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：

 1 #include <assimp/Importer.hpp>      // C++ importer interface
 2 #include <assimp/scene.h>           // Output data structure
 3 #include <assimp/postprocess.h>     // Post processing flags
 4 bool DoTheImportThing(const std::string& pFile)
 5 {
 6     // Create an instance of the Importer class
 7     Assimp::Importer importer;
 8     // And have it read the given file with some example postprocessing
 9     // Usually - if speed is not the most important aspect for you - you'll 
10     // propably to request more postprocessing than we do in this example.
11     const aiScene* scene = importer.ReadFile(pFile,
12         aiProcess_CalcTangentSpace |
13         aiProcess_Triangulate |
14         aiProcess_JoinIdenticalVertices |
15         aiProcess_SortByPType);
16 
17     // If the import failed, report it
18     if (!scene)
19     {
20         //DoTheErrorLogging(importer.GetErrorString());
21         std::printf("failed to import %s!\n", pFile.c_str());
22         return false;
23     }
24     // Now we can access the file's contents. 
25     //DoTheSceneProcessing(scene);
26     if (scene->HasMeshes())
27     {
28         std::printf("has %d meshes!\n", scene->mNumMeshes);
29         for (int i = 0; i < scene->mNumMeshes; ++i)
30         {
31             std::printf("%d: %u vertices!\n", i, scene->mMeshes[i]->mNumVertices);
32             if (scene->mMeshes[i]->HasFaces())
33                 std::printf("%d: %u faces!\n", i, scene->mMeshes[i]->mNumFaces);
34         }
35     }
36     // We're done. Everything will be cleaned up by the importer destructor
37     return true;
38 }
39 
40 
41 int main()
42 {
43     std::string File = ".\\bottle.stl";
44     DoTheImportThing(File);
45 
46     system("pause");
47     return 0;
48 }

　　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-5.0.1\code\PostProcessing\JoinVerticesProcess.cpp

 1     // A little helper to find locally close vertices faster.
 2     // Try to reuse the lookup table from the last step.
 3     const static float epsilon = 1e-5f;
 4     // Squared because we check against squared length of the vector difference
 5     static const float squareEpsilon = epsilon * epsilon;
 6 
 7     // Square compare is useful for animeshes vertices compare
 8     if ((lhs.position - rhs.position).SquareLength() > squareEpsilon) {
 9         return false;
10     }