POV-Ray : Newsgroups : povray.advanced-users : Curved, hollow cylinders Server Time
25 Dec 2024 10:28:16 EST (-0500)
  Curved, hollow cylinders (Message 1 to 4 of 4)  
From: tgl
Subject: Curved, hollow cylinders
Date: 17 Aug 2007 23:40:00
Message: <web.46c669e8a3c5c29266be0b530@news.povray.org>
Advanced users
Is there a reasonably easy way to outline an irregular and curved 2D shape
with hollow cylinders?
 Thanx
 tgl


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From: Chris B
Subject: Re: Curved, hollow cylinders
Date: 18 Aug 2007 07:25:16
Message: <46c6d71c$1@news.povray.org>
"tgl" <aub### [at] sympaticoca> wrote in message 
news:web.46c669e8a3c5c29266be0b530@news.povray.org...
> Advanced users
> Is there a reasonably easy way to outline an irregular and curved 2D shape
> with hollow cylinders?
> Thanx
> tgl
>

Hi Aubrey,
I think that the difficultly very much depends on how you want to define the 
irregular, curved 2D shape that you start from.

If you've got a succession of points on the curve you can make a spline, or 
if your starting point is a spline, then you should be able to use 
Spline_Trans to translate a succession of objects to points on the spline. 
This could get a bit fiddly if you want to avoid gaps and overlaps.

If you start with any form of 'extruded' object based on your irregular 2D 
shape then you could use successive calls to the Trace function to identify 
a set of positions around the perimeter. This could be the easiest way if 
your starting point is a vector graphic defined in InkScape which can export 
POV-Ray prism objects. If the 2D shape is roughly circular you could start 
each trace at the centre and sweep around in a circle with each successive 
trace, identifying points where your cylinders will be placed. The tricky 
bit here is avoiding 'blind' spots, where part of the perimeter is masked by 
another part of the perimeter (and still fiddly if you want to avoid gaps 
and overlaps).

Regards,
Chris B.


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From: Mike Williams
Subject: Re: Curved, hollow cylinders
Date: 18 Aug 2007 13:05:16
Message: <WVY2aHAaWyxGFwJ3@econym.demon.co.uk>
Wasn't it tgl who wrote:
> Advanced users
>Is there a reasonably easy way to outline an irregular and curved 2D shape
>with hollow cylinders?

You might consider the difference of two spheresweep objects that follow
the same path but have a different radius.

-- 
Mike Williams
Gentleman of Leisure


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From: honnza
Subject: Re: Curved, hollow cylinders
Date: 6 Oct 2007 06:35:00
Message: <web.4707643d31725d8ca9ce4df50@news.povray.org>
Mike Williams <nos### [at] econymdemoncouk> wrote:
> Wasn't it tgl who wrote:
> > Advanced users
> >Is there a reasonably easy way to outline an irregular and curved 2D shape
> >with hollow cylinders?
>
> You might consider the difference of two spheresweep objects that follow
> the same path but have a different radius.
>
> --
> Mike Williams
> Gentleman of Leisure

What about using a hollow sphere_sweep with differenced clear ends?
difference{
  sphere_sweep{
  //any sweep from A to B, 0.9 thick
  }
  sphere{A,1 pigment{Clear}}
  sphere{B,1 pigment{Clear}}
}


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