiNode;
    pScene->mRootNode->mParent = nullptr;
    pScene->mFlags |= AI_SCENE_FLAGS_ALLOW_SHARED;
    // search for root(<amf>) element
    AMFNodeElementBase *root_el = nullptr;

    for (AMFNodeElementBase *ne : mNodeElement_List) {
        if (ne->Type != AMFNodeElementBase::ENET_Root) {
            continue;
        }

        root_el = ne;
        break;
    } // for(const CAMFImporter_NodeElement* ne: mNodeElement_List)

    // Check if root element are found.
    if (root_el == nullptr) {
        throw DeadlyImportError("Root(<amf>) element not found.");
    }

    // after that walk through children of root and collect data. Five types of nodes can be placed at top level - in <amf>: <object>, <material>, <texture>,
    // <constellation> and <metadata>. But at first we must read <material> and <texture> because they will be used in <object>. <metadata> can be read
    // at any moment.
    //
    // 1. <material>
    // 2. <texture> will be converted later when processing triangles list. \sa Postprocess_BuildMeshSet
    for (const AMFNodeElementBase *root_child : root_el->Child) {
        if (root_child->Type == AMFNodeElementBase::ENET_Material) {
            Postprocess_BuildMaterial(*((AMFMaterial *)root_child));
        }
    }

    // After "appearance" nodes we must read <object> because it will be used in <constellation> -> <instance>.
    //
    // 3. <object>
    for (const AMFNodeElementBase *root_child : root_el->Child) {
        if (root_child->Type == AMFNodeElementBase::ENET_Object) {
            aiNode *tnode = nullptr;

            // for <object> mesh and node must be built: object ID assigned to aiNode name and will be used in future for <instance>
            Postprocess_BuildNodeAndObject(*((AMFObject *)root_child), mesh_list, &tnode);
            if (tnode != nullptr) {
                nodeArray.push_back(tnode);
            }
        }
    } // for(const CAMFImporter_NodeElement* root_child: root_el->Child)

    // And finally read rest of nodes.
    //
    for (const AMFNodeElementBase *root_child : root_el->Child) {
        // 4. <constellation>
        if (root_child->Type == AMFNodeElementBase::ENET_Constellation) {
            // <object> and <constellation> at top of self abstraction use aiNode. So we can use only aiNode list for creating new aiNode's.
            Postprocess_BuildConstellation(*((AMFConstellation *)root_child), nodeArray);
        }

        // 5, <metadata>
        if (root_child->Type == AMFNodeElementBase::ENET_Metadata) meta_list.push_back((AMFMetadata *)root_child);
    } // for(const CAMFImporter_NodeElement* root_child: root_el->Child)

    // at now we can add collected metadata to root node
    Postprocess_AddMetadata(meta_list, *pScene->mRootNode);
    //
    // Check constellation children
    //
    // As said in specification:
    // "When multiple objects and constellations are defined in a single file, only the top level objects and constellations are available for printing."
    // What that means? For example: if some object is used in constellation then you must show only constellation but not original object.
    // And at this step we are checking that relations.
nl_clean_loop:

    if (nodeArray.size() > 1) {
        // walk through all nodes
        for (NodeArray::iterator nl_it = nodeArray.begin(); nl_it != nodeArray.end(); ++nl_it) {
            // and try to find them in another top nodes.
            NodeArray::const_iterator next_it = nl_it;

            ++next_it;
            for (; next_it != nodeArray.end(); ++next_it) {
                if ((*next_it)->FindNode((*nl_it)->mName) != nullptr) {
                    // if current top node(nl_it) found in another top node then erase it from node_list and restart search loop.
                    nodeArray.erase(nl_it);

                    goto nl_clean_loop;
                }
            } // for(; next_it != node_list.end(); next_it++)
        } // for(std::list<aiNode*>::const_iterator nl_it = node_list.begin(); nl_it != node_list.end(); nl_it++)
    }

    //
    // move created objects to aiScene
    //
    //
    // Nodes
    if (!nodeArray.empty()) {
        NodeArray::const_iterator nl_it = nodeArray.begin();

        pScene->mRootNode->mNumChildren = static_cast<unsigned int>(nodeArray.size());
        pScene->mRootNode->mChildren = new aiNode *[pScene->mRootNode->mNumChildren];
        for (size_t i = 0; i < pScene->mRootNode->mNumChildren; i++) {
            // Objects and constellation that must be showed placed at top of hierarchy in <amf> node. So all aiNode's in node_list must have
            // mRootNode only as parent.
            (*nl_it)->mParent = pScene->mRootNode;
            pScene->mRootNode->mChildren[i] = *nl_it++;
        }
    } // if(node_list.size() > 0)

    //
    // Meshes
    if (!mesh_list.empty()) {
        MeshArray::const_iterator ml_it = mesh_list.begin();

        pScene->mNumMeshes = static_cast<unsigned int>(mesh_list.size());
        pScene->mMeshes = new aiMesh *[pScene->mNumMeshes];
        for (size_t i = 0; i < pScene->mNumMeshes; i++)
            pScene->mMeshes[i] = *ml_it++;
    } // if(mesh_list.size() > 0)

    //
    // Textures
    pScene->mNumTextures = static_cast<unsigned int>(mTexture_Converted.size());
    if (pScene->mNumTextures > 0) {
        size_t idx;

        idx = 0;
        pScene->mTextures = new aiTexture *[pScene->mNumTextures];
        for (const SPP_Texture &tex_convd : mTexture_Converted) {
            pScene->mTextures[idx] = new aiTexture;
            pScene->mTextures[idx]->mWidth = static_cast<unsigned int>(tex_convd.Width);
            pScene->mTextures[idx]->mHeight = static_cast<unsigned int>(tex_convd.Height);
            pScene->mTextures[idx]->pcData = (aiTexel *)tex_convd.Data;
            // texture format description.
            strcpy(pScene->mTextures[idx]->achFormatHint, tex_convd.FormatHint);
            idx++;
        } // for(const SPP_Texture& tex_convd: mTexture_Converted)

        // Create materials for embedded textures.
        idx = 0;
        pScene->mNumMaterials = static_cast<unsigned int>(mTexture_Converted.size());
        pScene->mMaterials = new aiMaterial *[pScene->mNumMaterials];
        for (const SPP_Texture &tex_convd : mTexture_Converted) {
            const aiString texture_id(AI_EMBEDDED_TEXNAME_PREFIX + ai_to_string(idx));
            const int mode = aiTextureOp_Multiply;
            const int repeat = tex_convd.Tiled ? 1 : 0;

            pScene->mMaterials[idx] = new aiMaterial;
            pScene->mMaterials[idx]->AddProperty(&texture_id, AI_MATKEY_TEXTURE_DIFFUSE(0));
            pScene->mMaterials[idx]->AddProperty(&mode, 1, AI_MATKEY_TEXOP_DIFFUSE(0));
            pScene->mMaterials[idx]->AddProperty(&repeat, 1, AI_MATKEY_MAPPINGMODE_U_DIFFUSE(0));
            pScene->mMaterials[idx]->AddProperty(&repeat, 1, AI_MATKEY_MAPPINGMODE_V_DIFFUSE(0));
            idx++;
        }
    } // if(pScene->mNumTextures > 0)
} // END: after that walk through children of root and collect data

} // namespace Assimp

#endif // !ASSIMP_BUILD_NO_AMF_IMPORTER
