开源代码·Assimp导入stl模型顶点数量问题

　　使用Assimp示例代码导入stl文件：

#include <assimp/Importer.hpp>      // C++ importer interface
#include <assimp/scene.h>           // Output data structure
#include <assimp/postprocess.h>     // Post processing flags
bool DoTheImportThing(const std::string& pFile)
{
    // Create an instance of the Importer class
    Assimp::Importer importer;
    // And have it read the given file with some example postprocessing
    // Usually - if speed is not the most important aspect for you - you'll 
    // propably to request more postprocessing than we do in this example.
    const aiScene* scene = importer.ReadFile(pFile,
        aiProcess_CalcTangentSpace |
        aiProcess_Triangulate |
        aiProcess_JoinIdenticalVertices |
        aiProcess_SortByPType);

    // If the import failed, report it
    if (!scene)
    {
        //DoTheErrorLogging(importer.GetErrorString());
        std::printf("failed to import %s!
", pFile.c_str());
        return false;
    }
    // Now we can access the file's contents. 
    //DoTheSceneProcessing(scene);
    if (scene->HasMeshes())
    {
        std::printf("has %d meshes!
", scene->mNumMeshes);
        for (int i = 0; i < scene->mNumMeshes; ++i)
        {
            std::printf("%d: %u vertices!
", i, scene->mMeshes[i]->mNumVertices);
            if (scene->mMeshes[i]->HasFaces())
                std::printf("%d: %u faces!
", i, scene->mMeshes[i]->mNumFaces);
        }
    }
    // We're done. Everything will be cleaned up by the importer destructor
    return true;
}


int main()
{
    std::string File = ".\bottle.stl";
    DoTheImportThing(File);

    system("pause");
    return 0;
}

　　输出：

has 1 meshes!
0: 553770 vertices!
0: 190624 faces!

　　MeshLab导入同一stl模型的结果：

0:  95314 vertices!
0: 190624 faces!

　　问题在于顶点合并：

　　assimp-5.0.1codePostProcessingJoinVerticesProcess.cpp

    // A little helper to find locally close vertices faster.
    // Try to reuse the lookup table from the last step.
    const static float epsilon = 1e-5f;
    // Squared because we check against squared length of the vector difference
    static const float squareEpsilon = epsilon * epsilon;

    // Square compare is useful for animeshes vertices compare
    if ((lhs.position - rhs.position).SquareLength() > squareEpsilon) {
        return false;
    }