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

[Anthony Judge]

Just to be clear, I have successfully built models with the Mobius
strip, as indicated in the following

https://www.laetusinpraesens.org/docs10s/images/tenperc_files/mobius_borro_three.x3d

I enclose screen shots of the 2-twist and 1-twist version (thre latter
in wireframe)

Tony

On 28/08/2023, Anthony Judge <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, 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://spri-open-resources.s3.us-east-2.amazonaws.com/trimobius/index.html
>>
>>
>> The X3D file that this page is rendering may be retrieved at
>> https://spri-open-resources.s3.us-east-2.amazonaws.com/trimobius/mobius.x3d
>>
>> 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 <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
>>> <anthony.judge at gmail.com>
>>> www.laetusinpraesens.org
>>>
>>> _______________________________________________
>>> x3d-public mailing list
>>> x3d-public at web3d.org
>>> http://web3d.org/mailman/listinfo/x3d-public_web3d.org
>>
>>
>
>
> --
> Anthony Judge
> <anthony.judge at gmail.com>
> www.laetusinpraesens.org
> https://en.wikipedia.org/wiki/Anthony_Judge
>


-- 
Anthony Judge
<anthony.judge at gmail.com>
www.laetusinpraesens.org
https://en.wikipedia.org/wiki/Anthony_Judge
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