Generate mesh distance field when importing

I’m studying the method of generating mesh distance field in v4.26. I noticed for any static mesh imported, UE4 will filter the vertices excluding who is without materials or not opaque. But UE4 filters the vertices and then rebuild triangles from veritces, which can also be done via filtering submeshes(LODModel.Sections). During the rebuilding, it gets the normal of this triangle, but if we have indices of vertices, we can do this whenever we need.
Looking forward to your opinions!