self.vertices = (v3, v2, v1)    #v3 is the smallest

(v3, v2, v1) would reverse the winding order and make the facet inside out. The code rotates the list of vertices to start with the smallest. So for a given triangle the order will be consistent because, given the starting point, the winding order determines which vertex must come next. On 14 December 2016 at 18:34, Maurice van Peursem <openscad@vanpeursem.net> wrote: > There is a small error in your script, line 35 should be: > > self.vertices = (v3, v2, v1) #v3 is the smallest > > Maurice > > > > They may be the exactly the same geometry but in a different order. >> >> OpenScad outputs the vertices and facets in an order that depends on >> machine addresses. I run all mine through a Python script that sorts them, >> so that they can be compared for real differences. < >> https://github.com/nophead/Mendel90/blob/master/c14n_stl.py> >> https://github.com/nophead/Mendel90/blob/master/c14n_stl.py >> >> > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >