[OpenSCAD] Getting more information

Dan Shriver tabbydan at gmail.com
Thu Jul 4 12:45:17 EDT 2019


When I finally get to view things in preview, it looks like the whole
structure has yellow or black facets with all the edges being purple.  I
find this confusing.  Shouldn't some of the facets be yellow or black and
others be purple.  Why should any of the edges be purple?  I'm not
understanding this.

[image: image.png]

On Thu, Jul 4, 2019 at 11:51 AM adrianv <avm4 at cornell.edu> wrote:

> The typical behavior when a polyhedron is invalid is that it works in
> preview
> but fails in render.  Use the "thrown together" option with preview, not
> render.  Faces that are incorrectly oriented will appear in purple.
>
> There's an example here, along with other advice on debugging polyhedra:
>
>
> https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/The_OpenSCAD_Language#Debugging_polyhedra
>
>
> DanS wrote
> > I'm not sure how to use View->Thrown Together properly
> >
> > If I do render.  I see this:
> >
> > [image: image.png]
> >
> > If right after that I go into View and select Thrown Together  I don't
> see
> > anything in the console that indicates work is being done, my object
> > entirely disappears.  I was expecting that if it will take some time it
> > might indicate it is calculating.  Likewise, I thought the end result
> > would
> > be the same drawing but with some facets in a different color (indicating
> > maybe missing / degenerate vertices caused things to be inside out).
> What
> > is the proper way to use View -> Throw Together
> >
> > On Thu, Jul 4, 2019 at 11:03 AM adrianv <
>
> > avm4@
>
> > > wrote:
> >
> >> DanS wrote
> >> > I'm still trying to debug my own code but am frustrated in that I
> can't
> >> > see
> >> > where the problem exists.  I get some errors and other messages from
> >> > OpenScad but unfortunately they don't point to what it was in my code
> >> that
> >> > triggered it:
> >> >
> >> > ERROR: CGAL error in CGAL_Nef_polyhedron3(): CGAL ERROR: assertion
> >> > violation! Expr: e_below != SHalfedge_handle() File:
> >> >
> >>
> /opt/mxe/usr/x86_64-w64-mingw32.static.posix/include/CGAL/Nef_3/SNC_FM_decorator.h
> >> > Line: 426
> >>
> >> I don't recognize this error specifically, but typically if you get
> >> errors
> >> relating to polyhedra it means you have constructed an invalid
> polyhedron
> >> with the polyhedron module.  You can select View->Thrown Together in
> >> preview
> >> which will show reversed faces.  But otherwise you just have to work
> >> through
> >> your construction.
> >>
> >>
> >> > Likewise, I sometimes get this warning:
> >> >
> >> >
> >> > DEPRECATED: Using ranges of the form [begin:end] with begin value
> >> greater
> >> > than the end value is deprecated.
> >>
> >> Yeah, this one is extremely annoying.  There appears to be no way to get
> >> OpenSCAD to give you more information about this.  It can be anywhere in
> >> your code, or anything that you include.  It could be a degenerate case,
> >> in
> >> which case you can solve the problem by replacing every occurrence of
> >> [a:b]
> >> in your code with [a:1:b].  But if it's a mistake in your code, that
> will
> >> just cause the loop to not run---it won't tell you where the problem is.
> >>
> >>
> >>
> >>
> >> --
> >> Sent from: http://forum.openscad.org/
> >>
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> >>
>
> > Discuss at .openscad
>
> >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
> >>
> >
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>
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> >
> >
> > image.png (27K)
> > <http://forum.openscad.org/attachment/26707/0/image.png>
>
>
>
>
>
> --
> Sent from: http://forum.openscad.org/
>
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