[OpenSCAD] Unusual hull() and minkowski modelling

nop head nop.head at gmail.com
Fri Jun 17 13:29:16 EDT 2016


Is 3D Minkowski still processed with CGAL? I think there was some work to
bypass CGAL for hull and minkowski to speed them up in the convex case,
which is simple and in the concave case I think it now does a convex
decomposition and unions the results. The union will be done in CGAL and
hence slow. Not sure as my memory is failing.

On 17 June 2016 at 18:18, Ronaldo <rcmpersiano at gmail.com> wrote:

> Rudolf,
>
> I usually like your approach, your way of thinking, and certainly the
> experience you bring to the discussions. For me, it is like a counterpoint
> to mine ways. And I like diversity.
>
> I agree that the ideas I expressed will have a short live. May be in the
> next version. My intention however was to show the gain in expressiveness
> when you mix 3D objects with lower dimension ones. I can't see anything
> clearer then express a sweep as a minkowski of a solid with a curve or
> polyline. And it would be a gain to express the sweep as such. I am not
> saying that it should be done that way now because minkowski is lot
> expensive yet. May be in the future.
>
> I disagree however that your 'Occam's razor' solution to the drop code is
> clearer then mine. I agree that the definition point3() is polemics due to
> its use of degenerescence but the drop code is clearer then using a almost
> degenerated cylinder. The ideal would be to have primitives point(),
> edge(),
> polygon(), etc that were mixable with 3D solids in a proper way. In that
> case, who would code a drop like yours?
>
> Observe that minkowski is processed by CGAL and the library accepts and
> process correctly the mix of 3D with lower dimension figures. There is no
> real complexities or break in robustness in those mixing. Neither
> theoretically nor in the algorithms. What is missing is a way to express
> this without to resort to degenerated codes.
>
> Ronaldo
>
>
>
> --
> View this message in context:
> http://forum.openscad.org/Unusual-hull-and-minkowski-modelling-tp17730p17747.html
> Sent from the OpenSCAD mailing list archive at Nabble.com.
>
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