Re: [artworks] How to close this shape?

  • From: Bernard Boase <b.boase@xxxxxxx>
  • To: artworks@xxxxxxxxxxxxx
  • Date: Wed, 16 Feb 2011 19:41:33 GMT

On 15 Feb, Martin Wuerthner <lists@xxxxxxxxxxxxxxx> wrote:

> In message <bae5aca551.boase@xxxxxxxxxxxxxxxxx>
>           Bernard Boase <b.boase@xxxxxxx> wrote:

>> I just wrote some DrawScript code which produces a drawfile containing
>> a superellipse shape. On this first attempt I draw the four quadrants
>> separately but the outcome is in fact one path in Draw.

>> On importing that into AW I was surprised that the shape doesn't have
>> an "inside" (to be coloured). The shift-F1 Line/Shape info dialoge
>> says (under Computer area) "not closed", so that must be the reason --
>> but why?

> There is an important distinction between open shapes (a sequence of
> line and curve elements with an open start and an open end) and a
> closed shape, where the last element is joined to the first. A closed
> path needs to contain an explicit closing element, just having the
> last point coincide with the first is not enough to close the shape.

It turns out that the quadrants I drew were connected by Moves, not by 
Draws, hence the lack of connectedness of the whole curve. I have now 
recast the DrawScript code to make a closed shape correctly using 
PROCSmoothClose() and no PROCMove()s, and this is nicely fillable in 
Draw and AW.

>> Given that such a shape has rather a lot of closely spaced points,
>> it's only possible to investigate the indivdual points near the
>> "joins" (of the quadrants) by first Scaling the shape and then Zooming
>> in maximally. But even doing that fails to make clear why the shape is
>> not closed, or suggest how it might be closed.

And there is now a variable in my program with which I can reduce the 
number of points plotted, making things more easily visible on 
enlargement.

>> Can anyone suggest what I might try?

> I would have thought that this should be really obvious once you got
> as far as opening the Line/Shape info dialogue: Select the option
> button labelled "Closed".

Thank you, Martin, for your encouragement, advice and information.

-- 
Bernard
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