It is not so difficult to extend the tube for your particular case.  Truly
even the general case is not very difficult: you just need to extrapolate
the last segment  of p a tiny bit.  But in your case, the segments are
(almost) parallel to the x and y axes, so you can just add .01 to the
appropriate coordinate to make a p_inside shape which is a bit longer in
each direction.  It's a little bit ugly.  I wonder if it would be worth
adding a path_extrapolate function to BOSL2 for this kind of situation.
To do the general case you simply take unit(p[0]-p[1]) * tiny + p[0] to
create a new point at the start, and a similar thing at the end, where tiny
is some small number.

On Fri, Oct 14, 2022 at 10:13 AM Mr Yura Volodin via Discuss <
discuss@lists.openscad.org> wrote:

Is this little longer to  do difference( )?

In these cases where the Inner and outer are same number of points,
difference ( ) command can be completely avoided and everything should be 1
polyhedron.

This make things much faster and simpler.

On Sat, 15 Oct, 2022, 1:34 am Adrian Mariano, avm4@cornell.edu wrote:

You aren't paying attention.  I did it that way---combining the inner and
outer tube wall into a single polyhedron---but he is also using the
difference() operator to remove various objects that are passing through
the tube, so using a single polyhedron does not work in this case.

On Fri, Oct 14, 2022 at 8:28 PM Sanjeev Prabhakar sprabhakar2006@gmail.com
wrote:

OK
I missed to see there is no green color inside tube

On Sat, 15 Oct, 2022, 8:56 am Adrian Mariano, avm4@cornell.edu wrote:

Is this little longer to  do difference( )?
In these cases where the Inner and outer are same number of points, difference ( ) command can be completely avoided and everything should be 1 polyhedron.
This make things much faster and simpler.

Yes if it only the goal. But in my case I need tonehole rims and other details.They must not affect internals. So I am forced to use difference()...

On Sat, 15 Oct, 2022, 1:34 am Adrian Mariano, avm4@cornell.edu wrote:

It is not so difficult to extend the tube for your particular case.  Truly even the general case is not very difficult: you just need to extrapolate the last segment  of p a tiny bit.  But in your case, the segments are (almost) parallel to the x and y axes, so you can just add .01 to the appropriate coordinate to make a p_inside shape which is a bit longer in each direction.  It's a little bit ugly.  I wonder if it would be worth adding a path_extrapolate function to BOSL2 for this kind of situation.   To do the general case you simply take unit(p[0]-p[1]) * tiny + p[0] to create a new point at the start, and a similar thing at the end, where tiny is some small number. 

On Fri, Oct 14, 2022 at 10:13 AM Mr Yura Volodin via Discuss discuss@lists.openscad.org wrote:

---------- Forwarded message ----------
From: Mr Yura Volodin yur_vol@yahoo.com
To: OpenSCAD general discussion Mailing-list discuss@lists.openscad.org
Cc: 
Bcc: 
Date: Fri, 14 Oct 2022 14:12:38 +0000 (UTC)
Subject: [OpenSCAD] Re: Where is "path_pos_from_start" in BOLS2 ?
Yes, now I use your separate code  to subtracte tubes.
On Thursday, October 13, 2022 at 11:52:56 PM GMT+3, Adrian Mariano avm4@cornell.edu wrote:

Ah, I didn't notice that there was other stuff being subtracted.  In that case, you just just use the tube() module as you were doing before, instead of using fulltube().   I fixed tube() first before writing fulltube() as an alternative.   (Using the approach in fulltube() is nicer if you don't need to subtract other stuff, since you don't get z-fighting, and it should be faster as well.)

To really do it right, though, you should make the length of the last segment a little longer at each end for the inside tube so the model doesn't have z-fighting at the ends. 

It seems complicated to extrapolate beyond bented end of tube. In my case I increase thickness of internals HULLs and translated down a bit.

---------- Forwarded message ----------
From: Mr Yura Volodin via Discuss discuss@lists.openscad.org
To: OpenSCAD general discussion Mailing-list discuss@lists.openscad.org
Cc: Mr Yura Volodin yur_vol@yahoo.com
Bcc: 
Date: Fri, 14 Oct 2022 14:12:38 +0000 (UTC)
Subject: [OpenSCAD] Re: Where is "path_pos_from_start" in BOLS2 ?

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org