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/** @file Implementation of the STL importer class */

#ifndef ASSIMP_BUILD_NO_STL_IMPORTER

#include "STLLoader.h"

#include <assimp/ParsingUtils.h>

#include <assimp/fast_atof.h>

#include <assimp/importerdesc.h>

#include <assimp/scene.h>

#include <assimp/DefaultLogger.hpp>

#include <assimp/IOSystem.hpp>

#include <memory>

namespace Assimp {

namespace {

static constexpr aiImporterDesc desc = {

    "Stereolithography (STL) Importer",

    "",

    "",

    "",

    aiImporterFlags_SupportTextFlavour | aiImporterFlags_SupportBinaryFlavour,

    0,

    0,

    0,

    0,

    "stl"

};

// A valid binary STL buffer should consist of the following elements, in order:

// 1) 80 byte header

// 2) 4 byte face count

// 3) 50 bytes per face

static bool IsBinarySTL(const char *buffer, size_t fileSize) {

    if (fileSize < 84) {

        return false;

    }

    const char *facecount_pos = buffer + 80;

    uint32_t faceCount(0);

    ::memcpy(&faceCount, facecount_pos, sizeof(uint32_t));

    const uint32_t expectedBinaryFileSize = faceCount * 50 + 84;

    return expectedBinaryFileSize == fileSize;

}

static const size_t BufferSize = 500;

static const char UnicodeBoundary = 127;

// An ascii STL buffer will begin with "solid NAME", where NAME is optional.

// Note: The "solid NAME" check is necessary, but not sufficient, to determine

// if the buffer is ASCII; a binary header could also begin with "solid NAME".

static bool IsAsciiSTL(const char *buffer, size_t fileSize) {

    if (IsBinarySTL(buffer, fileSize))

        return false;

    const char *bufferEnd = buffer + fileSize;

    if (!SkipSpaces(&buffer, bufferEnd)) {

        return false;

    }

    if (buffer + 5 >= bufferEnd) {

        return false;

    }

    bool isASCII(strncmp(buffer, "solid", 5) == 0);

    if (isASCII) {

        // A lot of importers are write solid even if the file is binary. So we have to check for ASCII-characters.

        if (fileSize >= BufferSize) {

            isASCII = true;

            for (unsigned int i = 0; i < BufferSize; i++) {

                if (buffer[i] > UnicodeBoundary) {

                    isASCII = false;

                    break;

                }

            }

        }

    }

    return isASCII;

}

} // namespace

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

// Constructor to be privately used by Importer

STLImporter::STLImporter() :

        mBuffer(),

        mFileSize(0),

        mScene() {

    // empty

}

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

// Destructor, private as well

STLImporter::~STLImporter() = default;

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

// Returns whether the class can handle the format of the given file.

bool STLImporter::CanRead(const std::string &pFile, IOSystem *pIOHandler, bool /*checkSig*/) const {

    static const char *tokens[] = { "STL", "solid" };

    return SearchFileHeaderForToken(pIOHandler, pFile, tokens, AI_COUNT_OF(tokens));

}

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

const aiImporterDesc *STLImporter::GetInfo() const {

    return &desc;

}

void addFacesToMesh(aiMesh *pMesh) {

    pMesh->mFaces = new aiFace[pMesh->mNumFaces];

    for (unsigned int i = 0, p = 0; i < pMesh->mNumFaces; ++i) {

        aiFace &face = pMesh->mFaces[i];

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

        for (unsigned int o = 0; o < 3; ++o, ++p) {

            face.mIndices[o] = p;

        }

    }

}

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

// Imports the given file into the given scene structure.

void STLImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) {

    std::unique_ptr<IOStream> file(pIOHandler->Open(pFile, "rb"));

    // Check whether we can read from the file

    if (file == nullptr) {

        throw DeadlyImportError("Failed to open STL file ", pFile, ".");

    }

    mFileSize = file->FileSize();

    // allocate storage and copy the contents of the file to a memory buffer

    // (terminate it with zero)

    std::vector<char> buffer2;

    TextFileToBuffer(file.get(), buffer2);

    mScene = pScene;

    mBuffer = &buffer2[0];

    // the default vertex color is light gray.

    mClrColorDefault.r = mClrColorDefault.g = mClrColorDefault.b = mClrColorDefault.a = 0.6f;

    // allocate a single node

    mScene->mRootNode = new aiNode();

    bool bMatClr = false;

    if (IsBinarySTL(mBuffer, mFileSize)) {

        bMatClr = LoadBinaryFile();

    } else if (IsAsciiSTL(mBuffer, mFileSize)) {

        LoadASCIIFile(mScene->mRootNode);

    } else {

        throw DeadlyImportError("Failed to determine STL storage representation for ", pFile, ".");

    }

    // create a single default material, using a white diffuse color for consistency with

    // other geometric types (e.g., PLY).

    aiMaterial *pcMat = new aiMaterial();

    aiString s;

    s.Set(AI_DEFAULT_MATERIAL_NAME);

    pcMat->AddProperty(&s, AI_MATKEY_NAME);

    aiColor4D clrDiffuse(ai_real(1.0), ai_real(1.0), ai_real(1.0), ai_real(1.0));

    if (bMatClr) {

        clrDiffuse = mClrColorDefault;

    }

    pcMat->AddProperty(&clrDiffuse, 1, AI_MATKEY_COLOR_DIFFUSE);

    pcMat->AddProperty(&clrDiffuse, 1, AI_MATKEY_COLOR_SPECULAR);

    clrDiffuse = aiColor4D(0.05f, 0.05f, 0.05f, 1.0f);

    pcMat->AddProperty(&clrDiffuse, 1, AI_MATKEY_COLOR_AMBIENT);

    mScene->mNumMaterials = 1;

    mScene->mMaterials = new aiMaterial *[1];

    mScene->mMaterials[0] = pcMat;

    mBuffer = nullptr;

}

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

// Read an ASCII STL file

void STLImporter::LoadASCIIFile(aiNode *root) {

    MeshArray meshes;

    std::vector<aiNode *> nodes;

    const char *sz = mBuffer;

    const char *bufferEnd = mBuffer + mFileSize;

    std::vector<aiVector3D> positionBuffer;

    std::vector<aiVector3D> normalBuffer;

    // try to guess how many vertices we could have

    // assume we'll need 160 bytes for each face

    size_t sizeEstimate = std::max(1ull, mFileSize / 160ull) * 3ull;

    positionBuffer.reserve(sizeEstimate);

    normalBuffer.reserve(sizeEstimate);

    while (IsAsciiSTL(sz, static_cast<unsigned int>(bufferEnd - sz))) {

        std::vector<unsigned int> meshIndices;

        aiMesh *pMesh = new aiMesh();

        pMesh->mMaterialIndex = 0;

        meshIndices.push_back((unsigned int)meshes.size());

        meshes.push_back(pMesh);

        aiNode *node = new aiNode;

        node->mParent = root;

        nodes.push_back(node);

        SkipSpaces(&sz, bufferEnd);

        ai_assert(!IsLineEnd(sz));

        sz += 5; // skip the "solid"

        SkipSpaces(&sz, bufferEnd);

        const char *szMe = sz;

        while (!IsSpaceOrNewLine(*sz)) {

            sz++;

        }

        size_t temp = (size_t)(sz - szMe);

        // setup the name of the node

        if (temp) {

            if (temp >= AI_MAXLEN) {

                throw DeadlyImportError("STL: Node name too long");

            }

            std::string name(szMe, temp);

            node->mName.Set(name.c_str());

            pMesh->mName.Set(name.c_str());

        } else {

            mScene->mRootNode->mName.Set("<STL_ASCII>");

        }

        unsigned int faceVertexCounter = 3;

        for (;;) {

            // go to the next token

            if (!SkipSpacesAndLineEnd(&sz, bufferEnd)) {

                // seems we're finished although there was no end marker

                ASSIMP_LOG_WARN("STL: unexpected EOF. \'endsolid\' keyword was expected");

                break;

            }

            // facet normal -0.13 -0.13 -0.98

            if (!strncmp(sz, "facet", 5) && IsSpaceOrNewLine(*(sz + 5)) && *(sz + 5) != '\0') {

                if (faceVertexCounter != 3) {

                    ASSIMP_LOG_WARN("STL: A new facet begins but the old is not yet complete");

                }

                faceVertexCounter = 0;

                sz += 6;

                SkipSpaces(&sz, bufferEnd);

                if (strncmp(sz, "normal", 6)) {

                    ASSIMP_LOG_WARN("STL: a facet normal vector was expected but not found");

                } else {

                    if (sz[6] == '\0') {

                        throw DeadlyImportError("STL: unexpected EOF while parsing facet");

                    }

                    aiVector3D vn;

                    sz += 7;

                    SkipSpaces(&sz, bufferEnd);

                    sz = fast_atoreal_move(sz, vn.x);

                    SkipSpaces(&sz, bufferEnd);

                    sz = fast_atoreal_move(sz, vn.y);

                    SkipSpaces(&sz, bufferEnd);

                    sz = fast_atoreal_move(sz, vn.z);

                    normalBuffer.emplace_back(vn);

                    normalBuffer.emplace_back(vn);

                    normalBuffer.emplace_back(vn);

                }

            } else if (!strncmp(sz, "vertex", 6) && IsSpaceOrNewLine(*(sz + 6))) { // vertex 1.50000 1.50000 0.00000

                if (faceVertexCounter >= 3) {

                    ASSIMP_LOG_ERROR("STL: a facet with more than 3 vertices has been found");

                    ++sz;

                } else {

                    if (sz[6] == '\0') {

                        throw DeadlyImportError("STL: unexpected EOF while parsing facet");

                    }

                    sz += 7;

                    SkipSpaces(&sz, bufferEnd);

                    positionBuffer.emplace_back();

                    aiVector3D *vn = &positionBuffer.back();

                    sz = fast_atoreal_move(sz, vn->x);

                    SkipSpaces(&sz, bufferEnd);

                    sz = fast_atoreal_move(sz, vn->y);

                    SkipSpaces(&sz, bufferEnd);

                    sz = fast_atoreal_move(sz, vn->z);

                    faceVertexCounter++;

                }

            } else if (!::strncmp(sz, "endsolid", 8)) {

                do {

                    ++sz;

                } while (!IsLineEnd(*sz));

                SkipSpacesAndLineEnd(&sz, bufferEnd);

                // finished!

                break;

            } else { // else skip the whole identifier

                do {

                    ++sz;

                } while (!IsSpaceOrNewLine(*sz));

            }

        }

        if (positionBuffer.empty()) {

            pMesh->mNumFaces = 0;

            ASSIMP_LOG_WARN("STL: mesh is empty or invalid; no data loaded");

        }

        if (positionBuffer.size() % 3 != 0) {

            pMesh->mNumFaces = 0;

            throw DeadlyImportError("STL: Invalid number of vertices");

        }

        if (normalBuffer.size() != positionBuffer.size()) {

            pMesh->mNumFaces = 0;

            throw DeadlyImportError("Normal buffer size does not match position buffer size");

        }

        // only process position buffer when filled, else exception when accessing with index operator

        // see line 353: only warning is triggered

        // see line 373(now): access to empty position buffer with index operator forced exception

        if (!positionBuffer.empty()) {

            pMesh->mNumFaces = static_cast<unsigned int>(positionBuffer.size() / 3);

            pMesh->mNumVertices = static_cast<unsigned int>(positionBuffer.size());

            pMesh->mVertices = new aiVector3D[pMesh->mNumVertices];

            for (size_t i = 0; i < pMesh->mNumVertices; ++i) {

                pMesh->mVertices[i].x = positionBuffer[i].x;

                pMesh->mVertices[i].y = positionBuffer[i].y;

                pMesh->mVertices[i].z = positionBuffer[i].z;

            }

            positionBuffer.clear();

        }

        // also only process normalBuffer when filled, else exception when accessing with index operator

        if (!normalBuffer.empty()) {

            pMesh->mNormals = new aiVector3D[pMesh->mNumVertices];

            for (size_t i = 0; i < pMesh->mNumVertices; ++i) {

                pMesh->mNormals[i].x = normalBuffer[i].x;

                pMesh->mNormals[i].y = normalBuffer[i].y;

                pMesh->mNormals[i].z = normalBuffer[i].z;

            }

            normalBuffer.clear();

        }

        // now copy faces

        addFacesToMesh(pMesh);

        // assign the meshes to the current node

        pushMeshesToNode(meshIndices, node);

    }

    // now add the loaded meshes

    mScene->mNumMeshes = (unsigned int)meshes.size();

    mScene->mMeshes = new aiMesh *[mScene->mNumMeshes];

    for (size_t i = 0; i < meshes.size(); i++) {

        mScene->mMeshes[i] = meshes[i];

    }

    root->mNumChildren = (unsigned int)nodes.size();

    root->mChildren = new aiNode *[root->mNumChildren];

    for (size_t i = 0; i < nodes.size(); ++i) {

        root->mChildren[i] = nodes[i];

    }

}

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

// Read a binary STL file

bool STLImporter::LoadBinaryFile() {

    // allocate one mesh

    mScene->mNumMeshes = 1;

    mScene->mMeshes = new aiMesh *[1];

    aiMesh *pMesh = mScene->mMeshes[0] = new aiMesh();

    pMesh->mMaterialIndex = 0;

    // skip the first 80 bytes

    if (mFileSize < 84) {

        throw DeadlyImportError("STL: file is too small for the header");

    }

    bool bIsMaterialise = false;

    // search for an occurrence of "COLOR=" in the header

    const unsigned char *sz2 = (const unsigned char *)mBuffer;

    const unsigned char *const szEnd = sz2 + 80;

    while (sz2 < szEnd) {

        if ('C' == *sz2++ && 'O' == *sz2++ && 'L' == *sz2++ &&

                'O' == *sz2++ && 'R' == *sz2++ && '=' == *sz2++) {

            // read the default vertex color for facets

            bIsMaterialise = true;

            ASSIMP_LOG_INFO("STL: Taking code path for Materialise files");

            const ai_real invByte = (ai_real)1.0 / (ai_real)255.0;

            mClrColorDefault.r = (*sz2++) * invByte;

            mClrColorDefault.g = (*sz2++) * invByte;

            mClrColorDefault.b = (*sz2++) * invByte;

            mClrColorDefault.a = (*sz2++) * invByte;

            break;

        }

    }

    const unsigned char *sz = (const unsigned char *)mBuffer + 80;

    // now read the number of facets

    mScene->mRootNode->mName.Set("<STL_BINARY>");

    pMesh->mNumFaces = *((uint32_t *)sz);

    sz += 4;

    if (mFileSize < 84ull + pMesh->mNumFaces * 50ull) {

        throw DeadlyImportError("STL: file is too small to hold all facets");

    }

    if (!pMesh->mNumFaces) {

        throw DeadlyImportError("STL: file is empty. There are no facets defined");

    }

    pMesh->mNumVertices = pMesh->mNumFaces * 3;

    aiVector3D *vp = pMesh->mVertices = new aiVector3D[pMesh->mNumVertices];

    aiVector3D *vn = pMesh->mNormals = new aiVector3D[pMesh->mNumVertices];

    aiVector3f *theVec;

    aiVector3f theVec3F;

    for (unsigned int i = 0; i < pMesh->mNumFaces; ++i) {

        // NOTE: Blender sometimes writes empty normals ... this is not

        // our fault ... the RemoveInvalidData helper step should fix that

        // There's one normal for the face in the STL; use it three times

        // for vertex normals

        theVec = (aiVector3f *)sz;

        ::memcpy(&theVec3F, theVec, sizeof(aiVector3f));

        vn->x = theVec3F.x;

        vn->y = theVec3F.y;

        vn->z = theVec3F.z;

        *(vn + 1) = *vn;

        *(vn + 2) = *vn;

        ++theVec;

        vn += 3;

        // vertex 1

        ::memcpy(&theVec3F, theVec, sizeof(aiVector3f));

        vp->x = theVec3F.x;

        vp->y = theVec3F.y;

        vp->z = theVec3F.z;

        ++theVec;

        ++vp;

        // vertex 2

        ::memcpy(&theVec3F, theVec, sizeof(aiVector3f));

        vp->x = theVec3F.x;

        vp->y = theVec3F.y;

        vp->z = theVec3F.z;

        ++theVec;

        ++vp;

        // vertex 3

        ::memcpy(&theVec3F, theVec, sizeof(aiVector3f));

        vp->x = theVec3F.x;

        vp->y = theVec3F.y;

        vp->z = theVec3F.z;

        ++theVec;

        ++vp;

        sz = (const unsigned char *)theVec;

        uint16_t color = *((uint16_t *)sz);

        sz += 2;

        if (color & (1 << 15)) {

            // seems we need to take the color

            if (!pMesh->mColors[0]) {

                pMesh->mColors[0] = new aiColor4D[pMesh->mNumVertices];

                for (unsigned int j = 0; j < pMesh->mNumVertices; ++j) {

                    *pMesh->mColors[0]++ = mClrColorDefault;

                }

                pMesh->mColors[0] -= pMesh->mNumVertices;

                ASSIMP_LOG_INFO("STL: Mesh has vertex colors");

            }

            aiColor4D *clr = &pMesh->mColors[0][i * 3];

            clr->a = 1.0;

            const ai_real invVal((ai_real)1.0 / (ai_real)31.0);

            if (bIsMaterialise) // this is reversed

            {

                clr->r = (color & 0x1fu) * invVal;

                clr->g = ((color & (0x1fu << 5)) >> 5u) * invVal;

                clr->b = ((color & (0x1fu << 10)) >> 10u) * invVal;

            } else {

                clr->b = (color & 0x1fu) * invVal;

                clr->g = ((color & (0x1fu << 5)) >> 5u) * invVal;

                clr->r = ((color & (0x1fu << 10)) >> 10u) * invVal;

            }

            // assign the color to all vertices of the face

            *(clr + 1) = *clr;

            *(clr + 2) = *clr;

        }

    }

    // now copy faces

    addFacesToMesh(pMesh);

    aiNode *root = mScene->mRootNode;

    // allocate one node

    aiNode *node = new aiNode();

    node->mParent = root;

    root->mNumChildren = 1u;

    root->mChildren = new aiNode *[root->mNumChildren];

    root->mChildren[0] = node;

    // add all created meshes to the single node

    node->mNumMeshes = mScene->mNumMeshes;

    node->mMeshes = new unsigned int[mScene->mNumMeshes];

    for (unsigned int i = 0; i < mScene->mNumMeshes; ++i) {

        node->mMeshes[i] = i;

    }

    if (bIsMaterialise && !pMesh->mColors[0]) {

        // use the color as diffuse material color

        return true;

    }

    return false;

}

void STLImporter::pushMeshesToNode(std::vector<unsigned int> &meshIndices, aiNode *node) {

    ai_assert(nullptr != node);

    if (meshIndices.empty()) {

        return;

    }

    node->mNumMeshes = static_cast<unsigned int>(meshIndices.size());

    node->mMeshes = new unsigned int[meshIndices.size()];

    for (size_t i = 0; i < meshIndices.size(); ++i) {

        node->mMeshes[i] = meshIndices[i];

    }

    meshIndices.clear();

}

} // namespace Assimp

#endif // !! ASSIMP_BUILD_NO_STL_IMPORTER