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From: Mike Williams
Subject: Experimenting with Greebles
Date: 11 May 2006 22:15:50
Message: <4463efd6@news.povray.org>
Inspired by the SOTW discussion of greebles.


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From: gonzo
Subject: Re: Experimenting with Greebles
Date: 11 May 2006 23:45:00
Message: <web.4464044713a22e0884e35afb0@news.povray.org>
"Mike Williams" <nos### [at] econymdemoncouk> wrote:
> Inspired by the SOTW discussion of greebles.

No red light?

How do I know which one's the on/off switch?

RG


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From: Sven Littkowski
Subject: Re: Experimenting with Greebles
Date: 12 May 2006 00:59:46
Message: <44641642@news.povray.org>
Not bad. I like it. Still, I would replace that long chain of spheres at the 
front of the one long box. And replace the white color with a light gray 
just a bit lighter than the regular gray. White is too bright. Otherwise it 
is a damn good work!

Hey, I am waiting now for the windows! And for a more complex ship shape.

Greetings,

Sven


"Mike Williams" <nos### [at] econymdemoncouk> schrieb im Newsbeitrag 
news:4463efd6@news.povray.org...
> Inspired by the SOTW discussion of greebles.
>
>
>
>


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From: Mike Williams
Subject: Re: Experimenting with Greebles
Date: 12 May 2006 01:57:10
Message: <M1+wyCAjNCZEFwh+@econym.demon.co.uk>
Wasn't it Sven Littkowski who wrote:
>Not bad. I like it. Still, I would replace that long chain of spheres at the 
>front of the one long box.

It's fairly tricky to get the random number generator to produce
aesthetic repetitions all the time. If there are too few reps, then the
result just looks too random, but if there are too many reps then it
will occasionally produce long chains like that. I've got it currently
set to perform repeats one time in seven.

> And replace the white color with a light gray 
>just a bit lighter than the regular gray. White is too bright. 

I deliberately arranged for a small number of nearly white units
(rgb 0.9) and a small number of nearly black units (rgb 0.1) just to
break up the overall blue-grey-ness and give it some highlights.

Each unit in this image chooses a random pigment from this colour_map

#declare cmap = colour_map {
   [0.02 rgb 0.1]
   [0.04 rgb <0.2,0.2,0.3>]
   [0.97 rgb <0.5,0.5,0.6>]
   [0.98 rgb 0.9]
 }

>Otherwise it 
>is a damn good work!
>
>Hey, I am waiting now for the windows!

I'm not sure how windows might work.

> And for a more complex ship shape.

At the moment I can only generate rectangular panels of these greebles.
I tried generating a rectangular panel and then using an intersection on
it to create a triangular patch, but the render time went through the
roof, presumably because it loses the bounding boxes on the little
pieces, so it has to test each ray against thousands of greeble units.
This image rendered in 1m 53s, but a similar model made from triangular
patches would take several days.

-- 
Mike Williams
Gentleman of Leisure


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From: Slime
Subject: Re: Experimenting with Greebles
Date: 12 May 2006 02:15:37
Message: <44642809$1@news.povray.org>
> At the moment I can only generate rectangular panels of these greebles.
> I tried generating a rectangular panel and then using an intersection on
> it to create a triangular patch, but the render time went through the
> roof, presumably because it loses the bounding boxes on the little
> pieces, so it has to test each ray against thousands of greeble units.
> This image rendered in 1m 53s, but a similar model made from triangular
> patches would take several days.

Try intersecting each individual greeble with the sides of the triangle,
instead of making one huge intersection.

To save on memory, you can test each greeble to see if it's inside the
triangle before doing this, so you don't include the ones which will be
entirely clipped away.

 - Slime
 [ http://www.slimeland.com/ ]


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From: Thomas de Groot
Subject: Re: Experimenting with Greebles
Date: 12 May 2006 02:52:06
Message: <44643096$1@news.povray.org>
"Mike Williams" <nos### [at] econymdemoncouk> schreef in bericht
news:4463efd6@news.povray.org...
> Inspired by the SOTW discussion of greebles.

This looks very interesting indeed!

SOTW.... ? Did I miss something? I cannot find any discussion on greebles in
the POV-Ray ng's...

Thomas


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From: Mike Williams
Subject: Re: Experimenting with Greebles
Date: 12 May 2006 03:11:10
Message: <Rkin2BASQDZEFwTd@econym.demon.co.uk>
Wasn't it Slime who wrote:
>> At the moment I can only generate rectangular panels of these greebles.
>> I tried generating a rectangular panel and then using an intersection on
>> it to create a triangular patch, but the render time went through the
>> roof, presumably because it loses the bounding boxes on the little
>> pieces, so it has to test each ray against thousands of greeble units.
>> This image rendered in 1m 53s, but a similar model made from triangular
>> patches would take several days.
>
>Try intersecting each individual greeble with the sides of the triangle,
>instead of making one huge intersection.

Unfortunately, with this system, I don't keep a record of where the
individual greeble units are going to end up being placed. They're
created deep inside a recursive routine and can form part of a union
that is translated many levels higher in the recursion hierarchy.

Several copies of the same greeble are translated to different
locations, allowing the construction of repetitive patterns, so I can't
pass down the information about the translations from the higher levels
to the lower levels.


I think the way to go might be to look for a way to subdivide an
arbitrary triangle into a set of rectangular panels and then fill in the
bits round the edge with triangular greebles. Don't want to use
triangular subdivision everywhere, because that would end up with the
overall pattern having an odd triangular look to it. Don't want to just
slice the arbitrary triangle into lots of tiny squares, because I want
to end up with a range of greeble sizes.

-- 
Mike Williams
Gentleman of Leisure


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From: Mike Williams
Subject: Re: Experimenting with Greebles
Date: 12 May 2006 03:11:11
Message: <T0FnCEAPTDZEFwzV@econym.demon.co.uk>
Wasn't it Thomas de Groot who wrote:
>
>"Mike Williams" <nos### [at] econymdemoncouk> schreef in bericht
>news:4463efd6@news.povray.org...
>> Inspired by the SOTW discussion of greebles.
>
>This looks very interesting indeed!
>
>SOTW.... ? Did I miss something? I cannot find any discussion on greebles in
>the POV-Ray ng's...

It was mentioned in passing in this thread:
http://news.povray.org/povray.binaries.images/thread/%3C445ef575%40news.povray.org%3E/

-- 
Mike Williams
Gentleman of Leisure


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From: Sven Littkowski
Subject: Greebles - Links!
Date: 12 May 2006 10:26:32
Message: <44649b18@news.povray.org>
> SOTW.... ? Did I miss something? I cannot find any discussion on greebles 
> in
> the POV-Ray ng's...

Oh, there are a few times this subject has risen. Someone form this 
newsgroup ("DLG" or so) gave me even some oh-soo-useful links in one of my 
own threads, which I like herewith to share with you:
http://en.wikipedia.org/wiki/Greeble
http://www.econym.demon.co.uk/isotut/pigment.htm
http://www.scifi-meshes.com/tutorials/norling/greeble/greeble.html

More examples of Greebles and POV-Ray in my threads "SF: Preview 11+: 
Imperial Carrier" within this newsgroup.

Best greetings,

Sven


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From: Thomas de Groot
Subject: Re: Greebles - Links! Thanks!!!
Date: 12 May 2006 10:33:35
Message: <44649cbf@news.povray.org>
Thanks a lot Mike and Sven!!
There are so many messages to read, that I tend to become rather selective
in view of the time it takes to read them all, so I missed those. The
downside is of course that I might miss interesting stuff...

Thomas


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