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From: Orchid XP v7
Subject: Guess the algorithm
Date: 18 Nov 2007 10:37:29
Message: <47405c39$1@news.povray.org>
Take a look at this:

http://www.nullsoft.com/free/monkey/

Anybody got any ideas what the cave-building algorithm is? (As in, I'd 
like to copy it...)


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From: Alain
Subject: Re: Guess the algorithm
Date: 18 Nov 2007 12:22:25
Message: <474074d1$1@news.povray.org>
Orchid XP v7 nous apporta ses lumieres en ce 2007/11/18 10:37:
> Take a look at this:
> 
> http://www.nullsoft.com/free/monkey/
> 
> Anybody got any ideas what the cave-building algorithm is? (As in, I'd 
> like to copy it...)
It's looks like it's based on tubes. You travel a tube and it encounters other 
tubes at various angles. Any triangle that is inside any tube is removed. All 
edges are smoothed, a little like for a blob.
You could use splines to place blob components, you then place the camera inside 
the blob. Use a low strenght, or a large treshold value.

-- 
Alain
-------------------------------------------------
   If it weren't for pickpockets, I'd have no sex life at all.
   	Rodney Dangerfield


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From: Orchid XP v7
Subject: Re: Guess the algorithm
Date: 18 Nov 2007 14:14:12
Message: <47408f04$1@news.povray.org>
Alain wrote:

> It's looks like it's based on tubes. You travel a tube and it encounters 
> other tubes at various angles. Any triangle that is inside any tube is 
> removed. All edges are smoothed, a little like for a blob.

Yeah, but it looks a little more complex than that. There are large 
chambers that don't appear to be "tube-like", and there are passages 
that aren't quite circular, and so on. (Maybe the tube diammeter varies 
or something?)

Well anyway, it looks like it could be *awesom* with true 
light-sourcing, global illumination, and maybe some volumetric light 
scattering. ;-)


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From: scott
Subject: Re: Guess the algorithm
Date: 19 Nov 2007 04:27:43
Message: <4741570f@news.povray.org>
>> It's looks like it's based on tubes. You travel a tube and it encounters 
>> other tubes at various angles. Any triangle that is inside any tube is 
>> removed. All edges are smoothed, a little like for a blob.
>
> Yeah, but it looks a little more complex than that. There are large 
> chambers that don't appear to be "tube-like", and there are passages that 
> aren't quite circular, and so on. (Maybe the tube diammeter varies or 
> something?)

My immediate thought was that you take the nVidia "Cascades" demo and invert 
it so you are inside the geometry, not outside it...

Take a look at the "rock generation" part of these slides, they have some 
useful info for building geometry like this, and most of it is directly 
portable to POV iso-surfaces:

http://developer.download.nvidia.com/presentations/2007/gdc/CascadesDemoSecrets.zip


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From: Invisible
Subject: Re: Guess the algorithm
Date: 19 Nov 2007 06:06:31
Message: <47416e37$1@news.povray.org>
scott wrote:

> My immediate thought was that you take the nVidia "Cascades" demo and 
> invert it so you are inside the geometry, not outside it...

Yeah, that demo sounds quite interesting. Pitty my graphics card is 
insufficiently expensive to run it...

> Take a look at the "rock generation" part of these slides, they have 
> some useful info for building geometry like this, and most of it is 
> directly portable to POV iso-surfaces:

Mmm, OK.


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From: Ross
Subject: Re: Guess the algorithm
Date: 19 Nov 2007 11:51:32
Message: <4741bf14$1@news.povray.org>
"Invisible" <voi### [at] devnull> wrote in message
news:47416e37$1@news.povray.org...
> scott wrote:
>
> > My immediate thought was that you take the nVidia "Cascades" demo and
> > invert it so you are inside the geometry, not outside it...
>
> Yeah, that demo sounds quite interesting. Pitty my graphics card is
> insufficiently expensive to run it...
>

2007 Happily awaits your arrival ;)


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From: Alain
Subject: Re: Guess the algorithm
Date: 19 Nov 2007 12:00:23
Message: <4741c127$1@news.povray.org>
Orchid XP v7 nous apporta ses lumieres en ce 2007/11/18 14:14:
> Alain wrote:
> 
>> It's looks like it's based on tubes. You travel a tube and it 
>> encounters other tubes at various angles. Any triangle that is inside 
>> any tube is removed. All edges are smoothed, a little like for a blob.
> 
> Yeah, but it looks a little more complex than that. There are large 
> chambers that don't appear to be "tube-like", and there are passages 
> that aren't quite circular, and so on. (Maybe the tube diammeter varies 
> or something?)
> 
> Well anyway, it looks like it could be *awesom* with true 
> light-sourcing, global illumination, and maybe some volumetric light 
> scattering. ;-)
Most large chambers are the intersection of several conduits. When over 5 
twisting tubes intersect, you loose the apearance of tubes. On ocasions, I saw 
some bits of "floating" objects in those large chambers.
Some passages are actualy made of 2 or more almost parallel tubes, and some of 
those may be flattened.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you've tried rendering hair with 
each strand as an object.
Quietly Watching


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From: Orchid XP v7
Subject: Re: Guess the algorithm
Date: 19 Nov 2007 13:14:02
Message: <4741d26a@news.povray.org>
>> Yeah, that demo sounds quite interesting. Pitty my graphics card is
>> insufficiently expensive to run it...
> 
> 2007 Happily awaits your arrival ;)

And what's that meant to mean?


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From: Orchid XP v7
Subject: Re: Guess the algorithm
Date: 19 Nov 2007 13:16:58
Message: <4741d31a$1@news.povray.org>
Alain wrote:

> Most large chambers are the intersection of several conduits. When over 
> 5 twisting tubes intersect, you loose the apearance of tubes. On 
> ocasions, I saw some bits of "floating" objects in those large chambers.
> Some passages are actualy made of 2 or more almost parallel tubes, and 
> some of those may be flattened.

Mmm, seems plausible. You'd have to have some fairly high-order 
smoothing to blur out the details though. Also, are the tunnels entirely 
random? Do they all run more or less parallel with perturbed paths? Are 
the statistics random or carefully tuned?

Time to experiement, I think... ;-)


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From: Alain
Subject: Re: Guess the algorithm
Date: 19 Nov 2007 22:16:22
Message: <47425186$1@news.povray.org>
Orchid XP v7 nous apporta ses lumieres en ce 2007/11/19 13:17:
> Alain wrote:
> 
>> Most large chambers are the intersection of several conduits. When 
>> over 5 twisting tubes intersect, you loose the apearance of tubes. On 
>> ocasions, I saw some bits of "floating" objects in those large chambers.
>> Some passages are actualy made of 2 or more almost parallel tubes, and 
>> some of those may be flattened.
> 
> Mmm, seems plausible. You'd have to have some fairly high-order 
> smoothing to blur out the details though. Also, are the tunnels entirely 
> random? Do they all run more or less parallel with perturbed paths? Are 
> the statistics random or carefully tuned?
> 
> Time to experiement, I think... ;-)
There are tunels that seems perpendicular to the one you travel, but most 
intersect at a sharp angle.
Possibility: generate the main tunel.
Randomly generate a cluster of points around it's path, in a radius about twice 
the radius.
For each point, select a random direction and curvature. Possibly add some 
radius variance.

At times, you bet filled whireframe, and the mesh resolution is fairly low at 
"high" quality. If you deselect "Disable hair effect", you get small sticks at 
the triangles angles that seems to corespond to the normals.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you've gained twenty pounds 
sitting at the computer, but can't tell because your beard covers your stomach.
Taps a.k.a. Tapio Vocadlo


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