c++ - 来自 .ply 文件的 Garbage Face 相关信息

Question

我正在尝试使用 ASSIMP从 ply 文件中提取顶点/法线/面信息，然后使用 OpenGL 渲染它。以下是代码:

void PLYParser::importFile(std::string sFilePath)
{
    const aiScene* scene = aiImportFile (sFilePath.c_str(), aiProcess_Triangulate); // TRIANGLES!

    if (!scene)
    {
        std::cerr << "ERROR: reading mesh %s\n" << sFilePath << std::endl;
        return;
    }

    printf ("  %i animations\n", scene->mNumAnimations);
    printf ("  %i cameras\n", scene->mNumCameras);
    printf ("  %i lights\n", scene->mNumLights);
    printf ("  %i materials\n", scene->mNumMaterials);
    printf ("  %i meshes\n", scene->mNumMeshes);
    printf ("  %i textures\n", scene->mNumTextures);

      for (unsigned int m_i = 0; m_i < scene->mNumMeshes; m_i++)
      {
          const aiMesh* mesh = scene->mMeshes[m_i];
          printf ("    %i vertices in mesh\n", mesh->mNumVertices);
          g_point_count = mesh->mNumVertices;
          for (unsigned int v_i = 0; v_i < mesh->mNumVertices; v_i++)
          {
            if (mesh->HasPositions ())
            {
              const aiVector3D* vp = &(mesh->mVertices[v_i]);
              printf ("      vp %i (%f,%f,%f)\n", v_i, vp->x, vp->y, vp->z);
            }
            if (mesh->HasNormals ())
            {
              const aiVector3D* vn = &(mesh->mNormals[v_i]);
              printf ("      vn %i (%f,%f,%f)\n", v_i, vn->x, vn->y, vn->z);
            }
            if (mesh->HasTextureCoords (0))
            {
              const aiVector3D* vt = &(mesh->mTextureCoords[0][v_i]);
              printf ("      vt %i (%f,%f)\n", v_i, vt->x, vt->y);
            }
            if (mesh->HasTangentsAndBitangents ())
            {
              // NB: could store/print tangents here
            }

            if( mesh->HasFaces() )
            {
                const struct aiFace * vf = &(mesh->mFaces[m_i]);
                if (vf->mNumIndices == 3)
                {
                   printf ("      vf (%f,%f,%f)\n", vf->mIndices[0],vf->mIndices[1], vf->mIndices[2]);
                }
            }
          }
        }

      std::cout << "Parsing over" << std::endl ;
}

顶点值打印的很好，但是与面部相关的信息有点像这样的垃圾:

vp 5107 (0.003326,0.079200,0.001920)
vf (0.000000,-0.000000,26815622223676999148426976713858144581866377154979840994523259353566101584147672957460702289212360863380556296293016572911077072166495943380764853993996288.000000)

Q1.我在面部相关代码中做错了吗？

Q2.另外，我解析的任何层文件中似乎都没有正常的相关信息。我必须手动计算所有内容的法线。 ply 是否完全没有正常信息？

附言: 我已经在几个不同的 ply 文件上尝试了代码，我仍然得到面部信息的垃圾值。

---

编辑 1:

for (unsigned int m_i = 0; m_i < scene->mNumMeshes; m_i++)
      {
          const aiMesh* mesh = scene->mMeshes[m_i];
          printf ("    %i vertices in mesh\n", mesh->mNumVertices);
          g_point_count = mesh->mNumVertices;

          for (unsigned int v_i = 0; v_i < mesh->mNumFaces; v_i++)
          {
              if (mesh->HasFaces())
              {
                  for (unsigned int f_i = 0; f_i < mesh->mNumFaces; f_i++)
                  {
                      const struct aiFace* vf = mesh->mFaces + f_i;

                      if (vf->mNumIndices == 3)
                      {
                          printf("      vf (%u,%u,%u)\n", vf->mIndices[0], vf->mIndices[1], vf->mIndices[2]);
                      }
                  }
              }
          }
        }

我通过将代码更改为上面的代码来获取备用数字作为输出 -

  vf (0,1,2)
  vf (3,4,5)
  vf (6,7,8)
  vf (9,10,11)
  vf (12,13,14)
  vf (15,16,17)
  ..
  ..
  and so on.

Answer 1

A1。

第一期:

printf ("      vf (%f,%f,%f)\n", vf->mIndices[0], vf->mIndices[1], vf->mIndices[2]);

vf->mIndices的类型是unsigned int*，所以格式说明符%f是错误的，应该是%u。试试这个:

printf ("      vf (%u,%u,%u)\n", vf->mIndices[0], vf->mIndices[1], vf->mIndices[2]);

第二期:

您需要像当前对顶点列表所做的那样遍历网格的面列表。只需删除当前在顶点循环中处理面的代码，并为面添加另一个循环(与顶点循环处于同一级别)，如下所示:

for (unsigned int v_i = 0; v_i < mesh->mNumVertices; v_i++)
{
    // ...
}

if (mesh->HasFaces())
{
    for (unsigned int f_i = 0; f_i < mesh->mNumFaces; f_i++)
    {
        const struct aiFace* vf = mesh->mFaces + f_i;

        if (vf->mNumIndices == 3)
        {
            printf("      vf (%u,%u,%u)\n", vf->mIndices[0], vf->mIndices[1], vf->mIndices[2]);
        }
    }
}

A2。

可以为每个顶点指定法线信息(每个名为 nx、ny 和 nz 的顶点元素有 3 个额外的 float 属性) 在 PLY 文件中。由于格式灵活，每个面的法线也可以用类似的方式指定。这完全取决于用于生成此文件的工具导出的内容。