how to get the normal vector of a suface from a STL file

[chopin1998]

i'm a newbie of freeCAD, and CAD...

i have a STL file, i need to know some normal vector of surfaces,

after lots of Google, here is my answer:

Gui.Selection.getSelectionEx()[0].SubObjects[0].Faces[0].normalAt(0,0).

But when i open my STL file, i cannot choose a surface by mouse?

what should i do?
Thank you very much!

[wmayer]

Try this:

Code: Select all

def getNormal(cb):
    if cb.getEvent().getState() == coin.SoButtonEvent.UP:
        pp = cb.getPickedPoint()
        if pp:
            vec = pp.getNormal().getValue()
            index = coin.cast(pp.getDetail(), "SoFaceDetail").getFaceIndex()
            print ("Normal: {}, Face index: {}".format(str(vec), index))

from pivy import coin
meth=Gui.ActiveDocument.ActiveView.addEventCallbackPivy(coin.SoMouseButtonEvent.getClassTypeId(), getNormal)

If you are done then run:

Code: Select all

Gui.ActiveDocument.ActiveView.removeEventCallbackPivy(coin.SoMouseButtonEvent.getClassTypeId(), meth)

[Kunda1]

#documentation

[chopin1998]

got it, need use part

[openBrain]

got it, need use part

I'm pretty sure this post will be highly useless if one has the same problem and land here...

[mario52]

hi

#documentation

done Get_the_normal_vector_of_a_suface_from_a_STL_file

mario