POV-Ray : Newsgroups : povray.text.tutorials : Creating complex yo-yo string... Server Time
20 Apr 2024 12:12:52 EDT (-0400)
  Creating complex yo-yo string... (Message 1 to 3 of 3)  
From: Shawn Fumo
Subject: Creating complex yo-yo string...
Date: 7 Nov 1999 00:40:37
Message: <382511A5.1CD4@the-spa.com>
Ok.. a bit of an odd request here.. ;)

I do quite a bit of yo-yo stuff, and a lot of it involves "string
tricks" where you mount the yo-yo groove onto the string and do various
manipulations, etc... Or picture tricks involving cat's cradle kinds of
things...

Now, it came to my mind that Poser would be a great way to illustrate
tricks because of the ease of positioning the person and hands/fingers
in various ways. So that is fairly straight-forward.

Of course creating the yo-yo is not that bad, and positioning it would
be a breeze if I'm not animating it.

So, then the problem becomes the string... Now, creating the string
itself I don't think would be bad.. yo-yo string is one long strand that
is folded in half and wound, and so that candycane type of woven effect
like shown in Chris's chain links inlcude file would work for the shape
of the string. Or I can just cop out and have it be a spline with I
guess some sort of sphere sweep going along it or various other
things...

So basically I need to figure out a good way to position the string,
having it wrap around the fingers. So I would want most of the string
segments to be straight, but then have it curved around the fingers or
the axle of the yo-yo.

I saw that animation on the p.binaries.animations of the tank treads,
and actually that looks a lot like what I'd be doing... I would guess
calculated in so that an non-existant cylinder would be in the place of
the respective fingers, with an approximate radius...

So, I know it can happen, and I am pretty sure it involves bezier
splines, but I really have no idea how to approach it or the
calculations involved? Or perhaps some sort of include file/macro has
already been done?

Thanks... =)
Shawn

-------
sha### [at] the-spacom
http://www.the-spa.com/shawn.fumo/
-------


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From: Ken
Subject: Re: Creating complex yo-yo string...
Date: 7 Nov 1999 02:35:22
Message: <38252BB9.885C4170@pacbell.net>
Shawn Fumo wrote:

> So basically I need to figure out a good way to position the string,
> having it wrap around the fingers. So I would want most of the string
> segments to be straight, but then have it curved around the fingers or
> the axle of the yo-yo.

Some resources for you to explore. Some may or may not be applicable but
may give you some ideas none the less.

http://www.glue.umd.edu/~tvp/interp.html

http://members.xoom.com/flappy/spilin/index.html

http://www.ch.cam.ac.uk/MMRG/people/mdm/torpatch.html

http://www.geocities.com/SiliconValley/Pines/8625/piper/piper.html

-- 
Ken Tyler -  1200+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/


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From: Ken
Subject: Re: Creating complex yo-yo string...
Date: 7 Nov 1999 02:37:20
Message: <38252C2F.B1A6EB46@pacbell.net>
and...

http://www2.fwi.com/~parkerr/traces.html

-- 
Ken Tyler -  1200+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/


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