Not sure why you say bottleneck. I have designed hundreds of objects and never had a problem with them having overlaps so that they create solid objects. My threads all slightly overlap the inner or outer cylinders because they are created by a reusable routine that does that. On Wed, 7 Jun 2023, 22:44 neri-engineering via Discuss, < discuss@lists.openscad.org> wrote: > > > > ---------- Forwarded message ---------- > From: neri-engineering <neri-engineering@protonmail.com> > To: OpenSCAD general discussion Mailing-list <discuss@lists.openscad.org> > Cc: > Bcc: > Date: Wed, 07 Jun 2023 21:43:02 +0000 > Subject: [OpenSCAD] Re: STL best practices & tools > Yes, I understand your "overlap by nudging a diameter slightly" strategy. > I see traces of that in other people's open source code, all over the place. > > It's "only a workaround" (not good practice in general) because if you > want to begin to do truly powerful things, by combining pieces of re-usable > code in various ways, in ways that you have not yet even considered, then > you'll soon realize that the "nudge strategy" will lead to all sorts of > bottlenecks. This is why I've decided that the only elegant solution is to > address the issue in OpenSCAD, in CGAL, or in any other piece of code that > is forcing you to do things this way. > > By the way... "bottlenecks" and "forcing you to do things"... hrm where > else do I see that pattern. > > I am still investigating. This is a large undertaking. > > Sent with Proton Mail <https://proton.me/> secure email. > > ------- Original Message ------- > On Wednesday, June 7th, 2023 at 3:24 PM, nop head <nop.head@gmail.com> > wrote: > > I don't know how you get 11 volumes. It should be just two. If made an > object like that with my library it would just be two, the inside and the > outside. My threads slightly overlap the cylinder they surround and gears > are just linear extruded from 2D versions so are always just one piece. > > On Wed, 7 Jun 2023, 21:13 neri-engineering via Discuss, < > discuss@lists.openscad.org> wrote: > >> >> >> >> ---------- Forwarded message ---------- >> From: neri-engineering <neri-engineering@protonmail.com> >> To: OpenSCAD general discussion Mailing-list <discuss@lists.openscad.org> >> Cc: >> Bcc: >> Date: Wed, 07 Jun 2023 20:12:18 +0000 >> Subject: [OpenSCAD] Re: STL best practices & tools >> By the way I'm not necessarily looking for a solution. I am studying an >> interesting issue because that study itself is a very worthwhile endeavor; >> such studies oftentimes lead to very interesting new techniques for solving >> problems. >> >> I'm going bottom-up and top-down at the same time to try to nail down a >> simple example (consisting of two simple polyhedron) which demonstrates my >> "issue that I am studying" - which is an STL file compiled without warnings >> or errors, yet which contains more than one volume (where two polyhedron >> are touching at a face, in a very natural and non-disturbing manner). >> >> I am starting on the bottom-up approach, but I did manage to isolate >> something from the top-down avenue; this screenshot below shows that I'm >> able to compile a part without errors or warnings from CGAL yet it consists >> of more than one 3D piece. So no, I wasn't imagining things, and I wasn't >> delusional, in my earlier statements. >> >> [image: screw.png] >> >> I'm still working on the bottom-up so I can give code for exposing this >> issue, then I will continue further on studying possible workarounds to >> this issue (whether post-STL-generation or actually finding an easy fix in >> OpenSCAD and/or CGAL, e.g. maybe it's just a matter of casting to 32 bits >> too early). >> >> I'm not looking for a temporary workaround; I find the study itself to be >> fascinating. I want to get to the bottom of this to see if there are any >> elegant low-hanging-fruit solutions that can be suggested. >> >> The fact that my models consist of many pieces does not bother me >> whatsoever. However, eventually it will become an issue. For example >> working with other tools sometimes leads to issues, e.g. the to->FreeCAD >> importer, and I also had some machinists complain about my STL files, which >> was embarrassing to me. >> >> Sent with Proton Mail <https://proton.me/> secure email. >> >> ------- Original Message ------- >> On Wednesday, June 7th, 2023 at 2:32 PM, Carsten Arnholm < >> arnholm@arnholm.org> wrote: >> >> On 07.06.2023 19:04, neri-engineering wrote: >> >> Are there any tips/docs on how to use polyfix. >> >> It is a command line program with these options >> >> Usage: polyfix [-verbose] [-maxiter <str>] [-dtol <str>] [-atol <str>] >> [-lumps] [-nflip] [-remesh <str>] [-overwrite] [-out <str>] [-zip] >> [-v] <input_filename> >> -verbose Verbose messages >> -maxiter=<str> [heal] Max iterations (def=10) >> -dtol=<str> [heal] Distance tolerance (def=1.0E-2) >> -atol=<str> [heal] Area tolerance (def=1.0E-6) >> -lumps [heal] Split into lumps (not supported for stl output) >> -nflip [heal] Flip faces with inward normals (experimental) >> -remesh=<str> [remesh] Heal & remesh surfaces to given edge length (set >> dtol to small value ~1.E-6) >> -overwrite [output] allow file overwrite, including input file. >> -out=<str> [output] output filename/format (.obj, .off, .amf, .stl, >> .astl) >> -zip [output] save output also to compressed zip file >> -v Show version number only >> >> In the short term I want to pass in a single STL file and have it reconcile faces that are coplanar and overlapping by area, facing in opposite directions (relative to "outside"). This operation could be done on a single connected polyhedron which has "spikes" that touch or very nearly touch, as well. I presume that an epsilon value is being used; I saw something in the source code. >> >> The dtol parameter is your epsilon parameter, it is the tolerance for >> merging vertices of the "triangle soup" that is STL. >> >> The atol parameter is the minimal triangle area required for an STL >> triangle to be valid. >> >> example use, merge STL vertices and remove resulting zero area faces, >> output as *.off format >> >> $ polyfix vase_with_handle.stl -out=off >> >> Parameters: >> input_file = vase_with_handle.stl >> out = off >> >> >> polyhedron 0 ================= volume=3789.18, dtol=0.01, atol=1e-06, >> maxiter=10 >> iteration 0: vertices=108390 faces=36130 >> warning: nonmanifold edges: uc(1)=108390 >> merged 90337 vertices >> removed 24 collapsed or zero area faces >> total changes=90361 >> no warnings >> >> iteration 1: vertices=18053 faces=36106 >> total changes=0 >> no warnings >> >> Summary: >> polyhedron 0: vertices=18053 faces=36106 : no warnings >> >> Writing: vase_with_handle.off >> ... polyfix finished, time used: 0d 00h 00m 01s >> >> Obviously you can override the defaults for dtol, atol etc. >> >> Good luck >> >> Carsten Arnholm >> >> >> >> >> >> ---------- Forwarded message ---------- >> From: neri-engineering via Discuss <discuss@lists.openscad.org> >> To: OpenSCAD general discussion Mailing-list <discuss@lists.openscad.org> >> Cc: neri-engineering <neri-engineering@protonmail.com> >> Bcc: >> Date: Wed, 07 Jun 2023 20:12:18 +0000 >> Subject: [OpenSCAD] Re: STL best practices & tools >> _______________________________________________ >> OpenSCAD mailing list >> To unsubscribe send an email to discuss-leave@lists.openscad.org >> > > > > > ---------- Forwarded message ---------- > From: neri-engineering via Discuss <discuss@lists.openscad.org> > To: OpenSCAD general discussion Mailing-list <discuss@lists.openscad.org> > Cc: neri-engineering <neri-engineering@protonmail.com> > Bcc: > Date: Wed, 07 Jun 2023 21:43:02 +0000 > Subject: [OpenSCAD] Re: STL best practices & tools > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >