Hello!

i juste noticed that a function that i use that produces a subelement for
joinings produces, sometimes, strange print-results, and that indeed the
design doesn't seem sound....

this is the relevant part:

trapez(10,5,10,30,2);

module trapez(oberbreite, unterbreite, hoehe, tiefe,rand)
{
ecken = [
//vorne
[-unterbreite/2,0,0], [unterbreite/2,0,0], //bodenlinie 0,1
[oberbreite/2,0,hoehe-rand], [oberbreite/2,0,hoehe], //rechts hoch 2,3
[-oberbreite/2,0,hoehe], [-oberbreite/2,0,hoehe-rand], //links runter
hoch 4,5

//hinten
[-unterbreite/2,tiefe,0], [unterbreite/2,tiefe,0], //bodenlinie 6,7
[oberbreite/2,tiefe,hoehe-rand], [oberbreite/2,tiefe,hoehe], //rechts
hoch 8,9
[-oberbreite/2,tiefe,hoehe], [-oberbreite/2,tiefe,hoehe-rand], //links
runter hoch 10,11
];

flaechen = [

 [0,5,4,3,2,1], //vorne
 [0,1,7,6], //unten
 [4,10,9,3], //oben
 [6,7,8,9,10,11], //rueck
 [1,2,8,7], //seite links unten
 [2,3,9,8], //seite links open
 [0,6,11,5], //seite rechts unten
 [5,11,10,4], //seite rechts open

];
polyhedron(ecken,flaechen);
}

i saw the lines on the polyhedron, but never got around finding out where
they come from, and since in most of my cases the project compiles and
checks fine i never asked further, but still, there seem to be some
weirdness in there, producing strange holes when printing.... (still when
throwing the stuff into a stl corrector, those problems go usually away,
would still be more satisfying to produce valid stuff in the first place...)

and when i check this with F12, all the surfaces are ok, but the edges are
all purple....

so how do i get rid of the spourious fold lines in the surfaces and how do
i get the edges to be not purple in throw together display?

thanks in advance!

--
ciao
Bruno

---==========
http://nohkumado.eu/, http://bboett.free.frhttp://aikido.nohkumado.eu/,
http://bboett.free.fr
http://aikido.zorn.free.fr

Hi,

The polyhedron that you provided looks OK to me and renders correctly in
OpenScad 2019.11.19.nightly. Which OpenScad version are you using ?

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

I still don't reproduce, using
https://files.openscad.org/snapshots/OpenSCAD-2019.01-RC2-x86_64.AppImage on
Ubuntu 18.04. Either I don't do exactly the same steps, or there is an issue
specific to some library version or even hardware ? I'm not familiar with
how OpenSCAD preview works, but since it uses OpenCSG, that could explain
different behavior in different environments. I think you should open an
issue to investigate further.

Among your two way of expressing the shape, my "programer's" advice is:
definitely the latter, because it's simpler, more concise, and it makes it
explicit that the shape is a linear extrusion of some polygon.

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