[x3d-public] Problem constructing Mobius strip by extrusion of rectangular cross-section

Brutzman, Donald (Don) (CIV) brutzman at nps.edu
Mon Sep 4 18:23:31 PDT 2023 

Hi Anthony.  Great work!

 

You are likely looking for CoordinateInterpolator2D node.  It does have a
MFVec2f keyValue array, and can output SFVec2f value_changed events if the
corresponding MFFloat key array is half the length of the keyValue array.

 

*	X3D Tooltips, CoordinateInterpolator2D
*
https://www.web3d.org/x3d/content/X3dTooltips.html#CoordinateInterpolator2D

 

*	X3D4 Architecture, 19 Interpolation component , 19.4.3
CoordinateInterpolator2D 
*
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-IS.proof/Pa
rt01/components/interpolators.html#CoordinateInterpolator2D
*	“This node linearly interpolates among a list of MFVec2f values to
produce an MFVec2f value_changed event. The number of coordinates in the
keyValue field shall be an integer multiple of the number of key frames in
the key field. That integer multiple defines how many coordinates will be
contained in the value_changed events.”

 

Example:

 

*	X3D Example Archives: X3D4WA, X3D for Web Authors, Chapter 07 Event
Animation Interpolation, Coordinate Interpolator 2D Example
*
https://www.web3d.org/x3d/content/examples/X3dForWebAuthors/Chapter07EventAn
imationInterpolation/CoordinateInterpolator2dExampleIndex.html

 

Am experimenting with a new Event Graph ROUTE Table to show routing chains,
hope it is helpful.

 

*
https://www.web3d.org/x3d/content/examples/X3dForWebAuthors/Chapter07EventAn
imationInterpolation/CoordinateInterpolator2dExample.html#EventGraph

 

I believe that we have full coverage for generation of values of any type in
X3D 4.0.  The references and 10-step process listed in the following chapter
link are likely useful.

 

*	X3D Example Archives: X3D4WA, X3D for Web Authors, Chapter 07 Event
Animation Interpolation
*
https://www.web3d.org/x3d/content/examples/X3dForWebAuthors/Chapter07EventAn
imationInterpolation/index.html

 

Have fun with X3D Animation!  8)

 

all the best, Don

-- 

Don Brutzman  Naval Postgraduate School, Code USW/Br        brutzman at nps.edu

Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA    +1.831.656.2149

X3D graphics, virtual worlds, navy robotics https://faculty.nps.edu/brutzman

 

-----Original Message-----
From: x3d-public <x3d-public-bounces at web3d.org> On Behalf Of Anthony Judge
Sent: Monday, September 4, 2023 5:34 PM
To: vmarchetti at kshell.com
Cc: X3D-Public <x3d-public at web3d.org>
Subject: Re: [x3d-public] Problem constructing Mobius strip by extrusion of
rectangular cross-section

 

Hi Vince

 

You responded in an encouraging manner to the issue above, now solved

-- enabling to make a variety of models.

 

I endeavoured to take the question further with him as follows:

 

I had hoped to experiment with extending the edges -- dynamically with  a
ROUTE. Manually I have explored changing the scale within the EXTRUSION). Is
it possible to do that with a scalarinterpolator?

 

To which he appropriately responded:

 

ScalarInterpolator interpolates scalars, and a scalar is a single number.
But in Extrusion, each scale is a 2D vector, and it is possible to specify
different scales for individual segments, so actually it's an array of 2D
vectors, or an MFVec2f value.

Unfortunately there is no interpolator node which outputs MFVec2f. It is
possible to use a script to manipulate this value, or you can try some other
workaround.

 

Has anyone addressed the issue -- such that I can make use of a script for
my purpose?

 

Thanks again

 

Tony

 

On 29/08/2023, Anthony Judge < <mailto:anthony.judge at gmail.com>
anthony.judge at gmail.com> wrote:

> Hi Vince

> 

> A colleague to whom I posed the same question has provided the answer 

> (snippet enclosed)

> 

> As he describes it: In your file "mobius_rect.x3d", the Möbius strip 

> does not close because the rectangle is rotated around a point which 

> is not its center of symmetry. If you move the rectangle so that it is 

> centered at the origin, then after 180° rotation it will coincide with 

> itself and the Möbius strip will close correctly. Please find attached 

> the modified version "mobius_rect3.x3d".

> 

> A wonderfully simple answer, the possibility of which I was not aware.

> 

> I can now play with the scale to explore other forms. However I am not 

> yet sure whether it is possible to do this through any ROUTE operation

> 

> Tony

> 

> On 28/08/2023, Anthony Judge < <mailto:anthony.judge at gmail.com>
anthony.judge at gmail.com> wrote:

>> Enclosed are the Extrusion snippets for both models

>> 

>> Tony

>> 

>> On 28/08/2023, Anthony Judge < <mailto:anthony.judge at gmail.com>
anthony.judge at gmail.com> wrote:

>>> Just to be clear, I have successfully built models with the Mobius 

>>> strip, as indicated in the following

>>> 

>>>  <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fww>
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fww

>>> w.laetusinpraesens.org%2Fdocs10s%2Fimages%2Ftenperc_files%2Fmobius_b

>>> orro_three.x3d&data=05%7C01%7Cbrutzman%40nps.edu%7C357e0836902145e88

>>> 43808dbada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C6382947

>>> 08702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2lu

>>> MzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=zchQd%2F%2B

>>> 8QKkLdnVmPn5y4N12N1o36K3c94AWgZvszvg%3D&reserved=0

>>> 

>>> I enclose screen shots of the 2-twist and 1-twist version (thre 

>>> latter in wireframe)

>>> 

>>> Tony

>>> 

>>> On 28/08/2023, Anthony Judge < <mailto:anthony.judge at gmail.com>
anthony.judge at gmail.com> wrote:

>>>> Hi Vince

>>>> 

>>>> Thanks for the interest.

>>>> 

>>>> I could easily  share screen shots but the matter is so simple that 

>>>> sharing the Extrusion of a 2-twist 360 orientation along the spine, 

>>>> with the Extrusion of a 1-twist 180 orientation might be simplest? 

>>>> It is the latter which fails and the former which is correct, but 

>>>> not what I want.

>>>> 

>>>> My thought is the difficulty is the manner in which the Extrusion 

>>>> relates the orientation to the spine. For the 180 degree case, what 

>>>> is effectively required is that the spine (or a "fake spine") 

>>>> follow the center of the rotating rectangular cross-section. Of 

>>>> course it does not. It follows one edge. So 360 connects up but 180
ends up offset.

>>>> 

>>>> Of course I may have messed up with the parameters of the Extrusion

>>>> 

>>>> Do you need the screen shots?

>>>> 

>>>> Tony

>>>> 

>>>> On 28/08/2023,  <mailto:vmarchetti at kshell.com> vmarchetti at kshell.com <
<mailto:vmarchetti at kshell.com> vmarchetti at kshell.com> wrote:

>>>>> Tony

>>>>> 

>>>>> This sounds like an interesting project for the X3D community to 

>>>>> help with.

>>>>> 

>>>>> As a proof of concept, this X-ITE rendering shows it is possible 

>>>>> to render Mobius-like geometry in X3D:

>>>>>  <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2F>
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2F

>>>>> spri-open-resources.s3.us-east-2.amazonaws.com%2Ftrimobius%2Findex

>>>>> .html&data=05%7C01%7Cbrutzman%40nps.edu%7C357e0836902145e8843808db

>>>>> ada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C638294708702

>>>>> 338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzI

>>>>> iLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=7ksBsbxogAYi

>>>>> EbX9CwInh9M3bQCUOrWLPa2OgBmJlHM%3D&reserved=0

>>>>> 

>>>>> 

>>>>> The X3D file that this page is rendering may be retrieved at

>>>>>  <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2F>
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2F

>>>>> spri-open-resources.s3.us-east-2.amazonaws.com%2Ftrimobius%2Fmobiu

>>>>> s.x3d&data=05%7C01%7Cbrutzman%40nps.edu%7C357e0836902145e8843808db

>>>>> ada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C638294708702

>>>>> 338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzI

>>>>> iLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=jgUj3T6WVMTQ

>>>>> oejiGTjsUkI94dzYfAWXG8%2BzvyvSMOg%3D&reserved=0

>>>>> 

>>>>> If you can share screenshots or webpages with your 

>>>>> not-satisfactory results, that may give us some hint as to what's 

>>>>> going on, and also sharing code may also help us.

>>>>> 

>>>>> Vince Marchettti

>>>>> Web3D Consortium

>>>>> 

>>>>> 

>>>>> 

>>>>>> On Aug 28, 2023, at 1:38 AM, Anthony Judge 

>>>>>> < <mailto:anthony.judge at gmail.com> anthony.judge at gmail.com>

>>>>>> wrote:

>>>>>> 

>>>>>> I have a working model of a Mobius strip, but it uses Indexed 

>>>>>> Faceset which I cannot manipulate as I had hoped to do. Basically 

>>>>>> I want to extend the edges of the strip, possibly dynamically.

>>>>>> 

>>>>>> So as an alternative I extruded a thin rectangular cross-section 

>>>>>> along a circular spine, but modifying the orientation of each 

>>>>>> element along the spine through 180 degrees.

>>>>>> 

>>>>>> This gives a correct result, except that the ends do not meet 

>>>>>> correctly -- the end is offset because it is rotated around the 

>>>>>> spine.

>>>>>> This is apparent if I change the orientation through 360 degrees, 

>>>>>> when the ends do connect correctly -- but I have two twists in 

>>>>>> the strip, which is not what I need for a Mobius strip

>>>>>> 

>>>>>> I can provide snippets of this simple issue and I can understand 

>>>>>> how the issue is created by using the spine/orientation 

>>>>>> combination with the extrusion.

>>>>>> 

>>>>>> Any comments/help?

>>>>>> 

>>>>>> Tony

>>>>>> 

>>>>>> --

>>>>>> Anthony Judge

>>>>>> < <mailto:anthony.judge at gmail.com> anthony.judge at gmail.com>

>>>>>>  <https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2F>
https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2F

>>>>>>
<http://www.laetusinpraesens.org%2F&data=05%7C01%7Cbrutzman%40nps.edu%7C3>
www.laetusinpraesens.org%2F&data=05%7C01%7Cbrutzman%40nps.edu%7C3

>>>>>> 57e0836902145e8843808dbada7db96%7C6d936231a51740ea9199f7578963378

>>>>>> e%7C0%7C0%7C638294708702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC

>>>>>> 4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7

>>>>>> C%7C%7C&sdata=5ct1jW86cfPyARtCoyTXqnPdG6W5gQx41Bga5XLtHRk%3D&rese

>>>>>> rved=0

>>>>>> 

>>>>>> _______________________________________________

>>>>>> x3d-public mailing list

>>>>>>  <mailto:x3d-public at web3d.org> x3d-public at web3d.org

>>>>>>  <http://web3d.org/mailman/listinfo/x3d-public_web3d.org>
http://web3d.org/mailman/listinfo/x3d-public_web3d.org

>>>>> 

>>>>> 

>>>> 

>>>> 

>>>> --

>>>> Anthony Judge

>>>> < <mailto:anthony.judge at gmail.com> anthony.judge at gmail.com>

>>>>  <https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fww>
https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fww

>>>> w.laetusinpraesens.org%2F&data=05%7C01%7Cbrutzman%40nps.edu%7C357e0

>>>> 836902145e8843808dbada7db96%7C6d936231a51740ea9199f7578963378e%7C0%

>>>> 7C0%7C638294708702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMD

>>>> AiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sd

>>>> ata=5ct1jW86cfPyARtCoyTXqnPdG6W5gQx41Bga5XLtHRk%3D&reserved=0

>>>>  <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fe>
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fe

>>>> n.wikipedia.org%2Fwiki%2FAnthony_Judge&data=05%7C01%7Cbrutzman%40np

>>>> s.edu%7C357e0836902145e8843808dbada7db96%7C6d936231a51740ea9199f757

>>>> 8963378e%7C0%7C0%7C638294708702338266%7CUnknown%7CTWFpbGZsb3d8eyJWI

>>>> joiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C300

>>>> 0%7C%7C%7C&sdata=IU%2FbeJvIOkCMor6mVrAhzmP%2FlrrYcawcC1rNvc7vfYw%3D

>>>> &reserved=0

>>>> 

>>> 

>>> 

>>> --

>>> Anthony Judge

>>> < <mailto:anthony.judge at gmail.com> anthony.judge at gmail.com>

>>>  <https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww>
https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww

>>> .laetusinpraesens.org%2F&data=05%7C01%7Cbrutzman%40nps.edu%7C357e083

>>> 6902145e8843808dbada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0

>>> %7C638294708702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLC

>>> JQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=5

>>> ct1jW86cfPyARtCoyTXqnPdG6W5gQx41Bga5XLtHRk%3D&reserved=0

>>>  <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen>
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen

>>> .wikipedia.org%2Fwiki%2FAnthony_Judge&data=05%7C01%7Cbrutzman%40nps.

>>> edu%7C357e0836902145e8843808dbada7db96%7C6d936231a51740ea9199f757896

>>> 3378e%7C0%7C0%7C638294708702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiM

>>> C4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%

>>> 7C%7C&sdata=IU%2FbeJvIOkCMor6mVrAhzmP%2FlrrYcawcC1rNvc7vfYw%3D&reser

>>> ved=0

>>> 

>> 

>> 

>> --

>> Anthony Judge

>> < <mailto:anthony.judge at gmail.com> anthony.judge at gmail.com>

>>  <https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww>
https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.

>> laetusinpraesens.org%2F&data=05%7C01%7Cbrutzman%40nps.edu%7C357e08369

>> 02145e8843808dbada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C

>> 638294708702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIj

>> oiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=5ct1jW

>> 86cfPyARtCoyTXqnPdG6W5gQx41Bga5XLtHRk%3D&reserved=0

>>  <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen>
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen.

>> wikipedia.org%2Fwiki%2FAnthony_Judge&data=05%7C01%7Cbrutzman%40nps.ed

>> u%7C357e0836902145e8843808dbada7db96%7C6d936231a51740ea9199f757896337

>> 8e%7C0%7C0%7C638294708702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wL

>> jAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C

>> &sdata=IU%2FbeJvIOkCMor6mVrAhzmP%2FlrrYcawcC1rNvc7vfYw%3D&reserved=0

>> 

> 

> 

> --

> Anthony Judge

> < <mailto:anthony.judge at gmail.com> anthony.judge at gmail.com>

>  <https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.l>
https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.l

> aetusinpraesens.org%2F&data=05%7C01%7Cbrutzman%40nps.edu%7C357e0836902

> 145e8843808dbada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C638

> 294708702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2

> luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=5ct1jW86cfP

> yARtCoyTXqnPdG6W5gQx41Bga5XLtHRk%3D&reserved=0

>  <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen.w>
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen.w

> ikipedia.org%2Fwiki%2FAnthony_Judge&data=05%7C01%7Cbrutzman%40nps.edu%

> 7C357e0836902145e8843808dbada7db96%7C6d936231a51740ea9199f7578963378e%

> 7C0%7C0%7C638294708702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwM

> DAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdat

> a=IU%2FbeJvIOkCMor6mVrAhzmP%2FlrrYcawcC1rNvc7vfYw%3D&reserved=0

> 

 

 

--

Anthony Judge

< <mailto:anthony.judge at gmail.com> anthony.judge at gmail.com>

 
<https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.laetus
inpraesens.org%2F&data=05%7C01%7Cbrutzman%40nps.edu%7C357e0836902145e8843808
dbada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C638294708702338266%7
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CJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=5ct1jW86cfPyARtCoyTXqnPdG6W5gQx41Bga5XLt
HRk%3D&reserved=0>
https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.laetusi
npraesens.org%2F&data=05%7C01%7Cbrutzman%40nps.edu%7C357e0836902145e8843808d
bada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C638294708702338266%7C
Unknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLC
JXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=5ct1jW86cfPyARtCoyTXqnPdG6W5gQx41Bga5XLtH
Rk%3D&reserved=0

 
<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen.wikipe
dia.org%2Fwiki%2FAnthony_Judge&data=05%7C01%7Cbrutzman%40nps.edu%7C357e08369
02145e8843808dbada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C6382947
08702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJB
TiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=IU%2FbeJvIOkCMor6mVrAhzmP%2
FlrrYcawcC1rNvc7vfYw%3D&reserved=0>
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fen.wikiped
ia.org%2Fwiki%2FAnthony_Judge&data=05%7C01%7Cbrutzman%40nps.edu%7C357e083690
2145e8843808dbada7db96%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C63829470
8702338266%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBT
iI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=IU%2FbeJvIOkCMor6mVrAhzmP%2F
lrrYcawcC1rNvc7vfYw%3D&reserved=0

 

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