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

#ifndef ASSIMP_BUILD_NO_MDC_IMPORTER

// internal headers

#include "MDCLoader.h"

#include "AssetLib/MD3/MD3FileData.h"

#include "MDCNormalTable.h" // shouldn't be included by other units

#include <assimp/importerdesc.h>

#include <assimp/scene.h>

#include <assimp/DefaultLogger.hpp>

#include <assimp/IOSystem.hpp>

#include <assimp/Importer.hpp>

#include <assimp/StringUtils.h>

#include <memory>

using namespace Assimp;

using namespace Assimp::MDC;

static constexpr aiImporterDesc desc = {

    "Return To Castle Wolfenstein Mesh Importer",

    "",

    "",

    "",

    aiImporterFlags_SupportBinaryFlavour,

    0,

    0,

    0,

    0,

    "mdc"

};

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

void MDC::BuildVertex(const Frame &frame,

        const BaseVertex &bvert,

        const CompressedVertex &cvert,

        aiVector3D &vXYZOut,

        aiVector3D &vNorOut) {

    // compute the position

    const float xd = (cvert.xd - AI_MDC_CVERT_BIAS) * AI_MDC_DELTA_SCALING;

    const float yd = (cvert.yd - AI_MDC_CVERT_BIAS) * AI_MDC_DELTA_SCALING;

    const float zd = (cvert.zd - AI_MDC_CVERT_BIAS) * AI_MDC_DELTA_SCALING;

    vXYZOut.x = frame.localOrigin.x + AI_MDC_BASE_SCALING * (bvert.x + xd);

    vXYZOut.y = frame.localOrigin.y + AI_MDC_BASE_SCALING * (bvert.y + yd);

    vXYZOut.z = frame.localOrigin.z + AI_MDC_BASE_SCALING * (bvert.z + zd);

    // compute the normal vector .. ehm ... lookup it in the table :-)

    vNorOut.x = mdcNormals[cvert.nd][0];

    vNorOut.y = mdcNormals[cvert.nd][1];

    vNorOut.z = mdcNormals[cvert.nd][2];

}

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

// Constructor to be privately used by Importer

MDCImporter::MDCImporter() :

        configFrameID(),

        pcHeader(),

        mBuffer(),

        fileSize() {

    // empty

}

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

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

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

    static constexpr uint32_t tokens[] = { AI_MDC_MAGIC_NUMBER_LE };

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

}

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

const aiImporterDesc *MDCImporter::GetInfo() const {

    return &desc;

}

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

// Validate the header of the given MDC file

void MDCImporter::ValidateHeader() {

    AI_SWAP4(this->pcHeader->ulVersion);

    AI_SWAP4(this->pcHeader->ulFlags);

    AI_SWAP4(this->pcHeader->ulNumFrames);

    AI_SWAP4(this->pcHeader->ulNumTags);

    AI_SWAP4(this->pcHeader->ulNumSurfaces);

    AI_SWAP4(this->pcHeader->ulNumSkins);

    AI_SWAP4(this->pcHeader->ulOffsetBorderFrames);

    if (pcHeader->ulIdent != AI_MDC_MAGIC_NUMBER_BE &&

            pcHeader->ulIdent != AI_MDC_MAGIC_NUMBER_LE) {

        throw DeadlyImportError("Invalid MDC magic word: expected IDPC, found ",

                                ai_str_toprintable((char *)&pcHeader->ulIdent, 4));

    }

    if (pcHeader->ulVersion != AI_MDC_VERSION) {

        ASSIMP_LOG_WARN("Unsupported MDC file version (2 (AI_MDC_VERSION) was expected)");

    }

    if (pcHeader->ulOffsetBorderFrames + pcHeader->ulNumFrames * sizeof(MDC::Frame) > this->fileSize ||

            pcHeader->ulOffsetSurfaces + pcHeader->ulNumSurfaces * sizeof(MDC::Surface) > this->fileSize) {

        throw DeadlyImportError("Some of the offset values in the MDC header are invalid "

                                "and point to something behind the file.");

    }

    if (this->configFrameID >= this->pcHeader->ulNumFrames) {

        throw DeadlyImportError("The requested frame is not available");

    }

}

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

// Validate the header of a given MDC file surface

void MDCImporter::ValidateSurfaceHeader(BE_NCONST MDC::Surface *pcSurf) {

    AI_SWAP4(pcSurf->ulFlags);

    AI_SWAP4(pcSurf->ulNumCompFrames);

    AI_SWAP4(pcSurf->ulNumBaseFrames);

    AI_SWAP4(pcSurf->ulNumShaders);

    AI_SWAP4(pcSurf->ulNumVertices);

    AI_SWAP4(pcSurf->ulNumTriangles);

    AI_SWAP4(pcSurf->ulOffsetTriangles);

    AI_SWAP4(pcSurf->ulOffsetTexCoords);

    AI_SWAP4(pcSurf->ulOffsetBaseVerts);

    AI_SWAP4(pcSurf->ulOffsetCompVerts);

    AI_SWAP4(pcSurf->ulOffsetShaders);

    AI_SWAP4(pcSurf->ulOffsetFrameBaseFrames);

    AI_SWAP4(pcSurf->ulOffsetFrameCompFrames);

    AI_SWAP4(pcSurf->ulOffsetEnd);

    const unsigned int iMax = this->fileSize - (unsigned int)((int8_t *)pcSurf - (int8_t *)pcHeader);

    if (pcSurf->ulOffsetBaseVerts + pcSurf->ulNumVertices * sizeof(MDC::BaseVertex) > iMax ||

            (pcSurf->ulNumCompFrames && pcSurf->ulOffsetCompVerts + pcSurf->ulNumVertices * sizeof(MDC::CompressedVertex) > iMax) ||

            pcSurf->ulOffsetTriangles + pcSurf->ulNumTriangles * sizeof(MDC::Triangle) > iMax ||

            pcSurf->ulOffsetTexCoords + pcSurf->ulNumVertices * sizeof(MDC::TexturCoord) > iMax ||

            pcSurf->ulOffsetShaders + pcSurf->ulNumShaders * sizeof(MDC::Shader) > iMax ||

            pcSurf->ulOffsetFrameBaseFrames + pcSurf->ulNumBaseFrames * 2 > iMax ||

            (pcSurf->ulNumCompFrames && pcSurf->ulOffsetFrameCompFrames + pcSurf->ulNumCompFrames * 2 > iMax) ||

            pcSurf->ulOffsetEnd > iMax) {

        throw DeadlyImportError("Some of the offset values in the MDC surface header "

                                "are invalid and point somewhere behind the file.");

    }

}

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

// Setup configuration properties

void MDCImporter::SetupProperties(const Importer *pImp) {

    // The AI_CONFIG_IMPORT_MDC_KEYFRAME option overrides the

    // AI_CONFIG_IMPORT_GLOBAL_KEYFRAME option.

    if (static_cast<unsigned int>(-1) == (configFrameID = pImp->GetPropertyInteger(AI_CONFIG_IMPORT_MDC_KEYFRAME, -1))) {

        configFrameID = pImp->GetPropertyInteger(AI_CONFIG_IMPORT_GLOBAL_KEYFRAME, 0);

    }

}

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

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

void MDCImporter::InternReadFile(

        const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) {

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

    // Check whether we can read from the file

    if (file == nullptr) {

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

    }

    // check whether the mdc file is large enough to contain the file header

    fileSize = static_cast<unsigned int>(file->FileSize());

    if (fileSize < sizeof(MDC::Header)) {

        throw DeadlyImportError("MDC File is too small.");

    }

    std::vector<unsigned char> mBuffer2(fileSize);

    file->Read(&mBuffer2[0], 1, fileSize);

    mBuffer = &mBuffer2[0];

    // validate the file header

    this->pcHeader = (BE_NCONST MDC::Header *)this->mBuffer;

    this->ValidateHeader();

    std::vector<std::string> aszShaders;

    // get a pointer to the frame we want to read

    BE_NCONST MDC::Frame *pcFrame = (BE_NCONST MDC::Frame *)(this->mBuffer +

                                                             this->pcHeader->ulOffsetBorderFrames);

    // no need to swap the other members, we won't need them

    pcFrame += configFrameID;

    AI_SWAP4(pcFrame->localOrigin[0]);

    AI_SWAP4(pcFrame->localOrigin[1]);

    AI_SWAP4(pcFrame->localOrigin[2]);

    // get the number of valid surfaces

    BE_NCONST MDC::Surface *pcSurface, *pcSurface2;

    pcSurface = pcSurface2 = reinterpret_cast<BE_NCONST MDC::Surface *>(mBuffer + pcHeader->ulOffsetSurfaces);

    unsigned int iNumShaders = 0;

    for (unsigned int i = 0; i < pcHeader->ulNumSurfaces; ++i) {

        // validate the surface header

        this->ValidateSurfaceHeader(pcSurface2);

        if (pcSurface2->ulNumVertices && pcSurface2->ulNumTriangles) {

            ++pScene->mNumMeshes;

        }

        iNumShaders += pcSurface2->ulNumShaders;

        pcSurface2 = reinterpret_cast<BE_NCONST MDC::Surface *>((BE_NCONST int8_t *)pcSurface2 + pcSurface2->ulOffsetEnd);

    }

    aszShaders.reserve(iNumShaders);

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

    // necessary that we don't crash if an exception occurs

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

        pScene->mMeshes[i] = nullptr;

    }

    // now read all surfaces

    unsigned int iDefaultMatIndex = UINT_MAX;

    for (unsigned int i = 0, iNum = 0; i < pcHeader->ulNumSurfaces; ++i) {

        if (!pcSurface->ulNumVertices || !pcSurface->ulNumTriangles) continue;

        aiMesh *pcMesh = pScene->mMeshes[iNum++] = new aiMesh();

        pcMesh->mNumFaces = pcSurface->ulNumTriangles;

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

        // store the name of the surface for use as node name.

        pcMesh->mName.Set(std::string(pcSurface->ucName, strnlen(pcSurface->ucName, AI_MDC_MAXQPATH - 1)));

        // go to the first shader in the file. ignore the others.

        if (pcSurface->ulNumShaders) {

            const MDC::Shader *pcShader = (const MDC::Shader *)((int8_t *)pcSurface + pcSurface->ulOffsetShaders);

            pcMesh->mMaterialIndex = (unsigned int)aszShaders.size();

            // create a new shader

            aszShaders.emplace_back(pcShader->ucName,

                    ::strnlen(pcShader->ucName, sizeof(pcShader->ucName)));

        }

        // need to create a default material

        else if (UINT_MAX == iDefaultMatIndex) {

            pcMesh->mMaterialIndex = iDefaultMatIndex = (unsigned int)aszShaders.size();

            aszShaders.emplace_back();

        }

        // otherwise assign a reference to the default material

        else

            pcMesh->mMaterialIndex = iDefaultMatIndex;

        // allocate output storage for the mesh

        aiVector3D *pcVertCur = pcMesh->mVertices = new aiVector3D[pcMesh->mNumVertices];

        aiVector3D *pcNorCur = pcMesh->mNormals = new aiVector3D[pcMesh->mNumVertices];

        aiVector3D *pcUVCur = pcMesh->mTextureCoords[0] = new aiVector3D[pcMesh->mNumVertices];

        aiFace *pcFaceCur = pcMesh->mFaces = new aiFace[pcMesh->mNumFaces];

        // create all vertices/faces

        BE_NCONST MDC::Triangle *pcTriangle = (BE_NCONST MDC::Triangle *)((int8_t *)pcSurface + pcSurface->ulOffsetTriangles);

        BE_NCONST MDC::TexturCoord *const pcUVs = (BE_NCONST MDC::TexturCoord *)((int8_t *)pcSurface + pcSurface->ulOffsetTexCoords);

        // get a pointer to the uncompressed vertices

        int16_t iOfs = *((int16_t *)((int8_t *)pcSurface +

                                     pcSurface->ulOffsetFrameBaseFrames) +

                         this->configFrameID);

        AI_SWAP2(iOfs);

        BE_NCONST MDC::BaseVertex *const pcVerts = (BE_NCONST MDC::BaseVertex *)((int8_t *)pcSurface + pcSurface->ulOffsetBaseVerts) +

                                                   ((int)iOfs * pcSurface->ulNumVertices * 4);

        // do the main swapping stuff ...

#if (defined AI_BUILD_BIG_ENDIAN)

        // swap all triangles

        for (unsigned int i = 0; i < pcSurface->ulNumTriangles; ++i) {

            AI_SWAP4(pcTriangle[i].aiIndices[0]);

            AI_SWAP4(pcTriangle[i].aiIndices[1]);

            AI_SWAP4(pcTriangle[i].aiIndices[2]);

        }

        // swap all vertices

        for (unsigned int i = 0; i < pcSurface->ulNumVertices * pcSurface->ulNumBaseFrames; ++i) {

            AI_SWAP2(pcVerts->normal);

            AI_SWAP2(pcVerts->x);

            AI_SWAP2(pcVerts->y);

            AI_SWAP2(pcVerts->z);

        }

        // swap all texture coordinates

        for (unsigned int i = 0; i < pcSurface->ulNumVertices; ++i) {

            AI_SWAP4(pcUVs->u);

            AI_SWAP4(pcUVs->v);

        }

#endif

        // boundary check for pcVerts

        auto surfStart = reinterpret_cast<const uint8_t*>(pcSurface);

        const uint8_t* surfEnd = surfStart + pcSurface->ulOffsetEnd;

        auto vertBufStart = reinterpret_cast<const uint8_t*>(pcVerts);

        const size_t needVertBytes = sizeof(MDC::BaseVertex) * pcSurface->ulNumVertices;

        if (vertBufStart < surfStart || vertBufStart + needVertBytes > surfEnd) {

            throw DeadlyImportError("MDCImporter: pcVerts points outside of surface block.");

        }

        const MDC::CompressedVertex *pcCVerts = nullptr;

        int16_t *mdcCompVert = nullptr;

        // access compressed frames for large frame numbers, but never for the first

        if (this->configFrameID && pcSurface->ulNumCompFrames > 0) {

            mdcCompVert = (int16_t *)((int8_t *)pcSurface + pcSurface->ulOffsetFrameCompFrames) + this->configFrameID;

            AI_SWAP2P(mdcCompVert);

            if (*mdcCompVert >= 0) {

                pcCVerts = (const MDC::CompressedVertex *)((int8_t *)pcSurface +

                                                           pcSurface->ulOffsetCompVerts) +

                           *mdcCompVert * pcSurface->ulNumVertices;

                auto cvertBufStart = reinterpret_cast<const uint8_t*>(pcCVerts);

                const size_t needCompVertBytes = sizeof(MDC::CompressedVertex) * pcSurface->ulNumVertices;

                if (cvertBufStart < surfStart || cvertBufStart > surfEnd ||

                    needCompVertBytes > static_cast<size_t>(surfEnd - cvertBufStart)) {

                    throw DeadlyImportError("MDCImporter: pcCVerts points outside of surface block.");

                }

            } else

                mdcCompVert = nullptr;

        }

        // copy all faces

        for (unsigned int iFace = 0; iFace < pcSurface->ulNumTriangles; ++iFace,

                          ++pcTriangle, ++pcFaceCur) {

            const unsigned int iOutIndex = iFace * 3;

            pcFaceCur->mNumIndices = 3;

            pcFaceCur->mIndices = new unsigned int[3];

            for (unsigned int iIndex = 0; iIndex < 3; ++iIndex,

                              ++pcVertCur, ++pcUVCur, ++pcNorCur) {

                uint32_t quak = pcTriangle->aiIndices[iIndex];

                if (quak >= pcSurface->ulNumVertices) {

                    ASSIMP_LOG_ERROR("MDC vertex index is out of range");

                    quak = pcSurface->ulNumVertices - 1;

                }

                // compressed vertices?

                if (mdcCompVert) {

                    MDC::BuildVertex(*pcFrame, pcVerts[quak], pcCVerts[quak],

                            *pcVertCur, *pcNorCur);

                } else {

                    // copy position

                    pcVertCur->x = pcVerts[quak].x * AI_MDC_BASE_SCALING;

                    pcVertCur->y = pcVerts[quak].y * AI_MDC_BASE_SCALING;

                    pcVertCur->z = pcVerts[quak].z * AI_MDC_BASE_SCALING;

                    // copy normals

                    MD3::LatLngNormalToVec3(pcVerts[quak].normal, &pcNorCur->x);

                    // copy texture coordinates

                    pcUVCur->x = pcUVs[quak].u;

                    pcUVCur->y = ai_real(1.0) - pcUVs[quak].v; // DX to OGL

                }

                pcVertCur->x += pcFrame->localOrigin[0];

                pcVertCur->y += pcFrame->localOrigin[1];

                pcVertCur->z += pcFrame->localOrigin[2];

            }

            // swap the face order - DX to OGL

            pcFaceCur->mIndices[0] = iOutIndex + 2;

            pcFaceCur->mIndices[1] = iOutIndex + 1;

            pcFaceCur->mIndices[2] = iOutIndex + 0;

        }

        pcSurface = reinterpret_cast<BE_NCONST MDC::Surface *>((BE_NCONST int8_t *)pcSurface + pcSurface->ulOffsetEnd);

    }

    // create a flat node graph with a root node and one child for each surface

    if (!pScene->mNumMeshes)

        throw DeadlyImportError("Invalid MDC file: File contains no valid mesh");

    else if (1 == pScene->mNumMeshes) {

        pScene->mRootNode = new aiNode();

        if (nullptr != pScene->mMeshes[0]) {

            pScene->mRootNode->mName = pScene->mMeshes[0]->mName;

            pScene->mRootNode->mNumMeshes = 1;

            pScene->mRootNode->mMeshes = new unsigned int[1];

            pScene->mRootNode->mMeshes[0] = 0;

        }

    } else {

        pScene->mRootNode = new aiNode();

        pScene->mRootNode->mNumChildren = pScene->mNumMeshes;

        pScene->mRootNode->mChildren = new aiNode *[pScene->mNumMeshes];

        pScene->mRootNode->mName.Set("<root>");

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

            aiNode *pcNode = pScene->mRootNode->mChildren[i] = new aiNode();

            pcNode->mParent = pScene->mRootNode;

            pcNode->mName = pScene->mMeshes[i]->mName;

            pcNode->mNumMeshes = 1;

            pcNode->mMeshes = new unsigned int[1];

            pcNode->mMeshes[0] = i;

        }

    }

    // create materials

    pScene->mNumMaterials = (unsigned int)aszShaders.size();

    pScene->mMaterials = new aiMaterial *[pScene->mNumMaterials];

    for (unsigned int i = 0; i < pScene->mNumMaterials; ++i) {

        aiMaterial *pcMat = new aiMaterial();

        pScene->mMaterials[i] = pcMat;

        const std::string &name = aszShaders[i];

        int iMode = (int)aiShadingMode_Gouraud;

        pcMat->AddProperty<int>(&iMode, 1, AI_MATKEY_SHADING_MODEL);

        // add a small ambient color value - RtCW seems to have one

        aiColor3D clr;

        clr.b = clr.g = clr.r = 0.05f;

        pcMat->AddProperty<aiColor3D>(&clr, 1, AI_MATKEY_COLOR_AMBIENT);

        if (name.length())

            clr.b = clr.g = clr.r = 1.0f;

        else

            clr.b = clr.g = clr.r = 0.6f;

        pcMat->AddProperty<aiColor3D>(&clr, 1, AI_MATKEY_COLOR_DIFFUSE);

        pcMat->AddProperty<aiColor3D>(&clr, 1, AI_MATKEY_COLOR_SPECULAR);

        if (name.length()) {

            aiString path;

            path.Set(name);

            pcMat->AddProperty(&path, AI_MATKEY_TEXTURE_DIFFUSE(0));

        }

    }

    // Now rotate the whole scene 90 degrees around the x axis to convert to internal coordinate system

    pScene->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);

}

#endif // !! ASSIMP_BUILD_NO_MDC_IMPORTER