Le 08/08/2018 à 18:48, BGimeno a écrit :
> Can someone think of a better way for cover the gaps left by these
> sphere_sweep (cubic_spline) curves with bicubic_patch?. I've been
> looking at before posting this message and I am stuck at the point at
> which, for the example given in the documentation I arrived to a
> self-referential loop. (in short: being a circular shape you need to
> know previously the point B to know point A and point A to calculate the
> point B).
> doc: http://www.povray.org/documentation/view/3.6.1/64/
> 
> Another point is commented by clipka a 2015 post on this issue.
>
http://news.povray.org/povray.tools.general/thread/%3Cweb.54e9d43835fbd8f37a3e03fe0%40news.povray.org%3E/
> 
> 
> If it is mathematically impossible to make a perfect circle based on
> patches, I suppose that the task of adjusting them smoothly to this form
> can not be carried out either.
> 
> Any help or idea to the respective one is welcome, thank you very much
> in advance.
> 
> Bruno Gimeno

I presume you can transfer each sphere_sweep into its own spline
(cubic_spline too), so you can generate as many points as you need along
each curve

Then you are at the problem of generating a surface from a non-plane
canvas of four sides.
And there is a lot of different results.

If you can compute a point as the center of the face, or if you can
compute parallel lines between two opposite sides, you can generate
meshes to fill the canvas.

With a central point, each triangle is connected to the central point
and the other side is along one spline of the side. Make as many
triangles as needed to cover the side, repeat for each side.

Probably more to your desire, we could distinguish the side as being
rather circular (the sphere_sweep make a small circle around the torus)
or rather straignt (the sphere_sweep follow the major circle of the torus).

Which mean you can draw straight line between the circular opposite
segments. And if you have straight lines, you can compute by
interpolation some intermediate circular segments on which to fix the
triangles of your mesh.

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