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/** @file Implementation of the DeterminePTypeHelperProcess and
 *  SortByPTypeProcess post-process steps.
*/

// internal headers
#include "SortByPTypeProcess.h"
#include "ProcessHelper.h"
#include <assimp/Exceptional.h>

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
SortByPTypeProcess::SortByPTypeProcess() :
        mConfigRemoveMeshes(0) {
    // empty
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
SortByPTypeProcess::~SortByPTypeProcess() {
    // nothing to do here
}

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool SortByPTypeProcess::IsActive(unsigned int pFlags) const {
    return (pFlags & aiProcess_SortByPType) != 0;
}

// ------------------------------------------------------------------------------------------------
void SortByPTypeProcess::SetupProperties(const Importer *pImp) {
    mConfigRemoveMeshes = pImp->GetPropertyInteger(AI_CONFIG_PP_SBP_REMOVE, 0);
}

// ------------------------------------------------------------------------------------------------
// Update changed meshes in all nodes
void UpdateNodes(const std::vector<unsigned int> &replaceMeshIndex, aiNode *node) {
    if (node->mNumMeshes) {
        unsigned int newSize = 0;
        for (unsigned int m = 0; m < node->mNumMeshes; ++m) {
            unsigned int add = node->mMeshes[m] << 2;
            for (unsigned int i = 0; i < 4; ++i) {
                if (UINT_MAX != replaceMeshIndex[add + i]) ++newSize;
            }
        }
        if (!newSize) {
            delete[] node->mMeshes;
            node->mNumMeshes = 0;
            node->mMeshes = nullptr;
        } else {
            // Try to reuse the old array if possible
            unsigned int *newMeshes = (newSize > node->mNumMeshes ? new unsigned int[newSize] : node->mMeshes);

            for (unsigned int m = 0; m < node->mNumMeshes; ++m) {
                unsigned int add = node->mMeshes[m] << 2;
                for (unsigned int i = 0; i < 4; ++i) {
                    if (UINT_MAX != replaceMeshIndex[add + i])
                        *newMeshes++ = replaceMeshIndex[add + i];
                }
            }
            if (newSize > node->mNumMeshes)
                delete[] node->mMeshes;

            node->mMeshes = newMeshes - (node->mNumMeshes = newSize);
        }
    }

    // call all subnodes recursively
    for (unsigned int m = 0; m < node->mNumChildren; ++m)
        UpdateNodes(replaceMeshIndex, node->mChildren[m]);
}

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void SortByPTypeProcess::Execute(aiScene *pScene) {
    if (0 == pScene->mNumMeshes) {
        ASSIMP_LOG_DEBUG("SortByPTypeProcess skipped, there are no meshes");
        return;
    }

    ASSIMP_LOG_DEBUG("SortByPTypeProcess begin");

    unsigned int aiNumMeshesPerPType[4] = { 0, 0, 0, 0 };

    std::vector<aiMesh *> outMeshes;
    outMeshes.reserve(pScene->mNumMeshes << 1u);

    bool bAnyChanges = false;

    std::vector<unsigned int> replaceMeshIndex(pScene->mNumMeshes * 4, UINT_MAX);
    std::vector<unsigned int>::iterator meshIdx = replaceMeshIndex.begin();
    for (unsigned int i = 0; i < pScene->mNumMeshes; ++i) {
        aiMesh *const mesh = pScene->mMeshes[i];
        ai_assert(0 != mesh->mPrimitiveTypes);

        // if there's just one primitive type in the mesh there's nothing to do for us
        unsigned int num = 0;
        if (mesh->mPrimitiveTypes & aiPrimitiveType_POINT) {
            ++aiNumMeshesPerPType[0];
            ++num;
        }
        if (mesh->mPrimitiveTypes & aiPrimitiveType_LINE) {
            ++aiNumMeshesPerPType[1];
            ++num;
        }
        if (mesh->mPrimitiveTypes & aiPrimitiveType_TRIANGLE) {
            ++aiNumMeshesPerPType[2];
            ++num;
        }
        if (mesh->mPrimitiveTypes & aiPrimitiveType_POLYGON) {
            ++aiNumMeshesPerPType[3];
            ++num;
        }

        if (1 == num) {
            if (!(mConfigRemoveMeshes & mesh->mPrimitiveTypes)) {
                *meshIdx = static_cast<unsigned int>(outMeshes.size());
                outMeshes.push_back(mesh);
            } else {
                delete mesh;
                pScene->mMeshes[i] = nullptr;
                bAnyChanges = true;
            }

            meshIdx += 4;
            continue;
        }
        bAnyChanges = true;

        // reuse our current mesh arrays for the submesh
        // with the largest number of primitives
        unsigned int aiNumPerPType[4] = { 0, 0, 0, 0 };
        aiFace *pFirstFace = mesh->mFaces;
        aiFace *const pLastFace = pFirstFace + mesh->mNumFaces;

        unsigned int numPolyVerts = 0;
        for (; pFirstFace != pLastFace; ++pFirstFace) {
            if (pFirstFace->mNumIndices <= 3)
                ++aiNumPerPType[pFirstFace->mNumIndices - 1];
            else {
                ++aiNumPerPType[3];
                numPolyVerts += pFirstFace->mNumIndices;
            }
        }

        VertexWeightTable *avw = ComputeVertexBoneWeightTable(mesh);
        for (unsigned int real = 0; real < 4; ++real, ++meshIdx) {
            if (!aiNumPerPType[real] || mConfigRemoveMeshes & (1u << real)) {
                continue;
            }

            *meshIdx = (unsigned int)outMeshes.size();
            outMeshes.push_back(new aiMesh());
            aiMesh *out = outMeshes.back();

            // the name carries the adjacency information between the meshes
            out->mName = mesh->mName;

            // copy data members
            out->mPrimitiveTypes = 1u << real;
            out->mMaterialIndex = mesh->mMaterialIndex;

            // allocate output storage
            out->mNumFaces = aiNumPerPType[real];
            aiFace *outFaces = out->mFaces = new aiFace[out->mNumFaces];

            out->mNumVertices = (3 == real ? numPolyVerts : out->mNumFaces * (real + 1));

            aiVector3D *vert(nullptr), *nor(nullptr), *tan(nullptr), *bit(nullptr);
            aiVector3D *uv[AI_MAX_NUMBER_OF_TEXTURECOORDS];
            aiColor4D *cols[AI_MAX_NUMBER_OF_COLOR_SETS];

            if (mesh->mVertices) {
                vert = out->mVertices = new aiVector3D[out->mNumVertices];
            }

            if (mesh->mNormals) {
                nor = out->mNormals = new aiVector3D[out->mNumVertices];
            }

            if (mesh->mTangents) {
                tan = out->mTangents = new aiVector3D[out->mNumVertices];
                bit = out->mBitangents = new aiVector3D[out->mNumVertices];
            }

            for (unsigned int j = 0; j < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++j) {
                uv[j] = nullptr;
                if (mesh->mTextureCoords[j]) {
                    uv[j] = out->mTextureCoords[j] = new aiVector3D[out->mNumVertices];
                }

                out->mNumUVComponents[j] = mesh->mNumUVComponents[j];
            }

            for (unsigned int j = 0; j < AI_MAX_NUMBER_OF_COLOR_SETS; ++j) {
                cols[j] = nullptr;
                if (mesh->mColors[j]) {
                    cols[j] = out->mColors[j] = new aiColor4D[out->mNumVertices];
                }
            }

            typedef std::vector<aiVertexWeight> TempBoneInfo;
            std::vector<TempBoneInfo> tempBones(mesh->mNumBones);

            // try to guess how much storage we'll need
            for (unsigned int q = 0; q < mesh->mNumBones; ++q) {
                tempBones[q].reserve(mesh->mBones[q]->mNumWeights / (num - 1));
            }

            unsigned int outIdx = 0;
            for (unsigned int m = 0; m < mesh->mNumFaces; ++m) {
                aiFace &in = mesh->mFaces[m];
                if ((real == 3 && in.mNumIndices <= 3) || (real != 3 && in.mNumIndices != real + 1)) {
                    continue;
                }

                outFaces->mNumIndices = in.mNumIndices;
                outFaces->mIndices = in.mIndices;

                for (unsigned int q = 0; q < in.mNumIndices; ++q) {
                    unsigned int idx = in.mIndices[q];

                    // process all bones of this index
                    if (avw) {
                        VertexWeightTable &tbl = avw[idx];
                        for (VertexWeightTable::const_iterator it = tbl.begin(), end = tbl.end();
                                it != end; ++it) {
                            tempBones[(*it).first].push_back(aiVertexWeight(outIdx, (*it).second));
                        }
                    }

                    if (vert) {
                        *vert++ = mesh->mVertices[idx];
                        //mesh->mVertices[idx].x = get_qnan();
                    }
                    if (nor) *nor++ = mesh->mNormals[idx];
                    if (tan) {
                        *tan++ = mesh->mTangents[idx];
                        *bit++ = mesh->mBitangents[idx];
                    }

                    for (unsigned int pp = 0; pp < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++pp) {
                        if (!uv[pp]) break;
                        *uv[pp]++ = mesh->mTextureCoords[pp][idx];
                    }

                    for (unsigned int pp = 0; pp < AI_MAX_NUMBER_OF_COLOR_SETS; ++pp) {
                        if (!cols[pp]) break;
                        *cols[pp]++ = mesh->mColors[pp][idx];
                    }

                    in.mIndices[q] = outIdx++;
                }

                in.mIndices = nullptr;
                ++outFaces;
            }
            ai_assert(outFaces == out->mFaces + out->mNumFaces);

            // now generate output bones
            for (unsigned int q = 0; q < mesh->mNumBones; ++q) {
                if (!tempBones[q].empty()) {
                    ++out->mNumBones;
                }
            }

            if (out->mNumBones) {
                out->mBones = new aiBone *[out->mNumBones];
                for (unsigned int q = 0, boneIdx = 0; q < mesh->mNumBones; ++q) {
                    TempBoneInfo &in = tempBones[q];
                    if (in.empty()) {
                        continue;
                    }

                    aiBone *srcBone = mesh->mBones[q];
                    aiBone *bone = out->mBones[boneIdx] = new aiBone();

                    bone->mName = srcBone->mName;
                    bone->mOffsetMatrix = srcBone->mOffsetMatrix;

                    bone->mNumWeights = (unsigned int)in.size();
                    bone->mWeights = new aiVertexWeight[bone->mNumWeights];

                    ::memcpy(bone->mWeights, &in[0], bone->mNumWeights * sizeof(aiVertexWeight));

                    ++boneIdx;
                }
            }
        }

        // delete the per-vertex bone weights table
        delete[] avw;

        // delete the input mesh
        delete mesh;

        // avoid invalid pointer
        pScene->mMeshes[i] = nullptr;
    }

    if (outMeshes.empty()) {
        // This should not occur
        throw DeadlyImportError("No meshes remaining");
    }

    // If we added at least one mesh process all nodes in the node
    // graph and update their respective mesh indices.
    if (bAnyChanges) {
        UpdateNodes(replaceMeshIndex, pScene->mRootNode);
    }

    if (outMeshes.size() != pScene->mNumMeshes) {
        delete[] pScene->mMeshes;
        pScene->mNumMeshes = (unsigned int)outMeshes.size();
        pScene->mMeshes = new aiMesh *[pScene->mNumMeshes];
    }
    ::memcpy(pScene->mMeshes, &outMeshes[0], pScene->mNumMeshes * sizeof(void *));

    if (!DefaultLogger::isNullLogger()) {
        char buffer[1024];
        ::ai_snprintf(buffer, 1024, "Points: %u%s, Lines: %u%s, Triangles: %u%s, Polygons: %u%s (Meshes, X = removed)",
                aiNumMeshesPerPType[0], ((mConfigRemoveMeshes & aiPrimitiveType_POINT) ? "X" : ""),
                aiNumMeshesPerPType[1], ((mConfigRemoveMeshes & aiPrimitiveType_LINE) ? "X" : ""),
                aiNumMeshesPerPType[2], ((mConfigRemoveMeshes & aiPrimitiveType_TRIANGLE) ? "X" : ""),
                aiNumMeshesPerPType[3], ((mConfigRemoveMeshes & aiPrimitiveType_POLYGON) ? "X" : ""));
        ASSIMP_LOG_INFO(buffer);
        ASSIMP_LOG_DEBUG("SortByPTypeProcess finished");
    }
}
