That is just a regular polyhedron, with 8 points.
https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_the_2D_Subsystem#polygon

You just need the list of xy points. This is a 2D shape, so remember to
extrude it.

Msquare

On Fri, 2 Jul 2021 at 16:26, disruptivesolutionsnl@gmail.com wrote:

You can make an arbitrary 8 sided shape by giving a list of vertices to
polygon(). If you want to specify the angles you would need to use some
trigonometry to work out the vertex positions, or perhaps use a library
with turtle mode paths.

On Fri, 2 Jul 2021 at 15:26, disruptivesolutionsnl@gmail.com wrote:

On Fri, 2 Jul 2021 16:26:09 +0200, you wrote:

On Fri, 2 Jul 2021 16:26:09 +0200, you wrote:

Hi Ben,

I'm newish here too, and an OS novice, but one of the books I've bought
has some examples from which I've extracted the following. Although it's
not a close match, with a revised function it might be a start.

function cartesian(radius,angle)=
[radiuscos(angle),radiussin(angle)];

module triangle(p1,p2,p3) {
polygon([p1,p2,p3]);
}

module regular_polygon(poly_edges,poly_radius) {
for(n=[0:poly_edges-1]) {
p1 = cartesian(poly_radius,n*360/poly_edges);
p2 = cartesian(poly_radius,(n+1)*360/poly_edges);
triangle([0,0],p1,p2);
}
}

// Octagon example
poly_edges = 8;
poly_radius = 20;
poly_height = 3;
linear_extrude(poly_height)
regular_polygon(poly_edges,poly_radius);

It's not super-obvious, but OpenSCAD has a built-in way to do this:

circle(r=poly_radius, $fn=poly_edges);

Additional regular polygon tips:

Note that OpenSCAD measures the "radius" of the polygon from the center
to the vertices.

function adjustr(r, n) = r / cos(360/n/2);

will give you an "adjusted" radius, such that circle(r=adjustr(r, n),
$fn=n) will give you a polygon where "r" is the distance from the center
to the middle of the edges.

Also note that OpenSCAD circle() behavior puts one vertex at [r, 0], so
that a square ends up diamond-oriented.  That's not wrong, but sometimes
it's more convenient to have an edge there.  For that, you want

rotate(360/n/2) circle(...);

If you combine those:

rotate(360/n/2) circle(r=adjustr(r, n), $fn=n);

then you end up with a polygon where one edge is aligned with the Y axis
and has its center at [r, 0].  If the number of sides is even, another
Y-aligned edge is at [-r,0], and if it's divisible by four then there
will be X-aligned edges at [0,r] and [0,-r].

On 7/2/2021 1:10 PM, Jordan Brown wrote:

Perhaps circle (and cylinder and sphere) should get additional options
so that these adjustments are built in, rather than everybody needing to
layer adjustments on top.

For the radius adjustment, there could be "ir", "or", "id", and "od"
parameters. "or" and "od" would be aliases for the current "r" and "d"
and specify to-vertex dimensions, while "ir" and "id" would specify
to-edge dimensions.

I don't know about the rotation adjustment, but perhaps it would be a
boolean or perhaps it would be an "align" parameter with options
"vertex" and "edge".

It's hard to tell when adding these small tweaks to the base (thus
cluttering the base more) is a win over having people or libraries
invent new names for new operations that are almost the same as the
existing operations.

It’s because you use Gmail.
Gmail has a policy that it will never show you an email that it can tell was sent by yourself.
Makes me crazy when testing groups.
I guess they think it would insult your memory?

--
David Gustavson
dbg@SCIzzL.com

On Fri, Jul 2, 2021, at 12:36 PM, Terry wrote:

Something like this?

r=50; sides=8; small_ang=30;
poly = [
for (a=[0:90:359],b=[-0.5,0.5])
let(ang=a+bsmall_ang)
r[cos(ang), sin(ang)]
]
polygon(poly);

Or do you need specific interior angles on the polygon?

• Revar

Terry,

Firstly we do not use OS as an abbreviation for OpenSCAD it gets confused for Operating System,
which is a more common term. What version of the OS are you running?

So what books??

BTW, people have missed the subtlety of the original request; different angles/lengths.

--
This email has been checked for viruses by AVG.
https://www.avg.com

Terry,

The Mailing-list Archive is not a Forum, I presume you are referring to it.
To save confusion, call it Empathy. (THE Forum is not dead yet, it's Schrodinger)

I did mention posting via Empathy had limitations. Gmail via web is probably your better option
(with your previously mentioned considerations).

Note that the format of the Empathy post/email is actually stored correctly for posterity,
it is just badly displayed.

But as I've said, things are not likely to get fixed in a hurry,
so for now it is probably not worth noting such things, unless they are critical.

Michael

--
This email has been checked for viruses by AVG.
https://www.avg.com

Well, as the Admin, I suffer for you all and actually get three copies of all your prose,
via different avenues to make sure things are working. (Plus three versions of Digests...)

So if you want to see your Gmail posts, subscribe another email address (#2) and set up
some email rules, either just throw away all the gmails, or remove all #2's emails except your gmails.

--
This email has been checked for viruses by AVG.
https://www.avg.com

On Fri, 2021-07-02 at 20:26 +0100, Terry wrote:

Apart from that not having unequal sides and angles, There is a FAR
easier way to draw a polygonal figure as a regular polygon.

Give this a try:

cylinder(h=3,d=40,$fn=8);

Sorry, not a clear enough description. Is it a simple or complex
polygon, is concave acceptable? How will you refer to the specific
corners? How will you ensure that all the angles are valid, or are you
just changing one or two, and hoping the rest will sort themselves out,
and whatever the result is, it doesn't matter?. Any 7 random x,y
coordinates can generate an 8 sided  polygon. What have you tried? Is a
Mk 1 eyeball good enough, or are you looking for precision, involving
doing some sums? https://www.mathsisfun.com/geometry/octagon.html

On 02/07/2021 15:26, disruptivesolutionsnl@gmail.com wrote:

Hardly 'critical' but the corruption of code in Empathy was serious
enough to get a warning mention IMO.

I see it occurs again in Revar's post. Empathy clearly doesn't like the
asterisk symbol. Sometimes treating it as a signal to switch on italics.
Who knows what other symbols are wrongly handled?

Original:
let(ang=a+bsmall_ang)
r[cos(ang), sin(ang)]

Empathy corruption:
let(ang=a+bsmall_ang)
r[cos(ang), sin(ang)]

So using its impressively large archive to search and use helpful code
from years before I became a subscriber is no longer sensible.

Terry

====================

On Sat, 3 Jul 2021 11:24:40 +1000, you wrote:

That particular book was John Craig's "OpenSCAD Cookbook".

I didn't interpret Ben's "... where I could change the angle of each
corner, so the lengths of the 'lines' between them is not equivalent,"
as you seem to have done. I assumed the lines between the corners could
vary in length, as Ben said, but not the RADII too. But until we hear
back from Ben, I guess we won't know. ;-)

In my post I was also careful to add: "Although it's not a close match,
with a revised function it might be a start."

Terry

====================

On Sat, 3 Jul 2021 10:49:09 +1000, you wrote:

I posted a reply at 11:14 and it promptly appeared in Empathy. (Actually
an hour before, according to the time stamp!) But nearly five hours
later I've still have not received it in my mail (nor another reply
posted at 11:37).

I'll try again. Here's a copy/paste from my Sent folder

Hardly 'critical' but the corruption of code in Empathy was serious
enough to get a warning mention IMO.

I see it occurs again in Revar's post. Empathy clearly doesn't like the
asterisk symbol. Sometimes treating it as a signal to switch on italics.
Who knows what other symbols are wrongly handled?

Original:
let(ang=a+bsmall_ang)
r[cos(ang), sin(ang)]

Empathy corruption:
let(ang=a+bsmall_ang)
r[cos(ang), sin(ang)]

So using its impressively large archive to search and use helpful code
from years before I became a subscriber is no longer sensible.

Terry

On Sat, 3 Jul 2021 11:24:40 +1000, you wrote:

I received your previous email "From: Terry terrypingm@gmail.com"
As previously explained gmail does not send emails from you to you.

Please do not report anything further re Empathy.
It is no longer supported. It is available for people to use as a convenience.

--
This email has been checked for viruses by AVG.
https://www.avg.com

Posted this at 11:37, promptly appeared in Empathy (at 10:37!) but five
hours later still not received the email. This is not an initiating
first post, but a reply, so not subject to the Gmail 'feature' already
discussed. I DID get the 'Discuss post acknowledgment'. I am getting
other emails to my gmail ID. So most likely culprit appears to be some
setting or filter in my email client (Forte's Agent). I'll focus on that
but would welcome any other ideas.

Anyway, I'll try again, but not optimistic.

That particular book was John Craig's "OpenSCAD Cookbook".

I didn't interpret Ben's "... where I could change the angle of each
corner, so the lengths of the 'lines' between them is not equivalent,"
as you seem to have done. I assumed the lines between the corners could
vary in length, as Ben said, but not the RADII too. But until we hear
back from Ben, I guess we won't know. ;-)

In my post I was also careful to add: "Although it's not a close match,
with a revised function it might be a start."

Terry

On Sat, 3 Jul 2021 10:49:09 +1000, you wrote:

OK, my misunderstanding. I thought that (daft) Gmail restriction applied
only to an initial post to the mailing list, not to replies to others'
posts. So it makes the thread confusing to follow in my client, and for
me at least it makes Empathy more than a convenience!

Terry

On Sun, 4 Jul 2021 00:21:46 +1000, you wrote:

I use the gmail web client and I see my own posts inserted into the thread.
If I start a new thread it will just be in my sent folder but when there
are replies it becomes a single thread in my inbox. I don't think it comes
from the mailing list.

So it looks to me like your email client isn't totally compatible with
gmail.

On Sat, 3 Jul 2021 at 15:49, Terry terrypingm@gmail.com wrote:

Michael,

Do you (anyone) also have insights as to what might be causing the
following:

1. Replies I see from others have subjects prefixed (automatically I
   assume) with '[OpenSCAD]'. But the few I see from me start with 'Re:'
   And subsequently this becomes, for example, 'Re: [OpenSCAD] Re: New and
   a question'.

2. Why is the Author of my last reply shown in my client as 'To:
   OpenSCAD general discussion' ?

3. I can send emails to myself successfully. Here's the full header of
   an example, for possible clues.

Return-Path: terrypingm@gmail.com
Received: from Terry-2016.home ([5.80.203.36])
by smtp.gmail.com with ESMTPSA id
f62sm6743541wmf.22.2021.07.03.09.36.18
for terrypingm@gmail.com
(version=TLS1 cipher=ECDHE-ECDSA-AES128-SHA bits=128/128);
Sat, 03 Jul 2021 09:36:18 -0700 (PDT)
From: Terry terrypingm@gmail.com
To: terrypingm@gmail.com
Subject: Test from gmail to gmail with Agent
Date: Sat, 03 Jul 2021 17:36:18 +0100
Message-ID: uf41eghqdp79d68kfmgpf0l93iqfh7hqmo@4ax.com
X-Mailer: Forte Agent 4.2/32.1118
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Agent-Received: from Gmail (POP) (pop.gmail.com); Sat, 03 Jul 2021
17:36:53 +0100
X-Agent-Junk-Probability: 0

Terry

====================

On Sun, 4 Jul 2021 00:21:46 +1000, you wrote:

nop head,

Very likely. Perhaps because no version of Agent supports IMAP. See also
my reply to Michael. Particularly my confirmation that (as I'd expect) I
can send myself emails to myself with my gmail address as both To and
From. Yet that seems to be contradicted by the behaviour I see with the
mailing list.

Yet hey, as must be obvious, email in general is largely a black art to
me. But I've only encountered so many puzzling issues since subscribing!

(I'll make sure I receive this by a BCC to myself. Tedious...)

Terry

====================

On Sat, 3 Jul 2021 16:09:10 +0100, you wrote:

Yes I can send emails to myself but the mailing list doesn't send my own
emails back to me. Gmail has a record of what I sent and puts it in the
thread in between the emails from the mailing list.

On Sat, 3 Jul 2021 at 17:54, Terry terrypingm@gmail.com wrote:

Ray, yeh, one off-thread comment & it spreads like weeds...

Terry,

The ONE person who developed "Empathy" (software), which is fairly new (=bugs),

and who had provided support, DIED.

Empathy has no support. It will not change anytime soon.

Don't report Empathy things, unless it is down or you can't logon.

IMAP has nothing to do with this.

Gmail does https://support.google.com/mail/answer/6588?hl=en  it's own thing, it is not a
plain-old-email-forwarder. Try Gmail's All-mail.

When they say 'to save you time and prevent clutter', they mean save them megabucks.

Some.member's replies are not to you. Your replies are not to some.member.

Everything is to/from the Mailing-list.

Replies (usually - unless someone specifically does something else) come to you from the
Mailing-list.

Because when some.member of the List received an email, some.member gets it from the List.

It is configured so the Return-To path is to the List.

So some.member's reply, is to the List not to you (notionally to everyone),

the List then sends it to everyone, including you@gmail, you get it from the List.

The List is configured, by default, with:

Receive own postings: Do you want to receive a copy of every message you post to the list? YES

so it sends your own Gmail post to you@gmail, but see above.

The Mailing-list prepends '[OpenSCAD]'. My Email client prepends 'RE: ', yours does whatever,

the Mailing-list cleans it up,

ALL Emails, including yours, in my inbox have '[OpenSCAD] Re: ' (or no 'Re:' for a new thread)

'Author' is not an internet mail term. When you reply, you reply to the Mailing-list.

Yes. One more time, Gmail DOES NOT SEND YOU YOUR OWN POSTS to Mailing-lists.

NO you cannot configure your PC Agent & IOS & Gmail to get what you want.

THE FORUM is not operational for new emails ATM.

Empathy is not a Forum, it has limitations which will not get fixed.

Life sux. Sorry.

We are looking at options, including whether Nabble changes back or other options,

but for now it is what it is. Changes will not happen quickly.

Michael

--
This email has been checked for viruses by AVG.
https://www.avg.com

Note for everyone:

&

We inherited Empathy when we were forced to migrate from Mailman2 to Mailman3 in Mid March.

The provider was no longer supporting Mailman2. It was inevitable, but we were pushed with little
notice.

Mailman3 was not specifically supported by Nabble. It took some Nabble customisation to get it to
function.

At the time Nabble, the Forum host, was acting normally, although we had previous problems and knew
we

probably would want to migrate away from Nabble, it was very niche, and support was waning.

I tested Empathy at that time to see whether it could replace Nabble.

It had potential, but there were significant limitations, with improvements it may be better.

There was Git based issues support and the developer was responsive to change.

We did not need people to access Empathy, because the Nabble hosted Forum was THE email archive.

Then in Mid May the developer DIED, and it became obvious the company was mostly a one man band.

Dear EMWD Clients:

With great sadness we report the death of our founder and president Brian Carpenter. With this
tragedy comes questions regarding the future operations of EMWD. We want to assure you that we are
working on continuing the level of service to which you are accustomed. We are considering several
offers for the company and are hoping to have all issues resolved soon.

Thank you for your patience as we work through this transition.

On behalf of Barbara Carpenter and Brian's family, we thank you for your business.

--EMWD Customer Support

Then in early June Nabble posted on their Forum, without sending it to administrators:

The feature which allows users to post by email probably will be removed.

Then in mid June, without informing administrators, they chopped Mailing-list support, including
all customisation

implemented for Mailman3. Nabble no longer accepted emails from the Mailing-List, and Forum posts
were not sent to the List.

The Forum was effectively defunct.

We were not alone, all the screams from many Administrators, did not seem to matter.

I won't go into further details, but I sent my 'IMPORTANT!...'
https://lists.openscad.org/empathy/thread/EAAMMV6J6NW3WFRSWQ7MINOSBEYDQ6XH  email. Which
included:

In the interim, I recommend you use the Mailing-list and do not post to the Forum.

Basically nobody will see your post unless they specifically go looking on the Forum.

If you are desperate to see messages via a Web page, use the Mailing-list Archive:

https://lists.openscad.org/empathy/list/discuss.lists.openscad.org

If you are also desperate to post new messages via a Web page you can also use the Archive,

but you will need to https://lists.openscad.org/register to create a password for the email address
that

you subscribed with, then you can logon to the Archive and post.

Note the editor there has limitations.

So today, we have a Mailing-list. We do not have a Forum (that gets updated).

The Empathy front-end to the Mailing-list archive, is not a Forum, it has bugs, is not ideal and
won't get fixed soon.

I don't recommend posting via Empathy, but if you make them vanilla, it sort of works, muchly.

We are considering the future, but it will not be screaming into resolution any time soon.

This is where we are at.

We will have to live within its limitations.

Your perseverance will be appreciated.

MichaelAtOz,

I used to say 'Forum Admin'

We appreciate all the feedback provided on future requirements, options and desires, we do not need
to repeat that exercise.

From: MichaelAtOz [mailto:oz.at.michael@gmail.com]
Sent: Sun, 4 Jul 2021 11:17
To: 'OpenSCAD general discussion'
Subject: [OpenSCAD] Re: problems that folk have with emails

Ray, yeh, one off-thread comment & it spreads like weeds...

Terry,

The ONE person who developed "Empathy" (software), which is fairly new (=bugs),

and who had provided support, DIED.

Empathy has no support. It will not change anytime soon.

Don't report Empathy things, unless it is down or you can't logon.

IMAP has nothing to do with this.

Gmail does https://support.google.com/mail/answer/6588?hl=en  it's own thing, it is not a
plain-old-email-forwarder. Try Gmail's All-mail.

When they say 'to save you time and prevent clutter', they mean save them megabucks.

Some.member's replies are not to you. Your replies are not to some.member.

Everything is to/from the Mailing-list.

Replies (usually - unless someone specifically does something else) come to you from the
Mailing-list.

Because when some.member of the List received an email, some.member gets it from the List.

It is configured so the Return-To path is to the List.

So some.member's reply, is to the List not to you (notionally to everyone),

the List then sends it to everyone, including you@gmail, you get it from the List.

The List is configured, by default, with:

Receive own postings: Do you want to receive a copy of every message you post to the list? YES

so it sends your own Gmail post to you@gmail, but see above.

The Mailing-list prepends '[OpenSCAD]'. My Email client prepends 'RE: ', yours does whatever,

the Mailing-list cleans it up,

ALL Emails, including yours, in my inbox have '[OpenSCAD] Re: ' (or no 'Re:' for a new thread)

'Author' is not an internet mail term. When you reply, you reply to the Mailing-list.

Yes. One more time, Gmail DOES NOT SEND YOU YOUR OWN POSTS to Mailing-lists.

NO you cannot configure your PC Agent & IOS & Gmail to get what you want.

THE FORUM is not operational for new emails ATM.

Empathy is not a Forum, it has limitations which will not get fixed.

Life sux. Sorry.

We are looking at options, including whether Nabble changes back or other options,

but for now it is what it is. Changes will not happen quickly.

Michael

<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_con
tent=emailclient>

Virus-free.
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_con
tent=emailclient> www.avg.com

--
This email has been checked for viruses by AVG.
https://www.avg.com

FWIW I've noticed that emails from this list seem to be frequently picked
up by Gmail's spam filter, and it sometimes doesn't get to my inbox at all
until a couple of people have replied (nophead in particular seems to have
been deemed trustworthy).

On Sun, Jul 4, 2021 at 1:14 AM MichaelAtOz oz.at.michael@gmail.com wrote:

Thanks for the report.
I mentioned I have three addresses subscribed as Admin. Sometimes I get two
emails, and the third turns up an hour or more later, always the Gmail
address.
It is a small subset of posters though. I have yet to get a correlation to
a specific cause.
That will be THE Gmail algorithm at work.

On Sun, 4 Jul 2021 at 18:52, Gareth Chen garethenator@gmail.com wrote:

On Sun, Jul 04, 2021 at 07:27:29PM +1000, Michael AtOz wrote:

Could it be that they are greylisting based on sender address? Or
maybe they accept the Email, tag it as "fishy", and postpone
delivering it into your mailbox for a while, waiting if they end up
seeing lots more of these similar-in-content fishy mails, indicating a
spam run.

Roger. 

--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110 **
**    Delftechpark 11 2628 XJ  Delft, 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.

Yes I just found two OpenSCAD emails in my spam folder. Previously it was
just a few people consistently but now it seems to be random since the
mailing list changed.

On Sun, 4 Jul 2021 at 12:07, Rogier Wolff R.E.Wolff@bitwizard.nl wrote:

I drew this to help me understand the parameters and follow the code
more easily. So may be helpful to others. Attached or here:
https://www.dropbox.com/s/mvuathppe8a1z3o/BenOctagonParameters.jpg?raw=1

Terry

====================

On Sun, 4 Jul 2021 11:27:07 +0200, you wrote:

If that’s what you want, then create a regular octagon and scale it along
the x-axis (or shrink it along y, I guess). No trig needed.

On Sun, Jul 4, 2021 at 7:28 AM Terry terrypingm@gmail.com wrote:

My mistake, that won't work. Gotta run now, but as long as the angles are
all 45 degrees, it's still easy enough to do. If no one beats me to it,
I'll do it this afternoon.

On Sun, Jul 4, 2021 at 7:28 AM Terry terrypingm@gmail.com wrote:

On Sun, 2021-07-04 at 13:00 +0100, nop head wrote:

Are they there because of headers indicating spam, and are they all
from gmail accounts? The reason I ask is that I have yet to have any
emails from this list show up in junk. FWIW, my email client is
Evolution.
On Sun, 4 Jul 2021 at 12:07, Rogier Wolff R.E.Wolff@bitwizard.nl
wrote: