obj format debugging -- vertices order determines face orientation and faces are invisible from back


  1. Vertices order determines face orientation.

    e.g., f 1 2 3 and f 1 3 2 are 2 opposite faces

  2. Another thing is, faces are invisible from backside by default!!!

    In Meshlab here is a setting back-face which by default is single. If set it as double, then the face will be visible from backside.

    Meanwhile, the Preview of MacOS also makes faces transparent from opposite orientation. Like this: Stupid sphere no?

Finally my sphere is correct:

correct sphere