Error importing STL.

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rew
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Error importing STL.

rew
Hi,

I have an STL file that I want to print. The first attempt went bad
because the object didn't stick to the brim I ordered.

This occasionally happens, and I then add a cylinder with say 6 radius
and 0.6 height to the corners to make it stick better. The extra
material is easy to clip away after printing.

So I load this model
  http://prive.bitwizard.nl/Top_vert_conic_sm_endstop_v3.STL

which is a "distributed" version of:
   https://github.com/brupje/beagle/blob/master/STL/Top_vert_conic_extruder_sm_endstop.STL

into openscad with
  import("Top_vert_conic_extruder_sm_endstop_v3.STL", convexity=5);

This views just fine (F5 - Preview), and renders too (F6-render).

Then I add one of my cylinders and it suddenly gets errors....  The
errors do not give any useful information as to what goes wrong:

When I hit "F6 - render", I get:


Compiling design (CSG Tree generation)...
Rendering Polygon Mesh using CGAL...
ERROR: CGAL error in CGAL_Nef_polyhedron3(): CGAL ERROR: assertion violation! Expr: pe_prev->is_border() || !internal::Plane_constructor::get_plane(pe_prev->facet(),pe_prev->facet()->plane()).is_degenerate() File: /usr/include/CGAL/Nef_3/polyhedron_3_to_nef_3.h Line: 251
Geometries in cache: 10
Geometry cache size in bytes: 1389248

in the log window, and many repetitions of:

Error !!!!!!!!!!!!!!!!!!!!!!!

in the stdout of openscad.

For "getting my print job done", it seems the github version is
"Better" in some way that it does not cause havoc with openscad.

I don't need help finding a workaround for this specific file: the one
from github works.

A better error message in openscad could help people less seasoned as
me in finding a workaround. I still need to print a few objects from
that set, so I would like to know WHAT is wrong, and how to fix/avoid
it.

screenshots at: http://prive.bitwizard.nl/f5.png
and http://prive.bitwizard.nl/f6.png


        Roger.

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tp3
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Re: Error importing STL.

tp3
On 10/10/2016 12:06 PM, Rogier Wolff wrote:
> So I load this model
>   http://prive.bitwizard.nl/Top_vert_conic_sm_endstop_v3.STL
>
Looks ok in Blender, but has some Zero-Faces that cause issues
in OpenSCAD.

The FAQ has some suggestions on how to fix those:
https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/FAQ#Why_is_my_imported_STL_file_only_showing_up_with_F5_but_not_F6.3F

> in the log window, and many repetitions of:
>
> Error !!!!!!!!!!!!!!!!!!!!!!!
>
Those are coming from libCGAL, which usually means some issues
in with the model which they did not really know how to handle.

> A better error message in openscad could help people less
> seasoned as me in finding a workaround. I still need to print
> a few objects from that set, so I would like to know WHAT is
> wrong, and how to fix/avoid it.
>
This would be nice, but especially in case of imported STL
files, that is not actually OpenSCAD code, but libCGAL, so
short of rewriting all that, that's not a lot we can do.

What's on the to-do list though is automatic fixing of those
zero-face issues which could hopefully reduce the STL import
problems quite a lot.

ciao,
  Torsten.


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