[Scilab-users] Compute normals to 3D surface

[Stéphane Mottelet]

Le 18/06/2018 à 10:55, arctica1963 a écrit :
> Hi Rafael,
>
> Xarrows() worked to generate the normals in  Scilab 6.0.1.
>
> <https://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/mailinglists.scilab.org/file/t495709/Moebius2_arrows.jpg>
>
> Getting closer to the solution, but it gets "confused" at position (x=1.5,
> y=0, z=0) where the vectors should change to inbound rather than outbound as
> the surface folds as shown in the illustrative figure before. At this point
> we actually see a double vector.
The Moebius ring is a non-orientable surface, that's why your normals 
field is not continous :

https://en.wikipedia.org/wiki/Orientability

S.

>  From x=0 to -1 it should be on the "inner"
> part if I'm looking at this right?
>
> Is it possible to just show the vector arrows along say z=0 only? Hopefully
> I am explaining this properly.
>
> Thanks for the help, very informative.
>
> Lester
>
>
>
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-- 
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet