[OpenSCAD] Rounded Polygon

William Adams will.adams at frycomm.com
Fri May 3 11:33:56 EDT 2019


Okay, a quick survey of an encyclopedia / dictionary yielded:

* 0
** circle
** oval/ellipse (requires some sort of non-arc curve)
*** egg-shaped (requires some sort of non-arc curve)
** annulus (one circle within another forming a ring)
** superellipse (see astroid below)
* 1
** cone with rounded end (arc)
* 2
** semicircle/circular segment (arc and a straight line)
** lens/vesical piscis (two convex curves)
** lune/crescent (one convex one concave curve)
** heart (two curves)
** tomoe (comma shape) --- requires non arc curves
* 3
** triangle
*** equilateral
*** isosceles
*** scalene
** sector (two straight edges, one convex arc)
** two straight edges, one concave arc
** Deltoid curve (three concave arcs)
** Reuleaux triangle (three convex arcs)
** Arbelos (one convex, two concave arcs)
* 4
** square
** rectangle
** parallelogram
** rhombus
** trapezoid/trapezium
** kite
** astroid (four concave arcs)
** salinon (four semicircles)

any obvious corrections or additions?

Other suggestions?

William

On Fri, May 3, 2019 at 11:03 AM William Adams <will.adams at frycomm.com>
wrote:

> Okay. Discussion of a list of two-dimensional shapes,
> mathematical/programmatic techniques for dividing shapes into regions, and
> the possible shapes which one can use in such deconstruction.
>
> Suggested text/terminology, esp. a book suited to a layman.
>
> Eventually the project may work up to 3 dimensional shapes, but for now,
> trying to limit it to stacks of two-dimensional shapes cut into a
> three-dimensional stock.
>
> William
>
> On Fri, May 3, 2019 at 10:43 AM nop head <nop.head at gmail.com> wrote:
>
>> I don't think topology is what you mean. For example a doughnut and a
>> teacup with a handle are topologically the same.
>>
>> On Fri, 3 May 2019 at 14:54, William Adams <will.adams at frycomm.com>
>> wrote:
>>
>>> I've been working through this sort of thing myself, and have been
>>> working up a series of basic modules which do rounded edged (and optionally
>>> bottomed) pockets so as to model projects for a hobby CNC.
>>>
>>> The problem of course is working up a reasonable definition of the
>>> shapes in terms of parameters --- I believe the field which covers this
>>> sort of thing is topology?
>>>
>>> Does anyone know of any good texts on this which might be approachable
>>> to a layman?
>>>
>>> William
>>>
>>>
>>> On Fri, May 3, 2019 at 7:11 AM nop head <nop.head at gmail.com> wrote:
>>>
>>>>  I use an inverted truncated rotate_extruded teardrop on the bottom
>>>> edges of my rounded objects so they don't need support when printing. I
>>>> assume that is what a "teardrop edge" is.
>>>>
>>>> [image: handle.png]
>>>>
>>>> On Fri, 3 May 2019 at 12:05, <arnholm at arnholm.org> wrote:
>>>>
>>>>> On 2019-05-03 11:58, adrianv wrote:
>>>>> > So I have a rounded box with a teardrop edge at the base, a rounded
>>>>> top
>>>>> > edge, and a more rounded interior bottom edge.
>>>>> >
>>>>> > <http://forum.openscad.org/file/t2477/fbox1.png>
>>>>>
>>>>> That's very, very nice (and clever)! But what is a "teardrop edge"
>>>>> precisely?
>>>>>
>>>>> Carsten Arnholm
>>>>>
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