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Chris Huff wrote:
> 1/(sqr(x)+sqr(z)+0.3) + sin(atan2(x,z)*7 + y*10)*0.025
So simple! Genius
--
David Fontaine <dav### [at] faricy net> ICQ 55354965
My raytracing gallery: http://davidf.faricy.net/
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From: sacrofts
Subject: Re: Who pulled the plug? - bathtub.jpeg (1/1)
Date: 15 Dec 2000 17:36:27
Message: <3a3a9ceb@news.povray.org>
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Yes, I wish we could have an archive of all these wonderful functions
people are coming across
I for one, just cannot come up with this sort of thing
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From: Rick [Kitty5]
Subject: Re: Who pulled the plug? - bathtub.jpeg (1/1)
Date: 15 Dec 2000 21:15:29
Message: <3a3ad041@news.povray.org>
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Yes, I wish we could have an archive of all these wonderful functions people
are coming across
I for one, just cannot come up with this sort of thing
thats the idea behind povray.co.uk - a functions section is now in the list
of things to do
--
Rick
POVray News & Resources - http://www.povray.co.uk
Kitty5 WebDesign - http://www.kitty5.com
Hi-Impact web site design & database driven e-commerce
TEL : +44 (01625) 266358 - FAX : +44 (01625) 611913 - ICQ : 15776037
PGP Public Key
http://pgpkeys.mit.edu:11371/pks/lookup?op=get&search=0x231E1CEA
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In article <3a3a9ceb@news.povray.org>, "sacrofts"
<sac### [at] tinyonlinecouk> wrote:
> Yes, I wish we could have an archive of all these wonderful functions
> people are coming across
> I for one, just cannot come up with this sort of thing
I have been building a list of isosurface functions I think are
useful...maybe I will include this one in it.
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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In article <3a3a0e23@news.povray.org>, "Lance Birch" <-> wrote:
> Ooo... very nice :) I'd like to see that made in to a stereogram :))
Hmm...any particular reason this would make a better stereogram than any
other scenes? Well, maybe if the view was directly above a vortex...
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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In article <MPG.14a492244e6b256098985c@news.povray.org>,
jam### [at] dh70qdu-netcom (Jamie Davison) wrote:
> I looked at the source, and whimpered...
>
> Too much mathematics <shudder>
It's not that hard...it's a pretty simple function, made of even simpler
pieces.
The full equation is:
1/(sqr(x)+sqr(z)+0.3) + sin(atan2(x,z)*7 + y*10)*0.025 = 0
The 1/(sqr(x)+sqr(z)+0.3) part is what gives it it's shape...it is based
on 1/R where R is the distance from the y axis. The equation for R is
sqrt(sqr(x) + sqr(z)), so that is just 1/(sqr(R)+0.3). The "+ 0.3" part
keeps it from going to 1/0 at the y axis, and limits the depth of the
vortex (Since the square of distance from the axis can't be negative, it
can't go further than 1/0.3. I just got this value by trial and error.).
You can graph the function 1/(sqr(x)+0.3) in any graphing program to get
a cross-section of the basic vortex.
The second half adds the ripples:
sin(atan2(x,z)*7 + y*10)*0.025
The value of atan2(x,z) is simply the angle around the y axis measured
in radians, similar to the "radial" pattern. I multiplied that by 7 to
get more ripples, giving it a higher frequency, and then added an amount
depending on height to make it spiral in as the sides of the vortex got
steeper (basically rotating the density field by a height-dependant
amount. Since the height changes more rapidly in the "walls" of the
vortex, it will spiral in tighter.).
I took the sin() of this value to get the waves and added the result to
the basic vortex shape...the sin() function produces a nice, smooth
periodic waveform which makes it useful for this sort of thing. The
*0.025 part scales the size of the ripples down, so they barely make an
impression on the surface.
So most of it was just piecing together simple little expressions...
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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From: Lance Birch
Subject: Re: Who pulled the plug? - bathtub.jpeg (1/1)
Date: 15 Dec 2000 22:07:32
Message: <3a3adc74@news.povray.org>
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Chris Huff wrote:
> In article <3a3a0e23@news.povray.org>, "Lance Birch" <-> wrote:
>
> > Ooo... very nice :) I'd like to see that made in to a stereogram :))
>
> Hmm...any particular reason this would make a better stereogram than any
> other scenes? Well, maybe if the view was directly above a vortex...
I just think it would look really interesting :)
To be able to see the vortex in 3D would be cool I think :)
Lance.
http://come.to/the.zone
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Chris Huff wrote:
> The full equation is:
My brain just fried....
--
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/
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On Fri, 15 Dec 2000 22:03:46 -0500, Chris Huff wrote...
> > I looked at the source, and whimpered...
> >
> > Too much mathematics <shudder>
>
> It's not that hard...it's a pretty simple function, made of even simpler
> pieces.
<foetal position>
<Whimper>
Make the bad man go away mommy...
<shake>
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In article <3A3B04B3.850794A2@pacbell.net>, lin### [at] povrayorg
wrote:
> > The full equation is:
> My brain just fried....
You really shouldn't rely on those Pentiums so much, especially for
things with division... ;-)
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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