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/** @file  OFFLoader.cpp
 *  @brief Implementation of the OFF importer class
 */

#ifndef ASSIMP_BUILD_NO_OFF_IMPORTER

// internal headers
#include "OFFLoader.h"
#include <assimp/ParsingUtils.h>
#include <assimp/fast_atof.h>
#include <memory>
#include <assimp/IOSystem.hpp>
#include <assimp/scene.h>
#include <assimp/DefaultLogger.hpp>
#include <assimp/importerdesc.h>

namespace Assimp {

static constexpr aiImporterDesc desc = {
    "OFF Importer",
    "",
    "",
    "",
    aiImporterFlags_SupportBinaryFlavour,
    0,
    0,
    0,
    0,
    "off"
};

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file.
bool OFFImporter::CanRead(const std::string &pFile, IOSystem *pIOHandler, bool /*checkSig*/) const {
    static const char *tokens[] = { "off" };
    return SearchFileHeaderForToken(pIOHandler, pFile, tokens, AI_COUNT_OF(tokens), 3);
}

// ------------------------------------------------------------------------------------------------
const aiImporterDesc *OFFImporter::GetInfo() const {
    return &desc;
}

// skip blank space, lines and comments
static void NextToken(const char **car, const char *end) {
    SkipSpacesAndLineEnd(car, end);
    while (*car < end && (**car == '#' || **car == '\n' || **car == '\r')) {
        SkipLine(car, end);
        SkipSpacesAndLineEnd(car, end);
    }
}

// ------------------------------------------------------------------------------------------------
// Imports the given file into the given scene structure.
void OFFImporter::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 OFF file ", pFile, ".");
    }

    // allocate storage and copy the contents of the file to a memory buffer
    std::vector<char> mBuffer2;
    TextFileToBuffer(file.get(), mBuffer2);
    const char *buffer = &mBuffer2[0];

    // Proper OFF header parser. We only implement normal loading for now.
    bool hasTexCoord = false, hasNormals = false, hasColors = false;
    bool hasHomogenous = false, hasDimension = false;
    unsigned int dimensions = 3;
    const char *car = buffer;
    const char *end = buffer + mBuffer2.size();
    NextToken(&car, end);

    if (car < end - 2 && car[0] == 'S' && car[1] == 'T') {
        hasTexCoord = true;
        car += 2;
    }
    if (car < end - 1 && car[0] == 'C') {
        hasColors = true;
        car++;
    }
    if (car < end - 1 && car[0] == 'N') {
        hasNormals = true;
        car++;
    }
    if (car < end - 1 && car[0] == '4') {
        hasHomogenous = true;
        car++;
    }
    if (car < end - 1 && car[0] == 'n') {
        hasDimension = true;
        car++;
    }
    if (car < end - 3 && car[0] == 'O' && car[1] == 'F' && car[2] == 'F') {
        car += 3;
        NextToken(&car, end);
    } else {
        // in case there is no OFF header (which is allowed by the
        // specification...), then we might have unintentionally read an
        // additional dimension from the primitive count fields
        dimensions = 3;
        hasHomogenous = false;
        NextToken(&car, end);

        // at this point the next token should be an integer number
        if (car >= end - 1 || *car < '0' || *car > '9') {
            throw DeadlyImportError("OFF: Header is invalid");
        }
    }
    if (hasDimension) {
        dimensions = strtoul10(car, &car);
        NextToken(&car, end);
    }
    if (dimensions > 3) {
        throw DeadlyImportError("OFF: Number of vertex coordinates higher than 3 unsupported");
    }

    NextToken(&car, end);
    const unsigned int numVertices = strtoul10(car, &car);
    NextToken(&car, end);
    const unsigned int numFaces = strtoul10(car, &car);
    NextToken(&car, end);
    strtoul10(car, &car); // skip edge count
    NextToken(&car, end);

    if (!numVertices) {
        throw DeadlyImportError("OFF: There are no valid vertices");
    }
    if (!numFaces) {
        throw DeadlyImportError("OFF: There are no valid faces");
    }

    pScene->mNumMeshes = 1;
    pScene->mMeshes = new aiMesh *[pScene->mNumMeshes];

    aiMesh *mesh = new aiMesh();
    pScene->mMeshes[0] = mesh;

    mesh->mNumFaces = numFaces;
    aiFace *faces = new aiFace[mesh->mNumFaces];
    mesh->mFaces = faces;

    mesh->mNumVertices = numVertices;
    mesh->mVertices = new aiVector3D[numVertices];
    mesh->mNormals = hasNormals ? new aiVector3D[numVertices] : nullptr;
    mesh->mColors[0] = hasColors ? new aiColor4D[numVertices] : nullptr;

    if (hasTexCoord) {
        mesh->mNumUVComponents[0] = 2;
        mesh->mTextureCoords[0] = new aiVector3D[numVertices];
    }
    char line[4096];
    buffer = car;
    const char *sz = car;
    const char *lineEnd = &line[4096];

    // now read all vertex lines
    for (unsigned int i = 0; i < numVertices; ++i) {
        if (!GetNextLine(buffer, line)) {
            ASSIMP_LOG_ERROR("OFF: The number of verts in the header is incorrect");
            break;
        }
        aiVector3D &v = mesh->mVertices[i];
        sz = line;

        // helper array to write a for loop over possible dimension values
        ai_real *vec[3] = { &v.x, &v.y, &v.z };

        // stop at dimensions: this allows loading 1D or 2D coordinate vertices
        for (unsigned int dim = 0; dim < dimensions; ++dim) {
            SkipSpaces(&sz, lineEnd);
            sz = fast_atoreal_move<ai_real>(sz, *vec[dim]);
        }

        // if has homogeneous coordinate, divide others by this one
        if (hasHomogenous) {
            SkipSpaces(&sz, lineEnd);
            ai_real w = 1.;
            sz = fast_atoreal_move<ai_real>(sz, w);
            for (unsigned int dim = 0; dim < dimensions; ++dim) {
                *(vec[dim]) /= w;
            }
        }

        // read optional normals
        if (hasNormals) {
            aiVector3D &n = mesh->mNormals[i];
            SkipSpaces(&sz, lineEnd);
            sz = fast_atoreal_move<ai_real>(sz, (ai_real &)n.x);
            SkipSpaces(&sz, lineEnd);
            sz = fast_atoreal_move<ai_real>(sz, (ai_real &)n.y);
            SkipSpaces(&sz, lineEnd);
            fast_atoreal_move<ai_real>(sz, (ai_real &)n.z);
        }

        // reading colors is a pain because the specification says it can be
        // integers or floats, and any number of them between 1 and 4 included,
        // until the next comment or end of line
        // in theory should be testing type !
        if (hasColors) {
            aiColor4D &c = mesh->mColors[0][i];
            SkipSpaces(&sz, lineEnd);
            sz = fast_atoreal_move<ai_real>(sz, (ai_real &)c.r);
            if (*sz != '#' && *sz != '\n' && *sz != '\r') {
                SkipSpaces(&sz, lineEnd);
                sz = fast_atoreal_move<ai_real>(sz, (ai_real &)c.g);
            } else {
                c.g = 0.;
            }
            if (*sz != '#' && *sz != '\n' && *sz != '\r') {
                SkipSpaces(&sz, lineEnd);
                sz = fast_atoreal_move<ai_real>(sz, (ai_real &)c.b);
            } else {
                c.b = 0.;
            }
            if (*sz != '#' && *sz != '\n' && *sz != '\r') {
                SkipSpaces(&sz, lineEnd);
                sz = fast_atoreal_move<ai_real>(sz, (ai_real &)c.a);
            } else {
                c.a = 1.;
            }
        }
        if (hasTexCoord) {
            aiVector3D &t = mesh->mTextureCoords[0][i];
            SkipSpaces(&sz, lineEnd);
            sz = fast_atoreal_move<ai_real>(sz, (ai_real &)t.x);
            SkipSpaces(&sz, lineEnd);
            fast_atoreal_move<ai_real>(sz, (ai_real &)t.y);
        }
    }

    // load faces with their indices
    faces = mesh->mFaces;
    for (unsigned int i = 0; i < numFaces;) {
        if (!GetNextLine(buffer, line)) {
            ASSIMP_LOG_ERROR("OFF: The number of faces in the header is incorrect");
            throw DeadlyImportError("OFF: The number of faces in the header is incorrect");
        }
        unsigned int idx;
        sz = line;
        SkipSpaces(&sz, lineEnd);
        idx = strtoul10(sz, &sz);
        if (!idx || idx > 9) {
            ASSIMP_LOG_ERROR("OFF: Faces with zero indices aren't allowed");
            --mesh->mNumFaces;
            ++i;
            continue;
        }
        faces->mNumIndices = idx;
        faces->mIndices = new unsigned int[faces->mNumIndices];
        for (unsigned int m = 0; m < faces->mNumIndices; ++m) {
            SkipSpaces(&sz, lineEnd);
            idx = strtoul10(sz, &sz);
            if (idx >= numVertices) {
                ASSIMP_LOG_ERROR("OFF: Vertex index is out of range");
                idx = numVertices - 1;
            }
            faces->mIndices[m] = idx;
        }
        ++i;
        ++faces;
    }

    // generate the output node graph
    pScene->mRootNode = new aiNode();
    pScene->mRootNode->mName.Set("<OFFRoot>");
    pScene->mRootNode->mNumMeshes = 1;
    pScene->mRootNode->mMeshes = new unsigned int[pScene->mRootNode->mNumMeshes];
    pScene->mRootNode->mMeshes[0] = 0;

    // generate a default material
    pScene->mNumMaterials = 1;
    pScene->mMaterials = new aiMaterial *[pScene->mNumMaterials];
    aiMaterial *pcMat = new aiMaterial();

    aiColor4D clr(0.6f, 0.6f, 0.6f, 1.0f);
    pcMat->AddProperty(&clr, 1, AI_MATKEY_COLOR_DIFFUSE);
    pScene->mMaterials[0] = pcMat;

    const int twosided = 1;
    pcMat->AddProperty(&twosided, 1, AI_MATKEY_TWOSIDED);
}

} // namespace Assimp

#endif // !! ASSIMP_BUILD_NO_OFF_IMPORTER