### Attempt to offer path_extrude in openscad

AM
Fri, Jan 27, 2023 9:31 PM

Guenther, I'm not sure what you mean.  Having points widely spaced can be
done, of course.  It's just harder to define the problem, I think, so
perhaps not the place to start.  Nothing in BOSL2 assumes anything about
point spacing, but if the points are far apart you may find that you don't
like the automatically computed derivatives, especially if the path is very
short.  And transitions between the sections may be more likely to do
something odd.  Consider a rectangle that is 10 x 3.  What are the
derivatives at the end?  Are they 45 deg angles?  Or do they respect the
aspect ratio of the rectangle?  Either option can be defended as correct.
The BOSL2 implementation is very general and should be able to handle any
situation, as long as the sections don't lead to a self-intersecting and
hence invalid polyhedron.

On Fri, Jan 27, 2023 at 3:39 PM Guenther Sohler guenther.sohler@gmail.com
wrote:

There are many great effects, which you can achieve when  having the
points of the path wide enough apart.
Of course The Tangent and the normals (but especially the angle between x
and y axis) need be correct, but then it looks really cool.
With my approach I can easily immitate your solution by using many points
close together and skip the axis scaling(maybe worth an option)
My Vision and my approach which I have chosen actually came true.

if  it's too different from BOSL extrude maybe we can choose another name .

On Fri, Jan 27, 2023 at 1:08 PM Rogier Wolff R.E.Wolff@bitwizard.nl
wrote:

FYI,

Freya Holmer worked on defining a "normal" or "reference" vector along
a path recently. She works in "gaming", so she has built what she
found out into some library that she is making. So for those wishing
to delve into that, it probably pays to watch her videos on youtube
and then delve into figuring out if she has published the code.

That said, she's interested in fluid curves and motions. So all her
"paths" are neat splines....

``````     Roger.
``````

On Fri, Jan 27, 2023 at 06:43:11AM -0500, Adrian Mariano wrote:

I agree with Sanjeev that it's better to focus on the case of points

close

together.  The problem is that some of the approaches are difficult to
define, or simply won't work, if you have the points on the path very
discrete and far apart.  You need to compute tangent and normal to the
path, so how do you do that at corners on a path with very few points?
There may be end effects in this computation, which will be more of a
nuisance if you have only four points.  One of the obvious algorithms

for

choosing the rotation of the sections relies on the path points being

close

together and may produce bizarre results when they are too far apart.

On Fri, Jan 27, 2023 at 4:39 AM Guenther Sohler <

wrote:

Thank you for the hint and the direct link.
I am happy to compare my implementation against yours to see where

are the

differences.

Sanjeer, Thank you for your input.
Your output looks very impressive and I want to reach that too.
Personally I believe the challenge is to get it correct with very few
points first.
The error will be much more clearly visible when choosing few points.
Finally, using many points to make it look smooth is just exercise.
Probably
spline and many other functions are viable.
Maybe its also there in BOSL2, will check later.

On Thu, Jan 26, 2023 at 10:50 PM Adrian Mariano avm4@cornell.edu

wrote:

Guenther, I'm a little unsure of your goal here.  If you are excited

to

implement path_sweep for the fun of it that's fine, of course, but

this has

been done before by many people in OpenSCAD, starting with
list-comprehension-demos and also in dotSCAD, and BOSL2.  These

methods

show the

possibilities. There are some very difficult questions about how to

rotate

the cross sections as you move around the path, and yes, it's

entirely

possible that you've gotten it wrong...assuming that you can figure

out

what "wrong" means.  It's not clear.  There was a very long thread

on the

forum many years ago about the various complications.  I implemented
several different algorithms in BOSL2 for choosing how to line up the
sections.  You might want to take a look to get more understanding

of the

issues.

On Thu, Jan 26, 2023 at 11:26 AM Guenther Sohler <
guenther.sohler@gmail.com> wrote:

Hi List,

right now i am attempting to add a path_extrude function to openscad
A demonstration what i am talking about is here:

https://youtu.be/igMupYGvX1s

(sorry, its in python, but still i hope you get the idea. )
This shows an arbitrary path_extrude of a square,
but in the video you can clearly see the triangles in the faces,
so i believe the cross section at the joints is not correct.
IMHO the square must turn to a deltoid especially when the base

square

is rotated by 45 degrees to be correct.
Can anybody shade some light on that for me ?

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**
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**

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GS
Guenther Sohler
Fri, Jan 27, 2023 9:50 PM

Hi Adrian, when i Use an rectangle 10x3 as a Profile , this Profile is
present in any Cross Section along the path when little apart from the
Corners of course.
This ist Independent from the original Rotation of the path or the Angles
between the path Segments.as Well as i. Bosl2: faces must Not interec.but
watch the Video. Pictures Tell more than 1000 words.

Adrian Mariano avm4@cornell.edu schrieb am Fr., 27. Jän. 2023, 22:31:

Guenther, I'm not sure what you mean.  Having points widely spaced can be
done, of course.  It's just harder to define the problem, I think, so
perhaps not the place to start.  Nothing in BOSL2 assumes anything about
point spacing, but if the points are far apart you may find that you don't
like the automatically computed derivatives, especially if the path is very
short.  And transitions between the sections may be more likely to do
something odd.  Consider a rectangle that is 10 x 3.  What are the
derivatives at the end?  Are they 45 deg angles?  Or do they respect the
aspect ratio of the rectangle?  Either option can be defended as correct.
The BOSL2 implementation is very general and should be able to handle any
situation, as long as the sections don't lead to a self-intersecting and
hence invalid polyhedron.

On Fri, Jan 27, 2023 at 3:39 PM Guenther Sohler guenther.sohler@gmail.com
wrote:

There are many great effects, which you can achieve when  having the
points of the path wide enough apart.
Of course The Tangent and the normals (but especially the angle between x
and y axis) need be correct, but then it looks really cool.
With my approach I can easily immitate your solution by using many
points close together and skip the axis scaling(maybe worth an option)
My Vision and my approach which I have chosen actually came true.

if  it's too different from BOSL extrude maybe we can choose another name
.

On Fri, Jan 27, 2023 at 1:08 PM Rogier Wolff R.E.Wolff@bitwizard.nl
wrote:

FYI,

Freya Holmer worked on defining a "normal" or "reference" vector along
a path recently. She works in "gaming", so she has built what she
found out into some library that she is making. So for those wishing
to delve into that, it probably pays to watch her videos on youtube
and then delve into figuring out if she has published the code.

That said, she's interested in fluid curves and motions. So all her
"paths" are neat splines....

``````     Roger.
``````

On Fri, Jan 27, 2023 at 06:43:11AM -0500, Adrian Mariano wrote:

I agree with Sanjeev that it's better to focus on the case of points

close

together.  The problem is that some of the approaches are difficult to
define, or simply won't work, if you have the points on the path very
discrete and far apart.  You need to compute tangent and normal to the
path, so how do you do that at corners on a path with very few points?
There may be end effects in this computation, which will be more of a
nuisance if you have only four points.  One of the obvious algorithms

for

choosing the rotation of the sections relies on the path points being

close

together and may produce bizarre results when they are too far apart.

On Fri, Jan 27, 2023 at 4:39 AM Guenther Sohler <

wrote:

Thank you for the hint and the direct link.
I am happy to compare my implementation against yours to see where

are the

differences.

Sanjeer, Thank you for your input.
Your output looks very impressive and I want to reach that too.
Personally I believe the challenge is to get it correct with very few
points first.
The error will be much more clearly visible when choosing few points.
Finally, using many points to make it look smooth is just exercise.
Probably
spline and many other functions are viable.
Maybe its also there in BOSL2, will check later.

On Thu, Jan 26, 2023 at 10:50 PM Adrian Mariano avm4@cornell.edu

wrote:

Guenther, I'm a little unsure of your goal here.  If you are

excited to

implement path_sweep for the fun of it that's fine, of course, but

this has

been done before by many people in OpenSCAD, starting with
list-comprehension-demos and also in dotSCAD, and BOSL2.  These

methods

show the

possibilities. There are some very difficult questions about how to

rotate

the cross sections as you move around the path, and yes, it's

entirely

possible that you've gotten it wrong...assuming that you can figure

out

what "wrong" means.  It's not clear.  There was a very long thread

on the

forum many years ago about the various complications.  I implemented
several different algorithms in BOSL2 for choosing how to line up

the

sections.  You might want to take a look to get more understanding

of the

issues.

On Thu, Jan 26, 2023 at 11:26 AM Guenther Sohler <
guenther.sohler@gmail.com> wrote:

Hi List,

right now i am attempting to add a path_extrude function to

A demonstration what i am talking about is here:

https://youtu.be/igMupYGvX1s

(sorry, its in python, but still i hope you get the idea. )
This shows an arbitrary path_extrude of a square,
but in the video you can clearly see the triangles in the faces,
so i believe the cross section at the joints is not correct.
IMHO the square must turn to a deltoid especially when the base

square

is rotated by 45 degrees to be correct.
Can anybody shade some light on that for me ?

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--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ **
+31-15-2049110 **
**    Delftechpark 11 2628 XJ  Delft, The Netherlands.  KVK: 27239233
**

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

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AM
Fri, Jan 27, 2023 10:08 PM

The rectangle I was talking about is the path, not the cross section.  The
point is that you need to decide how to orient the cross section at each
corner of the rectangle, and an ambiguity exists that does not exist in the
case with a smooth curve, so simply using the half-angle may not be the
desired result.  Video didn't seem notable.  Not sure what I was supposed
to be seeing.

On Fri, Jan 27, 2023 at 4:51 PM Guenther Sohler guenther.sohler@gmail.com
wrote:

Hi Adrian, when i Use an rectangle 10x3 as a Profile , this Profile is
present in any Cross Section along the path when little apart from the
Corners of course.
This ist Independent from the original Rotation of the path or the Angles
between the path Segments.as Well as i. Bosl2: faces must Not interec.but
watch the Video. Pictures Tell more than 1000 words.

Adrian Mariano avm4@cornell.edu schrieb am Fr., 27. Jän. 2023, 22:31:

Guenther, I'm not sure what you mean.  Having points widely spaced can be
done, of course.  It's just harder to define the problem, I think, so
perhaps not the place to start.  Nothing in BOSL2 assumes anything about
point spacing, but if the points are far apart you may find that you don't
like the automatically computed derivatives, especially if the path is very
short.  And transitions between the sections may be more likely to do
something odd.  Consider a rectangle that is 10 x 3.  What are the
derivatives at the end?  Are they 45 deg angles?  Or do they respect the
aspect ratio of the rectangle?  Either option can be defended as correct.
The BOSL2 implementation is very general and should be able to handle any
situation, as long as the sections don't lead to a self-intersecting and
hence invalid polyhedron.

On Fri, Jan 27, 2023 at 3:39 PM Guenther Sohler <
guenther.sohler@gmail.com> wrote:

There are many great effects, which you can achieve when  having the
points of the path wide enough apart.
Of course The Tangent and the normals (but especially the angle between
x and y axis) need be correct, but then it looks really cool.
With my approach I can easily immitate your solution by using many
points close together and skip the axis scaling(maybe worth an option)
My Vision and my approach which I have chosen actually came true.

if  it's too different from BOSL extrude maybe we can choose another
name .

On Fri, Jan 27, 2023 at 1:08 PM Rogier Wolff R.E.Wolff@bitwizard.nl
wrote:

FYI,

Freya Holmer worked on defining a "normal" or "reference" vector along
a path recently. She works in "gaming", so she has built what she
found out into some library that she is making. So for those wishing
to delve into that, it probably pays to watch her videos on youtube
and then delve into figuring out if she has published the code.

That said, she's interested in fluid curves and motions. So all her
"paths" are neat splines....

``````     Roger.
``````

On Fri, Jan 27, 2023 at 06:43:11AM -0500, Adrian Mariano wrote:

I agree with Sanjeev that it's better to focus on the case of points

close

together.  The problem is that some of the approaches are difficult to
define, or simply won't work, if you have the points on the path very
discrete and far apart.  You need to compute tangent and normal to the
path, so how do you do that at corners on a path with very few points?
There may be end effects in this computation, which will be more of a
nuisance if you have only four points.  One of the obvious

algorithms for

choosing the rotation of the sections relies on the path points being

close

together and may produce bizarre results when they are too far apart.

On Fri, Jan 27, 2023 at 4:39 AM Guenther Sohler <

wrote:

Thank you for the hint and the direct link.
I am happy to compare my implementation against yours to see where

are the

differences.

Sanjeer, Thank you for your input.
Your output looks very impressive and I want to reach that too.
Personally I believe the challenge is to get it correct with very

few

points first.
The error will be much more clearly visible when choosing few

points.

Finally, using many points to make it look smooth is just exercise.
Probably
spline and many other functions are viable.
Maybe its also there in BOSL2, will check later.

On Thu, Jan 26, 2023 at 10:50 PM Adrian Mariano avm4@cornell.edu

wrote:

Guenther, I'm a little unsure of your goal here.  If you are

excited to

implement path_sweep for the fun of it that's fine, of course, but

this has

been done before by many people in OpenSCAD, starting with
list-comprehension-demos and also in dotSCAD, and BOSL2.  These

methods

show the

possibilities. There are some very difficult questions about how

to rotate

the cross sections as you move around the path, and yes, it's

entirely

possible that you've gotten it wrong...assuming that you can

figure out

what "wrong" means.  It's not clear.  There was a very long thread

on the

forum many years ago about the various complications.  I

implemented

several different algorithms in BOSL2 for choosing how to line up

the

sections.  You might want to take a look to get more understanding

of the

issues.

On Thu, Jan 26, 2023 at 11:26 AM Guenther Sohler <
guenther.sohler@gmail.com> wrote:

Hi List,

right now i am attempting to add a path_extrude function to

A demonstration what i am talking about is here:

https://youtu.be/igMupYGvX1s

(sorry, its in python, but still i hope you get the idea. )
This shows an arbitrary path_extrude of a square,
but in the video you can clearly see the triangles in the faces,
so i believe the cross section at the joints is not correct.
IMHO the square must turn to a deltoid especially when the base

square

is rotated by 45 degrees to be correct.
Can anybody shade some light on that for me ?

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

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

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

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--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ **
+31-15-2049110 **
**    Delftechpark 11 2628 XJ  Delft, The Netherlands.  KVK: 27239233
**
shuttle.

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GS
Guenther Sohler
Fri, Jan 27, 2023 11:08 PM

Sorry, I got you wrong apparently.
I am now using a rectangle 3x10 as the extrude path and I have created a
polygon, which looks like an "U" Shape.
The thing rotates successfully  around the extrusion axis all 360 degrees
and there aren't manifold problems at all during that time.
In each corner the successor segment has exactly one orientation where it
fits, so I believe it's not ambiguous at all.

And yes, my implementation is missing the "closed loop option" but I can
implement that next.

[image: image.png]

On Fri, Jan 27, 2023 at 11:09 PM Adrian Mariano avm4@cornell.edu wrote:

The rectangle I was talking about is the path, not the cross section.  The
point is that you need to decide how to orient the cross section at each
corner of the rectangle, and an ambiguity exists that does not exist in the
case with a smooth curve, so simply using the half-angle may not be the
desired result.  Video didn't seem notable.  Not sure what I was supposed
to be seeing.

On Fri, Jan 27, 2023 at 4:51 PM Guenther Sohler guenther.sohler@gmail.com
wrote:

Hi Adrian, when i Use an rectangle 10x3 as a Profile , this Profile is
present in any Cross Section along the path when little apart from the
Corners of course.
This ist Independent from the original Rotation of the path or the Angles
between the path Segments.as Well as i. Bosl2: faces must Not interec.but
watch the Video. Pictures Tell more than 1000 words.

Adrian Mariano avm4@cornell.edu schrieb am Fr., 27. Jän. 2023, 22:31:

Guenther, I'm not sure what you mean.  Having points widely spaced can
be done, of course.  It's just harder to define the problem, I think, so
perhaps not the place to start.  Nothing in BOSL2 assumes anything about
point spacing, but if the points are far apart you may find that you don't
like the automatically computed derivatives, especially if the path is very
short.  And transitions between the sections may be more likely to do
something odd.  Consider a rectangle that is 10 x 3.  What are the
derivatives at the end?  Are they 45 deg angles?  Or do they respect the
aspect ratio of the rectangle?  Either option can be defended as correct.
The BOSL2 implementation is very general and should be able to handle any
situation, as long as the sections don't lead to a self-intersecting and
hence invalid polyhedron.

On Fri, Jan 27, 2023 at 3:39 PM Guenther Sohler <
guenther.sohler@gmail.com> wrote:

There are many great effects, which you can achieve when  having the
points of the path wide enough apart.
Of course The Tangent and the normals (but especially the angle between
x and y axis) need be correct, but then it looks really cool.
With my approach I can easily immitate your solution by using many
points close together and skip the axis scaling(maybe worth an option)
My Vision and my approach which I have chosen actually came true.

if  it's too different from BOSL extrude maybe we can choose another
name .

On Fri, Jan 27, 2023 at 1:08 PM Rogier Wolff R.E.Wolff@bitwizard.nl
wrote:

FYI,

Freya Holmer worked on defining a "normal" or "reference" vector along
a path recently. She works in "gaming", so she has built what she
found out into some library that she is making. So for those wishing
to delve into that, it probably pays to watch her videos on youtube
and then delve into figuring out if she has published the code.

That said, she's interested in fluid curves and motions. So all her
"paths" are neat splines....

``````     Roger.
``````

On Fri, Jan 27, 2023 at 06:43:11AM -0500, Adrian Mariano wrote:

I agree with Sanjeev that it's better to focus on the case of points

close

together.  The problem is that some of the approaches are difficult

to

define, or simply won't work, if you have the points on the path very
discrete and far apart.  You need to compute tangent and normal to

the

path, so how do you do that at corners on a path with very few

points?

There may be end effects in this computation, which will be more of a
nuisance if you have only four points.  One of the obvious

algorithms for

choosing the rotation of the sections relies on the path points

being close

together and may produce bizarre results when they are too far apart.

On Fri, Jan 27, 2023 at 4:39 AM Guenther Sohler <

wrote:

Thank you for the hint and the direct link.
I am happy to compare my implementation against yours to see where

are the

differences.

Sanjeer, Thank you for your input.
Your output looks very impressive and I want to reach that too.
Personally I believe the challenge is to get it correct with very

few

points first.
The error will be much more clearly visible when choosing few

points.

Finally, using many points to make it look smooth is just exercise.
Probably
spline and many other functions are viable.
Maybe its also there in BOSL2, will check later.

On Thu, Jan 26, 2023 at 10:50 PM Adrian Mariano avm4@cornell.edu

wrote:

Guenther, I'm a little unsure of your goal here.  If you are

excited to

implement path_sweep for the fun of it that's fine, of course,

but this has

been done before by many people in OpenSCAD, starting with
list-comprehension-demos and also in dotSCAD, and BOSL2.  These

methods

to show the

possibilities. There are some very difficult questions about how

to rotate

the cross sections as you move around the path, and yes, it's

entirely

possible that you've gotten it wrong...assuming that you can

figure out

what "wrong" means.  It's not clear.  There was a very long

forum many years ago about the various complications.  I

implemented

several different algorithms in BOSL2 for choosing how to line up

the

sections.  You might want to take a look to get more

understanding of the

issues.

On Thu, Jan 26, 2023 at 11:26 AM Guenther Sohler <
guenther.sohler@gmail.com> wrote:

Hi List,

right now i am attempting to add a path_extrude function to

A demonstration what i am talking about is here:

https://youtu.be/igMupYGvX1s

(sorry, its in python, but still i hope you get the idea. )
This shows an arbitrary path_extrude of a square,
but in the video you can clearly see the triangles in the faces,
so i believe the cross section at the joints is not correct.
IMHO the square must turn to a deltoid especially when the base

square

is rotated by 45 degrees to be correct.
Can anybody shade some light on that for me ?

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

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

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

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--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ **
+31-15-2049110 **
**    Delftechpark 11 2628 XJ  Delft, The Netherlands.  KVK: 27239233
**
shuttle.

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SP
Sanjeev Prabhakar
Sat, Jan 28, 2023 2:13 AM

Looks great 👌

On Sat, 28 Jan, 2023, 4:39 am Guenther Sohler, guenther.sohler@gmail.com
wrote:

Sorry, I got you wrong apparently.
I am now using a rectangle 3x10 as the extrude path and I have created a
polygon, which looks like an "U" Shape.
The thing rotates successfully  around the extrusion axis all 360 degrees
and there aren't manifold problems at all during that time.
In each corner the successor segment has exactly one orientation where it
fits, so I believe it's not ambiguous at all.

And yes, my implementation is missing the "closed loop option" but I can
implement that next.

[image: image.png]

On Fri, Jan 27, 2023 at 11:09 PM Adrian Mariano avm4@cornell.edu wrote:

The rectangle I was talking about is the path, not the cross section.
The point is that you need to decide how to orient the cross section at
each corner of the rectangle, and an ambiguity exists that does not exist
in the case with a smooth curve, so simply using the half-angle may not be
the desired result.  Video didn't seem notable.  Not sure what I was
supposed to be seeing.

On Fri, Jan 27, 2023 at 4:51 PM Guenther Sohler <
guenther.sohler@gmail.com> wrote:

Hi Adrian, when i Use an rectangle 10x3 as a Profile , this Profile is
present in any Cross Section along the path when little apart from the
Corners of course.
This ist Independent from the original Rotation of the path or the
Angles between the path Segments.as Well as i. Bosl2: faces must Not
interec.but watch the Video. Pictures Tell more than 1000 words.

Adrian Mariano avm4@cornell.edu schrieb am Fr., 27. Jän. 2023, 22:31:

Guenther, I'm not sure what you mean.  Having points widely spaced can
be done, of course.  It's just harder to define the problem, I think, so
perhaps not the place to start.  Nothing in BOSL2 assumes anything about
point spacing, but if the points are far apart you may find that you don't
like the automatically computed derivatives, especially if the path is very
short.  And transitions between the sections may be more likely to do
something odd.  Consider a rectangle that is 10 x 3.  What are the
derivatives at the end?  Are they 45 deg angles?  Or do they respect the
aspect ratio of the rectangle?  Either option can be defended as correct.
The BOSL2 implementation is very general and should be able to handle any
situation, as long as the sections don't lead to a self-intersecting and
hence invalid polyhedron.

On Fri, Jan 27, 2023 at 3:39 PM Guenther Sohler <
guenther.sohler@gmail.com> wrote:

There are many great effects, which you can achieve when  having the
points of the path wide enough apart.
Of course The Tangent and the normals (but especially the angle
between x and y axis) need be correct, but then it looks really cool.
With my approach I can easily immitate your solution by using many
points close together and skip the axis scaling(maybe worth an option)
My Vision and my approach which I have chosen actually came true.

if  it's too different from BOSL extrude maybe we can choose another
name .

On Fri, Jan 27, 2023 at 1:08 PM Rogier Wolff R.E.Wolff@bitwizard.nl
wrote:

FYI,

Freya Holmer worked on defining a "normal" or "reference" vector along
a path recently. She works in "gaming", so she has built what she
found out into some library that she is making. So for those wishing
to delve into that, it probably pays to watch her videos on youtube
and then delve into figuring out if she has published the code.

That said, she's interested in fluid curves and motions. So all her
"paths" are neat splines....

``````     Roger.
``````

On Fri, Jan 27, 2023 at 06:43:11AM -0500, Adrian Mariano wrote:

I agree with Sanjeev that it's better to focus on the case of

points close

together.  The problem is that some of the approaches are difficult

to

define, or simply won't work, if you have the points on the path

very

discrete and far apart.  You need to compute tangent and normal to

the

path, so how do you do that at corners on a path with very few

points?

There may be end effects in this computation, which will be more of

a

nuisance if you have only four points.  One of the obvious

algorithms for

choosing the rotation of the sections relies on the path points

being close

together and may produce bizarre results when they are too far

apart.

On Fri, Jan 27, 2023 at 4:39 AM Guenther Sohler <

wrote:

Thank you for the hint and the direct link.
I am happy to compare my implementation against yours to see

where are the

differences.

Sanjeer, Thank you for your input.
Your output looks very impressive and I want to reach that too.
Personally I believe the challenge is to get it correct with very

few

points first.
The error will be much more clearly visible when choosing few

points.

Finally, using many points to make it look smooth is just

exercise.

Probably
spline and many other functions are viable.
Maybe its also there in BOSL2, will check later.

On Thu, Jan 26, 2023 at 10:50 PM Adrian Mariano avm4@cornell.edu

wrote:

Guenther, I'm a little unsure of your goal here.  If you are

excited to

implement path_sweep for the fun of it that's fine, of course,

but this has

been done before by many people in OpenSCAD, starting with
list-comprehension-demos and also in dotSCAD, and BOSL2.  These

methods

to show the

possibilities. There are some very difficult questions about how

to rotate

the cross sections as you move around the path, and yes, it's

entirely

possible that you've gotten it wrong...assuming that you can

figure out

what "wrong" means.  It's not clear.  There was a very long

forum many years ago about the various complications.  I

implemented

several different algorithms in BOSL2 for choosing how to line

up the

sections.  You might want to take a look to get more

understanding of the

issues.

On Thu, Jan 26, 2023 at 11:26 AM Guenther Sohler <
guenther.sohler@gmail.com> wrote:

Hi List,

right now i am attempting to add a path_extrude function to

A demonstration what i am talking about is here:

https://youtu.be/igMupYGvX1s

(sorry, its in python, but still i hope you get the idea. )
This shows an arbitrary path_extrude of a square,
but in the video you can clearly see the triangles in the faces,
so i believe the cross section at the joints is not correct.
IMHO the square must turn to a deltoid especially when the base

square

is rotated by 45 degrees to be correct.
Can anybody shade some light on that for me ?

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SP
Sanjeev Prabhakar
Sat, Jan 28, 2023 10:39 AM

I have tried your example by creating slices of the solid produced from
path_extrude and it produces the right result
[image: Screenshot 2023-01-28 at 4.03.49 PM.png]

I had to write a code for creating slices for the path_extruded solid
nevertheless

On Thu, 26 Jan 2023 at 21:56, Guenther Sohler guenther.sohler@gmail.com
wrote:

Hi List,

right now i am attempting to add a path_extrude function to openscad
A demonstration what i am talking about is here:

https://youtu.be/igMupYGvX1s

(sorry, its in python, but still i hope you get the idea. )
This shows an arbitrary path_extrude of a square,
but in the video you can clearly see the triangles in the faces,
so i believe the cross section at the joints is not correct.
IMHO the square must turn to a deltoid especially when the base square is
rotated by 45 degrees to be correct.
Can anybody shade some light on that for me ?

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

I have tried your example by creating slices of the solid produced from path_extrude and it produces the right result [image: Screenshot 2023-01-28 at 4.03.49 PM.png] I had to write a code for creating slices for the path_extruded solid nevertheless On Thu, 26 Jan 2023 at 21:56, Guenther Sohler <guenther.sohler@gmail.com> wrote: > Hi List, > > right now i am attempting to add a path_extrude function to openscad > A demonstration what i am talking about is here: > > https://youtu.be/igMupYGvX1s > > (sorry, its in python, but still i hope you get the idea. ) > This shows an arbitrary path_extrude of a square, > but in the video you can clearly see the triangles in the faces, > so i believe the cross section at the joints is not correct. > IMHO the square must turn to a deltoid especially when the base square is > rotated by 45 degrees to be correct. > Can anybody shade some light on that for me ? > > > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >
GS
Guenther Sohler
Sat, Jan 28, 2023 12:40 PM

Hi Sanjeev, IT Looks great!
But i am Sure that its Not the result of my path_extrude. When extruding
its important to me, that the Cross Section ist constant through all length.
In your Pictures i See that the Profile becomes smaller towards the Corner.
In Order to compensate for that you Need to compensate this Loss of Profile
by the Inverterted  Dot-product. Have a Look into my checked in Code, Then
you will exactly realize, what i am talking About 😃

Sanjeev Prabhakar sprabhakar2006@gmail.com schrieb am Sa., 28. Jän. 2023,
11:40:

I have tried your example by creating slices of the solid produced from
path_extrude and it produces the right result
[image: Screenshot 2023-01-28 at 4.03.49 PM.png]

I had to write a code for creating slices for the path_extruded solid
nevertheless

On Thu, 26 Jan 2023 at 21:56, Guenther Sohler guenther.sohler@gmail.com
wrote:

Hi List,

right now i am attempting to add a path_extrude function to openscad
A demonstration what i am talking about is here:

https://youtu.be/igMupYGvX1s

(sorry, its in python, but still i hope you get the idea. )
This shows an arbitrary path_extrude of a square,
but in the video you can clearly see the triangles in the faces,
so i believe the cross section at the joints is not correct.
IMHO the square must turn to a deltoid especially when the base square is
rotated by 45 degrees to be correct.
Can anybody shade some light on that for me ?

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

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

SP
Sanjeev Prabhakar
Sat, Jan 28, 2023 1:07 PM

Hi Guenther,
I don't have the address of your website and code, but I understand what
you are saying.
I was just trying to explain that slices might solve the problem you might
be facing.
Thanks

On Sat, 28 Jan 2023 at 18:12, Guenther Sohler guenther.sohler@gmail.com
wrote:

Hi Sanjeev, IT Looks great!
But i am Sure that its Not the result of my path_extrude. When extruding
its important to me, that the Cross Section ist constant through all length.
In your Pictures i See that the Profile becomes smaller towards the Corner.
In Order to compensate for that you Need to compensate this Loss of
Profile by the Inverterted  Dot-product. Have a Look into my checked in
Code, Then you will exactly realize, what i am talking About 😃

Sanjeev Prabhakar sprabhakar2006@gmail.com schrieb am Sa., 28. Jän.
2023, 11:40:

I have tried your example by creating slices of the solid produced from
path_extrude and it produces the right result
[image: Screenshot 2023-01-28 at 4.03.49 PM.png]

I had to write a code for creating slices for the path_extruded solid
nevertheless

On Thu, 26 Jan 2023 at 21:56, Guenther Sohler guenther.sohler@gmail.com
wrote:

Hi List,

right now i am attempting to add a path_extrude function to openscad
A demonstration what i am talking about is here:

https://youtu.be/igMupYGvX1s

(sorry, its in python, but still i hope you get the idea. )
This shows an arbitrary path_extrude of a square,
but in the video you can clearly see the triangles in the faces,
so i believe the cross section at the joints is not correct.
IMHO the square must turn to a deltoid especially when the base square
is rotated by 45 degrees to be correct.
Can anybody shade some light on that for me ?

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

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

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

GS
Guenther Sohler
Sat, Jan 28, 2023 8:22 PM

Hi Sanjeev,

Thank you for coming back to me.
you can easily find my code in
in my code it does not make a difference, whether to use many slices or not
,
not facing any problems.
Right now i just make it overly more robust.

On Sat, Jan 28, 2023 at 2:08 PM Sanjeev Prabhakar sprabhakar2006@gmail.com
wrote:

Hi Guenther,
I don't have the address of your website and code, but I understand what
you are saying.
I was just trying to explain that slices might solve the problem you
might be facing.
Thanks

On Sat, 28 Jan 2023 at 18:12, Guenther Sohler guenther.sohler@gmail.com
wrote:

Hi Sanjeev, IT Looks great!
But i am Sure that its Not the result of my path_extrude. When extruding
its important to me, that the Cross Section ist constant through all length.
In your Pictures i See that the Profile becomes smaller towards the
Corner.
In Order to compensate for that you Need to compensate this Loss of
Profile by the Inverterted  Dot-product. Have a Look into my checked in
Code, Then you will exactly realize, what i am talking About 😃

Sanjeev Prabhakar sprabhakar2006@gmail.com schrieb am Sa., 28. Jän.
2023, 11:40:

I have tried your example by creating slices of the solid produced from
path_extrude and it produces the right result
[image: Screenshot 2023-01-28 at 4.03.49 PM.png]

I had to write a code for creating slices for the path_extruded solid
nevertheless

On Thu, 26 Jan 2023 at 21:56, Guenther Sohler guenther.sohler@gmail.com
wrote:

Hi List,

right now i am attempting to add a path_extrude function to openscad
A demonstration what i am talking about is here:

https://youtu.be/igMupYGvX1s

(sorry, its in python, but still i hope you get the idea. )
This shows an arbitrary path_extrude of a square,
but in the video you can clearly see the triangles in the faces,
so i believe the cross section at the joints is not correct.
IMHO the square must turn to a deltoid especially when the base square
is rotated by 45 degrees to be correct.
Can anybody shade some light on that for me ?

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

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

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