[OpenSCAD] Getting more information

adrianv avm4 at cornell.edu
Thu Jul 4 17:41:27 EDT 2019

DanS wrote
> So it seems like I only get the:
> DEPRECATED: Using ranges of the form [begin:end] with begin value greater
> than the end value is deprecated.
> warning under a special case:
> and the message appears partway through a bunch of other debug messages
> (suggesting it built one structure, and then later hits the error doing
> the
> difference or the later mirror.  

I have seen behavior with regards to debug message that suggest to me that
the code is not necessarily executed in order.   Does anybody know?  

> Also nothing is drawn because there is a
> problem somewhere.
> I should mention I DO have loops where start is greater than end, but in
> the cases I intend to be that way, I have an index value of -1.

You mean a step value of -1?  Like you wrote [10:-1:0]?  Nothing wrong with
that, and it should not trigger the message.  The warning message is just
for ranges that look like [a:b] where a>b.  Note also that it is only a
warning message.  You can still run your code to completion.  OpenSCAD will
count such a range starting at b and ascending to a.  (It will not start at
a and go by steps of -1 down to b.)  

> If I union arches2(16) with a cube I get the: "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" message

Unioning with a cube is supposed to be a test of validity of your
polyhedron.  I recall previously someone else said it might have to do with
rounding errors.  Have you tried simplifying your model until it works?  It
sounds like arches2(16) is producing an invalid result.  

> arches2(16) does a skin over a bunch of 16 vertex polygons (that you can
> roughly view as being horsehoes, wishbones, arches).  The second numeric
> argument represents a thickness (it has a default value), a boolean
> argument (default false) determines if the object is "solid" (that is not
> horseshoe shaped but a convex polygon with no concavity, also with fewer
> vertices)
> So I'm confused how to approach debugging this.

You said it's a skin over "a bunch" of 16 vertex polygons.  So what happens
if you skin the first two only.  Can you union the result with a cube?  Does
it look ok in thrown together mode?   

I do not know what it means that you got pink edges in "thrown together"
view.  I haven't seen that.  

Sent from: http://forum.openscad.org/

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