POV-Ray : Newsgroups : povray.binaries.images : Surface of antiblobs (52KB) Server Time: 19 Feb 2019 23:34:54 GMT
  Surface of antiblobs (52KB) (Message 1 to 9 of 9)  
From: Tor Olav Kristensen
Subject: Surface of antiblobs (52KB)
Date: 26 Aug 2000 21:38:39
Message: <39A837C1.14552514@online.no>
Now I just have to figure out how to make these 
blobs centres distribute evenly within this 
surface (or any surface in 3D) ...


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html


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From: David Fontaine
Subject: Re: Surface of antiblobs (52KB)
Date: 26 Aug 2000 22:16:53
Message: <39A83FAC.4A1BA866@faricy.net>
Tor Olav Kristensen wrote:

> Now I just have to figure out how to make these
> blobs centres distribute evenly within this
> surface (or any surface in 3D) ...

Sounds extremely hard. Have fun...

--
David Fontaine   <dav### [at] faricynet>   ICQ 55354965
Please visit my website:  http://davidf.faricy.net/


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From: Andrea Ryan
Subject: Re: Surface of antiblobs (52KB)
Date: 27 Aug 2000 02:00:26
Message: <39A87310.A1E68877@global2000.net>
Antiblobs?  What are these?  Are they MeagPov only objects?
Brendan


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From: Libellule
Subject: Re: Surface of antiblobs (52KB)
Date: 27 Aug 2000 03:47:10
Message: <39A88F80.7CCDFE7B@insectes.net>
> Now I just have to figure out how to make these blobs centres distribute
> evenly within this surface (or any surface in 3D) ...

You can calculate points on the surface of a Bézier bicubic patch, and evenly
spaced (u,v) coordinates will map to evenly spaced points along the surface. I
have been playing with bicubic patches lately, so if you have any questions,
don't hesitate to ask, because it's all fresh in my mind :-)

Of course, this is only useful if you're interested in Bézier patches, for
other surfaces...


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From: Jamie Davison
Subject: Re: Surface of antiblobs (52KB)
Date: 27 Aug 2000 13:38:02
Message: <MPG.1413185efc64b831989797@news.povray.org>
On Sat, 26 Aug 2000 21:46:57 -0400, Andrea Ryan wrote...
> Antiblobs?  What are these?  Are they MeagPov only objects?
> Brendan

I think that antiblobs in this case is used to describe a combination of 
a blob with a positive strength interacting with one or more blobs with 
negative strength.  And as such, they will work in official POV.

Of course I could be misinterpreting.

Bye for now,
     Jamie.


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From: Tor Olav Kristensen
Subject: Re: Surface of antiblobs (52KB)
Date: 28 Aug 2000 21:33:58
Message: <39AAD987.C8971111@online.no>
David Fontaine wrote:

> Tor Olav Kristensen wrote:
>
> > Now I just have to figure out how to make these
> > blobs centres distribute evenly within this
> > surface (or any surface in 3D) ...
>
> Sounds extremely hard.

I hope not !

I have an idea of simulating some kind of forces between
the blob centres (that are close enough to each other),
and then let many iterations move them in small steps at
the time (within the surface) until all the forces on each
blob sums to a force that is normal to the surface (where
the blob's centre is).


> Have fun...

I will (if I can find time for it ...)


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html


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From: Tor Olav Kristensen
Subject: Re: Surface of antiblobs (52KB)
Date: 28 Aug 2000 21:49:08
Message: <39AADD1C.1F7FDA43@online.no>
Andrea Ryan wrote:

> Antiblobs?  What are these?  Are they MeagPov only objects?

Antiblobs is just the name I use for some blobs created by
a macro I made in standard POV.

Each of these blobs contains one component with positive strength
and several others components with negative strengths.

The negative strength components are placed and adjusted by my
macro so that blobs that is close-enough neighbours, only touches
their neighbours in only one point.

To two blobs are deemed "close-enough" if the sum of their two
radii are greater than the distance between their centres.

Also see my answer to ddombrow in my thread "72 Antiblobs"
23. august:

http://news.povray.org/39A40A19.D6F760C%40online.no


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html


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From: Tor Olav Kristensen
Subject: Re: Surface of antiblobs (52KB)
Date: 28 Aug 2000 21:57:39
Message: <39AADF11.7BEA1F4A@online.no>
Libellule wrote:

> > Now I just have to figure out how to make these blobs centres distribute
> > evenly within this surface (or any surface in 3D) ...
>
> You can calculate points on the surface of a Bézier bicubic patch, and evenly
> spaced (u,v) coordinates will map to evenly spaced points along the surface. I
> have been playing with bicubic patches lately, so if you have any questions,
> don't hesitate to ask, because it's all fresh in my mind :-)
>
> Of course, this is only useful if you're interested in Bézier patches, for
> other surfaces...

Hmm... interesting...

Will Bézier patches allow me to get my 400 (20x20) antiblobs evenly
spaced within the surface ?

I.e.:
The distance between each pair of neighbours, measured when "walking"
upon the surface, is equal to the distance between all other pairs ?
(I haven't even quite convinced myself that this is possible.)

Please explain.


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html


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From: David Fontaine
Subject: Re: Surface of antiblobs (52KB)
Date: 29 Aug 2000 05:51:09
Message: <39AB4D1D.3242673F@faricy.net>
Tor Olav Kristensen wrote:

> David Fontaine wrote:
>
> > Tor Olav Kristensen wrote:
> >
> > > Now I just have to figure out how to make these
> > > blobs centres distribute evenly within this
> > > surface (or any surface in 3D) ...
> >
> > Sounds extremely hard.
>
> I hope not !
>
> I have an idea of simulating some kind of forces between
> the blob centres (that are close enough to each other),
> and then let many iterations move them in small steps at
> the time (within the surface) until all the forces on each
> blob sums to a force that is normal to the surface (where
> the blob's centre is).

Oh, that's right... every problem has a complicated (and possibly
complex) calculus solution and a 10-hour-parse solution. And then some
have a complicated vector math solution that takes ten hours to parse.

--
David Fontaine   <dav### [at] faricynet>   ICQ 55354965
Please visit my website:  http://davidf.faricy.net/


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