I am always disappointed with the spheres in OpenSCAL. With low $fn the look
- well - not so pretty, especially for small sizes. But even with high $fn they always have a flat spot on the top/bottom and you can easily distinguish a rotated sphere from a not rotated. Has anyone tried to create code for a Geodesic polyhedron <https://en.wikipedia.org/wiki/Geodesic_polyhedron> ? What I see from the wikipedia screens, I like it very much. Even the "truncated icosahedron" already looks much better than a sphere(r=2); -- Sent from: http://forum.openscad.org/ _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
I think that has been coded but simply rotate_extruding a semicircle with $fn set to a multiple of four gives a sphere with points on the poles. See https://github.com/nophead/NopSCADlib#Sphere ![]() I override the built in sphere with this to get hulls with the correct dimensions when the spheres are placed in the corners. On Sat, 30 Jan 2021 at 07:43, bassklampfe <[hidden email]> wrote: I am always disappointed with the spheres in OpenSCAL. With low $fn the look _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
In reply to this post by bassklampfe
On 2021-01-30 08:43, bassklampfe wrote:
> I am always disappointed with the spheres in OpenSCAL. With low $fn the > look > - well - not so pretty, especially for small sizes. But even with high > $fn > they always have a flat spot on the top/bottom and you can easily > distinguish a rotated sphere from a not rotated. > > Has anyone tried to create code for a Geodesic polyhedron > <https://en.wikipedia.org/wiki/Geodesic_polyhedron> ? What I see from > the > wikipedia screens, I like it very much. Even the "truncated > icosahedron" > already looks much better than a sphere(r=2); Write some OpenSCAD code with spheres, save it to an .scad file and run it with AngelCAD. You will then get a geodesic sphere mesh. sphere(r=2) usually means 2mm radius and that is very small, it will not be pretty regardless of mesh type. Try a larger radius first. Carsten Arnholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
Does a geodesic sphere have vertices on the 6 semi-axis lines? I think that is a requirement when using spheres to make accurate corners. There is no reason why a small sphere can't be pretty if $fa is set. ![]() On Sat, 30 Jan 2021 at 08:13, <[hidden email]> wrote: On 2021-01-30 08:43, bassklampfe wrote: _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
On 2021-01-30 09:24, nop head wrote:
> Does a geodesic sphere have vertices on the 6 semi-axis lines? No. > I think > that is a requirement when using spheres to make accurate corners. The question was whether anyone has tried to create code for a Geodesic polyhedron. The answer is yes. Carsten Arholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
In reply to this post by nophead
nop head <[hidden email]> wrote:
Yes, if it's based on the octahedron. The geodesic sphere based on the icosahedron doesn't have that property. In BOSL2, you may find a module called spheroid that is able to draw geodesic spheres in both styles. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
In reply to this post by bassklampfe
Ok, for some reasons my replies via email programm did not make it into the
mailing list. I will copy them here ------------------------ Ok, in the meantime I have found https://www.thingiverse.com/thing:1484333, which does a pretty good job for me. Even if written in OpenSCAD, it's pretty fast and does exactly what I want. I've added some minor tweaks, because there was a numeric overflow on small r's, but basically it's doing all I want. Thanks for your replies. ------------------------ I believe this picture explains, why I like geodesic sphere. Both rendered with r=5 and $fn=50; <http://forum.openscad.org/file/t2988/test-geodesic_sphere.png> -8<-cut-here-8<-cut-here-8<-cut-here-8<-cut-here-8<-cut-here-8<-cut-here- radius=5; $fn=50; use <geodesic_sphere.scad> color("darkgrey")translate([5,-10,0])rotate([90,0,0])linear_extrude(1)text("OpenSCAD",size=5,halign="left"); color("darkgrey")translate([-5,-10,0])rotate([90,0,0])linear_extrude(1)text("geodesic",size=5,halign="right"); scale(10/radius) { color("LightGreen") translate([-radius, 0, radius]) geodesic_sphere(radius); color("LightBlue") translate([radius, 0,radius]) sphere(radius); color("red") translate([+radius, 2*radius,radius]) difference(){geodesic_sphere(radius);sphere(radius);} color("yellow") translate([-radius, 2*radius,radius]) difference(){sphere(radius);geodesic_sphere(radius);} } -8<-cut-here-8<-cut-here-8<-cut-here-8<-cut-here-8<-cut-here-8<-cut-here- ------ Even in PrusaSlicer you can see the difference (see attached Picture) <http://forum.openscad.org/file/t2988/spheres-in-slicer.png> Ok folks, thank you for listening, for me this topic can be closed... -- Sent from: http://forum.openscad.org/ _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
In reply to this post by Ronaldo
In BOSL2, the command `spheroid(d=100, type=“octa”);` will make a sphere based on a subdivided octahedron, which guarantees maxima/minima on all three axes. With type=“icosa”, it subdivides an icosahedron, but maxima/minima on axes is only guaranteed for $fn that are modulo to both 4 and 5. -Revar On Jan 30, 2021, at 1:30 AM, Ronaldo Persiano <[hidden email]> wrote:
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In reply to this post by bassklampfe
> Ok, for some reasons my replies via email programm did not make it into the
> mailing list. > I will copy them here Because you didn't use the address you subscribed with. ie use the ...-openscad@ address and they make it, other addresses get discarded. -- This email has been checked for viruses by AVG. https://www.avg.com _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
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Am 31.01.21 um 03:22 schrieb MichaelAtOz:
> Because you didn't use the address you subscribed with. ie use the > ...-openscad@ address and they make it, other addresses get discarded. Yes, thanks. I figured this out by myself now. Thank you anyway. Regards. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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