is color an actual operator module ?
On 13.08.25 18:24, John David via Discuss wrote:
yea... lets set up a poll. That said, if the pole said to change it,
would the admin do so?
It's a hosted service currently, so "the maintainers" (assuming
that means OpenSCAD people) do not have any access to the mailman
configuration other than what the admin GUI provides.
ciao,
Torsten.
On 8/13/2025 4:32 AM, Leonard Martin Struttmann via Discuss wrote:
However, I have yet to find a use-case in my projects where
attachments are easier than the native translate()/rotate() OpenSCAD
primitives.
Quick: build a cube with a cylinder sticking out of the right side.
include <BOSL2/std.scad>
cube(10) attach(RIGHT) cylinder(h=10, r=3);
Yes, you can do that with rotate and translate. (Or is it translate and
rotate?)
How about if the cylinder is sticking out the corner of the cube?
include <BOSL2/std.scad>
cube(10) attach(RIGHT+FRONT+TOP) cylinder(h=10, r=3);
Now put a sphere at the end of the cylinder, with the sphere barely
touching the cylinder:
include <BOSL2/std.scad>
cube(10)
attach(RIGHT) cylinder(h=10, r=3)
attach(TOP, BOTTOM) sphere(r=3);
Versus:
cubesz = 10;
cylh = 10;
spherer = 3;
cube(cubesz);
translate([cubesz, cubesz/2, cubesz/2]) rotate([0,90,0]) {
cylinder(h=cylh, r=3);
translate([0,0,cylh + spherer])
sphere(r=spherer);
}
Note: I didn't need the variables, but I did if I wanted to avoid
duplicating the numbers.
On Wed, Aug 13, 2025 at 11:41:37AM -0400, John David via Discuss wrote:
Anyway, this was all very long-winded, BUT I think that NURBS will give you
want and need (it will look very weird at first), but you will have to
either see if there is downstream implementations of NURBS in your 3D
printing and CNC software.
A commercial company like BambuLab can't just make a fast 3D printer
and say: "Slicer and firmware is open source and will probably follow
in a few years". They have to have the "package" ready-to-go with the
first printer they sell. (you might get away with beta-quality
software on the first batch that goes out to testers, reviewers).
In open source software development, you have to make small steps that
end up being useful by themselves. So for openscad, defining cylinders
and spheres to be true curves already helps in making the previews
look better than what they are now. That could be an intermediate
goal.
Then, depending on the output format, the F6-render might create
triangles or keep curves. Or maybe the downsampling to triangles
happens at export time. (but I'd want to see what I'm exporting: When
a cylinder (d=1, h=2); renders like a cylinder and ends up in my STL
as a pentagon... that's not nice if I can no longer view that
situation in openscad.
Once, openscad can export real curves, slicers should become motivated
to support them and possibly pass them along to the GCODE. And once
that is possible, firmwares (like klipper) will be motivated to
implement them and get smoother curves on the 3D prints. You'd be
surprised how high you need to set the $fn for the lines to become
invisible. Acceptable is a lot earlier, but totally invisible takes
quite a high number.
this:
d = 50;
module slice (n)
{
cylinder (d=d, h=1.01, $fn = n);
}
for (i=[0:1:25]) {
htg = 21-i;
nn = floor (.5 + 18 * exp (1.88* htg/20));
echo (i, nn);
translate ([0,0,i]) slice (nn);
}
is my test for this case.
Eventually getting rid of this artefact should IMHO be a "goal" that
we might achieve with open source software in 1, 2, 5 or 10 years.
Roger.
--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110 **
** Verl. Spiegelmakerstraat 37 2645 LZ Delfgauw, The Netherlands.
** KVK: 27239233 **
f equals m times a. When your f is steady, and your m is going down
your a** is going up. -- Chris Hadfield about flying up the space shuttle.
** 'a' for accelleration.
On 8/13/2025 4:41 PM, John David via Discuss wrote:
Now, a couple of people have used the term "true circle". I am
assuming that you mean "a perfectly round shape defined by a single,
continuous mathematical curve, not a series of short lines".
Yes, that's what I mean by it. No matter what size it is, and no matter
how much you zoom in (well, OK, until you start hitting floating point
limits), you'll see a curve.
William asks about file formats that can represent curves. A quick scan
of the OBJ documentation says that it can.
The problem is really in implementing the boolean operations on them.
On Wed, 2025-08-13 at 18:30 +0200, Torsten Paul via Discuss wrote:
On 13.08.25 18:24, John David via Discuss wrote:
yea... lets set up a poll. That said, if the pole said to change it,
would the admin do so?
It's a hosted service currently, so "the maintainers" (assuming
that means OpenSCAD people) do not have any access to the mailman
configuration other than what the admin GUI provides.
Indeed. The mail client is the place to set up what the default reply
is. If your client doesn't do that, you need a better one.
On 8/13/2025 5:30 PM, Torsten Paul via Discuss wrote:
On 13.08.25 18:24, John David via Discuss wrote:
yea... lets set up a poll. That said, if the pole said to change it,
would the admin do so?
It's a hosted service currently, so "the maintainers" (assuming
that means OpenSCAD people) do not have any access to the mailman
configuration other than what the admin GUI provides.
I'd be happy to help with that aspect.
Again, noting that my experience is with Mailman 2 rather than Mailman
3, it's exposed in the Mailman admin GUI, on the General Options page.
On Wed, Aug 13, 2025 at 10:48:40AM -0600, larry via Discuss wrote:
On Wed, 2025-08-13 at 18:30 +0200, Torsten Paul via Discuss wrote:
On 13.08.25 18:24, John David via Discuss wrote:
yea... lets set up a poll. That said, if the pole said to change it,
would the admin do so?
It's a hosted service currently, so "the maintainers" (assuming
that means OpenSCAD people) do not have any access to the mailman
configuration other than what the admin GUI provides.
Indeed. The mail client is the place to set up what the default reply
is. If your client doesn't do that, you need a better one.
In my case I have a "reply all" and a "reply privately to author"
choice.
The thing is say: "evelyn@jlcpcb.com" might set the "reply-to:" in her
Emails to "support@jlcpcb.com". So that when I reply-to-autohor, this
ends up in their support group in case she's not at the office. In
this example, the author redirects "private" replies to a
group-known-to-them.
In other cases, say on my secondary seldomly-checked Email
address... I could set the reply-to to my normal address so that I don't
miss replies.
Especially in this last case the reply-to-author needs to honor the
reply-to header.
Just telling me to instruct my mail-client to
just-not-look-at-the-reply-to-field is not a viable solution.
Roger.
--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110 **
** Verl. Spiegelmakerstraat 37 2645 LZ Delfgauw, The Netherlands.
** KVK: 27239233 **
f equals m times a. When your f is steady, and your m is going down
your a** is going up. -- Chris Hadfield about flying up the space shuttle.
** 'a' for accelleration.
On 13.08.25 18:57, Jordan Brown via Discuss wrote:
Again, noting that my experience is with Mailman 2 rather than Mailman
3, it's exposed in the Mailman admin GUI, on the General Options page.
That is not the admin GUI they provide. They have a thing called
Affinity and that provides just a selection as DMARC mitigation.
ciao,
Torsten.
larry:
In Thunderbird, when I hit Reply, the reply goes to the value found in
the "Reply" field. Unfortunately, this is what I see just before I hit
Reply:
Not a hint that a Reply will go to anyone other than "larry".
If I change View, Headers from Normal to All I then see this:
I hope I can be forgiven if I have NO idea what that Reply To field
actually means.
I am not as certain as you, larry, that the mail client is the place to
deal with this issue.
Jon
On 8/13/2025 12:48 PM, larry via Discuss wrote:
On Wed, 2025-08-13 at 18:30 +0200, Torsten Paul via Discuss wrote:
On 13.08.25 18:24, John David via Discuss wrote:
yea... lets set up a poll. That said, if the pole said to change it,
would the admin do so?
It's a hosted service currently, so "the maintainers" (assuming
that means OpenSCAD people) do not have any access to the mailman
configuration other than what the admin GUI provides.
Indeed. The mail client is the place to set up what the default reply
is. If your client doesn't do that, you need a better one.
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Since all that I do with the 3D models that I create with OpenSCAD is
print them on a 3D printer, so long as the output looks smooth at the
level of 0.1 mm, I don't care about the other details.
On 8/13/2025 11:41 AM, John David via Discuss wrote:
I just got a half dozen private and small group replies (that do not
overlap each other), so I am just going to post a reply to the group...
I assure those of you who do not know the mathematics behind NURBS,
that they can indeed represent an exact circle (see:
https://en.wikipedia.org/wiki/Non-uniform_rational_B-spline#Example:_a_circle
for at least some details, and Gerald Farin's book on NURBS
https://www.farinhansford.com/books/nurbs/ for the math and
practicalities behind it). Now, a couple of people have used the term
"true circle". I am assuming that you mean "a perfectly round shape
defined by a single, continuous mathematical curve, not a series of
short lines". Depending on the degree of the NURBS, you get something
called C* and G* continuity (where * is the degree of the
object/NURBS). So yes, a NURB will exactly define a "true circle".
That said, there are practical implementation details that come into
play. Since you have evoked CNC/G-code, as well as NURB curves and
surfaces, they have to be evaluated as some epsilon. Even a G02
(clockwise arc in g-code), has to evaluate the mathematical expression
of an arc/circle at the precision of a machine's step size. This is
often well below 0.001" (I have machines whose step size are
0.00002"). Both a mathematical circle, as well as a NURBS with
appropriate knots sequences and weights of sqrt(2)/2, will
mathematically give you a fully mathematically continuous and exact
circle.
Since you also mentioned wanting these in 3D printing, and CNC, even
LinuxCNC has an experimental implementation, and I know commercial CNC
machines often have NURBS implemented directly in the G-Code
implementation. I am not familiar with any 3D printing software the
supports NURBS, but I have not needed to check. I will say that the
way NURBS are defined is so well-defined, that it is typically easy to
write a translator to go from one representation to another. In
addition, there are enough prototype implementations that a motivated
programmer should be able to port any one of a dozen
implementations/libraries to open-source 3D printing software. If you
go for that, hit me up, and I will dig through my archived class
projects -- back in 2001 I took Gerald Farin's PhD level class on
CAGD, as well as others. One of the other students and I made a game
of challenging each other with different implementations of evaluating
the N-Dimentional Bernstein Polynomials (and you can implement NURBS
based on them). Anyway, we ended up with something that is wicked
fast, and if I recall correctly I set mine up to cache the
intermediate results for various efficiency reasons (like further
subdivisions, etc.).
Anyway, this was all very long-winded, BUT I think that NURBS will
give you want and need (it will look very weird at first), but you
will have to either see if there is downstream implementations of
NURBS in your 3D printing and CNC software.
EBo --
On Wed, Aug 13, 2025 at 10:59 AM Rogier Wolff via Discuss
discuss@lists.openscad.org wrote:
On Aug 13, 2025, at 7:20 AM, William F. Adams via Discuss
<discuss@lists.openscad.org> wrote:
It is an interesting mathematical exercise to prove how a Bézier
curve cannot exactly represent a circle --- but I think it would be
even more interesting to show a real-world example where the want of
that ability has resulted in a difficulty making a part --- it's a
close enough approximation for most (or even the vast majority of)
usages.
We'd like to do 3D printing and CNCing with the results from the CAD
process, right?
Well... if I design a round hole for an object and the object that
goes inside, then I expect that object to be able to rotate. Any
deviation from a true circle will cause it to "not be able to rotate".
If you create sufficient tolerances that it does rotate, you'll get
it to fit tighter and less tight along the full rotation.
This design and wanting to CNC that with a low tolerance on a good CNC
isn't all that farfetched. So maybe my "visually a spline is close
enough to a circle" is not quite good enough.
I got educated on "computer graphics" mid 1980s. So back then: "looks
good" was important and "exact fit" maybe not so much. The wikipedia
article mentions late 1980s as the first implementation of NURBs.
Roger.
--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/
<https://www.BitWizard.nl/> ** +31-15-2049110 **
** Verl. Spiegelmakerstraat 37 2645 LZ Delfgauw, The Netherlands.
** KVK: 27239233 **
f equals m times a. When your f is steady, and your m is going down
your a** is going up. -- Chris Hadfield about flying up the space
shuttle.
** 'a' for accelleration.
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